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features ? minimal external circuitry requirements, no rf components on the pc board except matching to the receiver antenna high sensitivity, especially at low data rates sensitivity reduction possible even while receiving fully integrated vco low power consumption due to configurable self polling with a programmable time frame check supply voltage 4.5 v to 5.5 v operating temperature range -40c to 105c single-ended rf input for easy adaptation to /4 antenna or printed antenna on pcb low-cost solution due to high integration level esd protection according to mil-std 883 (4kv hbm) except pin pout (2kv hbm) high image frequency suppression due to 1 mhz if in conjunction with a saw front-end filter ? up to 40 db is thereby achievable with newer saws. programmable output port for sensitivity selection or for controlling external periphery communication to the microcontroller possible via a single, bi-directional data line power management (polling) is also possible by means of a separate pin via the microcontroller 2 different if bandwidth versions are available (300 khz and 600 khz) description the u3741bm is a multi-chip pll receiver device supplied in an so20 package. it has been specially developed for the demands of rf low-cost data transmission systems with low data rates from 1 kbaud to 10 kbaud (1 kbaud to 3.2 kbaud for fsk) in manchester or bi-phase code. the receiver is well suited to operate with atmel's pll rf transmitter u2741b. its main applications are in the areas of telemetering, security technology and keyless-entry systems. it can be used in the frequency receiving range of f 0 = 300 mhz to 450 mhz for ask or fsk data transmission. all the state- ments made below refer to 433.92-mhz and 315-mhz applications. uhf ask receiver ic u3741bm rev. 4662b?rke?10/04
2 u3741bm 4662b?rke?10/04 system block diagram block diagram demod control u3741bm 1...3 u2741b antenna antenna uhf ask/fsk remote control transmitter uhf ask/fsk remote control receiver 1 li cell keys c pll xto vco lna pll vco xto encoder atarx9x power amp. fsk/ask- demodulator and data filter if amp if amp 4 th order lpf 3 mhz lpf 3 mhz demod_out limiter out rssi sensitivity reduction standby logic polling circuit and control logic fe clk vco xto 64 f 50 k ? v s fsk/ask cdem avcc sens agnd dgnd mixvcc lnagnd lna_in data enable test pout mode lfgnd lfvcc xto lf dvcc lna
3 u3741bm 4662b?rke?10/04 pin configuration figure 1. pinning so20 sens fsk/ask cdem avcc agnd dgnd mixvcc lnagnd lna_in nc data enable test pout mode dvcc xto lfgnd lf lfvcc 1 2 3 4 5 6 7 8 9 10 20 19 18 17 16 15 14 13 12 11 pin description pin symbol function 1 sens sensitivity-control resistor 2 fsk/ask selecting fsk/ask. low: fsk, high: ask 3 cdem lower cut-off frequency data filter 4 avcc analog power supply 5 agnd analog ground 6 dgnd digital ground 7 mixvcc power supply mixer 8 lnagnd high-frequency ground lna and mixer 9lna_inrf input 10 nc not connected 11 lfvcc power supply vco 12 lf loop filter 13 lfgnd ground vco 14 xto crystal oscillator 15 dvcc digital power supply 16 mode selecting 433.92 mhz/315 mhz. low: 4.90625 mhz (usa). high: 6.76438 (europe) 17 pout programmable output port 18 test test pin, during operation at gnd 19 enable enables the polling mode low: polling mode off (sleep mode) h: polling mode on (active mode) 20 data data output/configuration input
4 u3741bm 4662b?rke?10/04 rf front end the rf front end of the receiver is a heterodyne configuration that converts the input signal into a 1-mhz if signal. according to the block diagram, the front end consists of an lna (low noise amplifier), lo (local oscillator), a mixer and rf amplifier. the lo generates the carrier frequency for the mixer via a pll synthesizer. the xto (crystal oscillator) generates the reference frequency f xto . the vco (voltage-controlled oscillator) generates the drive voltage frequency f lo for the mixer. f lo is dependent on the voltage at pin lf. f lo is divided by a factor of 64. the divided frequency is compared to f xto by the phase frequency detector. the current output of the phase frequency detector is connected to a passive loop filter and thereby generates the control voltage v lf for the vco. by means of that configuration, v lf is controlled in a way that f lo /64 is equal to f xto . if f lo is determined, f xto can be calculated using the following formula: the xto is a one-pin oscillator that operates at the series resonance of the quartz crys- tal. according to figure 2, the crystal should be connected to gnd via a capacitor cl. the value of that capacitor is recommended by the crystal supplier. the value of cl should be optimized for the individual board layout to achieve the exact value of f xto and hereby of f lo . when designing the system in terms of receiving bandwidth, the accuracy of the crystal and xto must be considered. figure 2. pll peripherals the passive loop filter connected to pin lf is designed for a loop bandwidth of b loop = 100 khz. this value for b loop exhibits the best possible noise performance of the lo. figure 2 shows the appropriate loop filter components to achieve the desired loop bandwidth. if the filter components are changed for any reason, please note that the maximum capacitive load at pin lf is limited. if the capacitive load is exceeded, a bit check may no longer be possible since f lo cannot settle in time before the bit check starts to evaluate the incoming data stream. therefore, self polling also does not work in that case. f lo is determined by the rf input frequency f rf and the if frequency f if using the follow- ing formula: f xto f lo 64 ------- - = dvcc xto lf lfvcc lfgnd v c c10 r1 c9 s l v s r1 = 820 ? c9 = 4.7 nf c10 = 1 nf f lo f rf f if ? =
5 u3741bm 4662b?rke?10/04 to determine f lo , the construction of the if filter must be considered at this point. the nominal if frequency is f if = 1 mhz. to achieve a good accuracy of the filter?s corner fre- quencies, the filter is tuned by the crystal frequency f xto . this means that there is a fixed relation between f if and f lo that depends on the logic level at pin mode. this is described by the following formulas: the relation is designed to achieve the nominal if frequency of f if = 1 mhz for most applications. for applications where f rf = 315 mhz, the mode must be set to ?0?. in the case of f rf = 433.92 mhz, the mode must be set to ?1?. for other rf frequencies, f if is not equal to 1 mhz. f if is then dependent on the logical level at pin mode and on f rf . table 1 summarizes the different conditions. the rf input either from an antenna or from a generator must be transformed to the rf input pin lna_in. the input impedance of that pin is provided in the electrical parame- ters. the parasitic board inductances and capacitances also influence the input matching. the rf receiver u3741bm exhibits its highest sensitivity at the best sig- nal-to-noise ratio in the lna. hence, noise matching is the best choice for designing the transformation network. a good practice when designing the network is to start with power matching. from that starting point, the values of the components can be varied to some extent to achieve the best sensitivity. if a saw is implemented into the input network, a mirror frequency suppression of ? p ref = 40 db can be achieved. there are saws available that exhibit a notch at ? f = 2 mhz. these saws work best for an intermediate frequency of if = 1 mhz. the selectivity of the receiver is also improved by using a saw. in typical automotive appli- cations, a saw is used. figure 3 on page 6 shows a typical input matching network for f rf = 315 mhz and f rf = 433.92 mhz using a saw. figure 4 on page 6 illustrates an input matching to 50 ? without a saw. the input matching networks shown in figure 4 are the reference net- works for the parameters given in the ?electrical characteristics?. mode 0 (usa) f if f lo 314 --------- - == mode 0 (europe) f if f lo 432.92 ----------------- - == table 1. calculation of lo and if frequency conditions local oscillator frequency intermediate frequency f rf = 315 mhz, mode = 0 f lo = 314 mhz f if = 1 mhz f rf = 433.92 mhz, mode = 1 f lo = 432.92 mhz f if = 1 mhz 300 mhz < f rf < 365 mhz, mode = 0 365 mhz < f rf < 450 mhz, mode = 1 f lo f rf 1 1 314 --------- - + ------------------- = f if f lo 314 --------- - = f lo f rf 1 1 432.92 ----------------- - + --------------------------- - = f if f lo 432.92 ----------------- - =
6 u3741bm 4662b?rke?10/04 figure 3. input matching network with saw filter figure 4. input matching network without saw filter please note that for all coupling conditions (see figure 3 and figure 4), the bond wire inductivity of the lna ground is compensated. c3 forms a series resonance circuit together with the bond wire. l = 25 nh is a feed inductor to establish a dc path. its value is not critical but must be large enough not to detune the series resonance circuit. for cost reduction, this inductor can be easily printed on the pcb. this configuration improves the sensitivity of the receiver by about 1 db to 2 db. in in_gnd out out_gnd case_gnd b3555 u3741bm c3 22p l 25n c16 100p c17 8.2p l3 toko ll2012 27nj 27n c2 8.2p l2 toko ll2012 f33nj 33n 1 2 3, 4 7, 8 5 6 8 9 rf in f rf = 433.92 mhz lnagnd lna_in in in_gnd out out_gnd case_gnd b3551 u3741bm c3 47p l 25n c16 100p c17 22p l3 toko ll2012 f47nj 47n c2 10p l2 toko ll2012 f82nj 82n 1 2 3, 4 7, 8 5 6 8 9 f rf = 315 mhz lnagnd lna_in rf in u3741bm 15p 25n 100p 3.3p toko ll2012 f22nj 22n 8 9 rf in f rf = 433.92 mhz lnagnd lna_in u3741bm 33p 25n 100p 3.3p toko ll2012 f39nj 39n 8 9 rf in f rf = 315 mhz lnagnd lna_in
7 u3741bm 4662b?rke?10/04 analog signal processing if amplifier the signals coming from the rf front end are filtered by the fully integrated 4th-order if filter. the if center frequency is f if = 1 mhz for applications where f rf = 315 mhz or f rf = 433.92 mhz is used. for other rf input frequencies, refer to table 1 to determine the center frequency. the u3741bm is available with 2 different if bandwidths. u3741bm-m2, the version with b if = 300 khz, is well suited for ask systems where atmel?s pll transmitter u2741b is used. the receiver u3741bm-m3 employs an if bandwidth of b if = 600 khz. this version can be used together with the u2741b in fsk and ask mode. if used in ask applications, it allows higher tolerances for the receiver and pll transmitter crys- tals. saw transmitters exhibit much higher transmit frequency tolerances compared to pll transmitters. generally, it is necessary to use b if = 600 khz together with such transmitters. rssi amplifier the subsequent rssi amplifier enhances the output signal of the if amplifier before it is fed into the demodulator. the dynamic range of this amplifier is dr rssi = 60 db. if the rssi amplifier is operated within its linear range, the best s/n ratio is maintained in ask mode. if the dynamic range is exceeded by the transmitter signal, the s/n ratio is defined by the ratio of the maximum rssi output voltage and the rssi output voltage due to a disturber. the dynamic range of the rssi amplifier is exceeded if the rf input signal is about 60 db higher compared to the rf input signal at full sensitivity. in fsk mode, the s/n ratio is not affected by the dynamic range of the rssi amplifier. the output voltage of the rssi amplifier is internally compared to a threshold voltage vth_red. vth_red is determined by the value of the external resistor r sense . r sense is connected between pin sense and gnd or vs. the output of the comparator is fed into the digital control logic. by this means it is possible to operate the receiver at lower sensitivity. if r sense is connected to vs, the receiver operates at a lower sensitivity. the reduced sensitivity is defined by the value of r sense , the maximum sensitivity by the sig- nal-to-noise ratio of the lna input. the reduced sensitivity is dependent on the signal strength at the output of the rssi amplifier. since different rf input networks may exhibit slightly different values for the lna gain, the sensitivity values given in the electrical characteristics refer to a specific input matching. this matching is illustrated in figure 4 on page 6 and exhibits the best possi- ble sensitivity. r sense can be connected to vs or gnd via a microcontroller or by the digital output port pout of the u3741bm receiver ic. the receiver can be switched from full sensitivity to reduced sensitivity or vice versa at any time. in polling mode, the receiver will not wake up if the rf input signal does not exceed the selected sensitivity. if the receiver is already active, the data stream at pin data will disappear when the input signal is lower than defined by the reduced sensitivity. instead of the data stream, the pattern accord- ing to figure 5 is issued at pin data to indicate that the receiver is still active. figure 5. steady l state limited data output pattern data t data_l_max t min2
8 u3741bm 4662b?rke?10/04 fsk/ask demodulator and data filter the signal coming from the rssi amplifier is converted into the raw data signal by the ask/fsk demodulator. the operating mode of the demodulator is set via pin ask/fsk. logic 'l' sets the demodulator to fsk, logic 'h' sets it into ask mode. in ask mode an automatic threshold control circuit (atc) is employed to set the detec- tion reference voltage to a value where a good signal-to-noise ratio is achieved. this circuit also implies the effective suppression of any kind of in-band noise signals or com- peting transmitters. if the s/n ratio exceeds 10 db, the data signal can be detected properly. the fsk demodulator is intended to be used for an fsk deviation of ? f 20 khz. lower values may be used but the sensitivity of the receiver is reduced in that condition. the minimum usable deviation is dependent on the selected baud rate. in fsk mode, only br_range0 and br_range1 are available. in fsk mode, the data signal can be detected if the s/n ratio exceeds 2 db. the output signal of the demodulator is filtered by the data filter before it is fed into the digital signal processing circuit. the data f ilter improves the s/n ratio as its bandpass can be adopted to the characteristics of the dat a signal. the data filter consists of a 1st-order high-pass and a 1st-order low-pass filter. the high-pass filter cut-off frequency is defin ed by an external capacitor connected to pin cdem. the cut-off frequency of the high-pass filter is defined by the following for- mula: in self-polling mode, the data filter must settle very rapidly to achieve a low current con- sumption. therefore, cdem cannot be increased to very high values if self polling is used. on the other hand, cdem must be large enough to meet the data filter require- ments according to the data signal. recommended values for cdem are given in the ?electrical characteristics? on page 23. t he values are slightly different for ask and fsk mode. the cut-off frequency of the low-pass filter is defined by the selected baud rate range (br_range). br_range is defined in the opmode register (refer to section ?configu- ration of the receiver? on page 17). br_range must be set in accordance to the used baud rate. the u3741bm is designed to operate with data coding where the dc level of the data signal is 50%. this is valid for mancheste r and bi-phase coding. if other modulation schemes are used, the dc level should always remain within the range of vdc_min = 33% and vdc_max = 66%. the sensitivity may be reduced by up to 1.5 db in that condition. each br_range is also defined by a minimum and a maximum edge-to-edge time (tee_sig). these limits are defined in the ?electrical characteristics? on page 23. they should not be exceeded to maintain full sensitivity of the receiver. f cu_df 1 2 30 k ? cdem ------------------------------------------------------------- =
9 u3741bm 4662b?rke?10/04 receiving characteristics the rf receiver u3741bm can be operated with and without a saw front-end filter. in a typical automotive application, a saw filter is used to achieve better selectivity. the selectivity with and without a saw front end-filter is illustrated in figure 6. this example relates to ask mode and the 300-khz bandwidth version of the u3741bm. fsk mode and the 600-khz version of the receiver exhibit similar behavior. note that the mirror fre- quency is reduced by 40 db. the plots are printed relative to the maximum sensitivity. if a saw filter is used, an insertion loss of about 4 db must be considered. when designing the system in terms of receiving bandwidth, the lo deviation must be considered as it also determines the if center frequency. the total lo deviation is cal- culated to be the sum of the deviation of the crystal and the xto deviation of the u3741bm. low-cost crystals are specified to be within 100 ppm. the xto deviation of the u3741bm is an additional deviation due to the xto circuit. this deviation is speci- fied to be 30 ppm. if a crystal of 100 ppm is used, the total deviation is 130 ppm in that case. note that the receiving bandwidth and the if-filter bandwidth are equivalent in ask mode but not in fsk mode. figure 6. receiving frequency response -100.0 -90.0 -80.0 -70.0 -60.0 -50.0 -40.0 -30.0 -20.0 -10.0 0.0 -6.0 -5.0 -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 df (mhz) dp (db) without saw with saw
10 u3741bm 4662b?rke?10/04 polling circuit and control logic the receiver is designed to consume less than 1 ma while being sensitive to signals from a corresponding trans mitter. this is achieved via the polling circuit. this circuit enables the signal path periodically for a short time. during this time the bit check logic verifies the presence of a valid transmitter si gnal. only if a valid signal is detected the receiver remains active and transfers the data to the connected microcontroller. if there is no valid signal present, the receiver is in sleep mode most of the time resulting in low current consumption. this condition is called polling mode. a connected microcontroller is disabled during that time. all relevant parameters of the polling l ogic can be configured by the connected micro- controller. this flexibility enables the user to meet the specifications in terms of current consumption, system response time, data rate etc. regarding the number of connection wires to the microcontroller, the receiver is very flexible. it can be either operated by a single bi-directional line to save ports to the con- nected microcontroller, it can be operated by up to three uni-directional ports. basic clock cycle of the digital circuitry the complete timing of the digital circuitry and the analog filtering is derived from one clock. according to figure 7, this clock cycle t clk is derived from the crystal oscillator (xto) in combination with a divider. the division factor is controlled by the logical state at pin mode. according to section ?rf front end? on page 4, the frequency of the crys- tal oscillator (f xto ) is defined by the rf input signal (f rfin ) which also defines the operating frequency of the local oscillator (f lo ). figure 7. generation of the basic clock cycle pin mode can now be set in accordance with the desired clock cycle t clk . t clk controls the following application-relevant parameters: timing of the polling circuit including bit check timing of analog and digital signal processing timing of register programming frequency of the reset marker f filter center frequency (f if0 ) most applications are dominated by two transmission frequencies: f send = 315 mhz is mainly used in the usa, f send = 433.92 mhz in europe. in order to ease the usage of all t clk -dependent parameters, the electrical characteristics display three conditions for each parameter. dvcc xto mode t clk f xto 16 15 14 xto divider :14/:10 l : usa (:10) h: europe (:14)
11 u3741bm 4662b?rke?10/04 usa applications (f xto = 4.90625 mhz, mode = l, t clk = 2.0383 s) europe applications (f xto = 6.76438 mhz, mode = h, t clk = 2.0697 s) other applications (t clk is dependent on f xto and on the logical state of pin mode. the electrical characteristic is given as a function of t clk ). the clock cycle of some function blocks depends on the selected baud rate range (br_range) which is defined in the opmode register. this clock cycle t xclk is defined by the following formulas for further reference: polling mode according to figure 3 on page 6, the receiv er stays in polling mode in a continuous cycle of three different modes. in sleep mode, the signal processing circuitry is disabled for the time period t sleep while consuming a low current of i s = i soff . during the start-up period, t startup , all signal processing circuits are enabled and settled. in the following bit check mode, the incoming data stream is analyzed bit by bit against a valid transmitter signal. if no valid signal is present, the receiver is set back to sleep mode after the period t bitcheck . this period varies check by check as it is a statistical process. an aver- age value for t bitcheck is given in ?electrical characteristics? on page 23. during t startup and t bitcheck the current consumption is i s = i son . the average current consumption in polling mode is dependent on the duty cycle of the active mode and can be calculated as: during t sleep and t startup , the receiver is not sensitive to a transmitter signal. to guaran- tee the reception of a transmitted command, the transmitter must start the telegram with an adequate preburst. the required length of the preburst is dependent on the polling parameters t sleep , t startup , t bitcheck and the startup time of a connected microcontroller (t start,c ). t bitcheck thus depends on the actual bit rate and the number of bits (n bitcheck ) to be tested. the following formula indicates how to calculate the preburst length. t preburst t sleep + t startup + t bitcheck + t start_ c sleep mode the length of period t sleep is defined by the 5-bit word sleep of the opmode register, the extension factor x sleep , according to figure 10 on page 13, and the basic clock cycle t clk . it is calculated to be: in us and european applications, the maximum value of t sleep is about 60 ms if x sleep is set to 1. the time resolution is about 2 ms in that case. the sleep time can be extended to almost half a second by setting x sleep to 8. x sleep can be set to 8 by bit x sleepstd or by bit x sleeptemp resulting in a different mode of action as described below: br_range = br_range0: t xclk = 8 t clk br_range1: t xclk = 4 t clk br_range2: t xclk = 2 t clk br_range3: t xclk = 1 t clk i spoll i soff t sleep i son t startup t bitcheck + () + t sleep t startup t bitcheck ++ ------------------------------------------------------------------------------------------------------------ = t sleep sleep x sleep 1024 t clk =
12 u3741bm 4662b?rke?10/04 x sleepstd = 1 implies the standard extension factor. the sleep time is always extended. x sleeptemp = 1 implies the temporary extension factor. the extended sleep time is used as long as every bit check is ok. if the bit check fails once, this bit is set back to 0 auto- matically resulting in a regular sleep time. this functionality can be used to save current in presence of a modulated disturber similar to an expected transmitter signal. the con- nected microcontroller is rarely activated in that condition. if the disturber disappears, the receiver switches back to regular polling and is again sensitive to appropriate trans- mitter signals. according to table 7 on page 19, the highest register value of sleep sets the receiver to a permanent sleep condition. the receiver remains in that condition until another value for sleep is programmed into the opmode register. this function is desirable where several devices share a single data line. figure 8. polling mode flow chart bit-check ok? sleep: 5-bit word defined by sleep0 to sleep4 in opmode register no yes sleep mode: all circuits for signal processing are disabled. only xto and polling logic is enabled. output level on pin ic_active => low i s = i son t sleep = sleep x sleep 1024 t clk start-up mode: the signal processing circuits are enabled. after the start-up time (t startup ) all circuits are in stable condition and ready to receive. i s = i son t startup bit-check mode: the incomming data stream is analyzed. if the timing indicates a valid transmitter signal, the receiver is set to receiving mode. otherwise it is set to sleep mode. i s = i son t bit-check receiving mode: the receiver is turned on permanently and passes the data stream to the connected microcontroller. it can be set to sleep mode through an off command via pin data or enable i s = i son off command x sleep : extension factor defined by x sleeptemp according to table 8 t clk : basic clock cycle defined by f xto and pin mode t startup : is defined by the selected baud rate range and t clk . the baud-rate range is defined by baud0 and baud1 in the opmode register. t bit-check : depends on the result of the bit check. if the bit check is ok, t bit-check depends on the number of bits to be checked (n bit-checked ) and on the utilized data rate. if the bit check fails, the average time period for that check depends on the selected baud-rate range on t clk . the baud-rate range is defined by baud0 and baud1 in the opmode register.
13 u3741bm 4662b?rke?10/04 figure 9. timing diagram for a completely successful bit check bit check mode in bit check mode, the incoming data stream is examined to distinguish between a valid signal from a corresponding transmitter and signals due to noise. this is done by subse- quent time frame checks where the distances between 2 signal edges are continuously compared to a programmable time window. the maximum count of this edge-to-edge test, before the receiver switches to receiving, mode is also programmable. configuring the bit check assuming a modulation scheme that contains 2 edges per bit, two time frame checks are verifying one bit. this is valid for manchester, bi-phase and most other modulation schemes. the maximum count of bits to be checked can be set to 0, 3, 6 or 9 bits via the variable n bitcheck in the opmode register. this implies 0, 6, 12 and 18 edge-to-edge checks respectively. if n bitcheck is set to a higher value, the receiver is less likely to switch to the receiving mode due to noise. in the presence of a valid transmitter signal, the bit check takes less time if n bitcheck is set to a lower value. in polling mode, the bit check time is not dependent on n bitcheck . figure 9 shows an example where 3 bits are tested successfully and the data signal is transferred to pin data. according to figure 10, the time window for the bit check is defined by two separate time limits. if the edge-to-edge time t ee is in between the lower bit check limit t lim_min and the upper bit check limit t lim_max , the check will be continued. if t ee is smaller than t lim_min or t ee exceeds t lim_max , the bit check will be terminated and the receiver switches to sleep mode. figure 10. valid time window for bit check for best noise immunity it is recommended to use a low span between t lim_min and t lim_max . this is achieved using a fixed frequency at a 50% duty cycle for the transmitter preburst. a ?11111...? or a ?10101...? sequence in manchester or bi-phase is a good choice in this regard. a good compromise between receiver sensitivity and susceptibility to noise is a time window of 25% regarding the expected edge-to-edge time t ee . using preburst patterns that contain various edge-to-edge time periods, the bit check limits must be programmed according to the required span. bit check enable ic data 1/2 bit polling mode number of checked bits: 3 bit check ok 1/2 bit 1/2 bit 1/2 bit 1/2 bit 1/2 bit receiving mode dem_out dem_out t ee t lim_min 1/f sig t lim_max
14 u3741bm 4662b?rke?10/04 the bit check limits are determined by means of the formula below: t lim_min = lim_min t xclk t lim_max = (lim_max ?1) t xclk lim_min and lim_max are defined by a 5-bit word each within the limit register. using the above formulas, lim_min and lim_ max can be determined according to the required t lim_min , t lim_max and t xclk . the time resolution when defining t lim_min and t lim_max is t xclk . the minimum edge-to-edge time t ee (t data_l_min , t data_h_min ) is defined according to the section ?receiving mode? on page 15. due to this, the lower limit should be set to lim_min 10. the maximum value of the upper limit is lim_max = 63. figure 11, figure 12 and figure 13 on page 15 illustrate the bit check for the default bit check limits lim_min = 14 and lim_max = 24. when the ic is enabled, the signal pro- cessing circuits are enabled during t startup . the output of the ask/fsk demodulator (dem_out) is undefined during that period. when the bit check becomes active, the bit check counter is clocked with the cycle t xclk . figure 11 shows how the bit check proceeds if the bit-check counter value cv_lim is within the limits defined by lim_min and lim_max at the occurrence of a signal edge. in figure 12, the bit check fails as the value cv_lim is lower than the limit lim_min. the bit check also fails if cv_lim reaches lim_max. this is illustrated in figure 13 on page 15. figure 11. timing diagram during bit check figure 12. timing diagram for failed bit check (condition: cv_lim < lim_min) bit check enable ic dem_out bit check counter 0 234 5 6 245 1 7 81 3 6789 11 12 13 14 10 1/2 bit 15 16 17 18 1 234 56 (lim_min = 14, lim_max = 24) 7 8 9 1011121314 15 1 2 34 1/2 bit 1/2 bit bit check ok bit check ok t startup t xclk bit check enable ic bit check counter 0 2 3 45 6 245 1 1 36789 1112 10 1/2 bit startup mode 0 (lim_min = 14, lim_max = 24) sleep mode bit check failed ( cv_lim < lim_min ) dem_out bit check mode
15 u3741bm 4662b?rke?10/04 figure 13. timing diagram for failed bit check (condition: cv_lim lim_max) duration of the bit check if no transmitter signal is present during t he bit check, the output of the ask/fsk demodulator delivers random signals. the bit check is a statistical process and t bitcheck varies for each check. therefore, an average value for t bitcheck is given in ?electrical characteristics?. t bitcheck depends on the selected baud rate range and on t clk . a higher baudrate range causes a lower value for t bitcheck resulting in lower current consumption in polling mode. in the presence of a valid transmitter signal, t bitcheck is dependant on the frequency of that signal, f sig and the count of the checked bits, n bitcheck . a higher value for n bitcheck thereby results in a longer period for t bitcheck requiring a higher value for the transmitter preburst t preburst . receiving mode if the bit check has been successful for all bits specified by n bitcheck , the receiver switches to receiving mode. according to figure 9 on page 13, the internal data signal is switched to pin data in that case. a connected microcontroller can be woken up by the negative edge at pin data. the receiver stays in that condition until it is switched back to polling mode explicitly. digital signal processing the data from the ask/fsk demodulator (dem_out) is digitally processed in different ways and as a result converted into the output signal data. this processing depends on the selected baud rate range (br_range). figure 14 on page 16 illustrates how dem_out is synchronized by the extended clock cycle t xclk . this clock is also used for the bit check counter. data can change its state only after t xclk elapsed. the edge-to-edge time period t ee of the data signal as a result is always an integral multiple of t xclk . the minimum time period between two edges of the data signal is limited to t ee t data_min . this implies an efficient suppression of spikes at the data output. at the same time, it limits the maximum frequency of edges at data. this eases the interrupt handling of a connected microcontroller. t data_min is to some extent affected by the pre- ceding edge-to-edge time interval t ee as illustrated in figure 15. if t ee is in between the specified bit check limits, the following level is frozen for the time period t data_min = tmin1, in case of t ee being outside that bit check limits t data_min = tmin2 is the relevant stable time period. the maximum time period for data to be low is limited to t data_l_max . this function ensures a finite response time during programming or switching off the receiver via pin data. t data_l_max is thereby longer than the maximu m time period indicated by the transmitter data stream. figure 16 gives an example where dem_out remains low after the receiver has switched to receiving mode. bit check enable ic bit check counter 0 2345 6 245 1 7 36 7 8 9 1112 10 1/2 bit startup mode 20 (lim_min = 14, lim_max = 24) sleep mode bit check failed (cv_lim = lim_max) 1314 15 1617 18 19 21 2223 24 0 1 dem_out bit check mode
16 u3741bm 4662b?rke?10/04 figure 14. synchronization of the demodulator output figure 15. debouncing of the demodulator output figure 16. steady l state limited data output pattern after transmission after the end of a data transmission, the receiver remains active and random noise pulses appear at pin data. the edge-to-edge time period t ee of the majority of these noise pulses is equal to or slightly higher than t data_min . switching the receiver back to sleep mode the receiver can be set back to polling mode via pin data or via pin enable. when using pin data, this pin must be pulled to low for the period t1 by the connected microcontroller. figure 17 illustrates the timing of the off command (see also figure 21 on page 21). the minimum value of t1 depends on the br_range. the maximum value for t1 is not limited but it is recommended not to exceed the specified value to prevent erasing the reset marker. this item is explained in more detail in the section ?configura- tion of the receiver? on page 17. setting the receiver to sleep mode via data is achieved by programming bit 1 of the opmode register to 1. only one sync pulse (t3) is issued. the duration of the off command is determined by the sum of t1, t2 and t10. after the off command, the sleep time t sleep elapses. note that the capacitive load at pin data is limited. the resulting time constant together with an optional external pull-up resis- tor may not be exceeded to ensure proper operation. clock bitcheck counter data t xclk dem_out t ee data tmin1 lim_min cv_lim < lim_max dem_out t ee tmin2 t ee cv_lim < lim_min or cv_lim lim_max bit check enable ic data sleep mode receiving mode tmin2 bit check mode t data_l_max dem_out
17 u3741bm 4662b?rke?10/04 if the receiver is set to polling mode via pin enable, an ?l? pulse (t doze ) must be issued at that pin. figure 18 illustrates the timing of that command. after the positive edge of this pulse, the sleep time t sleep elapses. the receiver remains in sleep mode as long as enable is held to ?l?. if the receiver is polled exclusively by a microcontroller, t sleep can be programmed to 0 to enable a instantaneous response time. this command is the faster option than via pin data at the cost of an additional connection to the microcontroller. figure 17. timing diagram of the off command via pin data figure 18. timing diagram of the off command via pin enable configuration of the receiver the u3741bm receiver is configured via two 12-bit ram registers called opmode and limit. the registers can be programmed by means of the bi-directional data port. if the register contents have changed due to a voltage drop, this condition is indicated by a certain output pattern called reset marker (rm). the receiver must be reprogrammed in that case. after a power-on reset (por), the registers are set to default mode. if the receiver is operated in default mode, there is no need to program the registers. table 3 on page 18 shows the structure of the registers. according to table 2 on page 18, bit 1 defines if the receiver is set back to polling mode via the off command, (see section ?receiving mode? on page 15) or if it is programmed. bit 2 represents the regis- ter address. it selects the appropriate register to be programmed. out1 (microcontroller) data (u3741bm) serial bi-directional data line x bit 1 ("1") x t1 t2 t3 t4 t5 t7 x x (start bit) startup mode off command receiver on t10 t sleep enable data (u3741bm) serial bi-directional data line x x x t sleep x toff receiver on startup mode t doze
18 u3741bm 4662b?rke?10/04 table 4 and the following illustrate the effect of the individual configuration words. the default configuration is highlighted for each word. br_range sets the appropriate baud rate range. at the same time it defines xlim. xlim is used to define the bit check limits t lim_min and t lim_max as shown in table 4. pout can be used to control the sensitivity of the receiver. in that application, pout is set to 1 to reduce the sensitivity. this implies that the receiver operates with full sensitiv- ity after a por. table 2. effect of bit 1 and bit 2 in programming the registers bit 1 bit 2 action 1 x the receiver is set back to polling mode (off command) 0 1 the opmode register is programmed 0 0 the limit register is programmed table 3. effect of the configuration words within the registers bit1 bit2 bit2 bit4 bit5 bit6 bit7 bit8 bit9 bit10 bit11 bit12 bit13 bit14 off command 1 opmode register 0 1 br_range n bitcheck v pout sleep x sleep 0 1 baud1 baud0 bitchk1 bitchk0 pout sleep4 sleep3 sleep2 sleep1 sleep0 x sleep std x sleep temp (default)00100010110 0 limit register 0 0 lim_min lim_max 0 0 lim_min5 lim_min4 lim_min3 lim_min2 lim_min1 lim_min0 lim_max5 lim_max4 lim_max3 lim_max2 lim_max1 lim_max0 (default)00111001100 0 table 4. effect of the configuration word br_range br_range baud rate range/extension factor for bit check limits (xlim) baud1 baud0 00 br_range0 (application usa/europe: br_range0 = 1.0 kbaud to 1.8 kbaud) (default) xlim = 8 (default) 01 br_range1 (application usa/europe: br_range1 = 1.8 kbaud to 3.2 kbaud) xlim = 4 10 br_range2 (application usa/europe: br_range2 = 3.2 kbaud to 5.6 kbaud) xlim = 2 11 br_range3 (application usa/europe: br_range3 = 5.6 kbaud to 10 kbaud) xlim = 1
19 u3741bm 4662b?rke?10/04 table 5. effect of the configuration word n bitcheck n bitcheck number of bits to be checked bitchk1 bitchk0 00 0 01 3 1 0 6 (default) 11 9 table 6. effect of the configuration bit vpout vpout level of the multi-purpose output port pout pout 00 (default) 11 table 7. effect of the configuration word sleep sleep start value for sleep counter (t sleep = sleep x sleep 1024 t clk ) sleep4 sleep3 sleep2 sleep1 sleep0 0 0 0 0 0 0 (receiver is continuously polling until a valid signal occurs) 00001 1 (t sleep 2ms for x sleep = 1 in us-/european applications) 00010 2 00011 3 . . . . . . . . . . . . . . . . . . 01011 11 (usa: t sleep = 22.96 ms, europe: t sleep = 23.31 ms) (default) . . . . . . . . . . . . . . . . . . 11101 29 11110 30 1 1 1 1 1 31 (permanent sleep mode) table 8. effect of the configuration word x sleep x sleep extension factor for sleep time (t sleep = sleep x sleep 1024 t clk ) x sleepstd x sleeptemp 0 0 1 (default) 01 8 (x sleep is reset to 1 if bit check fails once) 10 8 (x sleep is set permanently) 11 8 (x sleep is set permanently)
20 u3741bm 4662b?rke?10/04 conservation of the register information the u3741bm has an integrated power-on reset and brown-out detection circuitry to provide a mechanism to preserve the ram register information. according to figure 19 on page 21, a power-on reset (por) is generated if the supply voltage v s drops below the threshold voltage v threset . the default parameters are pro- grammed into the configuration registers in that condition. once v s exceeds v threset , the por is canceled after the minimum reset period t rst . a por is also generated when the supply voltage of the receiver is turned on. to indicate that condition, the receiver displays a reset marker (rm) at pin data after a reset. the rm is represented by the fixed frequency f rm at a 50% duty cycle. rm can be canceled via an ?l? pulse t1 at pin data. the rm implies the following characteristics: table 9. effect of the configuration word lim_min lim_min lower limit value for bit check lim_min < 10 is not applicable (t lim_min = lim_min xlim t clk ) 001010 10 001011 11 001100 12 001101 13 001110 14 (default) (usa: t lim_min = 228 s, europe: t lim_min = 232 s) . . . . . . . . . . . . . . . . . . 111101 61 111110 62 111111 63 table 10. effect of the configuration word lim_max lim_max upper limit value for bit check lim_max < 12 is not applicable (t lim_max = (lim_max - 1) xlim t clk ) 001100 12 001101 13 001110 14 . . . . . . . . . . . . . . . . . . 011000 24 (default) (usa: t lim_max = 375 s, europe: t lim_max = 381 s) . . . . . . . . . . . . . . . . . . 111101 61 111110 62 111111 63
21 u3741bm 4662b?rke?10/04 f rm is lower than the lowest feasible frequency of a data signal. by this means, rm cannot be misinterpreted by the connected microcontroller. if the receiver is set back to polling mode via pin data, rm cannot be canceled by accident if t1 is applied according to the proposal in the section ?programming the configuration register? on page 21 . by means of that mechanism, the receiver cannot lose its register information without communicating that condition via the reset marker rm. figure 19. generation of the power-on reset figure 20. timing of the register programming programming the configuration register the configuration registers are programmed serially via the bi-directional data line according to figure 20 and figure 21. figure 21. one-wire connection to a microcontroller v s por data (u3741bm) x 1/f rm v threset t rst out1 (microcontroller) data (u3741bm) serial bi-directional data line x bit 1 ("0") bit 2 ("1") bit 13 ("0") bit 14 ("1") x t1 t2 t3 t4 t5 t6 t8 t7 x x t sleep programming frame (start bit) (register select) (poll8) (poll8r) receiver on startup mode t9 internal pull-up resistor bi-directional data line data i/o u3741bm microcontroller data (u3741bm) out 1 (c)
22 u3741bm 4662b?rke?10/04 to start programming, the serial data line data is pulled to ?l? for the time period t1 by the microcontroller. when data has been released, the receiver becomes the master device. when the programming delay period t2 has elapsed, it emits 14 subsequent synchronization pulses with the pulse length t3. after each of these pulses, a program- ming window occurs. the delay until the program window starts is determined by t4, the duration is defined by t5. within the programming window, the individual bits are set. if the microcontroller pulls down pin data for the time period t7 during t5, the according bit is set to ?0?. if no programming pulse t7 is issued, this bit is set to ?1?. all 14 bits are subsequently programmed in this way. the time frame to program a bit is defined by t6. bit 14 is followed by the equivalent time wi ndow t9. during this window, the equivalent acknowledge pulse t8 (e_ack) occurs if the mode word just programmed is equivalent to the mode word that was already stored in that register. e_ack should be used to verify that the mode word was correctly transferred to the register. the register must be pro- grammed twice in that case. programming of a register is possible both during sleep and active mode of the receiver. during programming, the lna, lo, low-pass filter, if-amplifier and the demodulator are disabled. the programming start pulse t1 initiates the programming of the configuration registers. if bit 1 is set to ?1?, it represents the off command to set the receiver back to polling mode at the same time. for the length of the programming start pulse t1, the following convention should be considered: t1(min) < t1 < 1535 t clk : [t1(min) is the minimum specified value for the relevant br_range] programming (respectively off command) is initiated if the receiver is not in reset mode. if the receiver is in reset mode, programming (respectively off command) is not initiated, and the reset marker rm is still present at pin data. this period is generally used to switch the receiver to polling mode. in a reset condition, rm is not canceled by accident. t1 > 5632 t clk programming (respectively off command) is initiated in any case. rm is cancelled if present. this period is used if the connected microcontroller detected rm. if a configura- tion register is programmed, this time period for t1 can generally be used. note that the capacitive load at pin data is limited. the resulting time constant t together with an optional external pull-up resistor may not be exceeded to ensure proper operation.
23 u3741bm 4662b?rke?10/04 absolute maximum ratings stresses beyond those listed under ?absolute maximum ratings? may cause permanent damage to the device. this is a stress rating only and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of this specification is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability . parameters symbol min. max. unit supply voltage v s 6v power dissipation p tot 450 mw junction temperature t j 150 c storage temperature t stg -55 +125 c ambient temperature t amb -40 +105 c maximum input level, input matched to 50 w p in_max 10 dbm thermal resistance parameters symbol value unit junction ambient r thja 100 k/w electrical characteristics all parameters refer to gnd, t amb = -40c to +105c, v s = 4.5 v to 5.5 v, f 0 = 433.92 mhz and f 0 = 315 mhz, unless otherwise specified. (v s = 5 v, t amb = 25c) parameter test condition symbol 6.76438-mhz osc. (mode 1) 4.90625-mhz osc. (mode 0) variable oscillator unit min. typ. max. min. typ. max. min. typ. max. basic clock cycle of the digital circuitry basic clock cycle mode = 0 (usa) mode = 1 (europe) t clk 2.0697 2.0383 1/(f xto /10) 1/(f xto /14) s s extended basic clock cycle br_range0 br_range1 br_range2 br_range3 t xclk 16.6 8.3 4.1 2.1 16.3 8.2 4.1 2.0 8 t clk 4 t clk 2 t clk 1 t clk s s s s polling mode sleep time sleep and x sleep are defined in the opmode register t sleep sleep x sleep 1024 2.0697 sleep x sleep 1024 2.0383 sleep x sleep 1024 t clk ms start-up time br_range0 br_range1 br_range2 br_range3 t startup 1855 1061 1061 663 1827 1045 1045 653 896.5 512.5 512.5 320.5 t clk s s s s time for bit check average bit check time while polling br_range0 br_range1 br_range2 br_range3 t bitcheck 0.45 0.24 0.14 0.14 0.47 0.26 0.16 0.15 ms ms ms ms bit check time for a valid input signal f sig n bitcheck = 0 n bitcheck = 3 n bitcheck = 6 n bitcheck = 9 t bitcheck 3/f sig 6/f sig 9/f sig 3.5/f sig 6.5/f sig 9.5/f sig 3/f sig 6/f sig 9/f sig 3.5/f sig 6.5/f sig 9.5/f sig t xclk 3.5/f sig 6.5/f sig 9.5/f sig ms ms ms ms
24 u3741bm 4662b?rke?10/04 receiving mode intermediate frequency mode=0 (usa) mode=1 (europe) f if 1.0 1.0 f xto 64/314 f xto 64/432.92 mhz mhz baud rate range br_range0 br_range1 br_range2 br_range3 br_range 1.0 1.8 3.2 5.6 1.8 3.2 5.6 10.0 1.0 1.8 3.2 5.6 1.8 3.2 5.6 10.0 br_range0 2 s/t clk br_range1 2 s/t clk br_range2 2 s/t clk br_range3 2 s/t clk kbaud kbaud kbaud kbaud minimum time period between edges at pin data (figure 15) br_range0 br_range1 br_range2 br_range3 t data_min tmin1 tmin2 tmin1 tmin2 tmin1 tmin2 tmin1 tmin2 149 182 75 91 37.3 45.5 18.6 22.8 147 179 73 90 36.7 44.8 18.3 22.4 9 t xclk 11 t xcl 9 t xclk 11 t xclk 9 t xclk 11 t xclk 9 t xclk 11 t xclk s s s s s s s s maximum low period at data (figure 16) br_range0 br_range1 br_range2 br_range3 t data_l_max 2169 1085 542 271 2136 1068 534 267 131 t xclk 131 t xclk 131 t xclk 131 t xclk s s s s off command at pin enable (figure 18) t doze 3.1 3.05 1.5 t clk s configuration of the receiver frequency of the reset marker (figure 19) f rm 117.9 119.8 hz programming start pulse (figure 17, figure 20) br_range0 br_range1 br_range2 br_range3 after por t1 2188 1104 561 290 11656 3176 3176 3176 3176 2155 1087 553 286 11479 3128 3128 3128 3128 1057 t clk 533 t clk 271 t clk 140 t clk 5632 t clk 1535 t clk 1535 t clk 1535 t clk 1535 t clk s programming delay period (figure 17, figure 20) t2 795 798 783 786 384.5 t clk 385.5 t clk s synchroni- zation pulse (figure 17, figure 20) t3 265 261 128 t clk s electrical characteristics (continued) all parameters refer to gnd, t amb = -40c to +105c, v s = 4.5 v to 5.5 v, f 0 = 433.92 mhz and f 0 = 315 mhz, unless otherwise specified. (v s = 5 v, t amb = 25c) parameter test condition symbol 6.76438-mhz osc. (mode 1) 4.90625-mhz osc. (mode 0) variable oscillator unit min. typ. max. min. typ. max. min. typ. max. 1 4096 t clk ---------------------------------
25 u3741bm 4662b?rke?10/04 delay until the program window starts (figure 17, figure 20) t4 131 129 63.5 t clk s programming window (figure 17, figure 20) t5 530 522 256 t clk s time frame of a bit (figure 20) t6 1060 1044 512 t clk s programming pulse (figure 17, figure 20) t7 133 529 131 521 64 t clk 256 t clk s equivalent acknowledge pulse: e_ack (figure 20) t8 265 261 128 t clk s equivalent time window (figure 20) t9 534 526 258 t clk s off-bit programming window (figure 17) t10 930 916 449.5 t clk s electrical characteristics (continued) all parameters refer to gnd, t amb = -40c to +105c, v s = 4.5 v to 5.5 v, f 0 = 433.92 mhz and f 0 = 315 mhz, unless otherwise specified. (v s = 5 v, t amb = 25c) parameter test condition symbol 6.76438-mhz osc. (mode 1) 4.90625-mhz osc. (mode 0) variable oscillator unit min. typ. max. min. typ. max. min. typ. max. electrical characteristics all parameters refer to gnd, t amb = -40c to +105c, v s = 4.5 v to 5.5 v, f 0 = 433.92 mhz and f 0 = 315 mhz, unless otherwise specified. (v s = 5 v, t amb = 25c) parameters test conditions symbol min. typ. max. unit current consumption sleep mode (xto and polling logic active) is off 190 350 a ic active (startup-, bit check-, receiving mode) pin data = h is on 7.0 8.6 ma lna mixer third-order intercept point lna/mixer/if amplifier input matched according to figure 4 iip3 -28 dbm lo spurious emission at rf in input matched according to figure 4, required according to i-ets 300220 is lorf -73 -57 dbm noise figure lna and mixer (dsb) input matching according to figure 4 nf 7 db lna_in input impedance at 433.92 mhz at 315 mhz zi lna_in 1.0 || 1.56 1.3 || 1.0 k ? || pf k ? || pf 1 db compression point (lna, mixer, if amplifier) input matched according to figure 4, referred to rf in ip 1db -40 dbm
26 u3741bm 4662b?rke?10/04 maximum input level input matched according to figure 4, ber 10 -3 , ask mode p in_max -28 -20 dbm dbm local oscillator operating frequency range vco f vco 299 449 mhz phase noise vco/lo f osc = 432.92 mhz at 1 mhz at 10 mhz l (fm) -93 -113 -90 -110 dbc/hz dbc/hz spurious of the vco at f xto -55 -47 dbc vco gain k vco 190 mhz/v loop bandwidth of the pll for best lo noise (design parameter) r1 = 820 ? c9 = 4.7 nf c10 = 1 nf b loop 100 khz capacitive load at pin lf the capacitive load at pin lf is limited if bit check is used. the limitation therefore also applies to self polling. c lf_tot 10 nf xto operating frequency xto crystal frequency, appropriate load capacitance must be connected to xtal 6.764375 mhz 4.90625 mhz f xto 6.764375 -30 ppm 4.90625 -30 ppm 6.764375 4.90625 6.764375 +30 ppm 4.90625 +30 ppm mhz mhz series resonance resistor of the crystal f xto = 6.764 mhz 4.906 mhz r s 150 220 ? ? static capacitance of the crystal c xto 6.5 pf analog signal processing input sensitivity ask 300-khz if filter input matched according to figure 4 ask (level of carrier) ber 10 -3 , b = 300 khz f in = 433.92 mhz/315 mhz t = 25c, v s = 5 v f if = 1 mhz p ref_ask input sensitivity ask 300-khz if filter br_range0 -109 -111 -113 dbm input sensitivity ask 300-khz if filter br_range1 -107 -109 -111 dbm input sensitivity ask 300-khz if filter br_range2 -106 -108 -110 dbm input sensitivity ask 300-khz if filter br_range3 -104 -106 -108 dbm input sensitivity ask 600 khz if filter input matched according to figure 4 ask (level of carrier) ber 10 -3 , b = 600 khz f in = 433.92 mhz/315 mhz t = 25c, v s = 5 v f if = 1 mhz p ref_ask electrical characteristics (continued) all parameters refer to gnd, t amb = -40c to +105c, v s = 4.5 v to 5.5 v, f 0 = 433.92 mhz and f 0 = 315 mhz, unless otherwise specified. (v s = 5 v, t amb = 25c) parameters test conditions symbol min. typ. max. unit
27 u3741bm 4662b?rke?10/04 input sensitivity ask 600 khz if filter br_range0 -108 -110 -112 dbm input sensitivity ask 600 khz if filter br_range1 -106.5 -108.5 -110.5 dbm input sensitivity ask 600 khz if filter br_range2 -106 -108 -110 dbm input sensitivity ask 600 khz if filter br_range3 -104 -106 -108 dbm sensitivity variation ask for the full operating range compared to t amb = 25c, v s = 5 v 300-khz and 600-khz version f in = 433.92 mhz/315 mhz f if = 1 mhz p ask = p ref_ask + ? p ref ? p ref +2.5 -1.5 db sensitivity variation ask for full operating range including if filter compared to t amb = 25c, v s = 5 v 300-khz version f in = 433.92 mhz/315 mhz f if = 0.88 mhz to 1.12 mhz f if = 0.85 mhz to 1.15 mhz p ask = p ref_ask + ? p ref ? p ref +5.5 +7.5 -1.5 -1.5 db db sensitivity variation ask for full operating range including if filter compared to t amb = 25c, v s = 5 v 600-khz version f in = 433.92 mhz/315 mhz f if = 0.79 mhz to 1.21 mhz f if = 0.73 mhz to 1.27 mhz p ask = p ref_ask + ? p ref ? p ref +5.5 +7.5 -1.5 -1.5 db db input sensitivity fsk 600 khz if filter input matched according to figure 4, ber 10 -3 , b = 600 khz f in = 433.92 mhz/315 mhz t = 25c, v s = 5 v f if = 1 mhz p ref_fsk input sensitivity fsk 600 khz if filter br_range0 df 20 khz df 30 khz -95.5 -96.5 -97.5 -98.5 -99.5 -100.5 dbm dbm input sensitivity fsk 600 khz if filter br_range1 df 20 khz df 30 khz -94.5 -95.5 -96.5 -97.5 -98.5 -99.5 dbm dbm sensitivity variation fsk for the full operating range compared to t amb = 25c, v s = 5 v 600-khz version f in = 433.92 mhz/315 mhz f if = 1 mhz p fsk = p ref_fsk + ? p ref ? p ref +2.5 -1.5 db sensitivity variation fsk for full operating range including if filter compared to t amb = 25c, v s = 5 v 600-khz version f in = 433.92 mhz/315 mhz f if = 0.86 mhz to 1.14 mhz f if = 0.82 mhz to 1.18 mhz p fsk = p ref_fsk + ? p ref ? p ref +5.5 +7.5 -1.5 -1.5 db db fsk frequency deviation the sensitivity of the receiver is higher for higher values of ? f fsk br_range0 br_range1 br_range2 and br_range3 are not suitable for fsk operation ? f fsk 20 20 30 30 50 50 khz khz s/n ratio to suppress inband noise signals ask mode fsk mode snr ask snr fsk 10 2 12 3 db db dynamic range rssi ampl. ? r rssi 60 db electrical characteristics (continued) all parameters refer to gnd, t amb = -40c to +105c, v s = 4.5 v to 5.5 v, f 0 = 433.92 mhz and f 0 = 315 mhz, unless otherwise specified. (v s = 5 v, t amb = 25c) parameters test conditions symbol min. typ. max. unit
28 u3741bm 4662b?rke?10/04 lower cut-off frequency of the data filter f cu_df 0.11 0.16 0.20 khz recommended cdem for best performance ask mode br_range0 (default) br_range1 br_range2 br_range3 cdem 39 22 12 8.2 nf nf nf nf recommended cdem for best performance fsk mode br_range0 (default) br_range1 br_range2 and br_range3 are not suitable for fsk operation cdem 27 15 nf nf maximum edge-to-edge time period of the input data signal for full sensitivity br_range0 (default) br_range1 br_range2 br_range3 t ee_sig 1000 560 320 180 s s s s upper cut-off frequency data filter upper cut-off frequency programmable in 4 ranges via a serial mode word br_range0 (default) br_range1 br_range2 br_range3 f u 2.5 4.3 7.6 13.6 3.1 5.4 9.5 17.0 3.7 6.5 11.4 20.4 khz khz khz khz minimum edge-to-edge time period of the input data signal for full sensitivity br_range0 (default) br_range1 br_range2 br_range3 t ee_sig 270 156 89 50 s s s s reduced sensitivity r sense connected from pin sens to v s , input matched according to figure 4 p ref_red dbm (peak level) reduced sensitivity r sense = 56 k ? , f in = 433.92 mhz, (v s = 5 v, t amb = 25c) at b = 300 khz at b = 600 khz -71 -67 -76 -72 -81 -77 dbm dbm reduced sensitivity r sense = 100 k ? , f in = 433.92 mhz at b = 300 khz at b = 600 khz -80 -76 -85 -81 -90 -86 dbm dbm reduced sensitivity r sense = 56 k ? , f in = 315 mhz at b = 300 khz at b = 600 khz -72 -68 -77 -73 -82 -78 dbm dbm reduced sensitivity r sense = 100 k ? , f in = 315 mhz at b = 300 khz at b = 600 khz -81 -77 -86 -82 -91 -87 dbm dbm reduced sensitivity variation over full operating range r sense = 56 k ? r sense = 100 k ? p red = p ref_red + dp red ? p red 5 6 0 0 0 0 db db electrical characteristics (continued) all parameters refer to gnd, t amb = -40c to +105c, v s = 4.5 v to 5.5 v, f 0 = 433.92 mhz and f 0 = 315 mhz, unless otherwise specified. (v s = 5 v, t amb = 25c) parameters test conditions symbol min. typ. max. unit f cu_df 1 2 30k ? cdem ----------------------------------------------------------- =
29 u3741bm 4662b?rke?10/04 reduced sensitivity variation for different values of r sense values relative to r sense = 56 k ? r sense = 56 k ? r sense = 68 k ? r sense = 82 k ? r sense = 100 k ? r sense = 120 k ? r sense = 150 k ? p red = p ref_red + ? p red ? p red 0 -3.5 -6.0 -9.0 -11.0 -13.5 db db db db db db threshold voltage for reset v threset 1.95 2.8 3.75 v digital ports data output - saturation voltage low - internal pull-up resistor - maximum time constant - maximum capacitive load i ol = 1 ma t = c l (r pup //r ext ) without ext. pull-up resistor r ext = 5 k ? v oi r pup c l c l 39 0.08 50 0.3 61 2.5 41 540 v k ? s pf pf pout output - saturation voltage low - saturation voltage high i pout = 1 ma i pout = -1 ma v ol v oh v s - 0.3 v 0.08 v s - 0.14v 0.3 v v fsk/ask input - low-level input voltage - high-level input voltage fsk selected ask selected v il v ih 0.8 v s 0.2 v s v v enable input - low-level input voltage - high-level input voltage idle mode active mode v il v ih 0.8 v s 0.2 v s v v mode input - low-level input voltage - high-level input voltage division factor = 10 division factor = 14 v il v ih 0.8 v s 0.2 v s v v test input - low-level input voltage test input must always be set to low v il 0.2 v s v electrical characteristics (continued) all parameters refer to gnd, t amb = -40c to +105c, v s = 4.5 v to 5.5 v, f 0 = 433.92 mhz and f 0 = 315 mhz, unless otherwise specified. (v s = 5 v, t amb = 25c) parameters test conditions symbol min. typ. max. unit
30 u3741bm 4662b?rke?10/04 package information ordering information extended type number package remarks u3741bm-p2fl so20 2: if bandwidth of 300 khz, tube u3741bm-p2flg3 so20 2: if bandwidth of 300 khz, taped and reeled u3741bm-p3fl so20 3: if bandwidth of 600 khz, tube U3741BM-P3FLG3 so20 3: if bandwidth of 600 khz, taped and reeled technical drawings according to din specifications package so20 dimensions in mm 9.15 8.65 11.43 12.95 12.70 2.35 0.25 0.10 0.4 1.27 7.5 7.3 0.25 10.50 10.20 20 11 110
31 u3741bm 4662b?rke?10/04 revision history please note that the following page numbers referred to in this section refer to the specific revision mentioned, not to this document. changes from rev. 4662a - 06/03 to rev. 4662b - 10/04 1. put datasheet in a new template. 2. heading rows at table ?absolute maximum ratings? added. 3. table ?ordering information? on page 30 changed.
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