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Ordering number: EN 3507
Monolithic Linear IC
LA1136N, 1136NM, 1137N, 1137NM AM Tuners for Car Radios and Home Stereos
Overview
The LA1136N/NM and LA1137N/NM are high-performance AM electronic tuner ICs offering sophisticated functions. They are especially suited for use in car radio and home stereo (antenna: loop) applications.
Features
. Excellent cross modulation characteristic: Meets the . . . . . . . .
requirements for preventing not only adjacent-channel interference but also interference caused by all channels within broadcast band. Narrow-band signal meter output: Usable as auto search stop signal. Has linearity up to 100 dB. Local oscillation buffer output: Facilitates designing of electronic tuner system, frequency display, etc. OSC (with ALC): Improves tracking error because oscillation output is stabilized at a low level (350 mVrms: LA1137N) for varactor diode. MIX: Double-balanced differential MIX meeting the requirements for preventing spurious interference, IF interference. Good characteristic at high input: 130 dB input fm = 400 Hz 80%mod THD = 0.5% typ. High S/N: Good S/N at medium input (55 dB typ). Usable sensitivity: (S/N = 20 dB input): 25 dB (when using 2SK715 ) VCC variation compensation: Less variation in gain, distortion: 8 to 12 V
Functions
. MIX . OSC (with ALC) . IF amplifier . Detector . AGC (normal) . RF wide-band AGC . Auto search stop signal (Signal meter output) . Local oscillation buffer output . IF band switching circuit (for LA1136N only) . IF count buffer . Stop detector output (can be set independently) . Tweet prevention circuit . AGC (RF, IF) time constant switching circuit . IF AGC circuit . Pin-diode driver . AM stereo decoder IF output (for LA1136N only) . Circuit preventing incorrect seek operation
AM stereo capability (LA1136N only)
. IF band switching circuit on chip; controlled by . microcontroller for AM stereo; SUB S/N improved to Oscillating circuit . 6 dB for AM stereo decoder . IF output tweet characteristics: 10 dB increase, controlled by Improved . microcontroller modulation characteristics, especially Improved cross . . . . .
sensitivity suppression characteristics: 15 dB improvement, wide-band AGC operation even for SW band interference Improved low-frequency modulation distortion Improved temperature characteristics: S-meter, SD sensitivity Faster RF AGC response: RF: 1/3; IF: 1/8 (compared to predecessors) Improved capability for driving external RF AGC transistors: IB max = 200 A Measures to prevent incorrect seek operation IF count buffer on chip; controlled by microcontroller Time constant switching circuit on chip for RF and IF AGC IF AGC clear circuit on chip Measures that prevent stopping one station too soon
. . . .
SANYO Electric Co.,Ltd. Semiconductor Bussiness Headquarters
TOKYO OFFICE Tokyo Bldg., 1-10, 1 Chome, Ueno, Taito-ku, TOKYO, 110 JAPAN
93097HA(II)/4281TS(US) No.3507-1/28
LA1136N, 1136NM, 1137N, 1137NM
Package Dimensions
unit : mm unit : mm
3067-DIP24S
[LA1136N]
3112-MFP24S
[LA1136NM]
SANYO : DIP24S unit : mm unit : mm
SANYO : MFP24S
3021B-DIP20S
[LA1137N]
3036B-MFP20
[LA1137NM]
SANYO : DIP20Slim
SANYO : MFP20
Pd max - Ta
Allowable power dissipation, Pd max - mW Allowable power dissipation, Pd max - mW
Pd max - Ta
Mounted on 20 x 40 x 1.5 mm PCB Independent IC
Ambient temperature, Ta - C
Ambient temperature, Ta - C
No. 3507-2/28
LA1136N, 1136NM, 1137N, 1137NM
Pd max - Ta
Allowable power dissipation, Pd max - mW Allowable power dissipation, Pd max - mW
Pd max - Ta
Mounted on 20 x 40 x 1.5 mm PCB Independent IC
Ambient temperature, Ta - C
Ambient temperature, Ta - C
Specifications
Maximum Ratings at Ta = 25C
Parameter Maximum supply voltage Output voltage Input voltage Current drain Flow-out current Allowable power dissipation Symbol VCC max VO1 VO2 VIN ICC I20 Pd max Pd max1 Pd max2 Pd max1 Pd max2 Operating temperature Storage temperature Topr Tstg Pin 6 Pin 13 (LA1136N), Pin 10 (LA1137N) Pin 5 Pin 15+6+10, V11 = 0 (LA1137N) Pin 6+13+19, V14 = 0 (LA1136N) Pin 20 (LA1137N), Pin 24 (LA1136N) Ta % 65C (LA1136N), Ta % 77C (LA1137N) Independent IC, Ta % 47C (LA1136NM) With PCB, Ta % 80C (LA1136NM) Independent IC, Ta % 63C (LA1137NM) With PCB, Ta % 77C (LA1137NM) Conditions Pin 19 (LA1136N), Pin 15 (LA1137N) Ratings 12 13.4 15.5 5.6 60 2 680 540 680 540 680 -40 to +85 -40 to +125 Unit V V V V mA mA mW mW mW mW mW C C
Operating Conditions at Ta = 25C
Parameter Recommended supply voltage Supply voltage range Symbol VCC VCC op Conditions Ratings 8 7.5 to 10 Unit V V
No. 3507-3/28
LA1136N, 1136NM, 1137N, 1137NM
LA1136N, LA1136NM Operating Conditions at Ta = 25C, VCC = 8 V, fr = 1 MHz, fm = 400 Hz, See specified Test Circuit
Parameter Current drain Detection output Signal-to-noise ratio AGC figure-of-merit Total harmonic distortion Signal meter output voltage Stop detector sensitivity Local-oscillator buffer output voltage IF buffer output voltage IF count buffer output voltage IF count buffer output leakage voltage Antenna input level for RF AGC ON and tweet prevention Antenna input for wideband AGC ON Wideband/narrowband detector output ratio (weak input) Pin-diode driver current Symbol ICC1 ICC2 VO S/N AGC Conditions Quiescent 130 dB 74 dB, 30% modulation 74 dB, 30% modulation 74 dB, 30% modulation, reference output 10 dB below input 74 dB, 80% modulation 130 dB, 80% modulation Quiescent 130 dB V18 = 3.5 V 12 L L L L L L L L L L L L L L L Quiescent, 1.0 MHz receive signal, 1.4 MHz interference, zero modulation 21 dB, 30% modulation V1 = 0.7 V L L/H L Pin 14 17 L L L L L L L L L L L L L H L L H L L L L L L L L L L L L L H L L L L L 22 O O O O O O O O O O O O O O L O O O 4.0 56 92 62 98 2 5.5 min 22 30 -15.0 49 50 typ 38 45 -12.0 54 54 0.4 0.5 0 5.0 32 330 750 300 1.0 2.0 0.3 7.5 38 max 52 60 -9.0 Unit mA dBm dB dB % V dB mVrms 1,000 mVrms mVrms 10 mVrms 68 104 4 dB dB dB mA
THD1 THD2 VSM1 VSM2 SD VOSC Quiescent BUFF VIF BUFF 74 dB, zero modulation VIFCB 30 dB, zero modulation VIFCBL ANT1 ANT2 - IANTD 74 dB, zero modulation
3.5 26 270 530 260
Note)
SW voltage: H = 5 V, L = GND, O = OPEN
LA1137N, LA1137NM Operating Characteristics at Ta = 25C, VCC = 8 V, fr = 1 MHz, fm = 400 Hz, See specified Test Circuit
Parameter Current drain Detection output Signal-to-noise ratio AGC figure-of-merit Total harmonic distortion Signal meter output voltage Stop detector sensitivity Local-oscillator buffer output voltage IF count buffer output voltage IF count buffer output leakage voltage Antenna input for RF AGC ON and tweet prevention Antenna input for wide band AGC ON Pin-diode driver current Symbol ICC1 ICC2 VO S/N AGC THD1 THD2 VSM1 VSM2 SD Conditions Quiescent 130 dB, zero modulation 74 dB, 30% modulation 74 dB, 30% modulation 74 dB, 30% modulation, reference output 10 dB below input 74 dB, 80% modulation 130 dB, 80% modulation Quiescent 130 dB, zero modulation V18 = 3.5 V, zero modulation 11 L L L L L L L L L H L H L L Quiescent, 1.0 MHz receive signal, 1.4 MHz interference signal, zero modulation V1 = 0.7 V SW 13 L L L L L L L L L L L H L L 18 O O O O O O O O O O O O O L 56 62 min 22 30 -15.0 50 48 typ 38 45 -12.0 55 52 0.3 0.4 0 5 33 350 300 10 68 max 52 60 -9.0 Unit mA dBm dB dB % V dB mVrms mVrms mVrms dB
56 1.0 2.0 0.3 7.5 39
3.5 27 290 260
VOSC BUFF Quiescent VIFCB VIFCBL ANT1 30 dB, zero modulation 74 dB, zero modulation
ANT2 IANTD
L L
L L
O O
92 4.0
98 5.5
104
dB mA
Note)
SW voltage: H = 5 V, L = 0 V, O = open Short the ammeter used to measure the pin-diode driver current when not in use.
No. 3507-4/28
High frequency signal level meter Voltmeter S-meter output
High frequency signal level meter
High frequency IHF signal level meter signal level meter with bandpass filter Distortion meter
LA1136N, LA1136NM Test Circuit
LA1136N, 1136NM, 1137N, 1137NM
No. 3507-5/28
Unit (resistance: , capacitance: F)
S-meter output Signal meter VHF signal meter
LA1137N, LA1137NM Test Circuit
VHF signal meter Distortion meter
LA1136N, 1136NM, 1137N, 1137NM
No. 3507-6/28
Unit (resistance: , capacitance: F)
LA1136N, 1136NM, 1137N, 1137NM
LA1136N Equivalent Circuit
No. 3507-7/28
LA1136N, 1136NM, 1137N, 1137NM
LA1137N Equivalent Circuit
No. 3507-8/28
LA1136N, 1136NM, 1137N, 1137NM
LA1136N Sample Application Circuit
LA1136N
.
Pins connected to the controller
No. 3507-9/28
Unit (resistance: , capacitance: F)
LA1136N, 1136NM, 1137N, 1137NM
LA1137N Sample Application Circuit
No. 3507-10/28
.
Pins connected to the controller
Unit (resistance: , capacitance: F)
LA1136N, 1136NM, 1137N, 1137NM
LA1136N, LA1137N Pin Specifications (Pins connected to an external microcontroller)
(1) IF Band Switching : Pin 12 Narrowband : 3.5 V or greater Wideband : 2.1 V or lower (2) Seek Detection : Pin 14 Station seek : 3.5 V or greater Receive mode : 1.5 V or lower (3) IF Count Buffer : Pin 17 IF count buffer enabled : 2.5 V or greater IF count buffer disabled : 1.2 V or lower (4) SD output, tweet prevention control pin: Pin 22 The function of pin 22 is determined by the control voltage on pin 14 as follows: [Pin 14] [Pin 22] HIGH (3.5 V or higher) SD output pin (active high) LOW (1.5 V or lower) Tweet prevention input pin Microcontroller control voltage, Tweet prevention HIGH (3.5 V or higher) off LOW (1.5 V or lower) on Note: It is necessary to modify the microcontroller specifications in order to implement tweet prevention. When a conventional microcontroller is used with the LA1136N or the LA1137N, the tweet prevention circuit does not operate, but all other functions operate independently.
Device Comparison
Comparison between LA1135, LA1136N and LA1137N
Parameter Packages Double-balanced mixer Oscillator Local-oscillator buffer IF amplifier Detector IF-band switching S-meter linearity Stop detector sensitivity IF count buffer AM stereo buffer IF AGC IF AGC time-constant switching IF AGC reset Wideband RF AGC RF AGC time-constant switching Antenna dumping Tweet prevention LA1135 DIP20S, MFP20 Yes LW to SW Yes Yes External capacitor No Approximately 80 dB S-meter load dependent No (requires 2 transistors) No Yes No (requires 1 transistor) No Yes No Transistor No LA1136N DIP24S, MFP24 Yes Supports AM stereo in LW and MW, low-band noise reduction Yes Yes Internal capacitor Yes Approximately 100 dB Yes Set by external resistor (Pin 10) Yes Yes Yes Yes Yes Yes Yes Pin-diode Yes LA1137N DIP20S, MFP20 Yes LW to SW Yes Yes Internal capacitor No Approximately 100 dB Yes Set by external resistor (Pin 9) Yes No Yes Yes Yes Yes Yes Pin-diode Yes
Active-HIGH stop detector output No (requires 2 transistors)
No. 3507-11/28
LA1136N, 1136NM, 1137N, 1137NM
LA1136N, LA1137N Usage Notes
1. 2. Do not connect the antenna alignment circuit and local oscillation circuit. The coils should be specified to obtain an output level of -25 dBm (43.6 mVrms) for the given input levels shown below, and under the conditions fm = 400 Hz, 30% modulation and fOSC = 1.45 MHz.
Antenna input Mixer input IF input Detector input 20.0 dB (Note) 30.5 dB 38.0 dB 106.0 dB
Input connections
Antenna input
Mixer input
IF input
Detector input
V12 = 0 for LA1136N
Unit (resistance: , capacitance: F) Note : The antenna input can be adjusted by changing the number of turns in the primary winding of the alignment coil in accordance with the AGC figure-of-merit. 3. Coil Design Notes (1) RF alignment coil Gain adjustment: The gain is adjusted by varying the primary turns ratio of the primary coil. Coupling: The design of this coil is geared towards critical coupling. The coupling is dependent on the turns ratio of the primary coil and the secondary coil: Tight coupling: High turns ratio Loose coupling: Low turns ratio With tight coupling, the selectivity characteristic develops a double hump; when making a tracking adjustment, it must be noted that misadjustment can occur, leading to a deterioration of the dual signal characteristics. With loose coupling, selectivity increases, but the sensitivity error within the band of the RF alignment itself also increases.
. .
. .
During design, be certain to confirm data such as that for coil specifications. Furthermore, it is also necessary to note that although the turns ratio of the primary and secondary coils have the greatest bearing on coupling, the shape of the coil core and the manner in which the coil is wound also have an impact.
No. 3507-12/28
LA1136N, 1136NM, 1137N, 1137NM
(2) Oscillator coil The oscillator for LA1136N and LA1137N can operate up to 100 MHz. Stray capacitance resulting from poor oscillator coil design can cause antiresonance in the range 50 to 100 MHz. This results inparasitic oscillations at the local-oscillator buffer output, which can prevent the PLL from locking.
Parasitic oscillations in the 50 to 100 MHz region
Required local oscillator signal
Countermeasure 1 Reduce the oscillator coil stray capacitance (tapping is recommended) 2 Connect a capacitor of 43 pF or greater between OSC BUFF (Pin 24 for LA1136N, and Pin 20 for LA1137N) and GND. (3) IF tank coil LA1136N Pin 13 load coil LA1137N Pin 10 load coil The IF tank coil connected to IF OUT has different specifications to that of the LA1135. The detector input impedance of the LA1135 is low, therefore for a QO of 70 to 80, the QL was 20 to 30. The detector input impedances of the LA1136N and LA1137N are higher. This means that the QO and QL of the tank coil are approximately the same. A coil with a QO of approximately 30 is recommended. 4. Recommended Coil Specifications
(1) RF alignment coil Primary coil
Secondary coil
No. 3507-13/28
LA1136N, 1136NM, 1137N, 1137NM
(2) Oscillator coil For use with SVC321, triple varactor diode
For use with quad varactor diode
(3) Mixer coil
Center frequency
(4) IF tank coil
Center frequency
No. 3507-14/28
LA1136N, 1136NM, 1137N, 1137NM
(5) Sample RF alignment coil selectivity characteristics (Mitsumi) New coil designs should have the same selectivity characteristics as shown below. RF characteristics at 600 kHz RF characteristics at 1 MHz
RF characteristics at 1.4 MHz
5.
Problems Concerning Wideband AGC
Because the LA1136N and the LA1137N offer many sophisticated functions, a number of their pins are dual-purpose pins. An example is pin 3 (on both the LA1136N and the LA1137N), which serves both as the wideband AGC input pin and the antenna dumping pin diode drive pin. As a result, particular attention must be given to the wiring pattern layout, since feedthrough of other signals as shown in the figure below can cause AGC to operate without input, resulting in reduced sensitivity.
Avoid direct feedthrough from the RF amplifier to the pin 3 line.
Unit (resistance: , capacitance: F) LA1136N/1137N Antenna, RF circuit
No. 3507-15/28
LA1136N, 1136NM, 1137N, 1137NM
6. Wideband AGC Sensitivity
The wideband AGC circuit two-signal sensitivity and shortwave interference suppression characteristics have been achieved by reducing the sensitivity by approximately 10 dB from that of previous devices. If a FET with low gm and high IDSS is used, the sensitivity can be increased by increasing the external sensitivity adjustment resistor (30 ). However, the voltage drop across this resistor can cause the cascade AGC transistor to saturate. Therefore, if the sensitivity is to be increased by a large amount, a choke coil should be added as shown in the figure below.
Unit (resistance: , capacitance: F)
7.
The local oscillation level increased during LW (approx. 50C or greater)
27 k should be added between pins 19 and 23 for LA1136N, and between pins 15 and 19 for LA1137N. Not necessary for MW. 8. Image Interference Reduction
Image interference in the alignment circuit can be reduced by up to 70 dB at fr = 1.4 MHz by injecting a 2.3 MHz trap signal into the primary coil. Note that this technique reduces the sensitivities at frequencies above 1.4 MHz. 9. Upgraded Features of LA1136 and LA1137 to LA1136N and LA1137N
Upgraded features IF count buffer output voltage 74 dB, zero modulation, fr = 1 MHz when STOP RQ = 0 V LA1136, LA1137 LA1136N, LA1137N
80 mVp-p Test circuit LA1137N
1.5 mVp-p
Signal detector output voltage when VCC OFF
0.7 V Test circuit LA1137N
5V
Unit (resistance: , capacitance: F)
No. 3507-16/28
LA1136N, 1136NM, 1137N, 1137NM
10. Application Circuit using the IF count method The LA1136N and LA1137N can be configured for tuning using either the stop detector or the IF count method. The application circuits are examples of tuners using the IF count method. The stop detector can be used in any of the application circuits by making the circuit modifications shown below.
The other pins are the same as those shown in the application circuits. 11. Improving Fidelity Distortion for low-frequency(fm % 100 Hz), high-modulation signals can be reduced by increasing the capacitance connected to RF AGC of pins 1 and 2 (LA1136N, LA1137N). However, increasing this capacitance (C2) by a large amount can increase the AGC response time to an unacceptable level. 12. Loop Antenna Specifications The recommended loop antennae for the LA1136N and LA1137N are the Korin 42579719100 (LA-1500) and 4257976000 (LA-100A). Note that these are the same antennae previously recommended for the LA1135. 13. AGC ON Level Frequency Characteristics The frequency at which the sensitivity decreases by -3 dB from the point when f = 1 MHz is as shown below.
Normal LA1136N, LA1137N LA1135 37 MHz 20 MHz Wideband 24 MHz 7 MHz
In other words, in AGC for the main signal, the point at which the AGC sensitivity drops 3 dB is 37 MHz, as shown in the diagram below. The AGC ON level -3 dB frequencies for narrowband and wideband AGC have been extended from those of the LA1135 to cover the entire SW3 shortwave band. As a result, the wideband AGC sensitivity is significantly increased and susceptibility to shortwave interference, reduced. This has been achieved without any increase in dispersion or distortion. Narrowband AGC ON level RF AGC ON mixer input level - dB
AGC ON level variation 1 dB up to 30 MHz
Antenna dumping ON input level - dB
Wideband AGC ON level
fr = 1 MHz
LA1136 RF AGC ON mixer input frequency - Hz
Pin 3 input - dB
Unit (resistance: , capacitance: F)
No. 3507-17/28
LA1136N, 1136NM, 1137N, 1137NM
14. Stop Detector Adjustment Although this explanation is for the LA1137N, it is identical for the LA1136N, except that the pin numbers are different. The LA1137N is designed for use with the following microcontrollers. Stop detection method: LM7001 (Sanyo) (SD output only) IF count method: LM7000 (Sanyo) LC7230 (Sanyo) (1) Support for the LM7001 The search stop detector uses the active HIGH signal of pin18.
S-meter load
Unit (capacitance: F)
Antenna input - dB
The IF signal from the IF amplifier is detected, on pin 16 the signal that determined the bandwidth characteristics through the narrowband filter BFU450CN (BFU450CN is equivalent to the amplifier emitter load) is detected, and the S-meter output is output by the S-meter drive circuit by driving with current the load on pin 17. Therefore, the S-meter output VSM on pin 17 has the following relationship with the S-meter load R17. VSM R17 In the above example, 3 k is changed to 4.5 k, but the R ratio of the output is 1.5x. However, the meter output has an upper limit; as a guide, saturation occurs when the upper limit is at about VCC - 1.4 V. The pin 18 SD output is generated by comparing the S-meter output described above with the reference voltage Vref on pin 9 (400 x R9). Using the recommended constants, Vref = 400 x 2.4 k = 1.0 (V). The comparator compares the electric potential of pin 17 with that of pin 9 and detects when the electric potential of pin 17 is greater than that of pin 9, in which event the transistor is turned off and the SD output changes from LOW to HIGH (GND to VDD). Note that, in consideration of differences in circuit configurations, Vref should be at least 0.7 V.
No. 3507-18/28
LA1136N, 1136NM, 1137N, 1137NM
(2) SD sensitivity adjustment method The SD sensitivity is determined by the voltage level of the two inputs to the comparator. Because the absolute value is determined by the resistor as described above, no matter which level, the sensitivity can be adjusted through both levels. However, from the standpoint of the stability of the system as a whole and given the possibility that the S-meter output will be used for other purposes, it is best to make adjustments by adjusting the value on pin 9. Because the S-meter I/O characteristics during a seek operation or a receive operation are basically as depicted in the diagram below, so allowing for potential differences, the setting level for the adjustable range should be 25 to 60 dB.
Receive mode
Station seek mode
Antenna input level - dB
IF count control voltage (STRQ) IF buffer signal
(3) Support for the LM7000 (IF count method) Implemented as shown in the figure at right.
15. Tweet Prevention Circuit (1) Cause and countermeasures for Tweet distortion The beat noise frequency characteristics for LA1137N is fr = 900 kHz and the corresponding circuit where it is generated are shown below. The minimum signal-to-noise ratio for tuners using a reference input signal is 30 dB. Tweet input
Signal Characteristics
Output - dB
Complete alignment (Maximum beat noise at 900 kHz)
Complete alignment (zero beat noise)
Antenna input - dB Mechanism behind the deterioration of the characteristics The 900 kHz RF input signal from the antenna is amplified by the FET RF amplifier before passing through the RF alignment stage to the mixer. If this signal is large, the varactor diodes can cause second-harmonic distortion of 1.8 MHz. The 900 kHz and 1.8 MHz components each generate an IF signal; (450 + ) kHz for the 900 kHz signal, and (450 - ) kHz for the 1.8 kHz signal. These two signals interact to produce a beat frequency at 2 x kHz.
No. 3507-19/28
LA1136N, 1136NM, 1137N, 1137NM
(2) Methods for improving tweet characteristics 1 A twin varactor diode can be used, as is used for FM detection. However, the chip size is four times that of a standard varactor diode having the same capacitance, resulting in increased cost and a narrower capacitance range.
2 The RF AGC ON level can be reduced to prevent the varactor diodes from distorting the signal. However, the signal-to-noise ratio is limited to approximately 50 dB or lower. 3 The varactor diodes can be replaced by an up-converter. However, this increases the susceptibility to interference. (3) Countermeasures for LA1136N, LA1137N Although this explanation is for the LA1137N, it is identical for the LA1136N, except that the pin numbers are different.
Output
Maximum beat noise with tweet prevention Inactive 10 dB Improvement Maximum beat noise with tweet prevention active Zero beat noise
The AGC ON level for fr = 90 kHz is reduced by 10 dB to reduce the signal level on the varactor diodes. The microcontroller determines when the tuner is receiving at 900 kHz and forces the HIGH-level signal present on pin 18 and SD VDD to LOW, reducing the ON level by 10 dB. This gives the signal-to-noise characteristics shown below.
Tweet prevention active
RF AGC on level
AGC variable gain
Stop detector cutoff circuit
Stop detector circuit
No. 3507-20/28
LA1136N, 1136NM, 1137N, 1137NM
(4) The accurate voltages for each pin During seek: When the voltage of pin 11 is HIGH 5 V, transistor N is ON and transistors N3, N4, N6, N7, N8 and N9, OFF. Pin 18 is connected to the collector of N10 and through a pull-up resistor to VDD. Pin 18 is the stop detector output when a carrier is present. When N10 is ON, pin 18 is LOW, V18 6 ON, and when N10 is OFF, pin 18 is HIGH, V18 6 VDD. During stop: When the voltage of pin 11 is LOW and the voltage of pin 18 is HIGH, transistor N5 is OFF, and transistors N3, N4, N7, N8, N9, P1 and P2, ON. The SD cut-off circuit for N8 and N9 are ON. Since N9 is ON, no current flows through the stop detector circuit. Therefore the voltage for pin 18 = VDD. When the microcontroller pulls pin 18 to ground, N5 and N7 turn OFF, and N3, N4, N6, N8, N9, P1 and P2, ON. As a result, N2 is also turned OFF and the amplifier load for fr = 900 kHz is R1. The amplifier load for fr = 900 kHz is R1 // R2. The AGC ON level is 10 dB lower for R1, R1//R2 than for other frequencies. 16. IF block AGC time constant switching circuit These tuners incorporate various AGC time constant switching circuits that serve to prevent incorrect stops during seek operations. A summary of these circuits is provided below. (1) Problems with IF AGC response, such as incorrect stops during seek operations 1 Incorrect stops (or overshoots) due to S-meter oscillation caused by transient response in IF AGC (secondary filter). 2 Overshoots of adjacent stations or weak signal stations due to the time required to discharge the electric charge that has built up in the IF AGC capacitor when a seek is initiated while the device is receiving a strong signal (2) Countermeasures Although this explanation is for the LA1137N, it is identical for the LA1136N, except that the pin numbers are different. Countermeasure for problem 1: When a high signal on pin 11 is detected during a seek operation, change the time constants as indicated below.
First-order filter t = 1 k x 4.7 F Second-order filter During receive During seek Unit (resistance: , capacitance: F)
Countermeasure for problem 2: AGC capacitor discharge times can be reduced by tracking the S-meter output voltage and rapidly discharging the AGC capacitor connected to pin 14 as shown below. This circuit is interlocked with the MUTE signal on pin 11 so that it operates only during seek. It also reduces the AGC time constant during seek to one-eighth of its normal value.
No. 3507-21/28
LA1136N, 1136NM, 1137N, 1137NM
17. Preventing Incorrect RF AGC time-constant switching, Seek Operation These tuners incorporate various circuits that serve to prevent incorrect stops during seek operation. A summary of the RF amplifiers is provided below. (1) Incorrect stops during RF AGC, and other problems 1 The RF AGC response time can cause incorrect seek and stop operation when moving from a weak-signal station to a strong-signal station. When seek operation starts from a strong station, the tuner can overshoot an adjacent weak station if the AGC time constant is too high. 2 If the wideband AGC ON level is too high, the varactor diodes can generate cross-modulation distortion causing incorrect seek operation. 3 Input FETs with high IDSS, required for correct seek and stop operation, are difficult to drive. (2) Countermeasures Countermeasure for problem 1: When the input signal goes from a strong to a weak station, the detector generates a pulse as shown in the figure below. The AGC capacitor C1 is charged rapidly for the duration of this pulse. It also reduces the AGC time constant during charging to one-third of its normal value.
Charging circuit
Countermeasure for problem 2: The wideband AGC ON level should be raised as far as practicable within cross-modulation disrtortion and sensitivity constraints. If a pin-diode is used, the sensitivity is not suppressed even if the AGC ON level is increased considerably. However, if the varactor diodes in the RF input circuit are exposed to strong interference signals of any frequency, the resulting non-lincarity can cause seek and stop operation errors. Previous devices used the same S-meter linearity for both seek and stop operations, where the linearity was extended to 100 dB by the IF AGC and RF AGC. When the wideband RF AGC operated, the S-meter signal was amplified causing incorrect stop operation. For example, modulation sidebands could stop the tuner one station too early. The S-meter linearity has now been restricted to approximately 60 dB minimum during the seek and stop operations for LA1136N and LA1137N. When the RF AGC operates during seek operation, the S-meter signal amplifier is disabled. This reduces the potential for tuning error when using the stop detector method (such as LM7001, etc.). Countermeasure for problem 3: For LA1137N, a transistor and base current supply circuit (200 A maximum) have been incorporated into a cascade AGC configuration to simplify the use of high IDSS FETs. An external resistor is required. Note that VAGC-0 = 6.1 V for no input signal. Also, VCC should be chosen carefully since it affects both the dynamic range and the sensitivity.
Discharging
Charging
Large IDSS Charging circuit Resistor added
No. 3507-22/28
LA1136N, 1136NM, 1137N, 1137NM
18. Gain Adjustment Method (1) AGC Operations The AGC circuits for LA1136N and LA1137N are configured based on the AGC circuit for LA1135. Although this explanation is for the LA1137N, it is identical for the LA1136N, except that the pin numbers are different. 1 IF stage Figure 1 Total harmonic distortion, THD - % AGC gain and distortion characteristics 500 k VR HW-60303 IF tank II gain attenuator
IF amplifer I
IF amplifier II
Detector
Set value
Maximum sensitivity, MS - dB
The IF stage block diagram is shown in the figure above. The output current from pin 12 is converted to a voltage and detected by pin 14 of the IF AGC circuit. IF Amplifier I prevents the input signal from exceeding the dynamic range of IF Amplifier II. The relationship between the gain and distortion of the IF stage is shown in Figure 1. Note that when the gain is decreased, the AGC ON level is increased causing distortion at the IF Amplifier II input (At maximum sensitivity, the antenna input is increased at output -25 dB.) This limits the effectiveness of using the IF tank II for decreasing gain. 2 RF stage The AGC for signal 1 of LA1137N operates as shown below. Figure 2 Gain adjustment Total harmonic distortion, Output - dB
Mixer coil, no attenuation Mixer coil, with attenuation Ceramic filter mismatch caused by resistor R
Doubletuned circuit
Distortion
Mixer input - dB The RF AGC circuit reduces the voltage on pin 1 (6 V when no input) by detecting and amplifying the mixer input signal. When operating, the voltage drops to 3.5 V, approximately 6 mA of antenna dumping current is driven from Pin 3 to hold the antenna input signal constant. When current flows from Pin 3, the voltage on Pin 1 drops to 0.6 V min. to control the drain-to-source voltage of the input FET. Because the RF AGC operates independently of the gain of IF tank I, the RF AGC gain can be reduced without increasing distortion (See Figure 2).
No. 3507-23/28
LA1136N, 1136NM, 1137N, 1137NM
3 RF alignment coil In general, the RF amplifier gain and fluctuations in the effective sensibility should be kept as low as possible. sensitivity Maximum sensitivity MS
Turns proportional to gain
Increase turns Effective sensitivity QS Number of turns Check the data in the diagram to determine the number of turns. 19. IF Count Buffer Although this explanation is for the LA1137N, it is identical for the LA1136N, except that the pin numbers are different. Circuit operations Pin 13 serves as both the count buffer input pin and output pin. When the control voltage with no load is HIGH 5 V, the IF buffer output is 300 mVrms and when LOW GND, 1 mVrms or lower. Supports Sanyo's LM7000 and LC7230.
Reverse circuit IF counter amplifier
IF buffer
Control voltage
No. 3507-24/28
LA1136N, 1136NM, 1137N, 1137NM
S-meter voltage, VSM [V] Total harmonic distortion, THD [%] S-meter voltage, VSM [V] Total harmonic distortion, THD [%] Selectivity Characteristics Difference frequency, f [kHz]
When f = 0, fr = 1 MHz, fm = 400 Hz 30% mod. When f = 0, ANT input becomes the 10 dB output level. Difference in input at each frequency
For
SD sensitivity
OUTPUT [dBm] Total harmonic distortion, THD [dB]
Fidelity Characteristics
Modulation frequency, fm [Hz]
Detection Output, THD - VS Characteristics Total harmonic distortion, THD [%]
IF Count Buffer Output - CL
Detection output
Modulation depth, VS [%]
IF count buffer output [dB]
OUTPUT [mVrms]
Load capacity, CL [pF]
No. 3507-25/28
LA1136N, 1136NM, 1137N, 1137NM
S/N74, Image interference ratio, IF interference ratio AF output, AF-OUT [dBm] Total harmonic distortion, THD [%] S-meter voltage, VSM [V] Band Characteristics (Tracking adjustment at each point) Supply Voltage Characteristics
IF interference ratio
Image interference ratio
SD sensitivity
M.S., Q.S. [dB]
Effective sensitivity (ANT input when S/N = 20 dB)
Maximum Sensitivity (ANT input when output -25 dB)
Total harmonic distortion, THD [%]
Oscillator buffer output, VOSC BUFF [Vrms]
(using varactor diode)
SD sensitivity, Q.S., M.S. [dB]
Receive, fr [kHz] Temperature Characteristics
Supply voltage VCC [V] Temperature Characteristics
VSM120 (Input when S-meter 130 dB)
SD sensitivity
(Maximum sensitivity, input when output -25 dB)
VSM74(S-meter output 74 dB input)
VSM30 30 dB Input ANT DON Level during Tweet prevention
(input when S/N = 20 dB)
(Input detection output 74 dB,
Tweet prevention ANT D. ON level
Total harmonic distortion, THD [%] (80% mod.)
Current drain
V1 (Pin 1 voltage)
Pin-diode driver
Ambient temperature, Ta [C]
Ambient temperature, Ta [C] No. 3507-26/28
Pin 1 voltage [V]
S-meter voltage, VSM [V]
Current drain, ICC [mA]
SD sensitivity, M.S., Q.S. [dB]
LA1136N, 1136NM, 1137N, 1137NM
Temperature Characteristics Stop detector sensitivity [dB]
Stop Detector Adjustment
IF buffer output (AM stereo output) [mVrms]
IF buffer output (74 dB Input, zero modulation)
IF count buffer output oscillator buffer output [mVrms]
Oscillator buffer (Quiescent)
Pin 10 - GND resistance, R10 []
IF count buffer output (30 dB Input, zero modulation)
Stop detector at VCC = 0 V
IF count buffer output leakage voltage [mVrms]
IF count buffer leakage (74 dB Input, zero modulation)
Ambient temperature, Ta [C] Overall characteristics AF-OUTPUT [dBm]
S-meter voltage, VSM [V] Total harmonic distortion, THD [%]
Stop detector voltage [V]
Fidelity Characteristics
AF output [dB] Total harmonic distortion, THD [dB]
fr = 1 MHz Input 74 dB AF-OUTPUT
Input [dB]
VCC = 8 V Ta = 25C fr = 1 MHz fm = 400 Hz 80% mod. M.S. = 17.5 dB Q.S. = 25 dB S/N74 = 54.5 dB AGCFOM = 53.5 dB SD sensitivity = 28 dB
Modulation frequency, fm [Hz]
Deemphasis FASS V.V. DIN AUDIO C.T. SFP450H Murata
No. 3507-27/28
LA1136N, 1136NM, 1137N, 1137NM
Cross-modulation Characteristics
Cross-modulation Characteristics
Target input
Target input Interference input
Target input
Interference input
Target input
Output [dBm]
Output [dBm]
Target input Target input
Target input Interference input
Target input Interference input
Interference input [dB]
Interference input [dB]
No products described or contained herein are intended for use in surgical implants, life-support systems, aerospace equipment, nuclear power control systems, vehicles, disaster/crime-prevention equipment and the like, the failure of which may directly or indirectly cause injury, death or property loss. Anyone purchasing any products described or contained herein for an above-mentioned use shall: 1 Accept full responsibility and indemnify and defend SANYO ELECTRIC CO., LTD., its affiliates, subsidiaries and distributors and all their officers and employees, jointly and severally, against any and all claims and litigation and all damages, cost and expenses associated with such use: 2 Not impose any responsibility for any fault or negligence which may be cited in any such claim or litigation on SANYO ELECTRIC CO., LTD., its affiliates, subsidiaries and distributors or any of their officers and employees jointly or severally. Information (including circuit diagrams and circuit parameters) herein is for example only; it is not guaranteed for volume production. SANYO believes information herein is accurate and reliable, but no guarantees are made or implied regarding its use or any infringements of intellectual property rights or other rights of third parties. This catalog provides information as of September, 1997. Specifications and information herein are subject to change without notice. No. 3507-28/28

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