 |
|
| If you can't view the Datasheet, Please click here to try to view without PDF Reader . |
|
|
|
| If you can't view the Datasheet, Please click here to try to view without PDF Reader . |
|
|
| Datasheet File OCR Text: |
| DS1227 DS1227 KickStarter Chip FEATURES * Provides PIN ASSIGNMENT VCCO2 VCCO3 VCCO1 PWRON VDCO 1 2 3 4 5 6 7 8 9 10 20 19 18 17 16 15 14 13 12 11 VCCO4 MODE4 SENSE INT/ACK OSCEXT BOOST ON1 ON4 RXIN RXOUT step-up regulation and microenergy management for battery-operated systems DC out for system power * Converts +3V to +6V DC input power source to +5V * "Kickstarts" system power upon detection of external stimuli: Clock/calendar alarm Sensor trip; such as from a photo diode Incoming activity to a serial port Any low-level signal transition VDCI GND ON/OFF3 OFF1 ON2/OFF2 * Shuts down microcontroller power under software control when operation complete powering of system functions * Provides 3 auxiliary power outputs for independent * Allows design of "power on demand" systems * Insures maximum life of main power source * Ideally suited for DS5000-based systems * Available in 20-pin DIP or SOIC packages * Operating temperature range of -40C to +85C 20-Pin DIP (300 Mil) See Mech. Drawing - Sect. 16, Pg. 1 VCCO2 VCCO3 VCCO1 PWRON VDCO VDCI GND ON/OFF3 OFF1 ON2/OFF2 1 2 3 4 5 6 7 8 9 10 20 19 18 17 16 15 14 13 12 11 VCCO4 MODE4 SENSE INT/ACK OSCEXT BOOST ON1 ON4 RXIN RXOUT 20-Pin SOIC (300 Mil) See Mech. Drawing - Sect. 16, Pg. 6 ORDERING INFORMATION DS1227: DS1227S: 20-Pin DIP 20-Pin SOIC DESCRIPTION The DS1227 Kickstarter is a unique CMOS circuit which combines power conversion and microenergy management functions for battery operated systems. Using its integral DC-DC converter, the DS1227 supplies +5V on demand from either a 3- or 6-volt battery input. The primary +5V output, typically tied to the microcontroller's VCC pin, is "kickstarted" on in response to any one of several possible momentary, external signal transitions. Two auxiliary +5V power supply outputs can then be independently enabled or disabled under software control. When the primary power supply output is disabled, also under software control, the auxiliary power supply outputs remain in the state selected. In this manner, individual portions of the system can be powered only 022698 1/20 DS1227 when they are required, minimizing the energy consumption of the system. The Kickstarter activates or kickstarts the primary VCC output in response to external momentary low-going signals. Examples of such signals include a clock/calendar alarm from a DS1283 Watchdog Timekeeper, or an incoming asynchronous serial data word from a host PC via the DS1275 Line Powered Transceiver, or a simple pushbutton switch. In addition, the DS1227 kickstarts primary system power in response to activity detected by an external sensor circuit. In this case, the Kickstarter can be signalled at regular intervals, typically from a DS1283 Watchdog Timekeeper, to momentarily apply power to the sensor and monitor an input for an active response. An application using the Kickstarter has the capability to wake-up from a ultra-low power state, perform a task using minimum energy, and then go back to sleep until the DS1227 is signalled to kickstart system operation once again. PIN DESCRIPTION PIN BOOST VDCO VDCI GND VCCO1 ON1 INT/ACK OFF1 PWRON1 I/O Input Output Input Output Input Input/Output Input Output Regulation mode control. Main DC supply voltage output. Main DC supply voltage input. System ground. Primary switched supply voltage output. On control for VCCO1. ON1 is negative edge triggered and internally pulled high via a weak resistor. Interrupt output/input; internally pulled low via a weak resistor during output; level activated via strong high voltage for input. Off control for VCCO1; edge-triggered active low. VCCO1 Power On signal output; Indicates when VCCO1 is powered on; Sometimes required for controlling external tri-state buffers in systems where microenergy management techniques are employed. Auxiliary switched supply voltage outputs. On/Off controls for VCCO2/VCCO3; level activated. DESCRIPTION VCCO2 ON2/OFF2 ON3/OFF3 VCCO4 ON4 SENSE MODE4 RXIN RXOUT OSCEXT Output Input Input Output Input Input Input/Output Input Output Output Momentarily switched VCC output. VCCO4 trigger; edge activated; active low. Sense input sampled just prior to VCCO4 off; turns on VCCO1 if active; active high. Selects VCCO4 on time; level sensitive input/current source output. Serial I/O input; On control for VCCO1 when serial activity detected; edge activated. Serial I/O output; Echos incoming serial data from RXIN when VCCO1 is turned on. Oscillator Signal Output; Gated by internal comparator when BOOST is enabled. Continuous when BOOST is disabled. 022698 2/20 DS1227 INPUT SUPPLY VOLTAGE The Kickstarter is capable of operating either in a regulated step-up DC-to-DC conversion (boost) mode or in a non-regulated supply voltage Pass-Through mode. In boost mode, the Kickstarter is designed to provide a regulated +5V output on the VCCO1, VCCO2, or VCCO3 voltage supply output pins from a +3V lithium source. Figure 1 illustrates the standard configuration for use of this mode. The BOOST pin should be tied low in order to enable step-up DC-to-DC conversion. VDCI is used for the DC power supply input and is tied through an inductor (270 H typical) to a +3V lithium cell. VDCO is the main DC output which is switched to the VCCO1, VCCO2, and VCCO3 outputs. This pin requires a large capacitor (typically 100 F) to ground for the boost regulation low pass output network. Further details of the boost voltage regulator operation are given in the "Boost Mode Operation" section of this data sheet. Figure 2 and Figure 3 illustrate the required configurations to select the supply voltage Pass-Through mode of operation. In both of these configurations the BOOST pin should be strapped directly to the VDCO pin. This connection causes the BOOST pin to remain at a high level at all times that a battery is connected. As a result, the internal boost regulator will be disabled when kickstarting occurs. When a +5V supply is used as the input DC power source, it should be directly connected to the VDCO in parallel with a filter capacitor as shown in Figure 2. The VDCI input itself should be grounded in this configuration. If a +6V supply is used, then it should be connected to the VDCI pin. A filter capacitor should still be connected to VDCO. The voltage on VDCO and subsequently on VCCO1, VCCO2, and VCCO3 (when they are enabled following kickstarting) will be a diode drop below the VDCI voltage. In both the Boost and Pass-Through modes, the DS1227 uses the voltage on VDCO as its own internal supply. DS1227 BOOST MODE CONFIGURATION Figure 1 DS1227 KICKSTARTER 270 uH (typ.) VDCI + +3V - VDCO 100 uF Filter (typ.) BOOST GND VCC01 VCC02 VCC03 .01 uF Bypass (typ.) 022698 3/20 DS1227 DS1227 +5V PASS-THROUGH MODE CONFIGURATION Figure 2 DS1227 KICKSTARTER VDCI VCC01 VCC02 VCC03 BOOST VDCO + +5 - 10 uF (typ.) GND DS1227 +6V PASS-THROUGH MODE CONFIGURATION Figure 3 DS1227 KICKSTARTER VDCI + +6V - BOOST VDCO 10 uF (typ.) GND VCC01 VCC02 VCC03 KICKSTARTER OPERATION A conceptual block diagram of the internal circuitry of the DS1227 is illustrated in Figure 4 for reference. While in an initial power down state, the DS1227 will sense activity from an external stimulus applied to one of three input pins and kickstart system power by applying voltage from the input power source to the primary VCCO output (VCCO1). Activity detected on any of the ON1, RXIN, and SENSE pins initiates the kickstarting action. When kickstarting occurs and the DS1227 is configured for boost operation, the on-chip, step-up DC-to-DC converter is started and the voltage on VDCO will be boosted from its initial VBAT level to VDCON before VCCO1 is turned on. If the DS1227 is configured for voltage Pass-Through operation, then the DC-to-DC converter will remain disabled and voltage on the VDCO line will be switched to the VCCO1 pin immediately following the detection of an active transition on a stimulus input. 022698 4/20 DS1227 Initially, when VCCO1 is off, the INT/ACK pin is collapsed to ground. At the time that voltage is switched to the VCCO1 output pin during kickstarting, the INT/ACK pin will be latched such that it will remain in a low state. This signals the microcontroller that a power on reset has occurred. The OFF1, ON2/OFF2, and ON3/OFF3 inputs are all ignored until the microcontroller acknowledges this power on reset condition. This acknowledgement is performed via the same INT/ACK pin, which also performs the function of an interrupt acknowledge input. This is made possible due to the fact that the pin has a weak NMOS pulldown which forms a latch. When INT/ ACK is externally driven with a sufficiently strong high signal (as described in the "Electrical Characteristics" section) the state of the latch will be switched and as a result the interrupt condition will be reset. After the power on reset interrupt has been acknowledged and the DS1227 is in a power on condition, the INT/ACK pin will be again taken low to signal the detection of active signalling on the ON1 or SENSE inputs. Further activity on the RXIN input will not cause a subsequent interrupt condition. The INT/ACK can be returned to its high (reset) state again by externally driving it with a sufficiently strong high signal. The OFF1 input is used to turn off the VCCO1 output under software control. It is typically interfaced to the system microcontroller via a port pin configured as an output. As noted above, it is active only when VCCO1 is on and INT/ACK has been set high. circuit is then momentarily powered from the Kickstarter's VCCO4 output in response to a negative going edge applied to the ON4 input. VCCO4 will stay powered for an amount of time determined by the circuitry on the MODE4 pin. During the time that VCCO4 is on, the SENSE pin has an internal pulldown device which is activated. SENSE is sampled just prior to the VCCO4 output being disconnected. If SENSE is externally driven high (VIH) at this time, it kickstarts VCCO1 power. Any time that VCCO4 power is off, the SENSE pin appears as a high impedance to external circuitry. The amount of time that VCCO4 is on is determined by the configuration of the MODE4 pin. MODE4 is intended to either be tied high (typically to VDCO) or tied to an external capacitor. The VCCO4 on time is thereby determined either by the amount of time between falling edges on ON4 or by the value of the capacitor. If the MODE4 pin is tied high at the time that ON4 is activated, then VCCO4 will remain on until the next falling edge is detected on ON4. Figure 5 illustrates the timing associated with this mode of operation. If the Kickstarter is also configured for boost regulation and VCCO1, VCCO2, and VCCO3 are turned off, the DC-DC converter will be briefly enabled so that +5V will be supplied on VCCO4 for the duration of the time that it is on. The alternative MODE4 configuration is illustrated in Figure 6A. As shown in the figure, it is recommended for most applications that a large resistor also be connected between MODE4 and ground in addition to the capacitor. For the configuration shown, the MODE4 pin will be sensed low by the Kickstarter just following the negative-going edge at ON4. Following this condition, a constant current specified as IM4ON is supplied out of the MODE4 pin. This will cause the voltage on MODE4 to rise linearly. VCCO4 will remain on until the voltage on MODE4 reaches a threshold specified as VM4OFF (approximately 0.5 VDCO). At this time, VCCO4 will be shut off. At the same time, the constant current source on the MODE4 pin will be disconnected and an internal resistive element (specified as RM4DIS) will be connected between the MODE4 pin and ground. This internal resistive element along with any external resistance will cause the voltage on the capacitor to decay exponentially until it reaches a threshold specified as VM4DIS (approximately 0.1 VDCO). When this condition is reached, the internal resistive element will be disconnected, and the MODE4 pin will appear as a high impedance until the next active transition occurs on ON4. The external re- STIMULUS INPUTS ON1 is a simple TTL-level compatible input which is designed to detect a negative-going edge. VCCO1 is kickstarted whenever an active edge is detected on this pin. The RXIN input can be used to initiate the kickstarting action in response to the detection of incoming serial data. In this configuration, the RXIN pin is interfaced to an incoming serial data line, typically from an RS232 transceiver. RXOUT is the corresponding output and is used to route the serial data to the microcontroller. RXIN remains internally disconnected from RXOUT until VCCO1 is powered on. At that time, the two lines are connected and serial data is passed straight through the device to the microcontroller. The SENSE pin is intended to be connected to an external sensor circuit which is powered from VCCO4. This 022698 5/20 DS1227 sistor (if present) will then cause the voltage on MODE4 to further decay until it reaches ground or until the next ON4 negative transition, whichever comes first. When MODE4 is initially grounded as described above, VCCO4 power is switched from the VDCO pin, regardless of whether or not VCCO1, VCCO2, or VCCO3, are powered on. This means that VCCO4 will be switched with the voltage present on VDCO, which could be from +3V to +5V depending on the configuration, input battery voltage used, and whether or not VCCO1, VCCO2, or VCCO3 are switched on. The above described sampling operation of VCCO4 and SENSE in response to ON4 also takes place when a kickstart has already occurred and VCCO1 is on. If SENSE is found to be active in this condition, an interrupt will be signalled on the INT/ACK pin. on or off as desired under control of the system application software. The ON2/OFF2 and ON3/OFF3 inputs are level activated. The corresponding VCCO output therefore turns on when the on/off pin is high and off when it is low. These inputs are active only if the VCCO1 output is on and the INT/ACK output has been set to a high state signalling a power on reset condition. When VCCO2 or VCCO3 are turned on, they will remain on until the corresponding control input is taken low by the software. This is true even if the OFF1 input is taken to its active low state at the time that either ON2/OFF2, ON3/OFF3, or both, are high. Once OFF1 is activated, the current states of ON2/OFF2 and ON3/OFF3 are internally latched and further activity on these pins is ignored. If both of the corresponding outputs (VCCO2 and VCCO3) are turned off at this time and boost operation has been selected, then the internal oscillator is killed and the DC-to-DC converter will be shut down. If either VCCO2 and/or VCCO3 are left switched on when OFF1 is activated, they will remain switched on even after VCCO1 has been turned off. If the DS1227 has been configured for boost operation, the DC-to-DC converter will remain operational during the entire time that VCCO1 is turned off so that +5 volts will continue to be supplied on either or both of these output pins. These pins can be shut off only when kickstarting occurs once again and VCCO1 is switched on and INT/ACK has been set high. MICRO ENERGY MANAGEMENT In addition to the kickstarting features described above, the DS1227 allows sections of system circuitry to be individually powered up or down under command of the microcontroller. This capability is referred to as the Micro Energy Management feature of the DS1227. VCCO2 and VCCO3 are auxiliary power supply outputs which may be switched on or off via the ON2/OFF2 and ON3/OFF3 pins, respectively. The ON2/OFF2 and ON3/OFF3 control pins are intended for connection to two microcontroller's port pins configured as outputs. The corresponding VCCO output pins can then be turned 022698 6/20 VDCI VCC0 (+5V) VCC01 DS5000FP BOOST HIENUF PWRON D VDCO Q CLR ON 4 ONE SHOT R MODE4 PWRON1 INT/ACK SQ Q RAM DC-DC CONVERTER DS1283 OSCEXT VCC04 VCC02 SENSE A/D RXIN EVENT TRIGGER CIRCUITS D/A DS1227 KICKSTARTER BLOCK DIAGRAM Figure 4 ON1 VCC03 DS1209 DS1203 OFF1 ON2/OFF2 ON3/OFF3 D2 G D1 Q1 Q2 LCD DISPLAY DS1227 022698 7/20 DS1227 SENSE INPUT TIMING; MODE4 STRAPPED HIGH Figure 5 MODE4 ON4 tD4ON tD4OFF VCC04 SENSE VCC01 MODE4 RC NETWORK CONNECTION Figure 6A ON4 tD4ON VCC04 tV4ON MODE4 SENSE VCC01 tM4OFF tM4OIS SENSE INPUT TIMING; MODE4 WITH RC NETWORK Figure 6B DS1227 KICKSTARTER MODE4 R C If I M4ON t V4ON uu 1 2 V DCO : R V DCO M4ON [ 1 C (I 2 ) 022698 8/20 DS1227 BOOST MODE OPERATION The DS1227 Kickstarter incorporates all of the necessary control and power switching functions required for its +3V to +5V step-up DC-to-DC converter. These functions include a bandgap reference, oscillator, voltage comparator, catch diode and an N-channel MOSFET. The only external components required are an output filter capacitor and a low cost inductor. The block diagram shown in Figure 7 illustrates the DC-to-DC converter. When kickstarting occurs from an initial powered down state (i.e., VCCO1, VCCO2, and VCCO3 turned off), an internal start sequence is initiated within the DS1227. During this sequence, the VCCO1 output remains shut off and the BOOST pin is sampled in order to determine if the DS1227 is configured for boost mode operation. If BOOST is low, then boost mode operation is enabled and the DC-to-DC converter is started. The internal DC-to-DC converter is started by enabling the on-chip 40 KHz oscillator. It then begins to build up the voltage on the VDCO filter capacitor. Internal counter logic insures that the DC-to-DC converter stays in start mode for a minimum of six clock periods (nominally 150 s @ 40 KHz). After this initial delay time, the VDCO output is monitored by the internal Error Comparator as it slews up to VDCON. As long as the VDCO voltage remains below the preset value, the Error Comparator will be switched high and the internal 40 KHz oscillator will be connected to the gate of the VDCI driver. The VDCI driver is a large N-channel MOSFET with a typical ON resistance of less than 4 Ohms and is capable of supplying a peak current of 450 mA. The output device is turned on during each ON half-cycle generated by the internal square-wave oscillator, and is turned off during each OFF half-cycle. During each ON half-cycle, the current through the inductor rises linearly, storing energy in the coil. When the output device is turned off, the external inductor's magnetic field collapses, and the voltage across the inductor reverses sign. The voltage at VDCI then rises until the internal diode is forward biased, delivering power to the VDCO output. The converter is thereby powered from its own VDCO output. This is often referred to as "bootstrapped" operation, since the circuit figuratively "lifts" itself up. In order to guarantee that the Kickstarter can bootstrap itself up to operating voltage, the VDCI voltage must be at the minimum level of VDCISU as listed in the DC characteristics section of this data sheet. When the voltage on VDCO rises to the VDCON threshold, the internal signal called "HIENUF" will be active and the VCCO1 PMOS device is switched on. As noted above, internal circuitry insures that this device will not be switched on for a minimum of 6 clock cycles from the time that the DC-to-DC converter is started. However, since the recommended values for the external LC components result in a time constant which is much longer than six cycles, the actual slew rate will in practice be much longer than this delay time. If loading of the VCCO outputs causes VDCO to drop below VDCOFF the DS1227 will deactivate HIENUF and the VCCO1 PMOS device as well as the other VCCO PMOS devices will be switched off. The VDCO voltage will then be monitored for the VDCON trip point before reconnecting the load. As a result, the power control regulation loop could oscillate between these two states until the VCCO1 node had sufficient charge to remain above the VDCOFF threshold. To prevent this from occurring, the value of the filter capacitor must be sufficiently large. For large capacitive loads on VCCO1 the output may dip below VDCOFF as a result of charge sharing and a larger regulation capacitor at VDCO may be required. For large resistive loads the inductance and capacitance values may need to be adjusted using a smaller inductor value and large capacitance. In order not to violate the peak VDCI current it may be necessary to use the external oscillator OSCEXT to drive an additional switchmode boost regulator, as shown in Figure 8. Following the above described start sequence, normal boost operation is performed by the converter. VDCO output voltage is constantly monitored by the error comparator. When VDCO voltage drops below the preset value, the error comparator switches high and connects the internal 40 KHz oscillator to the gate of the VDCI output driver. When the output voltage reaches the desired level, the error comparator inhibits the VDCI output driver until the load on VCCO1 discharges the output filter capacitor to less than the desired output level. INDUCTOR SELECTION The available output current from the Kickstarter's on-chip DC-DC boost converter is a function of the input voltage, external inductor value, output voltage and the operating frequency. For most applications, the inductor is the only design variable since the internal oscillator is preset to a fixed value of 40 KHz. The proper inductor must have the following characteristics: 022698 9/20 DS1227 1) the correct inductance value must be selected. 2) the inductor must be able to handle the required peak currents. 3) the inductor must have acceptable series resistance and must not saturate. When the internal N-channel MOSFET turns on, the current through the inductor rises linearly since: di V + where L is the inductance value dt L At the end of the on-time, tON, the peak current, IPK is: I PK + V t ON L where : t ON + 1 2f O The energy in the inductor is: EL + L I PK 2 2 At maximum load this cycle is repeated f0 (typically 40 KHz) times per second, and the power transferred through the coil is PL = f0 x EL. Since the coil only supplies the voltage above the input voltage: I OUT + PL V OUT * V IN DC-DC CONVERTER Figure 7 DC TO DC CONVERTER VDCO BOOST VDCI ERROR COMPARATOR EXTERNAL PINS - DQ + Q CLR CATCH DIODE VDCI DRIVER VCCO LOAD COMPARATOR + - HIENUF INTERNAL SIGNALS OSCEXT 8 CLK DELAY 40 KHZ OSCILLATOR M U X BANDGAP REFERENCE PWRON* (INTERNAL SIGNAL) 022698 10/20 DS1227 AUXILIARY BOOST SUPPLY CONFIGURATION Figure 8 100 H (typ.) 1N5418 VCCOAUX DS1227 KICKSTARTER OSCEXT 270 H (typ.) VDCI + +3V - VDCO 200 F (typ.) BOOST GND VCC01 VCC02 VCC03 The DC-DC converter's output current is provided both by the inductor and directly from the battery. If the load draws less than the maximum current, the VDCI n-channel MOSFET is turned on only often enough to keep the output voltage at the desired level. If the selected inductor has too high a value, the DS1227 will not be able to deliver the desired output power, even with the MOSFET turned on for every oscillator cycle. The available output power can be increased by either raising the input voltage or lowering the inductance. This causes the current to rise at a faster rate, and results in a higher peak current at the end of each cycle. The available output power increases since it is proportional to the square of the peak inductor current. The maximum inductance therefore is: L MAX + V IN 2 8 fO PL L I PK2 f O 2 and : I PK V IN + fL 2O where: IOUT = IOUT1 + IOUT2 + IOUT3 + IOUT4 If the inductance value is too low, the current at VDCI may rise above the maximum rating. The minimum allowed inductor value is expressed by: L MIN + V IN (I ) 450 mA) 2 f O I MAX MAX TYPES OF INDUCTORS The following is a brief discussion of various types of inductors which may be typically used with the DS1227 Kickstarter to facilitate boost mode operation. Table 1 lists some typical manufacturers of these types of inductors. Table 2 summarizes performance of the circuit for various inductors. Molded Inductors These are cylindrically wound coils which look similar to 1-watt resistors. They have the advantages of low cost and ease of handling, but have higher resistance, higher losses, and lower power handling capability than other types of inductors. since : P L + The required output power must include what is dissipated in the forward drop of the catch diode and each of the VCCO1, VCCO2, and VCCO3 pass transistors. This can be expressed as follows: POUT = VF IOUT + (IOUT12 RON1 + IOUT22 RON2 + IOUT32 RON3 + IOUT42 RON4) + VOUT IOUT Potted Toroidal Inductors A typical 1 mH, 0.82 ohm potted toroidal inductor (Dale TE-3Q4TA) is 0.685 in diameter by 0.385 high and 022698 11/20 DS1227 mounts directly onto a printed circuit board by its leads. Such devices offer high efficiency and mounting ease, but at a somewhat higher cost than molded inductors. Toroidal Cores In volume production, the toroidal core offers high performance, low size and weight, and low cost. They are, however, slightly more difficult for prototyping, in that manually winding turns onto a toroid is more tedious than on the plastic bobbins used with pot cores. Toroids are more efficient for a given size since the flux is more evenly distributed than in a pot core, where the effective core area differs between the post, side, top, and bottom. Since it is difficult to gap a toroid, manufacturers produce toroids using a mixture of ferromagnetic powder (typically iron or Mo-Permalloy powder) and a binder. The permeability is controlled by varying the amount of binder, which changes the effective gap between the ferromagnetic particles. Mo-Permally powder (MFP) cores have lower losses and are recommended for the highest efficiency, while iron powder cores are lower cost. Ferrite Cores (Pot Cores) Pot cores are very popular as switch-mode power supply applications since they offer high performance and ease of design. The coils are generally wound on a plastic bobbin, which is then placed between two pot core sections. A simple clip to hold the core sections together completes the inductor. Smaller pot cores mount directly onto printed circuit boards via the bobbin terminals. Cores come in a wide variety of sizes often with the center posts ground down to provide an air gap. The gap prevents saturation while accurately defining the inductance per turn squared. Pot cores are suitable for all DC-DC converters, but are usually used in the higher power applications. They are also useful for experimentation since it is easy to wind coils onto the plastic bobbins. COIL AND CORE MANUFACTURERS Table 1 TYPE Molded " " " " Potted Toroidal " " " Toroidal Core " " Ferrite Core " Note: TYPICAL MANUFACTURER Dale Cadell-Burns Gowanda Nytronics TRW Dale Gowanda TRW Torotel Prod. Allen Bradley Siemans Magnetics Stackpole Magnetics PART # 1HA-104 7070-29 1B253 WEE-470 LL-500 TE-3Q4TA 050AT1003 MH-1 PT 53-18 T0451S100A B64290-K38-X38 555130 57-3215 G-41408-25 DESCRIPTION 500 H, 0.5 ohms 220 H, 0.55 ohms 250 H, 0.44 ohms 470 H, 10 ohms 500 H, 0.75 ohms 1 mH, 0.82 ohms 100 H, 0.05 ohms 600 H, 1.9 ohms 500 uH, 5 ohms 500 nH/T2 4 H/T2 53 nH/T2 14 mm x 8 mm 14 x 8, 250 nH/T2 This list does not constitute an endorsement by Dallas Semiconductor and is not intended to be a comprehensive list of all manufacturers of these components. 022698 12/20 DS1227 INDUCTOR SELECTION FOR COMMON DESIGNS Table 2 VIN (V) 2 2 2 3 3 Note: VDCO (V) 5 5 5 5 5 IOUT (mA) 5 10 15 25 40 EFF. (%) 78 74 61 82 75 PART # CB 6860-21 G 1B253 G 1B103 CB 6860-21 CB 7070-29 INDUCTOR uH 470 250 100 470 220 Ohms 0.4 0.44 0.25 0.4 0.55 CB = Cadell-Burns, NY (516) - 746 -2310 G = Gowanda Electronics Corp., NY (716) - 532-2234 Other manufacturers listed in Table 1. High quality aluminum or tantalum filter capacitors will minimize output ripple, even if smaller capacitance values are used. Best results at reasonable cost are typically achieved in the 100 to 500 F range, in parallel with a 0.1 F ceramic capacitor. OUTPUT FILTER CAPACITOR In boost regulation mode, the DS1227's output voltage ripple on VDCO has two components, with approximately 90o phase difference between them. One component is created by the change in the capacitor's stored charge with each output pulse. The other ripple component is the product of the capacitor's charge/discharge current and its ESR (Effective Series Resistance). With low cost aluminum electrolytic capacitors, the ESR produced ripple is generally larger than that caused by the change in charge. V ESR + I PK x ESR + V IN x ESR (Volts p * p) 2Lf O OSCEXT FUNCTIONS The OSCEXT pin is connected to the internal 40 KHz oscillator (nominal frequency). When Boost mode is enabled (BOOST = 0) and the DC-to-DC converter is running, OSCEXT is active at the same time whenever the error comparator is switched high, i.e., whenever the internal oscillator is enabled to the gate of the VDCI driver. In this configuration it may be used to drive an auxiliary switch mode boost regulator as shown in Figure 8. In this circuit, OSCEXT drives an external NMOS switch with its drain pin connected to an additional inductor and filter capacitor as well as an external catch diode. The amount of supply current which can be realized at the +5V output is determined by the power ratings of the external components. Through proper selection of the these components, increased supply current can be realized than is possible using the Kickstarter's internal VDCI driver and catch diode. When the Pass-Through mode is enabled (BOOST = 1) and at least one of the VCCO outputs is switched on, the OSCEXT pin will be continuously driven with the 40 KHz frequency. In this configuration this pin could potentially be used to generated negative or doubled voltages as shown in Figure 9. Where VIN is the coil input voltage, L is its inductance, f is the oscillator frequency, and ESR is the equivalent series resistance of the filter capacitor. The output ripple resulting from the change in charge on the filter capacitor is: t DIS x I peak Q where, Q + 2 C t CHG x V IN L V dQ + and, I peak + V dQ + V IN x t CHG x t DIS 2LC Where tCHG and tDIS are the charge and discharge times for the inductor 1/2 fO can be used for nominal calculations). 022698 13/20 DS1227 VOLTAGE INVERTOR AND DOUBLER CONFIGURATIONS Figure 9 DS1227 KICKSTARTER OSCEXT + 10 F 1N4148 + 10 F VOSCEXT = -(VDCO - 2VF) 1N418 DS1227 KICKSTARTER 1N4148 VDCO + OSCEXT NOTE: VF = FORWARD 1N418 DIODE VOLTAGE 1N4148 VOSCEXT = 2(VDCO - VF) APPLICATION BRIEF The schematic shown in Figure 10 illustrates a typical application of the DS1227 Kickstarter in a microcontroller-based, battery powered system. Together with the Kickstarter, the system incorporates a DS5000FP Soft Microcontroller, a DS1283 Watchdog Timekeeper, and a DS1275 Line Powered RS232 Transceiver. Although the system is not designed to serve a specific application, this chip set could serve the majority of requirements for many types of hand-held instruments. Using the illustrated configuration provides the following major features: * Permanently powered operation from a +3V source for many applications * Data and event logging with time stamp and date * Reprogrammable through RS232 serial interface * Buttonless (autonomous) operation for many tasks 8051. It provides an embedded interface to 32 Kbytes of nonvolatile static RAM which can be dynamically partitioned for program and data storage, and may be loaded at any time via the on-chip serial port. With proper selection of RAM and the backup lithium source, nonvolatile storage can be maintained for over 10 years in the absence of VCC. The DS5000FP offers the standard low power operating and standby modes (i.e., Idle, Stop). More importantly, sophisticated crashproof circuitry in conjunction with the lithium energy source allows it to retain its entire operating state for the duration of a power outage without drawing current from its VCC line. Timekeeping is provided by the DS1283 Watchdog Timekeeper. Incorporating a self-contained clock and calendar, the DS1283 tracks hundredths of seconds, seconds, minutes, hours, days, date of the month, month, and years. When its chip enable is inactive (no read or write), the DS1283 consumes extremely low current, typically 500 nA. Two alarm functions are provided: a time-of-day Alarm, and a watchdog alarm. The time-of-day Alarm can generate an interrupt pulse up to one week in advance of the current time. The watchdog alarm can produce an interrupt at regular intervals ranging from .01 seconds to 99.99 seconds. Both alarms function when the part is operating in low power standby mode. COMPONENT DESCRIPTION The DS5000FP is an 8-bit microcontroller which is instruction set-compatible with the industry standard 022698 14/20 DS1227 The DS1275 Line Powered RS232 Transceiver allows the instrument to communicate with the RS232 port on a host computer (e.g., COM port on an IBM PC). It operates from a +5V supply and draws no power from the instrument's main energy source to create negative voltages. Instead, it steals power from the incoming RXD line to generate the negative voltages needed during transmission. INSTRUMENT OPERATION A common requirement of instruments is event logging with time stamp and date. The Dallas chip set provides this capability using the DS5000 and DS1283. The DS1283 interfaces directly to the DS5000FP embedded bus, and may be accessed by CE2. In this way, valuable port pins are conserved. Events can be recorded by the microcontroller and logged in RAM with the date and time. In the absence of VCC, the data will be retained in RAM by the backup lithium cell. The same energy cell provides backup to the DS1283, so that timekeeping is maintained in the absence of a primary energy source. Therefore, events may be time stamped and dated with confidence that the correct time has been maintained. Backup lithium current is managed by the DS5000FP and is distributed from the VCCO line in the absence of VCC. perform most instrument functions using minimal power. Using a 3.57 MHz crystal, the circuit in Figure 1 will draw approximately 8 mA during microcontroller operation. When the Kickstarter turns off the DS5000, the circuit draws approximately 5 A from the primary energy source. If a similar configuration were created with an ordinary CMOS microcontroller in stop mode, the current could be as high as 55 A. Idle mode operation would consume approximately 3 mA, which would excessively drain a primary power source over extended periods. The Dallas low power chip set provides a tento-one improvement over previously available alternatives. Achieving the lowest power instrument requires the DS1227 Kickstarter. Using the Kickstarter, low power operation is achieved by powering down the microcontroller. When this occurs, the DS5000 effectively consumes zero power. RAM and key registers are backed by the lithium button cell, with no power draw from VCC. When a task must be performed, the Kickstarter powers up the DS5000 to execute a function and powers it down when the function is complete (under software direction). The period for which power remains on is minimized in this way. Since most tasks require minimal processing time with long periods of waiting, the instrument may remain in a low power data retention mode for the majority of time. Therefore, even if an operator interface is necessary, the microcontroller can remain on for milliseconds (or microseconds) to perform a task, and remain off for the seconds between operations. The ability to react to external stimuli allows the instrument to operate autonomously for many applications. Fundamental to this operation is the kickstart caused by external stimuli. The following section describes the operation of the Kickstarter with respect to four different stimuli. PERMANENTLY POWERED OPERATION In order to achieve permanently powered operation, Dallas Semiconductor uses several techniques which conserve the life of a primary energy source. First, the illustrated chip set operates at extremely low power. These components are also capable of very low power data retention. Second, the crashproof circuitry of the DS5000 allows VCC to be removed and restored without disruption. This allows the energy management circuits of the Kickstarter to power down the microcontroller during periods when it is unused. Since the DS1227 can monitor external events and wakeup the DS5000 as necessary, the microcontroller and other circuitry may remain in low power data retention mode until needed. The DS5000, RAM, and DS1283 will be backed up via the button cell as show in Figure 1. Finally, the Kickstarter allows software-controlled powering of auxiliary circuits when tasks require them. Low operating power is a basic requirement of batteryoperated systems. The illustrated Dallas chip set can KICKSTARTING OPERATION The DS1227 receives primary power from a +3V lithium battery. Prior to a kickstart, battery voltage is present on VDCO, which is the main voltage output. When the system receives a kickstart stimulus, an on-chip boost regulator raises VDCO to +5V. Upon completion of power up, +5V is switched to the DS5000 on VCC01. Prior to kickstart, no power was supplied to this line. 022698 15/20 DS1227 TYPICAL APPLICATION OF DS1227 KICKSTARTER Figure 10 022698 16/20 TO AUXILIARY CIRCUITS POWER 44OK .001uF PHOTO DIODE LED 1M 5K VCC02 VCC03 VCC01 PWRON VDC0 VDC1 GND ON/OFF3 OFF1 ON/OFF2 1 2 3 4 5 6 7 8 9 10 DS1227 20 19 18 17 16 15 14 13 12 11 VCC04 MODE4 SENSE INT/ACK OSCEXT BOOST ON1 ON4 RXIN RXOUT + +3V LITHIUM (Primary Power BATTERY Source) DOUT 1 VDRV 2 DIN 3 GND 4 DS1275 VCC 8 RXIN 7 NC 6 TXOUT 5 TO RS232 4.7K 100uF P2.7 P2.6 P2.5 P2.4 P2.3 P2.2 P2.1 P2.0 P3.7 P3.6 P3.5 P3.4 P3.2 P3.1 P3.0 PSEN ALE EA RESET 68 70 73 34 32Kx8 SRAM P0.7 P0.6 P0.5 P0.4 P0.3 P0.2 P0.1 P0.0 P1.7 P1.6 P1.5 P1.4 P1.3 P1.2 P1.1 P1.0 75 77 79 1 5 7 9 11 31 29 27 25 21 19 17 15 DS5000FP VCC VCC GND GND +3V Lithium (button cell) ECE1 ECE2 ER/W VCC0 VLI XTAL2 XTAL1 16 8 18 80 76 4 6 20 24 26 28 30 33 35 37 71 69 67 65 61 59 57 55 A13 A12 A7 A6 A5 A4 A3 A2 A1 A0 DQ0 DQ1 DQ2 GND VCC WE A14 A8 A9 A11 OE A10 CE DQ7 DQ6 DQ5 DQ4 DQ3 INTA X1 X2 NC 32KHZ A5 A4 A3 A2 A1 A0 DQ0 DQ1 DQ2 GND EA14 EA13 EA12 EA11 EA10 EA9 EA8 EA7 EA6 EA5 EA4 EA3 EA2 EA1 EA0 ED7 ED6 ED5 ED4 ED3 ED2 ED1 ED0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 DS1283 28 27 26 25 24 23 22 21 20 19 18 17 16 15 VCC WE INTB VBAT RCLR SQW OE INTP CE DQ7 DQ6 DQ5 DQ4 DQ3 DS1227 The schematic in Figure 1 demonstrates four kickstart stimuli. They are real time clock alarm, RS232 incoming data, a sensor input, and a user switch. During the low power standby prior to kickstart, VCCO from the DS5000 provides battery power to the RAM and real time clock from the button cell. VDCO supplies the RS232 transceiver. While operating on battery power, the RTC can still issue alarms. If a time of day alarm is programmed, INTA will be taken low by the RTC when the alarm occurs. Th is is connected to ON1, and issues a Kickstart. Incoming RS232 activity will allow the transceiver to Kickstart the DS1227. Following the initial interrupt, all additional RS232 data is passed through the RXIN/ RXOUT pins of the DS1227 to the DS5000 without further action. In this way, the instrument can collect a table of data and dump it to a PC for analysis when necessary. Since the instrument will kickstart when it detects RS232 communication, it is unnecessary for an operator to take further action. Enough time should be allowed for the DS5000 to complete a power-on reset before sending meaningful data. Two additional methods of kickstarting are illustrated. One method involves the use of a sampled sensor. A periodic pulse (the watchdog alarm) from the DS1283 causes VCC04 to be applied to the LED. For example, this might occur every 250 ms. It remains on for the time it takes to charge the capacitor on Mode4 to 1/2 VDCO (1.5V). In this example, the on period is approximately 75 sec. Just prior to removing VCC04, the sense line is sampled. If the LED light path to the photodiode is blocked, the sense line will be high and the system will be kickstarted. If the light path is clear, the sense line will be low, and nothing will happen. This facilitates checking for the presence of an ID card in a reader. In the other method a user switch, which is momentarily closed, will start the system. This is tied to ON1 in a wired-OR configuration. All of the above kickstart stimuli cause the boost regulator to raise VDCO and turn on VCC01. In summary, the four kickstart stimuli are: 1) Time of Day Alarm - INTA goes low and Kickstarts VCC01. 2) RS232 Activity - Powers up VCC01 and routes all RS232 straight through to the DS5000. 3) INTB goes low periodically, VCC04 turns on, and the sense line is sampled. If high, a kickstart occurs. If low, no action. 4) A user switch momentarily pulls ON1 low and kick starts. Although the user switch is easily implemented, it may be unnecessary. By allowing the instrument to power up and determine the cause of the Kickstart, it is possible to achieve buttonless operation in many applications. Automatic response allows the instrument to function autonomously and save power by turning off unused circuits. Once the DS5000 receives power, it must read the INT/ ACK line (tied to INT0). A power-on condition causes this signal to be low. The DS5000 port pin should then acknowledge power up by driving this line high. This recognizes the interrupt and enables the kickstarter for further activity. The DS5000 may now turn on auxiliary loads VCC02 and VCC03 using ON/OFF 2 and 3 (tied to any port pins). These auxiliary supplies may supply circuits which are not always necessary (e.g. an A/D converter). Peripheral circuits remain powered down until needed. After an operation is complete, the DS5000 can turn off the auxiliary circuits. When processing of a task is complete, it may turn itself off using OFF1. An application may require that an auxiliary circuit remain on when the microcontroller is off. This might occur with an LCD display or dual slope A/D converter. Since the dual slope A/D takes a relatively long period to convert (40-50 mS), the microcontroller may be powered down while waiting. Since the INT/ACK line is tied to INT0, additional kickstart stimuli which occur while VCC01 is on will cause the DS5000 to receive an interrupt. This allows the DS5000 to take action for specific conditions. Precautions against excessive current drain are taken in this application. For example, the data input to the DS1275 RS232 transceiver is tri-stated when VCC01 is off. This is necessary to prevent a high signal from driving the RS232 bus and consuming power while the DS5000 is off. Similar precautions should be taken by the user in designing systems with switched power supplies. 022698 17/20 DS1227 ABSOLUTE MAXIMUM RATINGS* Input Voltage on any Pin Relative to Ground VDCI Peak Input Current Power Dissipation Plastic DIP (derate 7.41 mW/oC above +50oC) Small Outline (derate 12.5 mW/oC above +50oC) Operating Temperature Storage Temperature Lead Soldering Temperature -0.3 to 7.0V 450 mA - 555 mW - 937 mW -40C to +85C -55C to +125C 260C for 10 seconds * This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operation sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability. ELECTRICAL CHARACTERISTICS PARAMETER Startup Voltage VDCO Voltage Threshold for VCCO Turn-ON VDCO Voltage Threshold for VCCO Turn-OFF Operating Supply Current (BOOST=0) (BOOST=1) Standby Supply VCCO1 DC Source Current (VCCO1 = VDCO -0.25V) VCCO2, VCCO4 DC Source Current (VCCO2, VCCO4 = VDCO - 0.25V) VCCO3 Source Current (VCCO3 = VDCO - 0.25V) VCCO1, VCCO2, VCCO3, VCCO4 Voltage VCCO1, VCCO2, VCCO3, VCCO4 Voltage VCCO4 Voltage VCCO1 ON Resistance VCCO2, VCCO4 ON Resistance VCCO3 ON Resistance Efficiency SYMBOL VDCISU VDCON VDCOFF ICC 1.5 0.5 ISB ICCO1 ICCO2 ICCO4 ICCO3 VOUTB VOUTP VOUT4 RVCCO1 RVCCO2,4 RVCCO3 80 4.75 VDCO -0.25 VDCO -0.25 2.5 5.0 25 5.00 3.0 1.0 200 100 50 MIN 1.8 4.20 4.30 4.62 4.00 TYP MAX (tA = -40C to +85C) UNITS V V V NOTES 1 mA mA nA mA mA 4 2 2, 7 2, 7 10 5.25 mA V V V Ohms Ohms Ohms % 2, 7 1, 4 2 1, 8 022698 18/20 DS1227 PARAMETER Line Regulation +0.5VCCO < +VS < VCCO Oscillator Frequency Oscillator Duty Cycle OSCEXT ON Resistance VDCI Driver ON Resistance (@ IVDCI = 100 mA) VDCI Driver OFF Leakage Current (tA = 25o C) Catch Diode Forward Voltage Output Low Voltage, (OSCEXT, PWRON1) IOL = 1.6 mA Output High Voltage (OSCEXT, PWRON1) IOH = -80 A Input Low Current (INT, ON2/OFF2, ON3/OFF3, ON4, BOOST) Input Low Current (ON1, RXIN) Output High Current (PWRON1) Output Low Current (PWRON1) RXIN Current (VRXIN - VRXOUT < 500 mV) INT/ACK Input Transition Current INT/ACK Input Leakage Current 0.0 < VIN < 0.1, or VDCO - 0.1 < VIN < VDCO SENSE Resistance (VCCO4 ON) MODE4 Source Current (MODE4 = 0 when ON4 goes from 1 to 0) MODE4 Source Current Shutoff Voltage MODE4 Discharge Resistance (Following current source shutoff) MODE4 Discharge Resistance Shutoff Voltage SYMBOL VCCO MIN TYP MAX 0.4 UNITS % KHz % NOTES 1 40 50 ROSCEXT RVDCION IVDCIL VF VOL VOH 2.4 50 6 75 14 30 1.0 0.45 Ohms Ohms A V V 1 1 V IIL1 -1.0 1.0 A IIL2 IOH IOL IRXIN IACKT IACKL -50 -400 2.0 10 + 2.0 + 200 A A mA mA mA A 6 5 5 250 IM4ON 10 45 100 KOhms A VM4OFF RM4DIS 0.5VDCO 2 KOhms VM4DIS 0.1VDCO 022698 19/20 DS1227 NOTES: 1. Applicable only when Boost mode operation is in effect. 2. Applicable only when Pass Through mode operation is in effect. 3. Valid when 2.5V < VDCO < 5.0V. 4. Measured with Boost Mode operation in effect; ICCO1 = ICCO2 = ICCO3 = ICCO4 = 0. This value represents the amount of current drawn by the DS1227 itself during and does not include current supplied on the ICCO outputs nor does if boost operator includes inefficiencies of DC-to-DC conversion. 5. Input transition current on the INT/ACK pin is specified to indicate the amount of current required to switch the pin from a high to a low or from a low to a high condition. Once the pin has switched states, then the leakage current specification is applicable. 6. ON1 and RXIN have internal weak p-channel pull-up devices. 7. When BOOST operation is in effect, the total combined current supplied out of VCCO1, VCCO2, VCCO3, and VCCO4 is limited by the VDCI peak current. 8. Actual efficiency is dependent on external discrete component characteristics. 9. Battery replacement in the boost mode requires the discharge of the capacitor attached to VDCO (pin 5). The following, or similar, circuit is recommended (see Figure 11). BATTERY DISCHARGE CIRCUIT Figure 11 BATTERY CHANGE DETECTOR TO BATTERY VDCO (PIN 5) RB400D 2N7002 + 100 F 4M TC7SU04F 022698 20/20 |
Price & Availability of DS1227
 |
|
|
|
|
All Rights Reserved © IC-ON-LINE 2003 - 2022 |
| [Add Bookmark] [Contact Us] [Link exchange] [Privacy policy] |
|
Mirror Sites : [www.datasheet.hk]
[www.maxim4u.com] [www.ic-on-line.cn]
[www.ic-on-line.com] [www.ic-on-line.net]
[www.alldatasheet.com.cn]
[www.gdcy.com]
[www.gdcy.net] |