TL431, TL431A ADJUSTABLE PRECISION SHUNT REGULATORS SLVS005N - JULY 1978 - REVISED MARCH 2002 D D D D D D Equivalent Full-Range Temperature Coefficient . . . 30 ppm/C 0.2- Typical Output Impedance Sink-Current Capability . . . 1 mA to 100 mA Low Output Noise Adjustable Output Voltage . . . Vref to 36 V Available in a Wide Range of High-Density Packages description The TL431 and TL431A are three-terminal adjustable shunt regulators with specified thermal stability over applicable automotive, commercial, and military temperature ranges. The output voltage can be set to any value between Vref (approximately 2.5 V) and 36 V, with two external resistors (see Figure 17). These devices have a typical output impedance of 0.2 . Active output circuitry provides a very sharp turn-on characteristic, making these devices excellent replacements for Zener diodes in many applications, such as onboard regulation, adjustable power supplies, and switching power supplies. The TL431C and TL431AC are characterized for operation from 0C to 70C, and the TL431I and TL431AI are characterized for operation from -40C to 85C. D PACKAGE (TOP VIEW) CATHODE ANODE ANODE NC 1 8 2 7 3 6 4 5 REF ANODE ANODE NC P, PS, OR PW PACKAGE (TOP VIEW) CATHODE NC NC NC 1 8 2 7 3 6 4 5 REF NC ANODE NC TL431 . . . DBV PACKAGE (TOP VIEW) NC 1 NC 2 CATHODE 3 5 ANODE 4 REF NC - No internal connection TL431 . . . KTP PACKAGE (TOP VIEW) CATHODE ANODE ANODE REF LP PACKAGE (TOP VIEW) CATHODE ANODE REF TL431 . . . PK PACKAGE (TOP VIEW) REF ANODE CATHODE Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. Copyright 2002, Texas Instruments Incorporated PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. POST OFFICE BOX 655303 * DALLAS, TEXAS 75265 1 TL431, TL431A ADJUSTABLE PRECISION SHUNT REGULATORS SLVS005N - JULY 1978 - REVISED MARCH 2002 AVAILABLE OPTIONS PACKAGE TA 0C to 70C -40C to 85C SMALL OUTLINE (D, PS) TL431CD TL431CPSR TL431ACD TL431ACPSR SOT-23 (DBV) PLASTIC FLANGE MOUNT (KTP) TO-226AA (LP) PLASTIC DIP (P) TL431CDBVR TL431CKTPR TL431CLP TL431ACLP TL431CP TL431ACP TL431ILP TL431AILP TL431IP TL431AIP TL431ID TL431AID TL431IDBVR PLASTIC SHRINK SMALL OUTLINE (PW) TL431CPWR TL431ACPWR SOT-89 (PK) TL431CPKR TL431IPKR The D package is available taped and reeled. Add the suffix R to the device type (e.g., TL431CDR). The DBV, KTP, PK, PS, and PW packages are only available taped and reeled. The LP package also is available in ammo pack. Add the suffix M to the device type (e.g., TL431CLPM). symbol REF ANODE CATHODE functional block diagram CATHODE + REF _ Vref ANODE 2 POST OFFICE BOX 655303 * DALLAS, TEXAS 75265 TL431, TL431A ADJUSTABLE PRECISION SHUNT REGULATORS SLVS005N - JULY 1978 - REVISED MARCH 2002 equivalent schematic CATHODE 800 800 20 pF REF 150 3.28 k 2.4 k 7.2 k 4 k 10 k 20 pF 1 k 800 ANODE All component values are nominal. absolute maximum ratings over operating free-air temperature range (unless otherwise noted) Cathode voltage, VKA (see Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 V Continuous cathode current range, IKA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -100 mA to 150 mA Reference input current range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -50 A to 10 mA Package thermal impedance, JA (see Notes 2 and 4): DBV package . . . . . . . . . . . . . . . . . . . . . . . . 206C/W (see Notes 2 and 3): KTP package . . . . . . . . . . . . . . . . . . . . . . . . . 28C/W (see Notes 2 and 4): LP package . . . . . . . . . . . . . . . . . . . . . . . . . . 156C/W (see Notes 2 and 4): P package . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85C/W (see Notes 2 and 4): PK package . . . . . . . . . . . . . . . . . . . . . . . . . . . 52C/W (see Notes 2 and 4): PS package . . . . . . . . . . . . . . . . . . . . . . . . . . . 95C/W (see Notes 2 and 4): PW package . . . . . . . . . . . . . . . . . . . . . . . . . 149C/W Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260C Storage temperature range, Tstg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -65C to 150C Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under "recommended operating conditions" is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. NOTES: 1. Voltage values are with respect to the ANODE terminal unless otherwise noted. 2. Maximum power dissipation is a function of TJ(max), JA, and TA. The maximum allowable power dissipation at any allowable ambient temperature is PD = (TJ(max) - TA)/JA. Operating at the absolute maximum TJ of 150C can affect reliability. 3. The package thermal impedance is calculated in accordance with JESD 51-5. 4. The package thermal impedance is calculated in accordance with JESD 51-7. recommended operating conditions VKA IKA Cathode voltage TA free air temperature range Operating free-air Cathode current TL431C, TL431AC TL431I, TL431AI POST OFFICE BOX 655303 * DALLAS, TEXAS 75265 MIN MAX Vref 1 36 V 100 mA 0 70 -40 85 UNIT C 3 TL431, TL431A ADJUSTABLE PRECISION SHUNT REGULATORS SLVS005N - JULY 1978 - REVISED MARCH 2002 electrical characteristics over recommended operating conditions, TA = 25C (unless otherwise noted) TEST CIRCUIT PARAMETER TEST CONDITIONS IKA = 10 mA TL431C UNIT MIN TYP MAX 2440 2495 2550 mV 4 25 mV -1.4 -2.7 -1 -2 mV V Vref Reference voltage 2 VKA = Vref, VI(dev) Deviation of reference voltage over full temperature range (see Figure 1) 2 VKA = Vref, IKA = 10 mA, TA = 0C to 70C DVref DVKA Ratio of change g in reference voltage g to the change in cathode voltage 3 IKA = 10 mA Iref Reference current 3 IKA = 10 mA, R1 = 10 k, R2 = 2 4 A II(dev) Deviation of reference current over full temperature range (see Figure 1) 3 IKA = 10 mA, R1 = 10 k, R2 = , TA = 0C to 70C 0.4 1.2 A Imin Minimum cathode current for regulation 2 VKA = Vref 0.4 1 mA Ioff Off-state cathode current 4 0.1 1 A |zKA| Dynamic impedance (see Figure 1) 1 VKA = 36 V, Vref = 0 IKA = 1 mA to 100 mA, VKA = Vref, f 1 kHz 0.2 0.5 VKA = 10 V - Vref VKA = 36 V - 10 V The deviation parameters Vref(dev) and Iref(dev) are defined as the differences between the maximum and minimum values obtained over the recommended temperature range. The average full-range temperature coefficient of the reference voltage, Vref, is defined as: a Vref ppm C + V I(dev) V at 25C ref DTA Maximum Vref 10 6 VI(dev) Minimum Vref TA where: TA is the recommended operating free-air temperature range of the device. Vref can be positive or negative, depending on whether minimum Vref or maximum Vref, respectively, occurs at the lower temperature. Example: maximum Vref = 2496 mV at 30C, minimum Vref = 2492 mV at 0C, Vref = 2495 mV at 25C, TA = 70C for TL431C + aVref 4 mV 2495 mV 70C 10 6 [ 23 ppmC Because minimum Vref occurs at the lower temperature, the coefficient is positive. Calculating Dynamic Impedance + DD V The dynamic impedance is defined as: z KA KA I KA When the device is operating with two external resistors (see Figure 3), the total dynamic impedance of the circuit is given by: DV z |z | 1 R1 KA DI R2 + [ ) Figure 1. Calculating Deviation Parameters and Dynamic Impedance 4 POST OFFICE BOX 655303 * DALLAS, TEXAS 75265 TL431, TL431A ADJUSTABLE PRECISION SHUNT REGULATORS SLVS005N - JULY 1978 - REVISED MARCH 2002 electrical characteristics over recommended operating conditions, TA = 25C (unless otherwise noted) PARAMETER TEST CIRCUIT TEST CONDITIONS UNIT TYP MAX 2440 2495 2550 mV 5 50 mV -1.4 -2.7 -1 -2 mV V Vref Reference voltage 2 VKA = Vref, VI(dev) Deviation of reference voltage over full temperature range (see Figure 1) 2 VKA = Vref, IKA = 10 mA, TA = -40C to 85C DVref DVKA Ratio of change g in reference voltage g to the change in cathode voltage 3 IKA = 10 mA Iref Reference current 3 IKA = 10 mA, R1 = 10 k, R2 = 2 4 A II(dev) Deviation of reference current over full temperature range (see Figure 1) 3 IKA = 10 mA, R1 = 10 k, R2 = , TA = -40C to 85C 0.8 2.5 A Imin Minimum cathode current for regulation 2 VKA = Vref 0.4 1 mA Ioff Off-state cathode current 4 0.1 1 A |zKA| Dynamic impedance (see Figure 1) 2 VKA = 36 V, Vref = 0 IKA = 1 mA to 100 mA, VKA = Vref, f 1 kHz 0.2 0.5 POST OFFICE BOX 655303 IKA = 10 mA TL431I MIN VKA = 10 V - Vref VKA = 36 V - 10 V * DALLAS, TEXAS 75265 5 TL431, TL431A ADJUSTABLE PRECISION SHUNT REGULATORS SLVS005N - JULY 1978 - REVISED MARCH 2002 electrical characteristics over recommended operating conditions, TA = 25C (unless otherwise noted) TEST CIRCUIT PARAMETER TEST CONDITIONS IKA = 10 mA TL431AC UNIT MIN TYP MAX 2470 2495 2520 mV 4 25 mV -1.4 -2.7 -1 -2 mV V Vref Reference voltage 2 VKA = Vref, VI(dev) Deviation of reference voltage over full temperature range (see Figure 1) 2 VKA = Vref, IKA = 10 mA, TA = 0C to 70C DVref DVKA Ratio of change g in reference voltage g to the change in cathode voltage 3 IKA = 10 mA Iref Reference current 3 IKA = 10 mA, R1 = 10 k, R2 = 2 4 A II(dev) Deviation of reference current over full temperature range (see Figure 1) 3 IKA = 10 mA, R1 = 10 k, R2 = , TA = 0C to 70C 0.8 1.2 A Imin Minimum cathode current for regulation 2 VKA = Vref 0.4 0.6 mA Ioff Off-state cathode current 4 0.1 0.5 A |zKA| Dynamic impedance (see Figure 1) 1 VKA = 36 V, Vref = 0 IKA = 1 mA to 100 mA, VKA = Vref, f 1 kHz 0.2 0.5 VKA = 10 V - Vref VKA = 36 V - 10 V electrical characteristics over recommended operating conditions, TA = 25C (unless otherwise noted) TEST CIRCUIT PARAMETER 6 TEST CONDITIONS UNIT TYP MAX 2470 2495 2520 mV 5 50 mV -1.4 -2.7 -1 -2 mV V Vref Reference voltage 2 VKA = Vref, VI(dev) Deviation of reference voltage over full temperature range (see Figure 1) 2 VKA = Vref, IKA = 10 mA, TA = -40C to 85C DVref DVKA Ratio of change g in reference voltage g to the change in cathode voltage 3 IKA = 10 mA Iref Reference current 3 IKA = 10 mA, R1 = 10 k, R2 = 2 4 A II(dev) Deviation of reference current over full temperature range (see Figure 1) 3 IKA = 10 mA, R1 = 10 k, R2 = , TA = -40C to 85C 0.8 2.5 A Imin Minimum cathode current for regulation 2 VKA = Vref 0.4 0.7 mA Ioff Off-state cathode current 4 0.1 0.5 A |zKA| Dynamic impedance (see Figure 1) 2 VKA = 36 V, Vref = 0 IKA = 1 mA to 100 mA, VKA = Vref, f 1 kHz 0.2 0.5 POST OFFICE BOX 655303 IKA = 10 mA TL431AI MIN VKA = 10 V - Vref VKA = 36 V - 10 V * DALLAS, TEXAS 75265 TL431, TL431A ADJUSTABLE PRECISION SHUNT REGULATORS SLVS005N - JULY 1978 - REVISED MARCH 2002 PARAMETER MEASUREMENT INFORMATION VKA Input IKA Vref Figure 2. Test Circuit for VKA = Vref Input VKA IKA R1 Iref R2 Vref V KA +V ) ) ref 1 R1 R2 I ref R1 Figure 3. Test Circuit for VKA > Vref Input VKA Ioff Figure 4. Test Circuit for Ioff POST OFFICE BOX 655303 * DALLAS, TEXAS 75265 7 TL431, TL431A ADJUSTABLE PRECISION SHUNT REGULATORS SLVS005N - JULY 1978 - REVISED MARCH 2002 TYPICAL CHARACTERISTICS Table 1. Graphs FIGURE Reference input voltage vs Free-air temperature 5 Reference input current vs Free-air temperature 6 Cathode current vs Cathode voltage 7, 8 Off-state cathode current vs Free-air temperature 9 Ratio of delta reference voltage to change in cathode voltage vs Free-air temperature 10 Equivalent input noise voltage vs Frequency 11 Equivalent input noise voltage over a 10-second period 12 Small-signal voltage amplification vs Frequency 13 Reference impedance vs Frequency 14 Pulse response 15 Stability boundary conditions 16 Table 2. Application Circuits FIGURE 8 Shunt regulator 17 Single-supply comparator with temperature-compensated threshold 18 Precision high-current series regulator 19 Output control of a three-terminal fixed regulator 20 High-current shunt regulator 21 Crowbar circuit 22 Precision 5-V 1.5-A regulator 23 Efficient 5-V precision regulator 24 PWM converter with reference 25 Voltage monitor 26 Delay timer 27 Precision current limiter 28 Precision constant-current sink 29 POST OFFICE BOX 655303 * DALLAS, TEXAS 75265 TL431, TL431A ADJUSTABLE PRECISION SHUNT REGULATORS SLVS005N - JULY 1978 - REVISED MARCH 2002 TYPICAL CHARACTERISTICS REFERENCE VOLTAGE vs FREE-AIR TEMPERATURE REFERENCE CURRENT vs FREE-AIR TEMPERATURE 2600 VKA = Vref IKA = 10 mA 5 R1 = 10 k R2 = IKA = 10 mA Vref = 2550 mV 2560 2540 I ref - Reference Current - A V ref - Reference Voltage - mV 2580 2520 Vref = 2495 mV 2500 2480 2460 Vref = 2440 mV 2440 2420 2400 -75 -50 -25 0 25 50 100 75 4 3 2 1 125 0 -75 TA - Free-Air Temperature - C -50 Data is for devices having the indicated value of Vref at IKA = 10 mA, TA = 25C. -25 Figure 5 50 75 100 125 CATHODE CURRENT vs CATHODE VOLTAGE 150 800 VKA = Vref TA = 25C VKA = Vref TA = 25C 100 600 I KA - Cathode Current - A I KA - Cathode Current - mA 25 Figure 6 CATHODE CURRENT vs CATHODE VOLTAGE 125 0 TA - Free-Air Temperature - C 75 50 25 0 -25 -50 Imin 400 200 0 -75 -100 -2 -200 -1 0 2 1 3 -1 VKA - Cathode Voltage - V 0 1 2 3 VKA - Cathode Voltage - V Figure 7 Figure 8 Data at high and low temperatures are applicable only within the recommended operating free-air temperature ranges of the various devices. POST OFFICE BOX 655303 * DALLAS, TEXAS 75265 9 TL431, TL431A ADJUSTABLE PRECISION SHUNT REGULATORS SLVS005N - JULY 1978 - REVISED MARCH 2002 TYPICAL CHARACTERISTICS RATIO OF DELTA REFERENCE VOLTAGE TO DELTA CATHODE VOLTAGE vs FREE-AIR TEMPERATURE OFF-STATE CATHODE CURRENT vs FREE-AIR TEMPERATURE - 0.85 2.5 VKA = 3 V to 36 V - 0.95 2 V ref / V KA - mV/V I off - Off-State Cathode Current - A VKA = 36 V Vref = 0 1.5 1 0.5 0 -75 -1.05 -1.15 -1.25 -1.35 -50 -25 0 25 50 75 100 -1.45 -75 125 -50 -25 0 25 50 75 100 125 TA - Free-Air Temperature - C TA - Free-Air Temperature - C Figure 9 Figure 10 EQUIVALENT INPUT NOISE VOLTAGE vs FREQUENCY Vn - Equivalent Input Noise Voltage - nV/ Hz 260 IO = 10 mA TA = 25C 240 220 200 180 160 140 120 100 10 100 1k 10 k 100 k f - Frequency - Hz Figure 11 Data at high and low temperatures are applicable only within the recommended operating free-air temperature ranges of the various devices. 10 POST OFFICE BOX 655303 * DALLAS, TEXAS 75265 TL431, TL431A ADJUSTABLE PRECISION SHUNT REGULATORS SLVS005N - JULY 1978 - REVISED MARCH 2002 TYPICAL CHARACTERISTICS EQUIVALENT INPUT NOISE VOLTAGE OVER A 10-SECOND PERIOD V n - Equivalent Input Noise Voltage - V 6 5 4 3 2 1 0 -1 -2 -3 f = 0.1 to 10 Hz IKA = 10 mA TA = 25C -4 -5 -6 0 1 2 3 4 5 6 7 8 9 10 t - Time - s 19.1 V 1 k 500 F 910 2000 F VCC TL431 (DUT) 820 + VCC 1 F TLE2027 AV = 10 V/mV + - 16 k 16 160 k 16 k 1 F TLE2027 To Oscilloscope 22 F - 33 k AV = 2 V/V 0.1 F 33 k VEE VEE Figure 12. Test Circuit for Equivalent Input Noise Voltage POST OFFICE BOX 655303 * DALLAS, TEXAS 75265 11 TL431, TL431A ADJUSTABLE PRECISION SHUNT REGULATORS SLVS005N - JULY 1978 - REVISED MARCH 2002 TYPICAL CHARACTERISTICS SMALL-SIGNAL VOLTAGE AMPLIFICATION vs FREQUENCY A V - Small-Signal Voltage Amplification - dB 60 IKA = 10 mA TA = 25C 50 Output 15 k IKA 232 40 9 F + 30 - 8.25 k 20 GND 10 0 1k TEST CIRCUIT FOR VOLTAGE AMPLIFICATION 10 k 100 k 1M 10 M f - Frequency - Hz Figure 13 REFERENCE IMPEDANCE vs FREQUENCY |z KA| - Reference Impedance - 100 IKA = 10 mA TA = 25C 1 k 10 IKA 50 - + GND 1 TEST CIRCUIT FOR REFERENCE IMPEDANCE 0.1 1k 10 k 100 k 1M 10 M f - Frequency - Hz Figure 14 12 Output POST OFFICE BOX 655303 * DALLAS, TEXAS 75265 TL431, TL431A ADJUSTABLE PRECISION SHUNT REGULATORS SLVS005N - JULY 1978 - REVISED MARCH 2002 TYPICAL CHARACTERISTICS PULSE RESPONSE 6 TA = 25C Input Input and Output Voltage - V 5 220 Output 4 Pulse Generator f = 100 kHz 3 50 Output GND 2 TEST CIRCUIT FOR PULSE RESPONSE 1 0 -1 0 1 2 3 4 5 6 7 t - Time - s Figure 15 STABILITY BOUNDARY CONDITIONS 100 90 I KA - Cathode Current - mA 80 A VKA = Vref B VKA = 5 V C VKA = 10 V D VKA = 15 Vf 150 TA = 25C IKA + VBATT CL B - 70 Stable 60 C Stable 50 A TEST CIRCUIT FOR CURVE A 40 30 D IKA 20 10 0 0.001 150 R1 = 10 k CL + 0.01 0.1 1 10 R2 CL - Load Capacitance - F - The areas under the curves represent conditions that may cause the device to oscillate. For curves B, C, and D, R2 and V+ were adjusted to establish the initial VKA and IKA conditions with CL = 0. VBATT and CL then were adjusted to determine the ranges of stability. VBATT TEST CIRCUIT FOR CURVES B, C, AND D Figure 16 POST OFFICE BOX 655303 * DALLAS, TEXAS 75265 13 TL431, TL431A ADJUSTABLE PRECISION SHUNT REGULATORS SLVS005N - JULY 1978 - REVISED MARCH 2002 APPLICATION INFORMATION R (see Note A) VI(BATT) VO R1 0.1% Vref TL431 VO R2 0.1% + 1 ) R1 V R2 ref RETURN NOTE A: R should provide cathode current 1 mA to the TL431 at minimum VI(BATT). Figure 17. Shunt Regulator VI(BATT) VO TL431 Von 2 V Voff VI(BATT) Input VIT 2.5 V GND Figure 18. Single-Supply Comparator With Temperature-Compensated Threshold VI(BATT) R (see Note A) 2N222 2N222 30 0.01 F VO 4.7 k TL431 + 1 ) R1 V R2 VO R2 0.1% R1 0.1% NOTE A: R should provide cathode current 1 mA to the TL431 at minimum VI(BATT). Figure 19. Precision High-Current Series Regulator 14 POST OFFICE BOX 655303 * DALLAS, TEXAS 75265 ref TL431, TL431A ADJUSTABLE PRECISION SHUNT REGULATORS SLVS005N - JULY 1978 - REVISED MARCH 2002 APPLICATION INFORMATION VI(BATT) IN uA7805 OUT Common VO R1 TL431 + 1 ) R1 V R2 Minimum V + V ) 5 V VO ref ref O R2 Figure 20. Output Control of a Three-Terminal Fixed Regulator VI(BATT) VO R1 VO + 1 ) R1 V R2 ref TL431 R2 Figure 21. High-Current Shunt Regulator VI(BATT) VO R1 TL431 R2 C (see Note A) NOTE A: Refer to the stability boundary conditions in Figure 16 to determine allowable values for C. Figure 22. Crowbar Circuit POST OFFICE BOX 655303 * DALLAS, TEXAS 75265 15 TL431, TL431A ADJUSTABLE PRECISION SHUNT REGULATORS SLVS005N - JULY 1978 - REVISED MARCH 2002 APPLICATION INFORMATION IN VI(BATT) LM317 8.2 k OUT Adjust VO 5 V, 1.5 A 243 0.1% TL431 243 0.1% Figure 23. Precision 5-V 1.5-A Regulator VO 5 V VI(BATT) Rb (see Note A) 27.4 k 0.1% TL431 27.4 k 0.1% NOTE A: Rb should provide cathode current 1 mA to the TL431. Figure 24. Efficient 5-V Precision Regulator 12 V VCC 6.8 k 5V 10 k - 10 k 0.1% TL431 10 k 0.1% + X Not Used TL598 Feedback Figure 25. PWM Converter With Reference 16 POST OFFICE BOX 655303 * DALLAS, TEXAS 75265 TL431, TL431A ADJUSTABLE PRECISION SHUNT REGULATORS SLVS005N - JULY 1978 - REVISED MARCH 2002 APPLICATION INFORMATION R3 (see Note A) VI(BATT) R4 (see Note A) R1B R1A TL431 R2A + 1 ) R1B V R2B High Limit + 1 ) R1A V R2A Low Limit ref ref LED on When Low Limit < VI(BATT) < High Limit R2B NOTE A: R3 and R4 are selected to provide the desired LED intensity and cathode current 1 mA to the TL431 at the available VI(BATT). Figure 26. Voltage Monitor 650 12 V 2 k R TL431 Off Delay +R C In * 12 V 12 V V ref C On Figure 27. Delay Timer RCL 0.1% VI(BATT) R1 TL431 IO I out + RV ) I R1 + ref CL KA V I(BATT) I O h FE )I KA Figure 28. Precision Current Limiter POST OFFICE BOX 655303 * DALLAS, TEXAS 75265 17 TL431, TL431A ADJUSTABLE PRECISION SHUNT REGULATORS SLVS005N - JULY 1978 - REVISED MARCH 2002 APPLICATION INFORMATION VI(BATT) IO IO TL431 + VR ref S RS 0.1% Figure 29. Precision Constant-Current Sink 18 POST OFFICE BOX 655303 * DALLAS, TEXAS 75265 IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. All products are sold subject to TI's terms and conditions of sale supplied at the time of order acknowledgment. TI warrants performance of its hardware products to the specifications applicable at the time of sale in accordance with TI's standard warranty. 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