PROGRAMMABLE PRECISION SHUNT REGULATOR LM431/A/C FEATURES Programmable Output Voltage to 40V Guaranteed 0.5% Reference Voltage Tolerance Low (0.2Ω Typ.) Dynamic Output Impedance Cathode Current Range(Continuous) – 100 ~ 150 mA SOT-23 PKG Equivalent Full Range Temperature Coefficient of 50PPM/℃ Temperature Compensated For Operation Over Full Rate Operating Temperature Range Low Output Noise Voltage Fast Turn-on Response SOT-23 3L Package APPLICATION Shunt Regulator Precision High-Current Series Regulator High-Current Shunt Regulator Crowbar Circuit ORDERING INFORMATION DEVICE PWM Converter With Reference PACKAGE LM431SF Voltage Monitor SOT-23 3L * Refer to the page 2 for detailed ordering Information, Precision Current Limiter DESCRIPSION The LM431 is a three-terminal adjustable shunt regulator with specified thermal stability over applicable temperature VREF (Approx. 2.5V) and 40V with two external resistors. This device has a typical dynamic output impedance of 0.2Ω. Active output circuitry provides a very sharp turn-on characteristic, making this device excellent replacement for zener diodes in many applications. The LM431 is characterized for operation from 40℃ to +125℃. ABSOLUTE MAXIMUM RATINGS (Operating temperature range applies unless otherwise specified) CHARACTERISTIC SYMBOL MIN. MAX. UNIT VKA - 42 V IK -100 150 mA IREF -0.05 10 mA TJ -40 150 ℃ Operating Temperature Range TOPR -40 125 ℃ Storage Temperature Range TSTG -60 150 ℃ Cathode Voltage Cathode Current Range(Continuous) Reference Input Current Range Junction Temperature Range Apr. 2012 – Rev.1.1 -1- HTC PROGRAMMABLE PRECISION SHUNT REGULATOR LM431/A/C RECOMMENDED OPERATING CONDITIONS CHARACTERISTIC SYMBOL MIN. MAX. UNIT Cathode Voltage VKA VREF 40 V Cathode Current IK 0.5 100 mA Supplied As Status ORDERING INFORMATION Package Tolerance Order No. Package Marking 0.5% LM431CSF 431O Reel Active 1% LM431ASF 431O Reel Active SOT-23 LM 431 Package Type SF : SOT23 3L C : 0.5% A : 1% Tolerance Root Name Product Code PIN CONFIGURATION PIN DESCRIPTION 2 Pin No. Name Function 1 Cathode Input Supply Voltage 2 Anode Ground 3 Reference Reference Voltage TOP 1 3 SOT-23 PKG Apr. 2012 – Rev.1.1 SOT-23 -2- HTC PROGRAMMABLE PRECISION SHUNT REGULATOR LM431/A/C LM431 ELECTRICAL CHARACTERISTICS (TA=25℃, unless otherwise specified) CHARACTERISTIC Reference Voltage Deviation of Reference Voltage Ratio of Change in Reference Voltage to the Change in Cathode Voltage Reference Current Deviation of Reference Current SYMBOL VREF ΔVREF/ΔT ΔVREF/ΔVKA TEST CONDITION MIN. TYP. MAX. 0.5 % 2.487 2.500 2.512 1% 2.475 2.500 2.525 8 20 ΔVKA=10V -VREF -1.4 -2.7 ΔVKA=36V-10V -1.0 -2.0 UNIT V VKA =VREF, IK =10mA VKA = VREF, IK =10mA TA =Full Range mV mV/V IK =10mA IREF IKA=10mA, R1=10㏀, R2=∞ 1.8 4.0 uA ΔIREF/ΔT IK =10mA, R1=10㏀, R2=∞ TA =Full Range 0.4 1.2 uA 0.5 mA Minimum Cathode Current for Regulation IK(MIN) VKA= VREF Off-State Cathode Current IK(OFF) VKA=36V, VREF=0 0.17 0.90 uA VKA= VREF, IK =1mA~100mA f ≤ 1kHz 0.27 0.50 Ω Dynamic Impedance ZKA TEST CIRCUITS [ Fig 1. Test circuit for VKA = VREF ] Apr. 2012 – Rev.1.1 [ Fig 2. Test circuit for VKA ≥ VREF ] -3- HTC PROGRAMMABLE PRECISION SHUNT REGULATOR LM431/A/C [ Fig 3. Test circuit for IKA(OFF) ] The deviation parameters ΔVREF/ΔT and ΔIREF/ΔT 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, αVREF, is defined as : Where : ΔTA is the recommended operating free-air temperature range of the device. αVREF can be positive or negative, depending on whether minimum VREF or maximum VREF, respectively, occurs at the lower temperature. Calculating Dynamic Impedance The dynamic impedance is defined as : Z KA VKA I KA When the device is operating with two external resistors, the total dynamic impedance of the circuit is given by : Z' R1 V Z KA 1 R2 I Apr. 2012 – Rev.1.1 -4- HTC PROGRAMMABLE PRECISION SHUNT REGULATOR LM431/A/C TYPICAL OPERATING CHARACTERISTICS REFERENCE VOLTAGE vs JUNCTION TEMPERATUR 2.504 PULSE RESPONSE 6 5 Input & Output Voltage (V) VREF-Reference Voltage (V) 2.502 2.501 2.500 2.499 2.498 2.497 2.496 4 3 Output 2 1 2.495 0 0 20 40 60 80 100 120 -1 0 1 2 TJ-Junction Temperature (℃) 4 5 6 7 8 CATHODE CURRENT vs CATHODE VOLTAGE 0.15 800 VKA=VREF TA=25℃ 0.13 3 t-Time (us) CATHODE CURRENT vs CATHODE VOLTAGE VKA=VREF TA=25℃ 0.10 IKA-Cathode Current (uA) IKA-Cathode Current (mA) VKA=VREF IKA=10mA TA=25℃ Input 2.503 0.08 0.05 0.03 0.00 -0.03 -0.05 600 400 200 0 -0.08 -0.10 -200 -2.0 -1.0 0.0 1.0 2.0 -1.0 3.0 0.0 1.0 2.0 3.0 VKA-Cathode Voltage (V) VKA-Cathode Voltage (V) T.B.D Apr. 2012 – Rev.1.1 -5- HTC PROGRAMMABLE PRECISION SHUNT REGULATOR LM431/A/C APPICATION INFORMATION 1. Shunt Regulator LM431 Note A : R Should provide cathode current 1mA to the LM431 at minimum VI(BATT) 2. Precision High-Current Series Regulator LM431 Note A : R Should provide cathode current≥1mA to the LM431 at minimum VI(BATT) 3. Output Control of a Three-Terminal Fixed Regulator LM431 Apr. 2012 – Rev.1.1 -6- HTC PROGRAMMABLE PRECISION SHUNT REGULATOR LM431/A/C 4. High-Current Shunt Regulator LM431 5. Precision 5V 1.5A Regulator LM431 6. Efficient 5-V Precision Regulator LM431 NOTE A : RB Should provide cathode current≥1mA to the LM431. Apr. 2012 – Rev.1.1 -7- HTC PROGRAMMABLE PRECISION SHUNT REGULATOR LM431/A/C 7. PWM Converter With Reference LM431 8. Voltage Monitor LM431 NOTE A : R3 and R4 are selected to provide the desired LED intensity and cathode current ≥1mA to the LM431 at the available VI(BATT). 9. Delay Timer LM431 Apr. 2012 – Rev.1.1 -8- HTC PROGRAMMABLE PRECISION SHUNT REGULATOR LM431/A/C 10. Precision Current Limiter LM431 11. Precision Constant-Current Sink LM431 Apr. 2012 – Rev.1.1 -9- HTC