L431 ETC1
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Technical content
2.5V Low-Voltage Adjustable Precision Shunt Regulator NIKO-SEM L431 JAN-08-Y02 GENERAL DESCRIPTION The L431 is a three-terminal adjustable shunt regulator utilizing an a ccurate 2.5V band-gap reference. The output voltage can be set to any value between 2.5V (V REF) to 29V with two external resistors as shown in the typical application circuit. The device exhibit a wide operating current range of 0.4 to 100 mA with a typical dynamic impedance of 0.25 Ω. The cha- racteristics of these re ference make it exce- llent replacements for zener diodes in many applications such as digital voltmeters, power supplies, and op amp circuitry. The 2.5V volt reference makes it convenient to obtain a stable reference from 5.0V logic supplies. The L431 shunt regulator is available in three voltage tolerances (0.5%, 1.0% and 2%) and three package options (TO-92, SOT-23-3, SOT-23-5 and SOIC-8).
FEATURES
z Internal amplifier with 70 mA capability z Programmable output voltage to 29V z 0.25Ωtypical output impedance z Pin to pin compatible with TL431, LM431 , SC431 & AS431 z Trimmed band-gap design 0.5%, 1.0% and 2% with three package options z Low cost solution
APPLICATIONS
z Linear regulator controller z Precision voltage reference z Switching power supplies z Battery operating equipment z Instrumentation z PCs, Computer disk drives SYMBOL & BLOCK DIAGRAM Anode (A) CathodReference Cathode (K) Anode (A) Reference (R)
2.5 Vref
FUNCTIONAL BLOCK DIAGRAMSYMBOL (R) (K)
2.5V Low-Voltage Adjustable Precision Shunt Regulator NIKO-SEM L431 JAN-08-Y02 ABSOLUTE MAXIMUM RATINGS PARAMETER VALUE Cathode-Anode Reverse Breakdown Voltage - VKA 30V Anode-Cathode Forward Current - IAK 70 mA Reference Input Current - IREF 10 mA Storage Temperature Range - TSTG -65 to +150 °C Junction Temperature - TJ 150 °C Lead Temperature (Soldering, 10 Seconds) - TL 300 °C Continuous Power at 25 °C - PD TO-92 SOIC-8 SOT-23 700 mW 650 mW 200 mW RECOMMENDED CONDITIONS TYPICAL THERMAL RESISTANCES Parameter Rating Package θJA θJC Typ. Derating Cathode Voltage (VKA) V REF to 29V TO-92 160 °C/W 80 °C/W 6.3 mW/°C Cathode Current (IK) 10 mA SOIC-8 175 °C/W 45 °C/W 5.7 mW/°C SOT-23 575 °C/W 150 °C/W 1.7 mW/°C ELECTRICAL SPECIFICATIONS (Ambient temperature must be derated base on power dissipation and package thermal characteristics. The conditions are: VKA = VREF and IK = 10 mA unless otherwise stated) PARAMETER TEST CONDITIONS MIN TYP MAX UNITS TEST CIRCUIT TA = 25 °C, L431 (0.5%) 2.482 2.495 2.507 TA = 25 °C, L431 (1%) 2.470 2.495 2.520 Reference Voltage TA = 25 °C, L431 (2%) 2.445 2.495 2.550 V ∆VREF with Temp. 0.07 0.2 mV/°C 1 VREF to 10V -2.7 -1.0 Ration of Change in VREF to Cathode Voltage 10V to 30V -2.0 -0.4 0.3 mV/V 2 Reference Input Current 0.7 4 µA 2 IREF Temp. Deviation Over Temp. 0.4 1.2 µA 2 Min. IK for Regulation 0.4 1 mA 1 Off State Leakage V REF = 0V, VKA = 30V 0.04 250 nA 3 Dynamic Output Impedance f ≤ 1KHz, IK = 1 to 70 mA 0.25 0.5 Ω 1
2.5V Low-Voltage Adjustable Precision Shunt Regulator NIKO-SEM L431 JAN-08-Y02 TEST CIRCUITS IN VV KA KI REFI VREF - TEST CIRCUIT 2 - >(VKA VREF) REFI )VKA V - TEST CIRCUIT 1 - KAV REF(V IN - TEST CIRCUIT 3 - KAVVIN K (OFF)I (OFF STATE CURRENT) IK The areas under the curves represent conditions that may cause the device to oscillate. For curves B, C and D, R1 and VBATT 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. Stability Boundary Condition For Shunt Regulation VS. Cathode Current and Load Capacitance 102 3 4 56 CL Ik150 L431 2 3 Test Circuit for Vka = Vref 150 L431 2 3 10K Test Circuit for Vka > Vref Ik CLVBATT
2.5V Low-Voltage Adjustable Precision Shunt Regulator NIKO-SEM L431 JAN-08-Y02 Small-Signal Gain and Phase Shift VS. Frequency VS. Cathode Voltage Cathode Current Cathode Current VS. Cathode Voltage VS. Junction Temperature rz (Ω Reference Impedance VS. Junction Temperature Ratio of Delta Reference Voltage to Delta Cathode Voltage Δ Vref /Δ Vz (-m V/V) ΔVz = 3V to 30V 8.25K OUT Ik GND 15K L431 2 3 10uF 232 Test Circuit for Small Signal Gain and Phase
2.5V Low-Voltage Adjustable Precision Shunt Regulator NIKO-SEM L431 JAN-08-Y02 VS. Junction Temperature Off-State Cathode Current VS. Junction Temperature Reference Voltage VS. Frequency Reference Impedance Ω Reference Input Current VS. Junction Temperature
2.5V Low-Voltage Adjustable Precision Shunt Regulator NIKO-SEM L431 JAN-08-Y02 PIN CONFIGURATION DEVICE SELECTION GUIDE Device L431NA L431M3A L431VA L431M5A Package TO-92 SOT-23-3 SOIC-8 SOT-23-5 Marking L431N 1M3 L431V 1M5A Tolerance 0.5% 0.5% 0.5% 0.5%
2.5V Low-Voltage Adjustable Precision Shunt Regulator NIKO-SEM L431 JAN-08-Y02 APPLICATION CIRCUIT 10uF Cout Cin P01N02LM or P3055L L431 or L432 5V or 12V Vin Vout G D S A K R Niko Niko Vout = (1 + ) Vref R2
2.5V Low-Voltage Adjustable Precision Shunt Regulator NIKO-SEM L431 JAN-08-Y02 TO-92 MECHANICAL DATA mm mm B 4.318 5.334 I 0.356 0.533 C 12.7 15.5 J D 0.356 0.533 K E 1.143 1.27 1.397 L F 3.175 4.191 M G 0.762 1.270 N
2.5V Low-Voltage Adjustable Precision Shunt Regulator NIKO-SEM L431 JAN-08-Y02 SOT-23 (M3) MECHANICAL DATA mm mm A 0.95 H 0.10 0.15 0.25 B 2.60 2.80 3.00 I 0.37 C 1.40 1.60 1.80 J D 2.70 2.90 3.10 K E 1.00 1.10 1.30 L F 0.00 0.10 M G 0.35 0.4 0.5 N
2.5V Low-Voltage Adjustable Precision Shunt Regulator NIKO-SEM L431 JAN-08-Y02 SOIC-8 (D) MECHANICAL DATA mm mm A 4.8 5.0 H 0.4 1.27 B 3.8 4.0 I 0.18 0.25 C 5.8 6.2 J 0.22 D 0.35 0.48 K 0° 8° E 1.27 L F 1.65 M G 0.1 0.25 N
2.5V Low-Voltage Adjustable Precision Shunt Regulator NIKO-SEM L431 JAN-08-Y02 SOT-23 (M5) MECHANICAL DATA mm mm A 1.0 1.10 1.30 e 1.90(TYP) A2 0.70 0.80 0.90 L 0.37 b 0.35 0.40 0.50 C 0.10 0.15 0.25 D 2.70 2.90 3.10 E 1.40 1.60 1.80