2.5V Low-Voltage Adjustable Precision Shunt Regulator NIKO-SEM L431 GENERAL DESCRIPTION FEATURES The L431 is a three-terminal adjustable shunt regulator utilizing an accurate 2.5V band-gap reference. The output voltage can be set to any value between 2.5V (VREF) 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 0.25Ω. The characteristics of these reference make it excellent 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). 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 Cathode (K) Reference (R) + Cathod (K) - Reference (R) 2.5 Vref Anode (A) Anode (A) SYMBOL FUNCTIONAL BLOCK DIAGRAM 1 JAN-08-Y02 NIKO-SEM 2.5V Low-Voltage Adjustable Precision Shunt Regulator L431 ABSOLUTE MAXIMUM RATINGS PARAMETER VALUE Cathode-Anode Reverse Breakdown Voltage - VKA Anode-Cathode Forward Current - IAK Reference Input Current - IREF Storage Temperature Range - TSTG Junction Temperature - TJ Lead Temperature (Soldering, 10 Seconds) - TL Continuous Power at 25 °C - PD TO-92 SOIC-8 SOT-23 RECOMMENDED CONDITIONS Parameter Cathode Voltage (VKA) Cathode Current (IK) Rating VREF to 29V 10 mA 30V 70 mA 10 mA -65 to +150 °C 150 °C 300 °C 700 mW 650 mW 200 mW TYPICAL THERMAL RESISTANCES Package TO-92 SOIC-8 SOT-23 Typ. Derating θJA θJC 160 °C/W 80 °C/W 6.3 mW/°C 175 °C/W 45 °C/W 5.7 mW/°C 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 Reference Voltage ∆VREF with Temp. Ration of Change in VREF to Cathode Voltage Reference Input Current IREF Temp. Deviation Min. IK for Regulation Off State Leakage Dynamic Output Impedance TEST CONDITIONS MIN TA = 25 °C, L431 (0.5%) TA = 25 °C, L431 (1%) TA = 25 °C, L431 (2%) 2.482 2.470 2.445 VREF to 10V 10V to 30V -2.7 -2.0 Over Temp. VREF = 0V, VKA = 30V f ≤ 1KHz, IK = 1 to 70 mA 2 TEST TYP MAX UNITS CIRCUIT 2.495 2.507 1 2.495 2.520 V 2.495 2.550 0.07 0.2 mV/°C 1 -1.0 mV/V 2 -0.4 0.3 µA 0.7 4 2 µA 0.4 1.2 2 mA 0.4 1 1 nA 0.04 250 3 0.25 0.5 1 Ω JAN-08-Y02 2.5V Low-Voltage Adjustable Precision Shunt Regulator NIKO-SEM L431 TEST CIRCUITS VIN VKA VIN VKA IK I REF R1 I REF VIN VKA IK I K (OFF) V REF R2 - TEST CIRCUIT 2 (VKA > VREF) - TEST CIRCUIT 1 (VKA = VREF) Stability Boundary Condition For Shunt Regulation VS. Cathode Current and Load Capacitance - TEST CIRCUIT 3 (OFF STATE CURRENT) Test Circuit for Vka > Vref 150 1 Ik 3 R1 VBATT CL 1 2 2 L431 R2 10K 0 1 2 3 4 5 6 Test Circuit for Vka = Vref The areas under the curves represent conditions that may Ik 3 150 1 cause the device to oscillate. For curves B, C and D, R1 and VBATT were adjusted to establish the initial VKA and IKA 1 conditions with CL = 0. VBATT and CL then were adjusted L431 2 2 to determine the ranges of stability. CL 3 JAN-08-Y02 NIKO-SEM 2.5V Low-Voltage Adjustable Precision Shunt Regulator Small-Signal Gain and Phase Shift VS. Frequency L431 Test Circuit for Small Signal Gain and Phase OUT Ik 1 1 10uF L431 2 1 232 3 15K 2 2 8.25K GND Cathode Current VS. Cathode Voltage Cathode Current VS. Cathode Voltage Ratio of Delta Reference Voltage to Delta Cathode Voltage VS. Junction Temperature rz (Ω) ΔVref /ΔVz (-mV/V) Reference Impedance VS. Junction Temperature 4 ΔVz = 3V to 30V JAN-08-Y02 NIKO-SEM 2.5V Low-Voltage Adjustable Precision Shunt Regulator Off-State Cathode Current VS. Junction Temperature L431 Reference Input Current VS. Junction Temperature ∞ Reference Impedance VS. Frequency Ω Reference Voltage VS. Junction Temperature 5 JAN-08-Y02 NIKO-SEM 2.5V Low-Voltage Adjustable Precision Shunt Regulator L431 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% 6 JAN-08-Y02 2.5V Low-Voltage Adjustable Precision Shunt Regulator NIKO-SEM L431 APPLICATION CIRCUIT P01N02LM or P3055L Niko Vin + D Vout S Cin G R1 5V or 12V 1K + K R Cout + 10uF A Vout = (1 + 7 L431 or L432 Niko R1 R2 R2 ) Vref JAN-08-Y02 NIKO-SEM 2.5V Low-Voltage Adjustable Precision Shunt Regulator L431 TO-92 MECHANICAL DATA Dimension mm Min. Typ. Dimension Max. mm Min. Typ. Max. 2.540 2.667 A 4.445 5.207 H 2.413 B 4.318 5.334 I 0.356 C 12.7 15.5 J D 0.356 0.533 K E 1.143 1.397 L F 3.175 4.191 M G 0.762 1.270 N 1.27 8 0.533 JAN-08-Y02 NIKO-SEM 2.5V Low-Voltage Adjustable Precision Shunt Regulator L431 SOT-23 (M3) MECHANICAL DATA Dimension mm Min. A Typ. Dimension Max. 0.95 Min. Typ. Max. H 0.10 0.15 0.25 0.37 B 2.60 2.80 3.00 I 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 0.5 N 0.4 9 mm JAN-08-Y02 NIKO-SEM 2.5V Low-Voltage Adjustable Precision Shunt Regulator L431 SOIC-8 (D) MECHANICAL DATA Dimension mm Min. Typ. Dimension Max. mm Min. Typ. Max. 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 D 0.35 0.48 K E 1.27 F G 0.1 0.22 0° 8° L 1.65 M 0.25 N 10 JAN-08-Y02 NIKO-SEM 2.5V Low-Voltage Adjustable Precision Shunt Regulator L431 SOT-23 (M5) MECHANICAL DATA Dimension mm Dimension mm Min. Typ. Max. A 1.0 1.10 1.30 e A1 0.00 0.10 H 2.60 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 11 Min. Typ. Max. 1.90(TYP) 2.80 3.00 JAN-08-Y02