ADJUSTABLE SHUNT REGULATOR April 13, 1998 SC431 TEL:805-498-2111 FAX:805-498-3804 WEB:http://www.semtech.com DESCRIPTION The SC431 is a three terminal adjustable shunt regulator with thermal stability guaranteed over temperature. The output voltage can be adjusted to any value from 2.5V (VREF) to 36V with two external resistors. The SC431 has a typical dynamic output impedance of 0.25Ω. Active output circuitry provides a very sharp turn on characteristic, making the SC431 an excellent replacement for zener diodes. FEATURES • Wide operating current range 100µA to 150mA • Low dynamic output impedance 0.25 Ω typ. • Trimmed bandgap design + 0.5% • Alternate for TL431, LM431 & AS431 The SC431 shunt regulator is available in three voltage tolerances (0.5%, 1.0% and 2.0%) and three package options (SOT-23-3, SO-8 and TO-92). The three voltage tolerances allow the designer the opportunity to select the proper cost/tolerance for their application. APPLICATIONS • Linear Regulators • Adjustable Supplies • Switching Power Supplies • Battery Operated Computers • Instrumentation • Computer Disk Drives PIN CONFIGURATIONS BLOCK DIAGRAM SOT-23 -3 Lead (Top View) SOIC 8 Lead (Top View) SYMBOL DIAGRAM TO-92 (Top View) 1 © 1998 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 ADJUSTABLE SHUNT REGULATOR SC431 April 13, 1998 ABSOLUTE MAXIMUM RATINGS Parameter Symbol Maximum Units Cathode Voltage VZ 37 V Continous Cathode Current IZ 150 mA Reference Input Current IREF 10 mA Operating Junction Temperature Range TJ -40 to +150 °C TSTG -65 to +150 °C θJA 160 175 410 °C/W PD 0.78 0.71 0.30 W TLEAD 260 °C Storage Temperature Range Thermal Resistance TO-92 SO-8 SOT-23 Power Dissipation at TA = 25°C TO-92 SO-8 SOT-23 Lead Temperature (Soldering) 10 seconds ORDERING INFORMATION PACKAGE SO-8 (1) SOT-23 TO-92 (1) (1)(2) TOLERANCE 0.5% 1.0% 2.0% T/R Quantity SC431CS - .5 SC431CS - 1 SC431CS - 2 2.5K SC431CSK - .5 SC431CSK - 1 SC431CSK - 2 3K SC431CZ - .5 SC431CZ - 1 SC431CZ - 2 TR=3K, TA=2K Notes: (1) Add suffix ‘TR’ for Tape & Reel. (2) Add suffix ‘TA’ for Tape Ammo. 2 © 1998 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 ADJUSTABLE SHUNT REGULATOR SC431 April 13, 1998 ELECTRICAL CHARACTERISTICS Unless specified, TA = 25°C SC431 0.5% Parameter Symbol Reference Voltage VREF VREF Temp Deviation VDEV Ratio of Change in VREF to Change in Cathode Voltage ∆ V REF ∆VZ Reference Input Current IREF Temp Deviation Condition VZ = VREF IZ = 10mA (test circuit 1) Off State Cathode Current MAX MIN TYP MAX MIN TYP MAX 2.482 2.495 2.507 2.470 2.495 2.520 2.445 2.495 2.545 UNITS V 8 17 8 25 15 30 IZ = 10mA, ∆VZ = 10V to VREF -0.5 -2.7 -0.5 -2.7 -0.5 -2.7 IZ = 10mA, ∆VZ = 36V to 10V -1.0 -2.0 -1.0 -2.0 -1.0 -2.0 R1 = 10kΩ, R2 = ∞, IZ = 10mA (test circuit 2) 0.5 4 0.5 4 0.5 4 µA TA = -40 to +85°C, R1 = 10kΩ, R2 = ∞, IZ =10mA (test circuit 2) 0.4 1.2 0.4 1.2 0.4 1.2 µA 0.04 0.5 0.04 0.5 0.04 0.5 µA 0.25 0.5 0.25 0.5 0.25 0.5 Ω 100 µA IZ (off) VREF = 0V, VZ = 36V (test circuit 3) rZ f < 1kHz, VZ = VREF IZ = 100uA to 100mA (test circuit 1) Dynamic Output Impedance Minimum Operating Current TA = 25°C TYP SC431 2% TA = -40 to +85°C, VZ = VREF (test circuit 1) IZ = 10mA IREF IREF(DEV) MIN SC431 1% IZ (min) mV mV/V 100 VZ = VREF (test circuit 1) 100 TEST CIRCUITS Test Circuit 1: VZ = VREF Test Circuit 2: VZ > VREF Test Circuit 3: Off State Current RECOMMENDED OPERATING CONDITIONS Min Max Symbol Cathode Voltage, VZ VREF 36 V Cathode Current, IZ 0.1 150 mA 3 © 1998 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 ADJUSTABLE SHUNT REGULATOR SC431 April 13, 1998 TYPICAL CHARACTERISTICS Cathode Current vs. Cathode Voltage 300 Cathode Current vs. Cathode Voltage 150 VZ = VREF VZ = VREF o o TA = 25 C 200 50 IZ (mA) 100 IZ (µ µA) TA = 25 C 100 0 0 -100 -50 -200 -100 -300 -150 -2 -1 0 1 2 3 -2 -1 0 VZ (V) Reference Voltage vs. Junction Temperature 2.515 1 2 3 VZ (V) Reference Input Current vs. Junction Temperature 100 VZ = VREF IZ = 10mA 2.510 IZ = 10mA R1 = 10kΩ R2 = ∞ 80 IREF (nA) VREF (V) 2.505 2.500 60 40 2.495 20 2.490 2.485 0 -50 -25 0 25 50 75 100 125 -50 150 -25 0 25 Ratio of Delta Reference Voltage to Delta Cathode Voltage vs. Junction Temperature 75 100 125 150 125 150 Off-State Cathode Current vs. Junction Temperature 100 IZ = 10mA ∆VZ = 3V to 36V 0.4 10 0.3 1 VZ = 36V VREF = 0V IZ(off) ∆VZ (-mV/V) ∆VREF/∆ 0.5 50 TJ (°C) TJ (°C) 0.2 0.1 0.1 0.01 0 0.001 -50 -25 0 25 50 TJ (°C) 75 100 125 150 -50 -25 0 25 50 75 100 TJ (°C) 4 © 1998 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 ADJUSTABLE SHUNT REGULATOR SC431 April 13, 1998 TYPICAL CHARACTERISTICS (Cont.) Small-Signal Gain and Phase Shift vs. Frequency IZ = 10mA TA = 25°C AV (dB) 70 -180 -225 60 -270 50 -315 40 -360 30 -405 20 -450 10 -495 0 -540 -10 -585 -20 1.0E+02 1.0E+03 1.0E+04 1.0E+05 Phase Shift (deg) 80 Test Circuit For Small-Signal Gain and Phase Shift -630 1.0E+06 f (Hz) Reference Impedance vs. Frequency 100 IZ = 10mA TA = 25°C rZ (Ω Ω) 10 1 0.1 Notes for Application Circuit: 0.01 1.0E+03 1.0E+04 1.0E+05 1.0E+06 1.0E+07 1) Set VOUT according to the following equation: f (Hz) R1 V OUT = V REF 1 + + IREF R1 R 2 APPLICATION CIRCUIT 2) Choose the value for R as follows: • • The maximum limit for R should be such that the cathode current, IZ, is greater than the minimum operating current (100µA) at VIN(min). The minimum limit for R should be such that IZ does not exceed 150mA under all load conditions, and the instantaneous turn-on value for IZ does not exceed 200mA. Both of the following conditions must be met: R min ≥ R min ≥ VIN (max) 200 mA (to limit instantaneous turn-on IZ) VIN (max) − V OUT IOUT (min) + 150 mA (to limit IZ under normal operating conditions) 5 © 1998 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 ADJUSTABLE SHUNT REGULATOR SC431 April 13, 1998 OUTLINE DRAWING SOT-23 OUTLINE DRAWING SO-8 OUTLINE DRAWING TO-92 6 © 1998 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320