L431LM3B

NIKO-SEM 1.24V Low-Voltage Adjustable Precision Shunt Regulator FEATURES L431L GENERAL DESCRIPTION The L431L is a three-terminal adjustable shunt regulator utilizing an accurate 1.24V band gap reference. The output voltage can be set to any value between 1.24V (VREF) to 18V with two external resistors as shown in the typical application circuit. The device exhibit a wide operating current range of 0.2 to 100 mA with a typical dynamic impedance of 0.25 Ω . Active output circuitry provides a very sharp turn-on characteristic, making the L431L excellent replacements for low-voltage zener diodes in many applications, including on-board regulation and adjustable power supplies. When used with an opto-coupler, the L431L is ideal v oltage reference in isolated feedback circuits for 3.3V switching-mode power supplies. The L431L shunt regulator is available in two voltage tolerances (0.5% & 1.0%) and three package options (TO-92, SOT-23-3 and SO-8). Internal amplifier with 100 mA capability Programmable output voltage to 18V 0.25Ω typical output impedance Pin to pin compatible with TLV431A, TS431, SC431L & AS432 Trimmed bandgap design 0.5% & 1.0% with three package options Low output noise APPLICATIONS Linear regulator controller Precision voltage reference Switching power supplies Battery operating equipment Instrumentation PCs, Computer disk drives SYMBOL & BLOCK DIAGRAM Cathode (K) Reference (R) + Cathod (K) Reference (R) 1.24 Vref Anode (A) Anode (A) SYMBOL FUNCTIONAL BLOCK DIAGRAM 1 APR-25-2002 NIKO-SEM 1.24V Low-Voltage Adjustable Precision Shunt Regulator L431L ABSOLUTE MAXIMUM RATINGS PARAMETER Cathode-Anode Reverse Breakdown Voltage - VKA Anode-Cathode Forward Current - IAK Operating Cathode Current - IKA 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 VALUE 20V 1A 100 mA 1 mA -65 to +150 °C 150 °C 300 °C 700 mW 650 mW 200 mW RECOMMENDED CONDITIONS Parameter Cathode Voltage (VKA) Cathode Current (IK) Rating VREF to 18V 10 mA TYPICAL THERMAL RESISTANCES Package TO-92 SOIC-8 SOT-23 Typ. De-rating 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 Output Voltage - VREF Line Regulation - ∆VREF Load Regulation - ∆VREF Temperature Deviation - ∆VREF Reference Input Current - IREF Reference Input Current 0 < TJ < 105 °C Temperature Coefficient - ∆IREF Minimum Cathode Current for Regulation - IK(MIN) Off State Leakage - IK(MIN) VREF = 0V, VKA = 15V Dynamic impedance VKA = Vref, f ≦ 1kHz IK = 0.1 mA to 100 mA TEST TYP MAX UNITS CIRCUIT TA = 25 °C, L432 (0.5%) 1.234 1.240 1.246 V 1 TA = 25 °C, L432 (1%) 1.228 1.240 1.252 mV VKA = VREF to 15V 28 50 2 mV IK = 1 to 100 mA 3.9 6 1 mV 0 < TJ < 105 °C 5 12 1 µA 2.3 6 1 TEST CONDITIONS MIN 0.14 0.2 40 0.25 0.6 1 500 0.4 µA mA nA Ω 1 1 3 1 2 APR-25-2002 NIKO-SEM 1.24V Low-Voltage Adjustable Precision Shunt Regulator L431L TEST CIRCUITS VIN VKA VIN VKA VIN VKA I REF IK R1 V REF R2 I REF IK I K (OFF) - TEST CIRCUIT 1 (VKA = VREF ) - TEST CIRCUIT 2 ) (VKA > VREF - TEST CIRCUIT 3 (OFF STATE CURRENT) Applications Information – Stability Selection of load capacitance when using L431L as a shunt regulator When the L431L is used as a shunt regulator, two options for selection of CL are recommended for optimal stability: 1. No load capacitance across the device, decouple at the load. 2. Large capacitance across the device, optional decoupling at the load. The reason for this is that L431L exhibits instability with capacitances in the range of 1nF to 1uf (approx.) at light cathode currents (up to 3mA typical). The device is less stable the lower the cathode voltage has been set for. Therefore while the device will be perfectly stable operating at a cathode current of 10mA with a 0.1uF capacitor across it, it will oscillate transiently during start-up as the cathode current passes through the instability region. Selecting a very low (or preferably, no)capacitance, or alternatively a high capacitance (such as 10uF) will avoid this issue altogether. Since the user will probably wish to have local decoupling at the load anyway, the most cost effective method is to use no capacitance at all directly across the device. PCB trace/via resistance and inductance prevent the local load decoupling from causing the oscillation during the transient start-up phase. Note : if the L431L is located right at the load, so the load decoupling capacitor is directly across it, then this capacitor will have to be ≦ 100pF or ≧ 1uF. 3 APR-25-2002 NIKO-SEM 1.24V Low-Voltage Adjustable Precision Shunt Regulator L431L Small-Signal Gain and Phase Shift VS. Frequency Test Circuit for Small Signal Gain and Phase OUT 15K 1 1 10uF 8.25K 2 3 Iz 1 L431L 232 2 2 GND Stability Boundary Condition For Shunt Regulation VS. Cathode Current and Load Capacitance Test Circuit for Stability R 3 1 1 2 2 L431L CL Iz R1 R2 Cathode Current VS. Cathode Voltage Cathode Current VS. Cathode Voltage 4 APR-25-2002 NIKO-SEM 1.24V Low-Voltage Adjustable Precision Shunt Regulator Reference Voltage VS. Junction Temperature L431L Reference Impedance VS. Frequency Ω Ratio of Delta Reference Voltage to Delta Cathode Voltage VS. Junction Temperature ΔVz = 16V to Vref ΔVref /ΔVz (-mV/V) Reference Input Current VS. Junction Temperature ∞ 5 APR-25-2002 NIKO-SEM 1.24V Low-Voltage Adjustable Precision Shunt Regulator L431L Off-State Cathode Current VS. Junction Temperature Reference Impedance VS. Junction Temperature PIN CONFIGURATIONS rz (Ω) 6 APR-25-2002 NIKO-SEM 1.24V Low-Voltage Adjustable Precision Shunt Regulator L431L DEVICE SELECTION GUIDE Device Package Marking Tolerance L431LNB TO-92 L431LN 1% L431LM3B SOT-23-3 1LM3 1% L431LVB SOIC-8 L431LV 1% L431LM5B SOT-23-5 1LM5 1% APPLICATION CIRCUIT P01N02LM or P3055L Ni ko Vin Ci n 5V or 12V 1K + +D S G R1 + Vout K Co ut R 10uF A L431L Ni ko R2 Vout = (1 + R1 R2 ) Vref 7 APR-25-2002 NIKO-SEM 1.24V Low-Voltage Adjustable Precision Shunt Regulator L431L TO-92 MECHANICAL DATA mm Min. 4.445 4.318 12.7 0.356 1.143 3.175 0.762 1.27 Typ. Max. 5.207 5.334 15.5 0.533 1.397 4.191 1.270 mm Min. 2.413 0.356 Typ. 2.540 Max. 2.667 0.533 Dimension A B C D E F G Dimension H I J K L M N 8 APR-25-2002 NIKO-SEM 1.24V Low-Voltage Adjustable Precision Shunt Regulator L431L SOT-23 (M3) MECHANICAL DATA mm Min. 2.60 1.40 2.70 1.00 0.00 0.35 0.4 Typ. 0.95 2.80 1.60 2.90 1.10 3.00 1.80 3.10 1.30 0.10 0.5 Max. mm Min. 0.10 0.37 Typ. 0.15 Max. 0.25 Dimension A B C D E F G Dimension H I J K L M N 9 APR-25-2002 NIKO-SEM 1.24V Low-Voltage Adjustable Precision Shunt Regulator L431L SOIC-8 (D) MECHANICAL DATA mm Min. 4.8 3.8 5.8 0.35 1.27 1.65 0.1 0.25 Typ. Max. 5.0 4.0 6.2 0.48 mm Min. 0.4 0.18 0.22 0° 8° Typ. Max. 1.27 0.25 Dimension A B C D E F G Dimension H I J K L M N 10 APR-25-2002 NIKO-SEM 1.24V Low-Voltage Adjustable Precision Shunt Regulator SOT-23 (M5) MECHANICAL DATA mm mm Min. 2.60 0.37 Typ. 1.90(TYP) 2.80 L431L Dimension A A1 A2 b C D E Min. 1.0 0.00 0.70 0.35 0.10 2.70 1.40 Typ. 1.10 0.80 0.40 0.15 2.90 1.60 Max. 1.30 0.10 0.90 0.50 0.25 3.10 1.80 Dimension e H L Max. 3.00 11 APR-25-2002