GM431 2.5V ADJUSTABLE SHUNT REGULATOR Description Features The GM431is a three terminal adjustable shunt regulator with thermal stability guaranteed over temperature. The output voltage can be adjusted to any value between 2.5V (VREF) and 18V by using two external resistors. The GM431 has a typical dynamic output impedance of 0.2 . Active output circuitry provides a very unique turn on characteristic, making the GM431an excellent replacement for zener diodes in many applications such as on board regulation and adjustable power supplies. The GM431 is an ideal voltage reference for 3.0 to 3.3V switching power supplies. Sink Current Capability 1mA to 100mA Low dynamic out put impedance, 0.2 typ. Low output noise 0.5%, 1% or 2% reference voltage tolerance Alternate for TL431, LM431 & AS431 Temperature range -40°C to + 125°C Available in SOT-23, TO-92, SOT-89 and Sop- 8 packages The GM431 shunt regulator is available with 3 voltage tolerances 0.5%, 1.0% and 2.0% over full temperature range and four package options (SOT-23, TO-92, SOT-89 and SO-8). Application Switching power supplies Battery-operated computers Linear regulator Computer disk drives Adjustable supplies Instrumentation Logic Symbol Block Diagram Cathode Reference Cathode Reference VREF Anode www.gammamicro.com.tw GM431V1.07 Anode 1 GM431 2.5V ADJUSTABLE SHUNT REGULATORS Marking Information and Pin Configurations (Top View) SOT23 SOT89 AAXYW 3 Cathode 431G AYWW 431G AYWW Ref 1 Ref 1 2 3 Cathode Anode (GM431) Anode 2 RAXYW 1 Cathode 3 Ref (GM431R) GM431V1.07 AAX: Marking Code (see table below) RAX: Marking Code (see table below) G: Grade Code (A: 0.5%, B: 1.0%, C: 2.0%) A: Assembly/Test Site Code Y: Year W: Week code WW: Week 2 SO8 6. Anode 7. Anode 8. Ref Anode 2 1 Ref TO92 5. NC GM431G AYWW 3 Cathode 2 Anode 1. Cathode 2. Anode 4. NC 3. Anode GM431 2.5V ADJUSTABLE SHUNT REGULATOR Ordering Information Precision Device Code Grade Package Shipping GM431AT92B 0.5% A TO-92 1,000 Units/ESD Bag GM431AT92RL 0.5% A TO-92 2,000 Units/Ammo Pack (Tape) GM431AST23R 0.5% AAA SOT-23 3,000 Units/Tape & Reel GM431RAST23R 0.5% RAA SOT-23 3,000 Units/Tape & Reel GM431AS8T 0.5% A SO-8 100 Units/Tube GM431AS8R 0.5% A SO-8 2,500 Units/Tape & Reel GM431AST89R 0.5% A SOT-89 1,000 Units/Tape & Reel GM431BT92B 1.0% B TO-92 1,000 Units/ESD Bag GM431BT92RL 1.0% B TO-92 2,000 Units/Ammo Pack (Tape) GM431BST23R 1.0% AAB SOT-23 3,000 Units/Tape & Reel GM431RBST23R 1.0% RAB SOT-23 3,000 Units/Tape & Reel GM431BS8T 1.0% B SO-8 100 Units/Tube GM431BS8R 1.0% B SO-8 2,500 Units/Tape & Reel GM431BST89R 1.0% B SOT-89 1,000 Units/Tape & Reel GM431CT92B 2.0% A TO-92 1,000 Units/ESD Bag GM431CT92RL 2.0% C TO-92 2,000 Units/Ammo Pack (Tape) GM431CST23R 2.0% AAC SOT-23 3,000 Units/Tape & Reel GM431RCST23R 2.0% RAC SOT-23 3,000 Units/Tape & Reel GM431CS8T 2.0% C SO-8 100 Units/Tube GM431CS8R 2.0% C SO-8 2,500 Units/Tape & Reel GM431AST89R 2.0% C SOT-89 1,000 Units/Tape & Reel GM431V1.07 Ordering Number 3 GM431 2.5V ADJUSTABLE SHUNT REGULATORS Absolute Maximum Ratings PARAMETER Cathode Voltage Continuous Cathode Current Range Reference Input Current Range Power Dissipation at TA = 25°C SOT-23 TO-92 SOT-89 SO-8 Package Thermal Resistance SOT-23 TO-92 SOT-89 SO-8 Operating Ambient Temperature Range Storage Temperature Lead Temperature (soldering 10 sec.) SYMBOL RATINGS UNITS VKA IK IREF 20 -100 to 150 -50µA to 10mA V mA PD 0.23 0.78 0.8 0.6 W 336 132 132 163 -40 - 125 - 65 to 150 260 θJA TA °C/W °C °C °C Recommended Operating Conditions PARAMETER Cathode Voltage Cathode Current SYMBOL Min Max UNITS VKA IK VREF 10 18 100 V mA Equivalent Schematics Cathode 800 800 20pF Reference 3.28K 4K GM431V1.07 10k 4 2.4K 7.2K 20pF 1K Anode GM431 2.5V ADJUSTABLE SHUNT REGULATOR Electrical Characteristics (TA = 25°C unless otherwise specified) Parameter Symbol Condition GM431A Reference Voltage GM431B VREF VKA = VREF, IK = 10mA, Test circuit 1 GM431C VREF Deviation over Temperature Ratio of change in VREF to change in VKA Reference Input Current VREF(DEV) ∆VREF/∆VKA Min Typ Max 2.488 2.500 2.513 2.475 2.500 2.525 2.450 2.500 2.550 4 17 VKA = VREF, IK = 10mA, Full Range Test circuit 1 IK = 10mA ∆VKA = 10V to VREF -2.7 -1.0 ∆VKA = 18V to 10V -2 -0.4 Unit mV mV µA IREF IK = 10mA, R1 = 10K, R2 = ∞ Test circuit 2 1.3 4 µA IREF Deviation over Temperature VREF(DEV) IK = 10mA, R1 = 10K, R2 = ∞ Full range, Test circuit 2 0.4 1.2 µA Minimum Cathode Current IK(MIN) VKA = VREF Test circuit 1 0.4 1.0 mA Off-state cathode Current IK(OFF) VKA = 18V, VREF = 0V Test circuit 3 0.1 1 µA Dynamic Impedance |ZKA| VKA = VREF, IK = 1mA to 10mA, f ≤1kHz, Test circuit 1 0.2 0.5 Ω VKA VIN Test Circuits VIN IK VKA IK R1 VIN VKA IK(OFF) IREF VREF Test Circuit 1 VKA = VREF R2 VREF Test Circuit 2 VKA > VREF Test Circuit 3 Off-State GM431V1.07 VREF 5 GM431 2.5V ADJUSTABLE SHUNT REGULATORS Cathode current (mA) Typical Characteristics 200 2.5 150 2 Impedance 100 50 0 -50 1.5 1 0.5 -100 0 -150 -2 -1 0 2 1 Cathode Voltage (V) 3 IREF, Reference Input Current (mA)) Figure 5. Cathode Current vs. Cathode Voltage 0.6 0.5 0.4 0.3 0.2 0.1 0 -40 -20 0 20 40 60 80 100 120 TA Ambient Temperature (˚C) GM431V1.07 VREF, Reference Input Voltage (V) Figure 6. Reference Input Current vs. Ambient Temperature 6 2.500 2.498 2.496 2.494 2.492 2.490 2.488 2.486 -40 -20 0 20 40 60 80 100 120 TA Ambient Temperature (˚C) Figure 8. Reference Input Voltage vs. Ambient Temperature 0 100K 200K 300K 400K 500K 600K Frequency (Hz) Figure 7. Dynamic Impedance GM431 2.5V ADJUSTABLE SHUNT REGULATOR Design Guide for AC-DC SMPS (Switching Mode Power Supply) Use of Shunt Regulator in Transformer Secondary side control This example is applicable to both forward transformers and flyback transformers. A Shunt regulator is used on the secondary side as an error amplifier, and feedback to the primary side is provided via a photo-coupler. Transformer R1 SBD R3 GM384X series (+) IF VF Phototransistor IB R2 C1 Light Emitting Diode Output VO R5 GM431 (-) VREF R4 Figure 9. Typical Shunt Regulator/ Error Amplifier Determination of external constants for the Shunt Regulator DC Characteristic determination: In the application circuit above, R1 and R2 are protection resistors for the light emitting diode in the photo-coupler, and R2 is a bypass resistor to feed IK Minimum, and these are determined as shown below. The photo-coupler specification should be obtained separately from the manufacturer. Using the parameters in this circuit, the following formulas are obtained: R1 = V O – VF - V K IF + IB VF R2 = I B VK is the GM431 operating voltage, and is set at around 3V, taking into account a margin for fluctuation. R2 is the current shunt resistance for the 1ight emitting diode, in which a bias current IB of around 1/5 IF f1ows. Next, the output voltage can be determined by R3 and R4, and the following formula is obtained: R3 + R4 R4 ) VREF = 2.5V Typical The abSo1ute va1ueS of R3 and R4 are determined by the GM431 reference input current IREF and the AC characteristics described in the next Section. The IREF va1ue is around 0.7µA Typ. GM431V1.07 VO = VREF ( 7 GM431 2.5V ADJUSTABLE SHUNT REGULATORS AC Characteristic Determination: This refers to the determination of the gain frequency characteristic of the Shunt regulator as an error amp1ifier. Taking the configuration in Figure 10, the error amp1ifier characteristic is as Shown in Figure 10. G1 Gain G (dB) * fOSC: PWM Switching frequency G2 When R5= 0 F1 FAC F2 When R5= 0 fOSC Frequency f (Hz) Figure 10. GM431 Error Amplification Characteristic In Figure 17, the following formulas are obtained: Gain G1 = G0 ≅ 50 dB to 60 dB (determined by shunt regulator) R5 G2 = R 3 Corner frequencies f1 = 1/(2pC1G0R3) f2 = 1/(2pC1R5) G0 iS the Shunt regulator open-loop gain; this is given by the reciprocal of the reference voltage fluctuation: ∆VREF/∆VKA, and is approximately 50 dB. Practical Example Consider the example of a photocoupler, with an internal light emitting diode VF = 1.05 V and IF = 2.5mA, power supply output vo1tage V2 = 5V, and bias resistance R2 current of approximately 1/5 IF at 0.5mA. If the Shunt regulator VK = 3V, the following values are found. GM431V1.07 5V – 1.05V – 3V R1 = 2.5mA + 0.54mA = 316Ω 8 1.05V R2 = 0.54mA = 2.1kΩ Next, assume that R3 = R4 = 10k. This gives a 5V output. If R5 = 3.3 k, and C1 = 0.022 pF, the following values are found. G2 = 3.3kΩ / 10kΩ = 0.33 times (-10 dB) f1 = 1 / (2 × π × 0.022µF × 316 × 10 k) = 2.3 (Hz) f1 = 1 / (2 × π × 0.022µF × 3.3k) = 2.2 (kHz) 2 GM431 2.5V ADJUSTABLE SHUNT REGULATOR Package Outline Dimensions – SOT 23 0.110 - 0.120 (2.80 - 3.04) 0.003 - 0.007 (0.08 - 0.18) 0.013 - 0.017 (0.34 - 0.44) 0.013 - 0.017 (0.34 - 0.44) 0.083 - 0.104 (2.11 - 2.62) 0.047 - 0.055 (1.20 - 1.40) 0 - 8 typ 0.075 Typ. (1.91) 0.037 (0.93) Typ. 0.0150 - 0.0200 (0.382 - 0.508) 0.0005 - 0.0040 (0.025 - 0.102) Package Outline Dimensions – SOT 89 0.173 - 0.181 (4.39 - 4.59) 0.061 REF (1.550 REF) 0.084 - 0.090 (2.13 - 2.28) 0.155 - 0.167 (3.94 - 4.24) 0.055 - 0.063 (1.39 - 1.60) 0.014 - 0.017 (0.35 - 0.43) 0.090 - 0.102 (2.28 - 2.59) 8 0.035 - 0.047 (0.89 - 1.19) 0.016 - 0.023 (0.400 - 0.580) 0.013 - 0.021 (0.320 - 0.520) 0.059 BSC (1.49) BSC GM431V1.07 0.118 BSC (2.99) BSC 9 GM431 2.5V ADJUSTABLE SHUNT REGULATORS Package Outline Dimensions – TO 92 3.85 - 4.19 4.7 - 5.2 4.9 - 5.2 12.7 - 14.2 0.4 - 0.55 Typ. 1.22 - 1.32 2.10 - 2.27 Dimensions are in millimeters Package Outline Dimensions – SO 8 0.189 - 0.197 (4.800 - 5.004) 0.228 - 0.244 (5.791 - 6.198) 0.016 - 0.050 (0.406 - 0.270) D 0.014 - 0.020 (0.356 - 0.508) 0.050 (1.270) TYP 0.150 - 0.157 (3.810 - 3.988) 0.053 - 0.059 (1.346 - 1.753) GM431V1.07 SEATING PLAN 10 0.004 - 0.010 (0.012 - 0.254) 0.008 - 0.010 (0.203 - 0.254) 8.0 MAX GM431 2.5V ADJUSTABLE SHUNT REGULATOR Ordering Number GM 431 A APM Gamma Micro Circuit Type T92 R Output Accuracy Package Type Shipping Type A: 0.5% B: 1.0% C: 2.0% T92: TO-92 ST23:SOT-23 ST89: SOT-89 S8: SO-8 B: Bag RL: Ammo Pack (Tape) T: Tube R: Tape & Reel ST23 R Output Accuracy Package Type Shipping Type A: 0.5% B: 1.0% C: 2.0% ST23:SOT-23 R: Tape & Reel GM 431R A APM Gamma Micro Circuit Type GM431V1.07 Ordering Number 1 1 1