www.fairchildsemi.com LM431SAI Programmable Shunt Regulator Features Description • • • • The LM431SAI is three terminal output adjustable regulator with thermal stability over operating temperature range from -40°C to +85°C. The output voltage can be set any value between VREF (approximately 2.5 volts) and 36 volts with two external resistors. This device has a typical dynamic output impedance of 0.2Ω Active output circuit provides a sharp turn-on characteristic, making this device excellent replacement for Zener Diodes in many applications. Programmable Output Voltage to 36 Volts Low Dynamic Output Impedance 0.20 Typical Sink Current Capability of 1.0 to 100mA Equivalent Full-Range Temperature Coefficient of 50ppm/°C Typical • Temperature Compensated for Operation Over Full Rated Operating Temperature Range • Low Output Noise Voltage • Fast Turn-on Response SOT-23F 3 1 2 1. Cathode 2. Ref 3. Anode Internal Block Diagram + - Rev. 1.0.0 ©2009 Fairchild Semiconductor Corporation LM431SAI Absolute Maximum Ratings (Operating temperature range applies unless otherwise specified.) Parameter Symbol Value Unit Cathode Voltage VKA 37 V Cathode current Range (Continuous) IKA -100 ~ +150 mA Reference Input Current Range IREF -0.05 ~ +10 mA Thermal Resistance Junction-Air (Note1,2) MF Suffix Package RθJA 350 °C/W Power Dissipation (Note3,4) MF Suffix Package PD 350 mW Junction Temperature TJ 150 °C Operating Temperature Range TOPR -40 ~ +85 °C Storage Temperature Range TSTG -65 ~ +150 °C Note: 1. Thermal resistance test board Size: 76.2mm * 114.3mm * 1.6mm (1S0P) JEDEC Standard: JESD51-3, JESD51-7 2. Assume no ambient airflow. 3. TJMAX = 150°C, Ratings apply to ambient temperature at 25°C 4. Power dissipation calculation: PD = (TJ - TA)/RθJA Recommended Operating Conditions Parameter 2 Symbol Min. Typ. Max. Unit Cathode Voltage VKA VREF - 36 V Cathode Current IKA 1.0 - 100 mA LM431SAI Electrical Characteristics (TA = +25°C, unless otherwise specified) Parameter Symbol Reference Input Voltage VREF VREF(dev) Deviation of Reference Input Voltage OverTemperature Ratio of Change in Reference Input Voltage to the Change in Cathode Voltage Reference Input Current Deviation of Reference Input Current Over Full Temperature Range ΔVREF/ΔVKA IREF IREF(dev) LM431SAI Conditions Unit Min. Typ. Max. VKA=VREF, IKA=10mA 2.450 2.500 2.550 V VKA=VREF, IKA=10mA TMIN≤TA≤TMAX - 5 20 mV ΔVKA=10V-VREF - -1.0 -2.7 ΔVKA=36V-10V - -0.5 -2.0 IKA=10mA, R1=10KΩ,R2=∞ - 1.5 4 μA IKA=10mA, R1=10KΩ,R2=∞ TMIN≤TA≤TMAX - 0.8 2 μA mV/V IKA =10mA Minimum Cathode Current for Regulation IKA(MIN) VKA=VREF - 0.45 1.0 mA Off -Stage Cathode Current IKA(OFF) VKA=36V, VREF=0 - 0.05 1.0 μA VKA=VREF, IKA=1 to 100mA ,f ≥1.0kHz - 0.15 0.5 Ω Dynamic Impedance ZKA Note: 1. TMIN = -40°C, TMAX = +85°C 2. The deviation parameters VREF(dev) and IREF(dev)are defined as the differences between the maximum and minimum values obtained over the rated temperature range. The average full-range temperature coefficient of the reference input voltage, αVREF, is defined as: αV REF V REF ( dev ) ⎞ 6 ⎛ -------------------------------------⋅ 10 ⎝ ⎠ V REF ( at25°C ) ⎛ ppm ------------⎞ = --------------------------------------------------------⎝ °C ⎠ T MAX – T MIN VREF(min) VREF(dev) VREF(max) TMAX -TMIN where TMAX -TMIN is the rated operating free-air temperature range of the device. αVREF can be positive or negative depending on whether minimum VREF or maximum VREF, respectively, occurs at the lower temperature. Example: VREF(dev) = 4.5mV, VREF = 2500 mV at 25 °C, TMAX -TMIN = 125 °C for LM431SAI. αV REF 4.5mV ⎞ 6 ⎛ ---------------------⎝ 2500mV⎠ ⋅ 10 = ------------------------------------------ = 14.4ppm ⁄ °C 125°C Because minimum VREF occurs at the lower temperature, the coefficient is positive. 3 LM431SAI Test Circuits LM431SAI LM431SAI Figure 1. Test Circuit for VKA=VREF LM431SAI Figure 3. Test Circuit for lKA(OFF) 4 Figure 2. Test Circuit for VKA≥VREF LM431SAI Typical Performance Characteristics 800 150 VKA = VREF o VKA = VREF TA = 25 C o TA = 25 C 600 IKA, CATHODE CURRENT (uA) IK, Cathode Current (mA) 100 50 0 IKA(MIN) 400 200 0 -50 -200 -100 -2 -1 0 1 2 -1 3 0 1 2 3 VKA, CATHODE VOLTAGE (V) VKA, Cathode Voltage (V) Figure 4. Cathode Current vs. Cathode Voltage Figure 6. Reference Input Voltage vs. Ambient Temperature Figure 5. Cathode Current vs. Cathode Voltage Figure7. Reference Input Current vs. Ambient Temperature 6 60 o TA = 25 C IKA = 10mA 50 o TA=25 C 5 INPUT 4 Voltage Swing (V) Open Loop Voltage Gain (dB) 40 30 20 3 OUTPUT 2 10 1 0 0 -10 1k 10k 100k 1M 10M Frequency (Hz) Figure 8. Small Signal Voltage Amplification vs. Frequency 0 4 8 12 16 20 Time (us) Figure 9. Pulse Response 5 LM431SAI Typical Performance Characteristics (Continued) 5 140 4 A VKA = Vref B VKA = 5.0 V @ IK = 10mA 120 o A 100 80 Current(mA) IK, CATHODE CURRENT(mA) TA = 25 C stable stable 60 1 B 0 100p 1n 10n 1ٛ 100n 10ٛ CL, LOAD CAPACITANCE 5 4 3 2 1 0 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 0 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 Anode-Ref. Voltage(V) Figure 10. Stability Boundary Conditions Current(mA) 2 40 20 1.6 1.8 2.0 Ref.-Cathode Voltage(V) Figure 12. Reference-Cathode Diode Curve 6 3 Figure 11. Anode-Reference Diode Curve LM431SAI Typical Application R1 V O = V ref ⎛⎝ 1 + -------⎞⎠ R2 R1 V O = ⎛ 1 + -------⎞ V ref ⎝ R 2⎠ R1 V O = ⎛ 1 + -------⎞ V ref ⎝ R 2⎠ LM7805/MC7805 LM431SAI Figure 13. Shunt Regulator LM431SAI - LM431SAI Figure 14. Output Control for Figure 15. High Current Shunt Regulator Three-Termianl Fixed Regulator LM431SAI Figure 16. Current Limit or Current Source LM431SAI Figure 17. Constant-Current Sink 7 LM431SAI Mechanical Dimensions Package Dimensions in millimeters SOT-23F Marking 43A I 2% tolerance 8 LM431SAI Ordering Information Product Number Output Voltage Tolerance Package Operating Temperature LM431SAIMFX 2% SOT-23F -40 ~ +85°C DISCLAIMER FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. FAIRCHILD DOES NOT ASSUME ANY LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS. LIFE SUPPORT POLICY FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and (c) whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury of the user. 2. A critical component in any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. www.fairchildsemi.com 10/6/09 0.0m 001 Stock#DS400510 © 2009 Fairchild Semiconductor Corporation