Datasheet TLV431 (Diodes) - 10

TLV431 Application Notes
(continued)
Printed Circuit Board Layout Considerations (continued)
RS IOUT ZXTN25020CFH Vin Vout Q1 VREF  1 R  R3 V  V 1  OUT REF TLV431  2 R  IB V  (V  V ) R1 IN OUT BE 3 R  B I   V IOUT(max) REF    I  mA 18 B TLV431  h  ( FE min)   C1 R V EF R  0.1µF S R2 IOUT(max) GND
Figure 5. Series Regulator with Current Limit
Figure 5 adds current limit to the series regulator in Figure 4 by using a second TLV431. For currents below the limit, the circuit works normally supplying the required load current at the design voltage. However, should attempts be made to exceed the design current set by the second TLV431, the device begins to shunt current away from the base of Q1. This begins to reduce the output voltage and thus ensuring that the output current is clamped at the design value. Subject only to Q1’s ability to withstand the resulting power dissipation, the circuit can withstand either a brief or indefinite short circuit. AP1084 Vin Vin VR1 Vout Vout GND  1 R  V  V 1  OUT REF V R1  2 R  REG V  (V  V ) OUT REG REF V TLV431 REF (All features of the regulator such as short circuit protection, C1 thermal shutdown, etc, are 0.1µF R2 maintained.) GND
Figure 6. Increasing Output Voltage of a Fixed Linear Regulator
One of the useful applications of the TLV431 is to improve the accuracy and/or extend the range and flexibility of fixed-voltage regulators. In the Figure 6 circuit, both the output voltage and its accuracy are entirely determined by the TLV431, R1, and R2. However, the rest of the features of the regulator (up to 5A output current, output current limiting, and thermal shutdown) are all still available. TLV431 10 of 17 March 2024 Document number: DS32088 Rev. 9 - 2
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