TLVH431ACLP datasheet(16/54 Pages) TI

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8 Applications and Implementation

Note

Information in the following applications sections is not part of the TI component specification,

and TI does not warrant its accuracy or completeness. TI’s customers are responsible for

determining suitability of components for their purposes, as well as validating and testing their design

implementation to confirm system functionality.

8.1 Application Information

Figure 8-1 shows the TLVH431, TLVH431A, or TLVH431B used in a 3.3-V isolated flyback supply. Output

voltage VO can be as low as reference voltage VREF (1.24V ± 1%). The output of the regulator, plus the forward

voltage drop of the optocoupler LED (1.24 + 1.4 = 2.64V), determine the minimum voltage that can be regulated

in an isolated supply configuration. Regulated voltage as low as 2.7 Vdc is possible in the topology shown in

Figure 8-1.

The TLVH431 family of devices are prevalent in these applications, being designers go to choice for secondary

side regulation. Due to this prevalence, this section explains operation and design in both states of TLVH431 that

this application will see, open loop (Comparator + VREF) and closed loop (Shunt Regulator).

Further information about system stability and using a TLVH431 device for compensation see Compensation

Design With TL431 for UCC28600, SLUA671.

−

VCC

VFB

Current

Sense

Gate Drive

GND

Controller

TLVH431

3.3 V

120 V

Figure 8-1. Flyback With Isolation Using TLVH431 or TLVH432 as Voltage Reference and Error Amplifier

TLVH431, TLVH431A, TLVH431B, TLVH432, TLVH432A, TLVH432B

SLVS555N – NOVEMBER 2004 – REVISED JUNE 2024

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Product Folder Links: TLVH431 TLVH431A TLVH431B TLVH432 TLVH432A TLVH432B

TLVH431ACLP 数据表(PDF) 16 Page - Texas Instruments