TLV431ACDBVT datasheet(20/54 Pages) TI

20 / 54 page

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 TLV431, TLV431A, or TLV431B used in a 3.3V 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 431 family of devices are prevalent in these applications, being designers go to choice for secondary side

regulation. Due to this prevalence, this section will further go on to explain operation and design in both states of

TLV431 that this application will see, open loop (Comparator + Vref) and closed loop (Shunt Regulator).

Further information about system stability and using a TLV431 device for compensation can be found in the

application note Compensation Design With TL431 for UCC28600 (SLUA671).

Figure 8-1. Flyback with Isolation Using TLV431, TLV431A, or TLV431B as Voltage Reference and Error

Amplifier

TLV431, TLV431A, TLV431B

SLVS139Z – JULY 1996 – REVISED JUNE 2024

www.ti.com

Submit Document Feedback

Product Folder Links: TLV431 TLV431A TLV431B

TLV431ACDBVT Datasheet(PDF) 20 Page - Texas Instruments