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ATL431LI-Q1: ATL431LIAQDBZRQ1 IREF

Carsten Koeck
Prodigy 540 points

Part Number: ATL431LI-Q1

Customer is trying to replace TL431FDT-Q using ATL431LIAQDBZRQ1

It is used in the feedback loop of an isolated flyback controller as shown below

image.png

According to the datasheet IREF is supposed to be 0.4uA max.

Customer does measure 44uA 

Any idea why??

Using the TI device the output voltage of the flyback is off by 3V

Replacing the TI device with the Nexperia device will fix the issue.

BR

Carsten

  • 0
    TI__Genius 13970 points

    Hi Carsten,

    • What is the cathode voltage, cathode input resistance(Rs), and R1?
      • The 0.4uA(max) is for a test condition with a cathode current of 1mA and  R1=10kohm
    • Could you help provide scope captures of the device performance?
      • Instability of the shunt reference can sometimes present itself as voltage below expected
    • Has the customer tried the TL431AQDBZRQ1 as this seems to be a more direct cross to the TL431FDT-Q?

    Thanks,
    Joshua