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ATL431LI: Any change on related Discrete components, when changing from TL431 to ATL431/431LI

Part Number: ATL431LI
Other Parts Discussed in Thread: TL431, ATL431

Hi,

My customer finished AC/DC design with TL431IBIDBZR. However he found his following circuit is smaller (0.6mA) than required Cathode Current of TL431 (1mA Min). ATL431/ATL431LI is satisfied with Cathode current (0.1mA Min).

 

So, if he replaces TL431 to ATL431/ATL431LI, does he need to change value of any other components? If yes, please let us know the recommended value of each components. Please advise us.

Thanks and best regards,
M.HATTORI.

  • Hi Motoyasu,

    The ATL431/ATL431LI allow customers to modify their circuit to achieve lower Iq but they do not naturally lower the IKA.

    1. For shunt references the optocoupler + resistor control how much IKA goes into the ATL431. If you do not modify the circuit, it will consume the same amount of current. If you want to take advantage to the lower current, you can increase the resistor size or remove the resistor that is parallel to the optocoupler.

    2. While the devices have the same pinout, the ATL431 has a lower bandwidth than the TL431 which might cause changes in the stability network of 1uF/1kOhm. This would need to be tested and it is not something we can calculate.

    3. The output voltage is Vout = VKA * (1+R1/R2) + IREF*R1. The ATL431 has a higher VKA of 2.5V vs 2.495V so the output can increase. The ATL431 also has a lower IREF so the output can decrease depending on the size of R1.

    Those are the top 3 things I would look at when switching between a TL431 to ATL431/ATL431LI