TL431: Constant-current sink design

Muhammad Fariz Bin Nor Azhar

Part Number: TL431

Hi TI,

Currently I'm designing a tester to test power supply performance. I'm designing a constant-current sink to simulate loading (2A load) condition of the power supply.

I have some question to ask about this component as below:

1. Can we use two separate power source as below figure? Vi(batt) is my unit under test and Vsup(external) is a constant power source.

2. How to determine R1 value?

Thank you.

Best regards,

Fariz

over 5 years ago

0 Marcoo Z over 5 years ago

TI__Mastermind 19550 points

Hi Fariz,

Yes you can use two separate supplies as you pictured.

R1 is set based on how much current you want on the TL431.

The TL431 is in essence an error amplifier with a band gap reference and higher current will provide a more stable and higher gain circuit.

You can use the app note below for more details on how to choose components.

-Marcoo

0 Muhammad Fariz Bin Nor Azhar over 5 years ago in reply to Marcoo Z

Intellectual 480 points

Hi Marcoo Z,

Thank you for your explanation.

Best regards,

Fariz

Because of the holidays, TI E2E™ design support forum responses will be delayed from Dec. 25 through Jan. 2. Thank you for your patience.

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TL431: Constant-current sink design