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# TLVH431A-Q1: Max input voltage for shunt regulation circuit

Part Number: TLVH431A-Q1

Hi Champs,

My customer thinks to use TLVH431A-Q1 for High voltage node.

With attached configuration, what is the available maximum voltage as “input” node with following parameter?

Ik = 100uA,

R1 = 1.25M ohm,

R2 = 100k ohm,

Vo = 17.5V

Question.xlsx

Thanks and best regards,

Nobuo Fujihara

• Hi Nobuo,

The TLVH431 is a current based shunt voltage reference, as long as the device has enough current (Ik) to meet specifications then the device will function. There is no maximum input voltage (Vin) but based on your Rin there is a minimum and maximum voltage range that the device will function in.

The Vin based on Ik = 100uA is:
Vin (Ik = 100uA) = Vo + Rin*Ik = 17.5V + 199kohm*100uA = 37.5V
This is the minimum voltage needed at Vin to make the device function.

The maximum Vin based on your configuration is:
Vin (Max) = Vo + Rin*Ik(Max) = 17.5V + 199kohm*70mA = ~14k V.
This is the maximum voltage needed at Vin to make the device function.

I hope that answers the question.

-Marcoo

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