AMC1311-Q1: Fail-SafeOutput

Uzi-Wang

Part Number: AMC1311-Q1
Other Parts Discussed in Thread: AMC1311

Hi, I want to use the AMC1311 to sense Vdc voltage, but I just have positive voltage to AMC1311 VDD2 and differential AMP(single source).

Is there have any suggest circuits, can let me got the Fail-Safe output signal?

over 3 years ago

0 Alexander Smith over 3 years ago

TI__Mastermind 47595 points

Hi Uzi,

I'm not sure if I entirely understand the question. Do you mean you are only using VOUTP from the AMC1311 and would like to be able to identify the fail-safe protection?

As you can see in section 8.3.3 Fail-Safe Output of the DS, the fail-safe output is beyond the clipping voltage of the device. Therefor, fail-safe output can be identified when the output is beyond the clipping output magnitude.

This FAQ post may help: https://e2e.ti.com/support/amplifiers/f/14/t/889581

0 Uzi-Wang over 3 years ago in reply to Alexander Smith

Prodigy 30 points

Hi, Alexander

Sorry I didn't explain clearly.

The "Vout" Voltage can sense Vin full range Votlage.

When primary side occur LV or SHTDN signal Low will trigger Fail-safe function ,that makes Outn > Outp, but differential OPA can't deliver negative signlal to uC.

Do you have any suggestion circuits(digital / analog) can let uC sense Fail-safe output without add any extra power ?

0 Alexander Smith over 3 years ago in reply to Uzi-Wang

TI__Mastermind 47595 points

Hi Uzi,

The only solution I can think of is to change the gain of your differential to single-ended conversion such that the fail-safe voltage would be equal to 0V instead of negative. This would result in a slight loss of resolution which may be acceptable for your application.

Another option is to use a dual channel opamp and another input on your uC to create a comparator circuit.

This is outlined in detail in these two documents:

https://www.ti.com/lit/an/sbaa317/sbaa317.pdf?ts=1594219865648&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FISO224

https://www.ti.com/lit/an/sbaa299/sbaa299.pdf?ts=1594219835194&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FISO224

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AMC1311-Q1: Fail-SafeOutput