AMC1311: Full scale output for 6µs when VDD1 crosses 2.5V

Peter Schulz1

Part Number: AMC1311

Hi,

we've a Problem with the AMC1311 when the high side power supply VDD1 crosses 2.5V either when switching on or off.

In this moment the differential output goes to full scale for about 6µs. After this the differential output goes to the failsafe voltage as described in the datasheet chapter 8.3.3

The problem is that the short full scale pulse triggers our over voltage detection whilst the input signal shows no overvoltage.

Schematic:

Pulse on switching VDD1 on (20µs/DIV):

Pulse on switching VDD1 on (50µs/DIV):

Pulse on switching VDD1 off (20µs/DIV):

Any idea how to avoid this behaviour?

Thanks in advance.

Regards, Peter

over 5 years ago

0 Tom Hendrick over 5 years ago

TI__Guru**** 181521 points

Hi Peter,

This is part of the startup behavior of the AMC1311. You unfortunately can't get around it completely, but you can reduce the width of the pulse if you are able to ramp up your supply a little faster.

0 Peter Schulz1 over 5 years ago in reply to Tom Hendrick

Prodigy 40 points

Hi Tom,

thank you for your fast response.

If this is the normal behavior of the device it should be documented in the datasheet or at least in an application note. So one is able to filter this out without an additional design loop.

Regards,

Peter

0 Tom Hendrick over 5 years ago in reply to Peter Schulz1

TI__Guru**** 181521 points

Thanks for the feedback Peter, I'll see what we can do.

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AMC1311: Full scale output for 6µs when VDD1 crosses 2.5V