TMS320F28377S: Snubber on VREF on Launch design

Timothy Luca

Part Number: TMS320F28377S
Other Parts Discussed in Thread: OPA320, OPA350

I have a Launch Kit for the F28377S.Each of the Vref inputs is driven by an OPA320 hooked as a buffer; there is also a 2.2uF/560 milliohm network from Vref to ground. What is the purpose of this snubber network? If a different amplifier is used, is the snubber necessary?

Thanks,

Tim

over 8 years ago

0 Devin Cottier over 8 years ago

TI__Guru 60865 points

Hi Tim,

This network is used to ensure that the op-amp is stable. The network may need to change with different op-amps. OPA320 and OPA350 are good choices for driving the VREFHI and should result in similar snubber resistors.

0 Timothy Luca over 8 years ago in reply to Devin Cottier

Intellectual 790 points

Thanks for your response. Is there any particular need to use such a high bandwidth amplifier to drive Vref?

0 Devin Cottier over 8 years ago in reply to Timothy Luca

TI__Guru 60865 points

Hi Timothy,

Yes, high bandwidth and high capacitive load drive are both needed because the VREF pin draws brief but high current transients that need to be settled out to << 1 LSBs. The combination of the capacitor on the pin and the bandwidth of the op-amp allow the transients to be handled.

0 Timothy Luca over 8 years ago in reply to Devin Cottier

Intellectual 790 points

OK, thanks.

Tim

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TMS320F28377S: Snubber on VREF on Launch design