Our customer has verified TPS61170 internal Error amp transfer function by using open loop connection.
When change Vin voltage around 4.9V, there is "a dead point" at that voltage suddenly reduce voltage gain of Error amp.
We expect internal Error amp is powered by Vin supply voltage but if reduce it to below 4.8V then power source is changed to internal boost power supply. In this transition there is some non-liner Error amp function is happened.
Is this correct expectation?
Because we are seeing 1KHz 20mV range output ripple noise at this dead point Vin voltage on TPS61170-280EVM.
Could you tell us the workaround to avoid this internal Error amp power supply transition side effect for eliminating 1KHz ripple noise at high gain OP-amp circuit power supply?
Should we add large RC filter to Vin pin?