I have TX1 with the main input voltage from 12-19V. It will be at a table level and not varying but may be say 12V or 18V or other level. I also have a battery back where both input voltage and battery voltage feed VDD_MUX via two diodes. The problem is that when Vin removed the level will fall quickly to ~8V of the li-ion battery.
The VIN_PWR_BAD signal will be asserted when the monitoring circuit (same as found on standard carrier board) see a rapid change in voltage. This will cause the TX1 to shut down.
How can I get it to gracefully change over to a much lower voltage? i.e. 18V(external battery) to 8V(internal battery). Changing the circuit time constant will do little to fix this as it is up to a 10V swing.
If I have micro monitor the vin_pwr_bad only during rise above 10V and ignore any glitches until voltage drops below 7.6V and then assert VIN_PWR_BAD, will the TX1 cope? I would have the micro output a modified PWR_BAD signal to the TX1.
Basically we do not suggest to change voltage so big and so rapidly. It is theoretical workable to use micro controller to monitor vin_pwr_bad not be asserted during changing input voltage, but as lack of tests and experience on it, you might need to estimate the potential risk.
Thanks, but how exactly do we estimate the risk?
We could not find any information other than min and max voltages.
So what data is available to determine if it is possible?
I have no idea about data you mentioned. Suggest not to change voltage like that.