Hi,
I'm using TPS3850G50 to monitor a 5 V voltage rail and a watchdog timer from a RPI board; I must also provide a manual reset switchbutton.
Under-/over-voltage condition, manual reset and watchdog timing fault must all activate the same output signal to the RPI.
The requested watchdog timing is about 1.0-1.2 s; reset duration is requested to be more than 2 s.
This is the scheme I designed:
Pin SET1 is enabled high by RPI once the watchdog timer is ready.
WDI windows is set to 0.9-1.6 s by CWD NC and both SET0 and SET1 high.
WDO and RESET outputs are connected together and OR-ed, as they are both open-drain outputs.
WDO (reset) timing is set to 3.2 s by CRST cap = 1 uF.
Currently my issues are:
- WDI is not working: I suppose this is because GP10 output has 3.3 V max level, while WDI min is required to be 0.8 x Vdd = 4 V; there I should add a level translator;
- the manual reset is not working: when I close switch button S2, the voltage at SENSE pin goes down to 4.5 V as expected by the R1/R6 divider, which is below Vdd - 4% = 4.8 V, but this does not trigger the RESET pin.
Any idea about it?
Thank you in advance
