cupoftea
Advanced Member level 6
Hi,
We have a 600W Mains PSU with big_battery backup.........there is a micro controlling the switch in/out of the big_battery when the mains fails.
When only the big_battery is connected, the micro must detect this, and then switch the big_battery on to the mains power module......and indeed allow the big_battery to power the micro instead of the coin cell.
The micro needs to be able to detect if the big_battery is there or if the mains is there...........so the micro has a coin cell connected to its VBAT pin (pin1).
Thing is, when we manually switch in the big_battery, the micro does not switch on the PFET which switches the big_battery into the cct.
We just get zero volts out of the micro pin thats supposed to switch on the n channel signal fet. (which would then switch on the series PFETs)
So i am guessing that the VBAT pin is ESD damaged, and the micro is not "seeing" the coin cell?
Is it true that the VBAT pin has no ESD diodes?...and likely the VBAT pin was ESD zapped when the guy manually inserted the coin cell?
When we manually switch in the 3V3 supply (which ultimately comes from the big_battery), the micro works fine....its just not working when only supplied by the coin cell...do you agree the VBAT pin is likely ESD damaged?
STM32F334C8
We have a 600W Mains PSU with big_battery backup.........there is a micro controlling the switch in/out of the big_battery when the mains fails.
When only the big_battery is connected, the micro must detect this, and then switch the big_battery on to the mains power module......and indeed allow the big_battery to power the micro instead of the coin cell.
The micro needs to be able to detect if the big_battery is there or if the mains is there...........so the micro has a coin cell connected to its VBAT pin (pin1).
Thing is, when we manually switch in the big_battery, the micro does not switch on the PFET which switches the big_battery into the cct.
We just get zero volts out of the micro pin thats supposed to switch on the n channel signal fet. (which would then switch on the series PFETs)
So i am guessing that the VBAT pin is ESD damaged, and the micro is not "seeing" the coin cell?
Is it true that the VBAT pin has no ESD diodes?...and likely the VBAT pin was ESD zapped when the guy manually inserted the coin cell?
When we manually switch in the 3V3 supply (which ultimately comes from the big_battery), the micro works fine....its just not working when only supplied by the coin cell...do you agree the VBAT pin is likely ESD damaged?
STM32F334C8