Hi
I’m Favaro here from Texa Italy, i’m using the PMIC tps65217D with a AM3352 and with a single lithium battery cell.
I’ve a problem with a particular situation at startup of board and with a low voltage Battery now I try to explain the condition of test:
1) Suppose that the Pmic is powered only from AC 4,6V power supply generator
2) Battery is simulated with a voltage generator ( I know that is not the same thing but it is a fast setup to detect the problem)
3) I attached the schematic where the V_PSYS is the AC external voltage 4,6V.
4) The problem is simulated when the battery go low and NO AC present, the battery go <Vuvlo ( 3,3V) we say 3,00V vbypass and Vint_ldo =2,3V
5) Well if I connect a 4,6V the board start, wakeup signal go low for 5 sec and wait pwren, but if I remove AC plug and reconnect it before ONE second and with low battery voltage, i see that Vint_LDO stay at 2,3V but no AC rise is detected so I’m into fault condition with battery not charging and power supply AC connected; all is frozen. I red that with the battery low if AC<Vuvlo+Voffset the pmic detect a AC removal , the next rise AC is performed into 3mS up to 4,3V so minus of 50mS from datasheet but it is losted. The problem is that the power path is still again the battery and it is not in charging but the power AC is connected.
6) If I wait more then one second between AC removed and next AC present all restart .
7) If the battery is above the Vuvlo any fault on AC power supply is bypassed and all work fine.
How can I investigate on the Problem?
It was enough have always the charger enabled so with the battery low it will arrive to charge state and a little uP on board , not AM3352 can awake it and perform a reset PMIC so it will restart using ac power.
Is possible to modify the internal reset state register to have a different initial condition? Mybe can be useful.
When the system is frozen it is not sensible to reset or PButton.
I see that if i perform AC on ---> off---> on sequence the Vldo1 out remain low so the Sitare is not able to produce a power good.
please suggest me something to do , we have discover this only with particular situation and next month we start with thousand pieces for mass production.
