TPS65218: PWR_EN pin design

Carleen,
I have forwarded your question to a product specialist to help you.

Please share your schematic for me to review.

How often does the system reset? Every 1 second? Every 20 seconds?

PWR_EN and AC_DET are both critical for power-on.
The simplest way to power-on the device is for PWR_EN to be pulled high at all times and for AC_DET to be connected directly to GND.

With this wiring, the TPS65218 device will power-on as soon a VIN is applied at VIN_BIAS (and VIN should also be the supply to all VIN_DCDCx pins and usually VIN_LDO1 pin).


If you still see system reset with PWR_EN = Hi and AC_DET = Lo, then the system is resetting due to a fault. You can monitor PGOOD and PGOOD_BU pins to look for a fault. You should see one of the DCDCx rails go out of tolerance for >50us before PGOOD or PGOOD_BU goes low.

If possible, you should try changing STRICT bit to 0b during initialization to test if loose VPG and VOV limits prevent system reset.

Hi Brain,

Thanks for your help.

We tied PWR_EN to high and AC_DET to low. 

The VIN is applied to VIN_BIAS, VIN_DCDCx(1-4), VIN_LDO1, IN_BU.

In our original design, we connect PMIC_PWR_EN with RTC_PMIC_PWR_EN. But now we tied to high.

We use TPS65218D0.

I'll send you our sch file soon.

Thanks.

Carleen

When power on first, after 20 seconds or more, we get reset, but after that, it happens quickly like 5 seconds. Wh changed STRIC to 0 too. no help.

How is the PB pin of the TPS65218D0 connected?

PB pin is pullup to high and connected to a reset button (not connect yet).

Please provide scope shots of the issue occurring. You can trigger on VIN ramp and will need to show PWR_EN, AC_DET, PB, any DCDC1-4 voltage, PGOOD, either DCDC5-6, and PGOOD_BU. They do not all need to be on the same scope shot, but the conditions should be the same when you move the scope probes from one test point to another.