Can PWRON pin be connected directly to VBAT pin on TPS65930?

Hi Alex,

According to the datasheet (Section 3.3, pg 24), you should be able to connect the PWRON pin directly to VBAT without using a pull-up.

Thanks,

Fern

I would recommend connecting a resistor to control the input current on this pin.

Does it matter if it is Master or Slave mode? The VBAT supply is generated by USB. And I believe there is already a current limiting function. So the resistor may not be needed.

Also does 32KHz clock or IO.1P8 to be present before PWRON goes high?

   We have the 32KHz clock driven by an oscillator and the one change we made that caused the TPS65930 to consistently power-up in slave mode was to have the 32KHz clock present when PWRON was applied.  If the 32KHz oscillator is powered by VIO the device never powered up.  Is the PWRON input sampled by the 32KHz clock?  Since slave mode requires a 32KHz oscillator and a crystal cannot be used, what power rail should it be driven from?  Are there any power boundary issues to be concerned about?

The TPS65950 on the BeagleBoard powers-up in master mode and uses a 32K crystal.  Since our design uses a 32K oscillator and not a crystal does this clock need to be present to power-up successfully in master mode also?

What exactly is the voltage supplied to IO.1P8 used for inside the device?

I didnt understand your comment about pull-up resistor. You provide power from any source it is recommended that you have a resistor on this supply.

For slave mode 32K clock has to be available before powering the device. Internal clock is bypassed in this mode. Supplying the 32K clock with VIO will not help (chicken and egg). You will have to find another source available on your platform.

IO is always 1.8V on this device.

Some additional questions:

1)      Since the 32KHz clock is required to power-up in slave mode and IO.1P8 should be connected to VIO per a previous email, am I correct in assuming that it is OK to drive the 32KHz clock input from an oscillator without power present at the IO.1P8 pin?

2)      If we use an external 32KHz oscillator (not a crystal) and power-up in master mode, does the 32KHz clock need to be present for the TPS65930 to power-up?

3)      Am I correct in assuming PWRON can be tied to the VBAT.USB rail (3.6V) in both master and slave modes?