Using POWER_ON to reset AM3517 board

Dave Pulvermacher

Other Parts Discussed in Thread: TPS650732, AM3517

I put a switch in to pull POWER_ON (from the TPS650732) low (it is otherwise pulled up to Vsys). I would still like to tie POWER_ON to the AM3517, though, in order to give the 3517 the ability to reset the board. I see on a ref schematic that POWER_ON is going into a GPIO on the 3517. My only concern is whether or not the GPIO will be pulling that line down during startup, therefore not allowing the DC convertors to enable. Suggestions?

over 14 years ago

0 BrandonAzbell over 14 years ago

TI__Guru 63530 points

Table 2-1 and Table 2-2 of the AM3517 datasheet provide information of the state of each pin when reset is active (BALL RESET STATE) and just after reset is released (BALL RESET REL STATE).

0 Bernie Thompson TI over 14 years ago

TI__Mastermind 41665 points

You would need to choose a GPIO pin carefully to ensure that the one you choose is not pulled low during reset, and that the software you are running is not setting the pin low unless you really wanted to reset the device. I think table 2-1 of the datasheet may be of some help to you, this table defines the power up, reset, and post reset defaults of the various pins of the device, this way you could choose a pin that is pulled high (or is high impedance with an external pull up resistor) before and after reset.

0 Dave Pulvermacher over 14 years ago in reply to Bernie Thompson TI

Intellectual 870 points

Thanks guys. Looks like I can use pin F3, part of the GPMC port. It is internally pulled high on a reset.

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Using POWER_ON to reset AM3517 board