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TPS65910A3 Power up without a switch / button

shriram
Intellectual 705 points
Other Parts Discussed in Thread: AM3359

Hello Everyone,

We have recently switched our main processing core to use AM3359 and are in the process of developing our first board with the AM335x Starter Kit as reference.

We definetely need our board to start up, the moment power is applied, without having the user to press a button.

I have searched the forums and net to find a solution to achieve this with TPS65910A3 and have not yet found a method that works.

I tried soldering an R and C as described below (taken from a forum post : http://e2e.ti.com/support/power_management/pmu/f/43/t/191121.aspx)

R = 510K (0402)

C = 10uF (0805)

Tested on AM335x Development Kit (i replaced R112 to 510K, and soldered C=10uF between pins 2,4 of SW5),

I am able to start the starter kit the moment power is applied, but restarting it happens only after a pause of approximately 30 seconds. I guess this is because of the capacitance. Trying lower capacitance value doesnt provide enough delay to start the board.

Instead of using a digital circuit that simulates the button press here to PWRON pin, is there any other simple way to achieve this ?

I will be thankful for any suggestions / solutions.

Thanks very much in advance.

Ram

  • 0
    TI__Expert 6090 points

    Hi,

    You need to check the EEPROM application not. If the VMBHI_IT is mask , device will not start on battery plug. You will have to provide an external even to boot up the battery.

    The bset way is to pull PWRHOLD high , if VMBHI_IT is mask . This need min hardware changes. Also, you need to make sure that this signal shoulf go low when you turn off the deivice by sofware or harware. Other wise device will turn on automatically, if this signal is left pulled high.