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Help to start a DC/ATX power supply

Discussion in 'Power Electronics' started by thomasvl, Aug 2, 2017.

  1. thomasvl


    Aug 2, 2017
    Hello guys,

    I would like to be able to start my DC/ATX power supply by myself but I can't find a component to do it. My input signal is an ON/OFF signal, so it will be low only for a short time. I thought about using a relay, with my PS_ON signal as my output, but since ON_OFF signal is low for a short time, my relay will pass my PS_ON from high to low only for a short time also, which means my power supply will work only during some ms.

    I then thought about using a flipflop, with a quartz for my clock but it will be too fast and problem will be the same as before, my PS_ON won't stay low.

    I would like to have smething which could make my PS_ON change its state everytime my ON_OFF goes low.

    If you have any idea, it will be more than welcome ^^

    Thanks a lot for your help

  2. davenn

    davenn Moderator

    Sep 5, 2009
    read your post, don't really understand what you are trying to do ??

    if you are trying to remote control the PSU, here is some info .......

    PS_ON# is an active-low, TTL-compatible signal that allows a motherboard to remotely control the power supply in conjunction with features such as soft on/off, Wake on LAN*, or wake-on-modem. When PS_ON# is pulled to TTL low, the power supply should turn on the four main DC output rails: +12VDC, +5VDC, +3.3VDC and -12VDC. When PS_ON# is pulled to TTL high or open-circuited, the DC output rails should not deliver current and should be held at zero potential with respect to ground. PS_ON# has no effect on the +5VSB output, which is always enabled whenever the AC power is present. Table 14 lists PS_ON# signal characteristics. The power supply shall provide an internal pull-up to TTL high. The power supply shall also provide de-bounce circuitry on PS_ON# to prevent it from oscillating on/off at startup when activated by a mechanical switch. The DC output enable circuitry must be SELV- compliant. The power supply shall not latch into a shutdown state when PS_ON# is driven active by pulses between 10ms to 100ms during the decay of the power rails.
    bushtech likes this.
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