ron minnich wrote:
I have four K7SEMs which I would like to run from one PC power supply.
Does anyone know if there are off-the-shelf cables available to do this type of thing? Essentially a "Y" connector for the mainboard power connector.
I've never seen any for ATX power supplies since you'd have to deal with a couple control signals.
ATX supply has a PWR_OK ouput and also PS_ON# input.
"PWR_OK is a “power good” signal. It should be asserted high by the power supply to indicate that the +12 VDC, +5VDC, and +3.3VDC outputs are above the undervoltage thresholds. Conversely, PWR_OK should be de-asserted to a low state when any of the +12 VDC, +5 VDC, or +3.3 VDC output voltages falls below its undervoltage threshold, or when mains power has been removed for a time sufficiently long such that power supply operation cannot be guaranteed beyond the power-down warning time."
"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 five main DC output rails: +12VDC, +5VDC, +3.3VDC, -5VDC, 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. The power supply shall provide an internal pull-up to TTL high. The power supply shall also provide debounce 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."
PS_ON# could just be pulled low with a jumper or switch to ground if you didn't care about power control by the motherboard since the ATX supply would be always on.
-Bari