[SOLVED] How's the sequence of two PSUs?

[Enshuo]

Hi all,
I've studied a schematic of two PSUs system. Two PSUs link to a same I2C signal (BMC_I2C_SDA) to BMC. So, it should be controlled by BMC. If so, how's the sequence for general design? PSU1 and PSU2 start at the same time or PSU1 first.

 

[schmitt trigger]

Are they identical voltages,
or is it one +5V and the other +3.3V?

 

[wwfeldman]

Hi all,
I've studied a schematic of two PSUs system. Two PSUs link to a same I2C signal (BMC_I2C_SDA) to BMC. So, it should be controlled by BMC. If so, how's the sequence for general design? PSU1 and PSU2 start at the same time or PSU1 first.

two power supplies, one I2C communication signal and a BMC.
(what's a BMC?)
what are the output voltages of the PSUs?
what voltage levels do the PSUs assume for the I2C connections?
likewise, what voltage level does the BMC assume for the I2C connection?

in general, (but not necessarily) the processor voltages should go on first, then the analog voltages.

please show the schematic

 

[Enshuo]

The output voltage is 12V. Two PSUs power-on (PSU1_PWR_ON_N and PSU2_PWR_ON_N) are triggered at the same time by CPLD after checked with a SW engineer. I thought it's controlled by I2C (PSU_PMBUS_SDA) of BMC (AST2500). Thank you, guys!