MPC5744 power supply

[hansonhe]

Hello,

There is a question about 5744 power supply, the specific situation is like this, now use DCDC to provide 3.3V voltage to 5744, use 5744 internal PMU module combined with transistor to provide 1.25V, at this time 5744 can not start, change the PMU power supply mode to LDO to provide 1.25V, the system can be used normally; at the time of testing, found that 3.3V if use DCDC power supply, there are many problems in the way. I would like to ask how many customers choose DCDC or LDO or use internal PMU module when this IC is powered.

Is the sequence of power start-up caused by it?

[petervlna]

Hello,

at the time of testing, found that 3.3V if use DCDC power supply, there are many problems in the way

Could you specify the issues? Are they related to customer design or to micro?

I would like to ask how many customers choose DCDC or LDO or use internal PMU module when this IC is powered.

This is hard to say how many customers use internal/ external regulation.

But in general as there is no high voltage detector on core voltage customers use external regulation as they are follwing safety requirements from our safety reference manual:

Is the sequence of power start-up caused by it?

Best would be to see the scope measurement of VDD_HV, VDD_LV and reset line after power on reset. Without further information I can only guess.

regards,

Peter