Hi Expert:
We are using MP6710+MP6570, the system is working now. But the Power Good signal seems abnormal, it always output low, which should indicate that the power is not good, but the system is working fine. which sources can triggger power not good?
Peter
Do you have a pullup on the pin?? Crap datasheet, but I believe that pin would count as a logic output and hence needs a pullup. I know, that it isn’t shown anywhere on the datasheet
sure, we have a pull up. usually, such function pin is OD, and block digram also shows it’s OD.
Peter
we use RED LED to show the power status, but this RED LED is always ON despete the system is working. It should be OFF according to normal POWER GOOD (assert high) function.
Peter
Does the datasheet even tell you what the power good logic is? Maybe that is really a power bad pin.
I might have missed it. I also don’t see any description of what might constitute power good? In regulators it usually means within 10% of setpoint.
There must be someone at MPS that can answer this complicated question.
Well can you try and force a BAD condition ( I know it doesn’t seem to be specified) but for instance overload the motor and see if the pin changes state. Shame you have to resort to experimentation on such a matter.
The datasheet doesn’t tell the power good logic. That’s why i am puzzled about this state. I am not sure POWER GOOD is asserted low or asserted high. Almost all POWER GOOD signal is asserted high or OD, this chip seems reversal. I am sure the designer of this chip is very clear about this.
Peter
You would think, but even if it is a power bad pin then the next question is what does that mean? It would be nice to know that as well. Does it work otherwise?
if it’s mean power bad, which means some exceptions must be detected by the chip internally. But now the chip is working, we are worry abou the potential issue.
Well good luck somebody there ought to be able to answer the question. Have you tried MPS Now? That seems to be where they try to push questions. I don’t know why
Hi Peter,
When power is good, the LED should turn on, so if you would like to indicate power good, the LED can be changed to green.
Best Regards,
Yu
