This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TPS7A8300: power good

Part Number: TPS7A8300
Other Parts Discussed in Thread: ASH, TPS7A83A

Hi,

I am using TPS7A8300 part in my circuit,Power good signal of this IC is using in the reset logic.

How I can test the power good functionality?

Right now my circuit is working fine,but I want to know that if something bad happen to my circuit the power good become low and it will reset my circuit.

So I want to know that How I can make my reset signal low?

Thanks

Ashu

  • Hi Ashu,

    The Power Good signal is based off of the voltage at the feedback node so if you force the output voltage lower than 82% of nominal the PG should trip Low. The other way you can cause PG to trip is to ramp down the input voltage until the part is in dropout and the output voltage falls below the PG threshold (this may only work at higher output voltages).

    Best Regards,
    Mark
  • hi mark,

    Please help me more for clear understanding.The power good voltage is depend on the VOUT.
    Page 7 of the datasheet . If I try to lower the output voltage less than the 0.82 of nominal PG automatically the power good pin voltage level is reduce.(0.82*Vout).

    Can you please elaborate, how I can do testing to test powergood?

    Thanks
    Ash
  • Hi Ashu,

    The Power Good pin is just a voltage comparator it is comparing the voltage at the FB pin to an internal voltage as seen in the internal block diagram. To make the power good go low the FB voltage must go below 82% of its nominal value. This can be done a couple of different ways. You can force the output or feedback to a voltage low enough the power good trips. There are some problems with this though as you may end up in current limit or the part will end up in dropout if you force the feedback voltage, which can cause damage to downstream devices. The safest thing to do is ramp the input voltage down until the comparator trips and forces the Power good low.

    You may also wan to consider using the TPS7A83A, which is pin to pin with the TPS7A83
    Regards,
    Mark