Dear support member.
I consider to use MP2316.
Please tell me about this device.
Q1
“PG will not de-assert low when input power is off and EN signal is high condition.”
Is this mean PG doesn’t output signal?
Q2
What is the purpose of diode between PG and EN?
best regards.
My guess, is that the internal transistor at the PG pin that pulls PG down ( de-asserts) can’t work if Vin is too low, because that transistor will have no gate drive. So in the event that Vin is low but the PG pullup is powered then you will get a incorrect PG signal.
The foolishness with the diode to the EN pin is an attempt to paper this over. So if for some reason you wish to separately power the PG pin, and that voltage is high while the Vin is too low for the PG pin to operate, BUT EN is low THEN the low EN would clamp the false PG signal to a low level. Of course if EN was high while Vin was too low and you were powering PG from an high external source, that trick won’t work.
Seems to be a really odd and convoluted concatenation of events to merit a paragraph in the datasheet.
Bottom line if Vin is too low the PG pin is going to be hi-Z. That may cause problems. Best idea is follow the datasheet suggestion and power PG from Vcc so the PG pin is only powered when the EN pin is high and Vin is valid… No false signals.
Dear Jshannon.
Thank you for answer.
I have an additional question.
I consider to use MP2316 in parallel
Can I connect PG pin and other EN pin?
I want to boot EN pin of mp2316 with PG pin of other MP2316.
Best regards.
I would think no problem, but why? That would be very good for sequencing different supplies but if both converters are in parallel then don’t they supply the same load? That suggests to me that unless one converter can fully support the load you run the risk of the first converter getting stuck and the PG never enabling the second converter
Hi ryota_arihara,
This states that if you have PG pulled up to an external voltage, it might show a logic high even if the input is off and EN is high. We recommend you avoid driving EN high without a valid input present regardless if PG is externally pulled up.
If you choose to use an external pull up or connect 2+ PG pins, then the diode is a good solution to properly pull down PG when EN is low, which would disable the output anyway. To avoid the diode, it’s best to use Vcc as a pull up for PG because Vcc will go away when Vin is off.
We not recommend you parallel two MP2316 outputs. A good to rule to follow with MPS parts is to only parallel devices that specifically list this feature. If you are looking to just use one MP2316’s PG to enable a second device, then this situation is fine. As @jshannon noted above, just remember that the second device’s operation will be dependent on the PG of the first.