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Tool/software:
Hi, I am trying to achieve 48V on Vdd with reference to RTN. I have added a bulk capacitance of 47uF from Vdd to RTN.
The Vdd voltage kept on resetting from 46V down to 0V and back up again. So I added a 2.2K load resistor and it maintained at 46.5V. At this point, I measured CDB and it was still held low at 0.155V even though Vdd is stable at 46.5V.
I then connected a separate board (draws about 4.65W) to Vdd of the TP2378 and Vdd now fluctuates between 4.7V to 0V and it goes up and down. CDB remains low.
Did the TPS2378 ever got out of current limiting mode even when Vdd was stable at 46.5V with a 2.2k load?
Hi Vivien,
Thanks for reaching out.
I will take a look on your question and get back to you early next week.
Best regards,
Diang
Hi Vivien,
Thanks for your patience.
CDB pin is an open drain pin (so does T2P). So it only has two status: High impedance or tie to RTN. It needs a pull up resistor to make its output between H/L.
PMP11257 (https://www.ti.com/tool/PMP11257) is a reference design using TPS2378 and its schematic is https://www.ti.com/lit/df/tidrnh8/tidrnh8.pdf
CDB pin normally is used as a power good signal to let the down stream circuit start up like the below example.
Best regards,
Diang