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Trouble with ADP1613 DC/DC

Question asked by pyraohms on Jan 18, 2018
Latest reply on Jan 23, 2018 by Fil

I have designed a circuit according to the reference circuit found in the ADP1613 datasheet. Attached is my schematics and PCB.

 

Problem is that when i power the circuit, my PSU current-limits even though no load (ive tried bleeder resistors, doesnt work). Even 500mA or current limit will do. This suggests to me that there must be a short circuit somewhere.

 

I have tried everything i can think of; altering compensation loop, added capacitance on soft-start, disconnected frequency pin from VCC to try both frequencies. double checked the component solder joints, double checked schematics vs. reference design. Nothing can bring the device out of its non-working state. I have tried three of them, all with the same problem. My PCB is professionaly manufactured, the soldering is professional.

 

Enable pin works. Adding 10uF on softstart gives a very slow start, but when the device hits a certain voltage, current limiting occurs.

 

This has come to a point where it drived me crazy. Is it something that i am missing?

 

I'll be happy to provide more details...

 

My schematic diagram

 

Reference design

 

 

PCB top side

 

PCB bottom side (there is a battery charger there too, only C20 SS cap is relevant)

 

The board

 

Please help me!

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