I recently bought a phone charger (built in 3.7v lithium battery and a 5v, 2A output).
There seems to be an issue with the output current - once it rises above around 200mA the output voltage falls sharply (with a properly charged internal lithium battery).
It would help hugely to determine the model of the boost regulator they are using in order to replace the faulty part of the circuit.
From the attached photo, you can see the main boost IC (IC5) (the other side of the board has the FET (SM8205A), inductor, diode (SK-34 schottky) and cap (100uF tantalum)). It seems to say 'L314' - however I could be wrong about that. Package seems to be a SOT-6.
Does anyone have any thoughts on what the boost controller could be, or what might be wrong?
The chip in the bottom corner of the photo is the battery charge management IC (IC1), marked 3143 - however my searching hasn't turned up any parts for that either.
Many thanks for any leads/ideas!
Andy