Hi,
We have an application powered by a single 3.7V 900 mAh LiPo cell. The cell is charged by a MP2607 with a USB-C power source. The system is designed to power off if the cell voltage drops to 3V and there is no USB power available.
Ichg is set to 445 mA with a 5k1 resistor. Charge timer is set to 2.28 hours with a 1 uF capacitor. Both status pins are connected directly to digital input pins of a PIC microcontroller, with 4k7 pull-ups to the Vsys pin of the MP2607
Testing shows that some cells discharge to ~2.76 V before system shutdown. When USB power is re-applied the cells don’t charge. No current flows into or out of the battery (measured with a sensitive ammeter) but the current drawn from the USB power supply is ~100 mA higher than the system normally draws when not charging the battery
Seen on an oscilloscope, one of the status pins is oscillating. STAT1 remains low, but STAT2 is high for ~3.6 milliseconds, then low for ~180 microseconds (see attached screenshot).
Has anyone else seen this sort of behaviour, or could anyone suggest what’s causing the failure to charge?
Thanks