MP2633 trickle charge issue

Good Afternoon,

We have a MP2633, it is supplied by a 5V external power supply, the Li ion battery is at 2.2V.
Mode is connectetd to 0V with a 100kohm, Ilim is tied at 0V with 33kOhm, TMR is tied at ground with a 470nF and Iset is tied at groud with 255k.

Rshunt is 20mOhm, and inductor of 4.7µH.

With this implementation we should have max charge current at 549mA, max input current of 1.2A.

My issue is the charger (MP2633) ties the output “/CHG” at 0V, but the current drawn on the 5V is 3mA.

It should be noticed that this implementation is fully operational on a battery with a voltage higher than 2.7V : Charging current as expected.

For information, please find my implementation

Good afternoon,

My last test revealed that, by changing the charge current resistor (R217 in my schematic, ISET) from 255kOhm to 105kOhm, the charger enters in the trickle charge, with a current of 300mA instead of 3mA with a 255kOhm.

It seems that there is a link between charge current and trickle charge current, which is not described in the datasheet (for the MP2636).

This link leads to issue when a very low battery, is connected to the charger.

As the current charge is low (in my case lower than 500mA/ 255kOhm connected to Iset), the charger falls in a state in which the trickle charge current does not reach 250mA, hence a very low battery could not be recover without human intervention.

Any suggestion?

Best regards,

Leny