LM5050-1: LM5050 application issues

Hi Reed,

What test are you performing which leads to this?

Regards,

Shiven Dhir

Hi Shiven,
1. first we did one cycle charge/discharge learning：0.5C charge → stand for 2 hours → 0.2 discharge to 0% → stand for 5H
2. stand for about 24H, 0.37C charge for 1H
3. potting AB adhesive 
4. stand for 2~10 days
5. tested the charge if is it ok
6. the result:
a. 1pcs burnd in the 3rd step
b. 3pcs burnd in the 5th step server minutes after the charge test 

Regards,

Gallon Tau

Hi Shiven,

We want to know if the circuit connection is correct?

The VS pin is connected to the IN pin, and without a charger, the OUT pin maintains a voltage of 25V. Is the chip in a normal operating state?

Additionally, is there a possibility of damaging the chip the moment the charger is plugged in (when CH+ is powered on)?

Thank you!

Regards,

Leon Lee.

Hi Leon,

The schematic is fine. Even if VOUT is 25V and INPUT is not present, controller is fine.

Please check when you hot plug the charger, the device ratings are not violated.

Regards,

Shiven Dhir

Hi Shiven,

Currently schematic is:

pin1 (VS) connects to charger+，pin6（OUT）connects to pack+/D of external MOSFET;

the operating condition is:

1. when charger is not present, VS will be not powered and there's no correct bias for internal circuit, but OUT pin is always has battery voltage（6s battery~25V） on it,  won't that cause a latch-up effect in the chip？ 

2. Pin3 (OFF)  is set to a low level by a RC4/RC3 voltage division, that means LM-5050 is set into turn on the MOSFET, however, when the VS is not powered, then MOSFET is turned off even OFF pin is LOW,  and it will turn on immedially once charger is plugged in.

This is where we suspect there might be a problem with this circuit.

Normally , should VS be connected to a constant and stable power supply but not a charger+ which will be not at present at most of time?  does OUT has 25V and VS is not powered will canse internal diodes reserve that cause latch-up or long time leakage cause thermal runaway?

Based on actual burnout cases, it appears that the OUT pin was short-circuited to ground, causing high current, while other components remained unburned

Regards,

Gallon Tau