Hi guys,

It's my first post here so please forgive my unprofessional wording.

I am working on troubleshooting bunch of overheating PCB boards. I found the 2 components on my charging circuit always heat-up or malfunction even after replacement.

The first issue component is the Power management chip LTC 4085 which connect the Li-ion battery, voltage converter chip, and the wall adaptor. 5v coming from wall adaptor and pass this LTC 4085 chip. When the charger is connected, the battery charging voltage is 4.2V to from pin 14. When charging is off, the battery voltage is supplied to the converter chip. The problem with this power management chip is , always get the wrong output on Pin14 to the battery. I have been replacing the chip, clean up the solder pads underneath but still many failed to have the correct output.( either 0v or >4,2v)

The second issue component is the voltage converter chip TPS63001, convert 5v to 3.3v. This component always gets heat up. However, has the correct output. Again, i have tried to replace the heat-up components and clean the solder pad, issue still there.

I have also tried adding noise filter Capacitor on charging cable to make sure the input voltage is steady around 5v.


Here is the schematics of the design:




Any suggestion what next component i should check to eliminate this heat-up issue? I appreciate any input!

Thanks


Sean

 

You're operating it above it's maximum rated spec's. Reread the datasheet and understand it. You're exceeding the junction temperature. Speak about the LTC4085, that is.

Also, unfortunately you schematics are too small-- we cannot see resistor values in order to see how the LTC is configured, which might given indication as to where to look next to determine why too much current is flowing through the LTC4085.

 

You're operating it above it's maximum rated spec's. Reread the datasheet and understand it. You're exceeding the junction temperature. Speak about the LTC4085, that is.

Also, unfortunately you schematics are too small-- we cannot see resistor values in order to see how the LTC is configured, which might given indication as to where to look next to determine why too much current is flowing through the LTC4085.

Thank you for your reply BobaMosfet. Here I found an enlarged schematic of the peripheral design on the LTC chip. The problem with the LTC chip is its rarely get overheat compared to the voltage converter chip. However, its often found malfunction and output the wrong voltage on Pin 14 to the battery, which always failed to charge up the battery. Is it something can be resulted from over limited current flow? I am wondering if the heat up can be the design problem. However, this design has been running well for few years until recently had overheating issue. Please let me know your thoughts! I appreciate your suggestion!

 

Hi guys,

It's my first post here so please forgive my unprofessional wording.

I am working on troubleshooting bunch of overheating PCB boards. I found the 2 components on my charging circuit always heat-up or malfunction even after replacement.

The first issue component is the Power management chip LTC 4085 which connect the Li-ion battery, voltage converter chip, and the wall adaptor. 5v coming from wall adaptor and pass this LTC 4085 chip. When the charger is connected, the battery charging voltage is 4.2V to from pin 14. When charging is off, the battery voltage is supplied to the converter chip. The problem with this power management chip is , always get the wrong output on Pin14 to the battery. I have been replacing the chip, clean up the solder pads underneath but still many failed to have the correct output.( either 0v or >4,2v)

The second issue component is the voltage converter chip TPS63001, convert 5v to 3.3v. This component always gets heat up. However, has the correct output. Again, i have tried to replace the heat-up components and clean the solder pad, issue still there.

I have also tried adding noise filter Capacitor on charging cable to make sure the input voltage is steady around 5v.


Here is the schematics of the design:

View attachment 144470


Any suggestion what next component i should check to eliminate this heat-up issue? I appreciate any input!

The particular specification being exceeded is the output current. So you need to use the current limiting function of that IC to limit the current to the correct value.
Thanks


Sean