BQ24600: Charging Issue

Hello Michael,

Thank you for getting back to me.

To anwser your questions,

1. Yes the PH pin is connected to the middle of the switching FETs and the inductor, I'll include a snippet below, (the pours are turned off to see more clearly, but they are connected.)

2. I am using an external 3.3V that is variable, when applying to the TS pin, I can recieve input of 0V to 3.2V, this is because I'm testing on a battery that doesn't have a NTC connection and I have to simulate the temperature statuses. 

Hi Michael,

I'll anwser your questions;

1. There is no charging happening at all, no matter of TS, from 0 to 3.3V there was no evidence of any sort of current being used by the power supply.

2. The STAT pin isn't connected to an adapter like it is shown on the TIs example schematic, it's simply connected to a test point. Although when I was debugging using the LED, the LED was dimly on constantly as well as flashing. When I meassured the voltage from STAT to GND I recieved 1.3V

3. Unfortunately I do not posse a scope.

4. Without anything connected between PACK+ and PACK-. these are my results;

VCC = 26.8V

Vref = 3.3V

REGN = 5.9V

While the battery is connected between PACK+ and PACK- ;

VCC = 27.4V

Vref = 3.3V

REGN = 5.9V

Hello,

Please connect the LED as shown in our Typical Application. Its status is critical to debugging the circuit.

What battery voltage are you attaching when this behavior is present?

Regards,

Mike Emanuel

Hi,

The battery voltage is at 24.2 when it's connected to the charger. The charger is set to stop any charging when the cell reaches 26.7V

As for the LED I have attached it and I am getting these results;

1. With no battery attached: The LED is DIM and is BLINKING (brighter when blinking).

2. With battery attached: The LED is DIM and is BLINKING (brighter when blinking).

Hi Patrick,

   Can you describe the frequency of the blinking in both scenarios?

Hi Kedar,

It blinks every 2 seconds. For both scenarios. It's like the charger doesn't want to pick up the battery being connected at all.

Hi PAtrick,

   Do you have a gauge or protector in your system? Can you debug if the charging and discharging FETS are open or closed?

Hi,

There is no gauge or a protector on the system we are trying to charge, we are attempting to charge a cell pack without a BMS to test for charging.

Hi Patrick,

   If you are directly connecting the battery to the output of the charger, then there should be no way the charger does not detect the battery voltage and start charging accordingly. Can you share your schematic?

Hi,

There is a PDF version of the schematic for more quality at the begining, here's a snippet taken from the PDF.

Hi,

   There are some net waveforms missing from this one around the BTST diode portion of the schematic. Can you take a waveform of the PH, and SR_N node when both battery present and battery absent?

Hello Kedar, 

Sorry for the late response I had to wait for feedback from a colleague of mine with a scope to run this test on his side. Although they have the PCB made by another manufacturer I'll have to doublecheck if their traces lack/have something that my PCBs print don't. Here are their results:

Hi,

Can you please provide waveforms of the PH node, SRN node, input voltage, and charge current? Just a table of the results is not enough.

Regards,

Mike Emanuel

Hi,

Unfortunately this is only what I can get off from them. I'll attempt to get my hands on a scope of my own so I can take these meassurements myself and I'll let you know when I get results. In the meantime I'll revise the schematic and compare it with many others out there while I am working on a new one more closely and while paying more attention to the schematic/layout.

I await your new results.

Regards,

Mike Emanuel