BQ24610 issues

Hi JK,

Any updates from your side yet?

Thanks,  

Tahar

Hi Tahar:

Thanks for the support - I am still doing the testing. 

I have two boards - both boards same, charging happens in one board, and in anothr nothing happens. In that non-working board BTST output is just 5volts even before battery is placed. In the working board, this is about 12V.

In the working  board - 

I have this doubt about regulation voltage - datasheet do not give a an answer anywhere. When you say the regulation voltage should measure 2.1V - under what condition ? I can measure 2.1 before battery is placed. Once the battery placed, that voltage comes down because battery voltage is down.  So the question is should I get the resistors fine tuned to get more than 2.1V at Vfb ? In this board, Charger cuts off at 11.05volts, i presume it is because regulation voltage never reaches 2.1V.

Since the LED are connected with Cathode connected to STAT1/STAT2/PG# pins as shown in typical application schematic in datasheet - so shouldnt FET on make the LED glow ? As per table 3, if there is a fault condition both FETs are off, and so LEDs also off ? In my case, LED on STAT2 never turns on - it should turn on when the charge is done. When the charge is done, charging on STAT1 LED  turns off, but STAT2 LED do not turn on.

In the non-working board, PG# is blinking all the time ( even in working board at times), i think it is because of some limitations on the adapter.

I have no clue why one board is not working at all, though the board is same as working board. I would assume some component went wrong there. I am now focusing to make the working board perfect, before turning to the other one.

Since I do not have a KEPCO power supply, my testing is slow. Can I use a regular power supply instead of Kepco. I think that should not be possible, right ?

Appreciate your help.

thanks

JK

Hi

The BTST goes only to 5V even the battery is attached. That should not be right. Can you please check the voltage before and after the inductor and the Zener Diode? Specially check the connection of the components.

The VFB pin is used to sensing output voltage of the battery. It is connected the output of a resistive voltage divider from the battery terminals to this node to adjust the output battery regulation voltage. If you look at figure 16 on page 15, the pin is sensing the battery voltage and as it hits the regulation level (2.1V), the charge should go to voltage regulation phase. Equation 01 on the same page provides a way to calculate the feedback resistors.   

If STAT1(LED)=ON and STAT(LED)=OFF, the battery charging is complete. If you never got this state, means that you never be able to complete the charging.

What is the voltage at Vcc ? That is what determines the PG status.

Since one board is working and you think they are the same. Well, there is no magic in engineering; it has to be something different between them. The way you described the issue, I would start checking the output side and see what make the BTST pin goes only to 5V. it can be bad connection or a short or something  

Thanks!

Tahar

The BTST goes only to 5V even the battery is attached. I  also got this problem, but i use the bq24600.

In this status, i found the high side MOSFET driver is always turn off. The Voltage of REGN Pin is 6V,if you don't use the schottky diode, use the 1n4148 or others like that, 1V lower than the Vregn is normal.

i don't know why this happend.

Hi

The RGN pin needs to be 6V. It is PWM low side driver positive supply output. It should be connected to a 1-μF ceramic capacitor from RGN to GND pin, and as close as possible to the IC. Use for low-side-driver and high-side driver bootstrap voltage by connecting a small signal Schottky diode REGN to BTST.

Please start debugging your circuit from the FB pin and see if you are getting the appropriate voltage level. If the FB pin voltage is in the charging regions, you should see the IC driving the MOSFET to charge up the battery. see if you MOSFET's are aproperiatly connected. Your TS pin voltage is fine based on you last post, but disable it by using the 10K ohm resistor just to make sure it is not causing the issue. Make sure that you CE is well connected to VREF and the IC is enabled with the aproperaite voltage level. Look at ACN, ACP, SRP and SRN pins are getting the appropriate signals. Is ACDRV providing the right driving volatges? what is your voltage at the SYS? Are you using the same battery for both boards?

Thanks,

Tahar

HI Tahar: 

Thanks for continued support - 

If you remember  - I had listed two issues

1. No charging happens

2. - charging happens - but LED status not OK

on Issue #1, I have set aside that for now, as the board has gone for other software testing. And it could be because of bad soldering or others issues, as both boards are identical.  I will re-visit this issue later.

On issue #2, I have got the board working better - basically LEDs are working as expected. I had added 10KOhm res  at TS pin. but the real turning point was when I reduced the battery rated voltage as 12.04 from 12.60, by changing resistor combination at Vfb pin. My battery spec tells to charge upto 12.40, but with available resistor combination, I made it to 12.04V. I took a battery charged with an external charger closer to 11.90, and then connected that to my board. When the battery voltage reached to 12.00, STAT1 LED  = off, STAT2 LED  = ON.  

But there is one issue now - dont know exactly when it started coming, I think even after changing the resistors to get it 12.00, I could see a proper behavior, but now the charge current became too low. When I connect an almost discharged battery, it gives only 200mA, though I set it for 1A.  I am still doing this testing, but I feel that current is gradually reducing, and it reaches to 0, much before 12.00Volts.

When I charge the same battery with an external adapter, battery takes  800mA from external adapter.

my ISET1 = 0.21, ISET2 =  0.21. and the Rsr = 10mOhm. ( these are the set value, and measured it correct too). My batery's Iterm is  20mA, but I set it now to 200mA, have seen this works fine ( before I started observing the new issue)

I have given a 1K pull up on CE pin - is that a problem?

BTW, I dont remember seeing a constant current charging - I always saw the current is decreasing - does it mean that charger somehow assumes the regulated voltage is reached ? I have even placed the battery that got discharged upto 9.45v, but even at that voltage, I saw current is reducing..

thanks

Hi,

CE needs to be high for enabling the IC, if you think that the pull up resistor is causing the problem, please remove it.

 The current should be constant till the regulation, measure the voltage at the VFB pin and see if the current is reducing before regulation (2.1V). That should confirm that the part is reducing the current before regulation.

As you hit the regulation, the voltage should stay constant and the current decrease. Keep in mind that in the voltage regulation phase, the charging current goes up (regulation current) and down (zero) with changing duty cycle (Bang bang type of current). The average will be as shown in figure 16 in the datasheet. For a 50% duty cycle you should get half of the regulation current.

Also double check that the SRP and SRN pins are getting the right signal and keep in mind the tolerance of the Rsns resistor.

Thanks

Tahar