Hi,
I am using BQ24074 Li Ion battery in my application. I have designed the charger IC to charge the battery at 800mA to 1.3A. But I am seeing the maximum charging current is 200mA. I tried changing ISET, ILIM and ITERM resistors but also it is not affecting much.
I am Using External wall adapter of 5V @ 1.5A
I am using EN1=Low and EN2=High.
currently my ISET= 1.1K , ILIM = 2K and ITERM = 1.18K
Can you please give me the exact tested values of ISET, ILIM and ITERM. So that I can use the same to aceive the below mentioned output
I need an battery to charge at 800mA or More.
Please help me to solve this issue ASAP.
Regards
Nanda Kumar M
Hello Nanda,
In my application (BQ24072T) I used ISET=845, ILIM=1.18K and TMR of 10K. I have EN1 tied to Vss via 10K and EN2 tied directly to OUT1 and OUT2. OUT1 and OUT2 are tied together. With an input voltage of 5.11v, I have observed the charging start with approx 900mAh on typical 3.7v battery that showed approx 3.85v before starting the charge cycle.
I think your ILIM is set too high... I show that would limit your current at 0.80Ah while your ISET value is set for 0.809Ah.
Do you have any LED's connected to nPGOOD or nCHG?
BTW: I just noticed that your question was about the BQ24074, which wasn't referenced in the datasheet for the BQ24072... but I see the datasheet for the BQ24074 DOES include the BQ24072 and I am looking for differences regarding the values I posted.
I am using BQ24074. I need the tested values of ISET,ITERM and ILIM. I need to charge the battery at 800mA. So kindly tell me the values for this if you have any.
Yes in my case I am using nPGOOG and nCHG LED. This will be ON when i connect charger input.
Page 23 of the latest datasheet for your charger says...
"Note that if ICHG is programmed as greater than the input current limit, the battery will not charge at the rate of ICHG, but at the slower rate of IIN(MAX) (minus the load current on the OUT pin, if any). In this case, the charger timers will be proportionately slowed down."
I realize after a closer look that your ILIM is determined using 1550 AOHMS compared to my charger using 1600. After calculating your ILIM using 1550 AOhms with a resistor value of 2K... I determined your input current limit to be 750 mAh... which is lower than your fast charge current. That would make your fast charge current higher than your input current limit and would make your battery charge at the slower rate... right?
Please try raising your ILIM resistor value to 1.2 kOhm.
Do the following calculations match with what you come up with?
For your ISET (fast charge current)... I calculate 800mAh = 1112.5 Ohms. For the nearest single component value, I might use 1.1 kOhm. Substituting with 1.1kOhm, I calculate your lower limit to be 809mAh.
For your ILIM (input current limit)... I calculate 1300mAh = 1192.31 Ohms. For the nearest single component value, I might use 1.2 kOhm. Substituting with 1.2kOhm, I calculate your upper limit to be 1292 mAh.
For your ITERM (termination current)... I suggest 50 mAh = 1833.33 Ohms. For the nearest single component value, I would use 1.8 kOhm. Substituting with 1.8kOhm, I calculate your termination current to be 49.09 mAh (if EN1 is not equal to EN2). OR you could just leave this one alone.
bump...