BQ24610: BQ24610 Charge Current Behaviour

Hi Ghild,

What do you mean by if power input increases? What are your test conditions:

• Input voltage
• Battery voltage (set by VFB resistors, and measured at SRN)
• sense resistor (between SRP and SRN)

Is it possible batteries are near full charge and have entered Constant Voltage loop, where current is expected to taper till termination?

I meant, if the voltage input increase the charge current decrease.

conditions:

• 2 cells configuration R1 100k R2 300k
• 3A Charge Current configuration ISET1 0.6V
• input voltage around 9V I can get charge current near 3A
• input voltage around 12V I can get charge current near 2A
• sense resistor 0.01R
• battery condition is about half-full
• and also during charging (battery like half full) the current is not constant is decreasing, it seems there is no threshold between Fast Charging state with Nearer full state.

Hi Ghild,

   This is not normal behavior. Have you been able to evaluate on a BQ24610 EVM board before starting your design?

   Constant voltage loop is only entered when batteries are close to being fully charged, and if battery is half full then it should be in CC phase. WHat is the actual SRN voltage measured in these tests? If possible can you share the schematic you have followed, and is it possible for you to obtain an EVM to test BQ24610 functionality?

I would like to see your schematic. I understand you have modeled it on the typical application schematic.

Hi Kedar,.

please tell me your email,. I prefer send it privately.,

Thanks,

See direct message on E2E.

Hi Ghild,

    I do not see any output capacitors on your schematic. These are C20, C23, C25 and C27 on the schematic of the user guide. The BQ24610 provides internal loop compensation. With this scheme, best stability occurs when the LC resonant frequency, fo , is approximately 12 kHz to 17 kHz for BQ24610. How are you connecting CE? Charge enable is active HIGH logic input. HI enables charge. LO disables charge. It has an internal 1-MΩ pulldown. Also do you have an external thermistor connected at TH or are you evaluating without a thermistor?

1. actually I already know about the capacitor output, I miss that., but after I add them, the charger current not come out., I am using Aluminum Electrolytic Capacitors 22uF (polar).
2. I am using MCU to sending 5V signal, to enable the BQ24610.
3. there is no thermistor, I set the thermistor pin voltage half of voltage reference.

Hi Ghild,

   Can you try using ceramic capacitors? The eletrcolytic capacitors will have a higher impedance (higher ESR and ESL than ceramic) and can affect the feedback compensation loop. What is measured voltage at TS, STAT1, STAT2. Can you also take a scope capture of VFB to see if there is any oscillation?

Hi Ghild,

   Have you been able to perform test with ceramic output capacitor?

Yes., I got better current than before, but not sure yet, because I am controlling ACSET make current gradually increasing., Soon I will test with fixed ACSET to see if the current stable at set position or not.,
I have another question, is it okay if I decrease R3,R5 and R7 from 100k to 50k ? 

Hi Kedar, 

Yes, without Cout cap, the current not follow the current setting, especially if the voltage input higher than battery level.
so yes, Cout cap solve my problem, thanks.