BQ24210 compared with BQ25050/60 or any charger "ok for solar Power Source"

All of the chargers mentioned above use buck topology which means the charger input has to be higher than your battery charge voltage. If your solar panel does not have high enough output voltage, then you should use bq25505 or bq25570. These two devices are boost chargers designed to work with low input voltage.

The difference between bq24210 is the input regulation voltage can be set by external resistor. This can be considered as the MPPT function. The input regulation voltage can be set based on the panels characteristic normally 80% of the open circuit voltage of the panel.

BQ25050, BQ25060, and BQ24230 do not have this function. The input voltage regulation is fixed and cannot be programmed based on the panel's MPPTvoltage threshold.

Hi Jing Zou, thanks for your inputs.

The solar panel that I'm planning to use has 5V / 1W to 3W and the circuit (system load) must be 3.3V and may consume 300-800mA. So I think that bq25505 and bq25570 won't apply.

Also, I discovered that bq24210 doesn't have power path support. And that may be necessary for what I'm planning to have.

While searching for alternatives I found some docs about BQ2403x family, that has Integrated Dynamic Power-Path Management (DPPM) and BQ2407x family, that has a hybrid DPM/DPPM topology.

Would you give me some words about them? would them be a good alternative for the MPPT feature while given power path support?

many thanks

I assume 5V/1W to 3W is under full sun. The open circuit voltage varies as the light strength fluctuates. Is your panel going to be under the sun all when charging?

The bq2403x has fixed input voltage regulation (VINDPM) meaning the MPPT threshold is fixed. It cannot be changed based on the panel voltage. We do not have a single cell linear charger with power path that specifically made for solar charging application.

First I would suggest you to fully characterize your panel under your end equipment's operating environment. If you are operating under full sun all time, meaning you have a constant 5V input all time, then you can use bq2403x or any of the power path device. However, this most likely not the case.

After characterization of your panel, you confirm it is a buck operation, then you can use bq24210 + LDO/buck to step down the voltage to 3.3V to supply your system.

Hi Jing Zou,

You are right. I thought that the panels voltage was constant at 5V and only the current would change with light strength. But I did some tests since your latest post and verified that both voltage and current fluctuates. So an IC with MPPT is essential.

In my case the panel will need to be connected to the sensor board full time. Initially, the goal was the panel to charge the battery and same time power the system during the day and then the battery supply power to the system during the night.

While studying the datasheet I saw a schematic where the system load is connected in parallel with the VBAT.

I have some concerns that I would like to minimize, please.

Perhaps I read it wrongly, but if I understood right the IC will enter in LOAD mode only after the power source to be disconnected. So, without power path feature is not possible to charge the battery efficiently while providing power to the system, right ?

Even if it would be possible to charge the battery and feed the system board, would not be possible the IC to detect the charge termination, since VBUS will always be greater than the VBAT. Then it will be always in Charge Mode, right ?

Anyway in order to test I ordered a bq2410, BQ25570 and some LDO to step down 5V to 3.3V .

many thanks again

Many thanks for your time and valuable informations Jing Zou !