BQ25171EVM: Charging 7-cell nickel metal hydride rechargeable batteries with the BQ25171

Hello,

Can you share any voltage / current waveforms? Would be good to see IN, OUT, TS. Also can share a photo of EVM showing how you have the jumpers set up.

Thanks,

Nick

Hello,

Thank you for confirming.
I've attached the schematic for your convenience, and I've also configured the EVM to the same settings.

BQ24151_EVA_20211025.pdf

Hello,

I've taken some photos of the current EVA board and will upload them here.

Hello,

The following is the waveform that was advised above.
CH setting is CH1 VIN (voltage) CH2 VOUT CH3 TS CH4 VIN (current)
The voltage seen in the VOUT section of CH2 is
The voltage seen at VOUT of CH2 is the voltage of Ni-MH rechargeable battery side.

Hello,

TS at 0V is below the hot threshold where there is no charging. What are the STAT1/2 pins showing?

You can verify the resistance are correct for TS (and ISET / VSET) using TP4/TP2/TP9.

Best regards,

Nick

Hello,

STAT1/2 pins have unlit LEDs
In the current configuration, at what voltage does the hot threshold have to be below to enable charging?

The TS voltage needs to be between the hot and cold thresholds:

Nick

In the datasheet, it says that when TS is not used, it is pulled down by 10KΩ.
However, in the case of a NiMH battery like this, it is recommended to adjust it within the above threshold instead of 10KΩ pull-down.
Is this correct?

I adjusted the voltage of TS by changing RS as you advised.
As a result, when the voltage is less than 1.05V, it drops to low after the start-up.
When the voltage is above 1.06V, the voltage remains HIGH, but the LED of STAT1 lights up.
The voltage remains high at 1.06V or higher, but STAT1 LED is lit and charging does not start.

In this case, what should I do next to fix this?