BQ25185EVM: I want to control the charging of BQ25185

Alecさん、ご返信ありがとうございます
。BATピンに2.35AhのLi-Ionバッテリーを接続しています。Li
-Ionバッテリーには充電状態を監視するガスゲージICが内蔵されており、バッテリーが80%充電されたらCEピンをHi(3.3V)にして充電を停止したいのですが、充電電流を完全に止めることができず、100～300mA程度の充電電流が流れ続けます。TS
/MR端子は10kでプルダウンして機能をキャンセルしています。

Thanks for your reply, Alec.
I have a 2.35Ah Li-Ion battery connected to the BAT pin.
The Li-Ion battery has a built-in gas gauge IC that monitors the charging status, and I would like to stop charging by setting the CE pin to Hi (3.3V) when the battery is 80% charged, but I cannot stop the charging current completely and a charging current of about 100 to 300mA continues to flow.
The TS/MR terminals are pulled down with 10k to cancel their functions.

Hello Masaru,

Thank you for clarifying the details of your system. Which path are you measuring this 100 to 300mA current on? Could you please confirm whether this is the charge current to the battery or the current to the system load? Specifically, is this current from VBUS to VSYS, VBUS to VBAT, or VBAT to VSYS?

Best regards,

Alec Lehman

Thank you for your support, Alec.
The 100 to 300 mA current after disabling CE is the current that flows from VBUS via the BAT terminal to the Li-Ion battery. This is information read via the I2C bus from the TI gas gauge IC built into the battery.
Charging does not stop even after disabling CE, and the charging current will reach zero when the battery is 100% charged.

Hello Ochi-san,

1. Can you share a waveform of this issue showing VSYS, VBAT, /CE, and IBUS? If you aren't able to show IBUS, could you show VIN instead?
2. What are your VBUS and VBAT voltages?
3. Can you provide your schematic for the BQ25185?

Best regards,

Alec Lehman

Thank you for your support, Alec.
I am sending the circuit diagram and signal waveforms.
The signal waveforms are VSYS, VBAT, and CE from top to bottom.
VSYS becomes disrupted when CE changes from enabled to disabled.

Hello Ochi-san,

Thank you for providing the waveform and schematic.

I have seen this behavior before, and it is typically related to the amount of capacitance on VBAT and VSYS. We are currently investigating this issue further.

In the meantime, could you try adding more capacitance to the SYS and BAT pins to see if that fixes it? Additionally, what is your input source voltage and expected system load current?

Best regards,

Alec Lehman