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[FAQ] BQ24040 and BQ2404X family Trouble Shooting Tips, No Output, Charge Current Low, Early Termination and Others.

What are some trouble shooting recommendation if we are seeing problems with the BQ24040 or similar devices.

This also applies to BQ21040, BQ24050 and BQ24090 family of devices. Some Trouble Shooting tip for the device family If the device does not start charge, no current to battery check: TS pin voltage needs to be between 278mV and 790mV for normal operation Check that input voltage is below OVP, 6.6V. Double check ISET and PRETERM resistors, low charge current could cause problems. Charge will start but current to battery is low of target: TS pin voltage needs to be in the normal range. At low temp half charge will reduce current TS between 790mV and 1230mV ISET2 pin, Float will limit current to 100mA Input voltage low, need 700mV to 1000mV drop across the device for full output current. Internal thermal limit, if the die temp reaches 125C output current is reduced to control thermal rise. The Charge May Terminate Early or at lower voltage: TS pin voltage needs to be in normal range. At hot temp charge voltage is reduce to 4.06V TS between 278mV and 178mV. Resistance between the battery and charger will increase voltage at BAT terminal and appear as higher battery voltage. Also: Battery or battery simulator required for test standard load will not work. CHG and PG pin will give some insight into condition of device. Check the voltage at ISET, it should be proportional to output current reduced by 400. Iout/400 * R-ISET. Voltage at ISET represents output current and voltage at PRETERM represents termination point. Battery voltage for normal charge current needs to be between 2.5V and 4.1V. Below or above and current is reduced.