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[FAQ] BQ24040: BQ2404X Family Devices Schematic and Layout Review

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Part Number: BQ24040

Hello Team

I have completed my design and layout can someone review it for me?

Best Regards,

Bill Johns,  Applications Engineer

Texas Instruments Inc

Dallas, Texas

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  • BQ24040 and BQ2404X family Checklist for Schematic and Layout Review.

    This also applies to BQ21040, BQ24050 and BQ24090 family of devices.

    Below items are good points to check during schematic and layout review for device. Note that some points may not apply to your specific device.

    Schematic / Layout:

    1. Pin 1 – IN, input filter capacitor 1uF to 10uF range required. Locate close to the device. Should be ceramic (MLCC) with good high frequency response. Voltage on the input may have a wide range size to match possible voltage range.

    2. Pin 2 – ISET, Resistor to ground to set output current should be located near the device with good return back to thermal pad.

    3. Pin 3 – VSS, Ground to thermal pad

    4. Pin 4 – PRETERM, Resistor to ground to set pre-charge and termination current should be located near the device with good return back to thermal pad.

    5. Pin 5 -- /PG, Open collector output pull up required. OK to float if not used.

    6. Pin 6 – NC (No Connect) – Open

    7. Pin 7 – ISET2, USB100/500 select pin pull high, low or float.

    8. Pin 8 -- /CHG, Open collector output pull up required. OK to float if not used.

    9. Pin 9 – TS, Connect to NTC resistor in battery pack or on board to limit temperature range of charge. Ground with 10k if not used. Note if used with removable battery pack protection from ESD or additional filtering is recommended.

    10. Pin 10 -- OUT, output filter capacitor 1uF to 10uF range required. Locate close to the device. Should be ceramic (MLCC) with good high frequency response. Voltage will be regulated to 4.2V lower voltage rating than input can be used.

    11. Thermal Pad – Linear regulators can have high power dissipation. Connect to thermal plane with mult vias.

    Power dissipation on ISET and PRETERM resistor is very low and can be small package.

    Also see layout section of Data Sheet, section 11.

    Best Regards,

    Bill Johns,  Applications Engineer

    Texas Instruments Inc

    Dallas, Texas

    For more information on Battery Charger Solutions see Link

    Search "FAQ" on E2E Forum for common questions on battery charger solutions. 

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