STMicroelectronics L6924U

The L6924U is a fully monolithic battery charger produced by STMicroelectronics. It is designed to safely charge single-cell Li-Ion/Polymer batteries from either a USB power source or an AC adapter. This device is ideal for space-limited portable products, integrating essential components such as the power MOSFET, reverse blocking diode, sense resistor, and thermal protection into a compact VFQFPN16 package.

The L6924U supports both low-power and high-power modes when operating from a USB source and can also charge from an AC wall adapter. It operates in linear mode when powered from an external voltage-regulated adapter or USB port, and in quasi-pulse mode when powered from a current-limited adapter, significantly reducing power dissipation. The device features closed-loop thermal control to prevent overheating and allows for the programming of various parameters such as fast-charge current, end-of-charge current threshold, and charge timer.

• Fully integrated solution with power MOSFET, reverse blocking diode, sense resistor, and thermal protection.
• Charges single-cell Li-Ion batteries from selectable AC adapter or USB input.
• Programmable charge current up to 1 A in AC adapter mode and up to 500 mA in USB mode.
• 4.2 V output voltage with ± 1% accuracy.
• Linear or quasi-pulse operating mode.
• Closed-loop thermal control.
• Programmable end-of-charge current and charge timer.
• (NTC) or (PTC) thermistor interface for battery temperature monitoring and protection.
• Status outputs to drive LEDs or to interface with a host processor.
• Small VFQFPN 16-lead package (3 x 3 mm).
• Gas gauge function, battery presence check, and protection from unsafe thermal conditions.

• GPS and MP3 players.
• USB-powered devices.
• Digital still cameras.
• Standalone chargers.
• Wireless appliances.

1. What is the L6924U used for?

   The L6924U is a fully monolithic battery charger used to safely charge single-cell Li-Ion/Polymer batteries from either a USB power source or an AC adapter.

2. What are the operating input voltage ranges for the L6924U?

   The operating input voltage ranges from 2.5 V to 12 V, with a start-up threshold of 4.1 V.

3. Can the L6924U operate in different modes?

   Yes, the L6924U can operate in both linear and quasi-pulse modes depending on the power source used.

4. How is the charge current programmed in the L6924U?

   The charge current can be programmed using external resistors connected to the IAC pin for AC adapter mode or the IUSB pin for USB mode.

5. What is the output voltage accuracy of the L6924U?

   The output voltage is regulated to 4.2 V with an accuracy of ± 1%.

6. Does the L6924U have thermal protection features?

   Yes, the L6924U features closed-loop thermal control to prevent overheating and includes an NTC or PTC thermistor interface for battery temperature monitoring and protection.

7. How does the L6924U indicate charging status?

   The L6924U provides two open collector outputs for diagnostic purposes, which can be used to drive external LEDs or communicate with a host microcontroller.

8. What is the package type and size of the L6924U?

   The L6924U comes in a small VFQFPN 16-lead package measuring 3 x 3 mm.

9. Does the L6924U have a gas gauge function?

   Yes, the L6924U includes a gas gauge function that monitors the battery voltage and current to estimate the battery's state of charge.

10. How does the L6924U handle battery presence and absence detection?

    The L6924U checks for battery presence and absence, and it monitors and protects the battery from unsafe thermal conditions.

11. Can the maximum charging time be programmed in the L6924U?

    Yes, the maximum charging time can be set using a capacitor connected between the TPRG pin and GND.