STMicroelectronics announces a Li-Ion battery charger chip – the L6924D, which integrates all of the required power elements, plus other functions, into a very small 3 x 3mm package intended for use in mobile phones, PDAs, digital cameras and MP3 players. All key charging system parameters are programmable, enabling the L6924D to be used across a full range of low cost as well as more sophisticated applications – the first battery charger chip to offer such flexibility.
The L6924D is a fully monolithic battery charger designed for single-cell Li-Ion and Li-Polymer battery packs. The ideal solution for space-limited portable products it is produced with ST’s robust BCD6 smart power technology and integrates the Power MOSFET, reverse blocking diode, sense resistor and thermal protection into a compact VFQFPN16 package.
Designers can choose between Linear and Quasi-Pulse charging modes, depending on the application’s requirements. Linear Mode suits applications with low-cost power adapters, such as an external voltage regulated adapter, when the L6924D can charge the battery in a Constant Current/Constant Voltage (CC/CV) profile. Operation in Quasi-Pulse Mode can be used when a current-limited adapter is available, dramatically reducing the power dissipation. Closed loop thermal control protects the device against overheating in either mode.
The L6924D has an operating input voltage range of 2.5V to 12V, making it suitable for use with a wide range of AC adapters. It is also USB compatible, allowing use in popular USB-powered computer peripherals. All the key parameters are programmable, including pre-charge current, pre-charge voltage threshold, fast-charge current, the end-of-charge current threshold and the charging time.
In addition its default charging parameters allow easy use in compact applications, with few external components, when full flexibility is not required; until now, different devices were required to cover simple and sophisticated applications. The L6924D provides two open collector outputs for diagnostic purposes, such as driving external LEDs or communicating with a host microcontroller, plus flexible control of charge process termination, Gas Gauge capability, and battery presence and temperature monitoring.
These features are increasingly important as the performance expectations – including the lifespan of the battery itself as well as the time between charges – for batteries in portable applications increase, to ensure that optimum battery charge conditions are maintained.
The L6924D battery charger is in volume production now and is available in the VFQFPN16 package priced at $0.90 in quantities of 10,000 units.
Further information is available at www.st.com/powermanagement
L6924D battery charger data sheet