MAX8844 lithium ion charger
Using the MAX8844 lithium ion charger IC released by Maxim Semiconductors you can design an very simple and efficiency charger circuit for charging a single cell lithium-ion battery .
The MAX8844 lithium ion charger integrate a current-sense circuit, MOSFET pass element, thermal-regulation circuitry, and eliminate the external reverse-blocking Schottky diode to create the simplest and smallest charging solutions for handheld equipment.
Also , using this charger solution the power source is optimized by the MAX8844Z using automatically select function between the USB or IN power source but if are both power sources connected the highest priority is for IN power source to ensure the shortest charging time for the system .
The MAX8844 charger chip accept an input voltages range from 4.25V to 28V (IN and USB), but the charging is disabled if the input voltage exceeds +7.5V for protection against unqualified or faulty AC adapters.
These charger IC is very easy to be implemented in applications like : Bluetooth Equipment , Cellular and Cordless Phones Charging Cradles and Docks, Digital Still Cameras , MP3 Players Smart Phones and PDAs , USB Appliances .
The maximum charging current is programmed by an external resistor connected from SETI to GND (RSETI).
Use the following equation to determine the fast-charge current (IFAST-CHARGE): FAST CHARGE= 1250V/RSETI,
where IFAST-CHARGE is in amps and RSETI is in ohms.
RSETI must always be 1.25k or higher due to the continuous charging current limit of 1ARMS.