Rainbow Electronics MAX8903A - Manual

General Description
The MAX8903A is an integrated 1-cell Li+ charger and
Smart Power Selector™ with dual (AC adapter and
USB) power inputs. The switch mode charger uses a
high switching frequency to eliminate heat and allow
tiny external components. It can operate with either
separate inputs for USB and AC adapter power, or from
a single input that accepts both. All power switches for
charging and switching the load between battery and
external power are included on-chip. No external
MOSFETs, blocking diodes, or current-sense resistors
are required.
The MAX8903A features optimized smart power control
to make the best use of limited USB or adapter power.
Battery charge current and SYS output current limit are
independently set. Power not used by the system
charges the battery. Charge current and SYS output
current limit can be set up to 2A while USB input cur-
rent can be set to 100mA or 500mA. Automatic input
selection switches the system from battery to external
power. The DC input operates from 4.15V to 16V with
up to 20V protection, while the USB input has a range
of 4.1V to 6.3V with up to 8V protection.
The MAX8903A internally blocks current from the bat-
tery and system back to the DC and USB inputs when
no input supply is present. Other features include pre-
qual charging and timer, fast charge timer, overvoltage
protection, charge status and fault outputs, power-OK
monitors, and a battery thermistor monitor. In addition,
on-chip thermal limiting reduces battery charge rate
and AC adapter current to prevent charger overheat-
ing. The MAX8903A is available in a 4mm x 4mm, 28-pin
thin QFN package.
Applications
PDAs, Palmtops, and Wireless Handhelds
Personal Navigation Devices
Smart Cell Phones
Portable Multimedia Players
Mobile Internet Devices
Ultra Mobile PCs
Features
♦ Efficient DC-DC Converter Eliminates Heat
♦ 4MHz Switching for Tiny External Components
♦ Instant On—Works with No Battery or Low
Battery
♦ Dual Current-Limiting Input Circuits—AC Adapter
or USB
Automatic Adapter/USB/Battery Switchover to
Support Load Transients
50m
Ω System-to-Battery Switch
Supports USB Spec
♦ Thermistor Monitor
♦ Integrated Current-Sense Resistor
♦ No External MOSFETS or Diodes
♦ 4.1V to 16V Input Operating Voltage Range
MAX8903A
2A 1-Cell Li+ DC-DC Charger for USB*
and Adapter Power
________________________________________________________________ Maxim Integrated Products 1
19-4410; Rev 0; 12/08
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
EVALUATION KIT
AVAILABLE
Pin Configuration appears at end of data sheet.
CHARGE AND
SYS LOAD
SWITCH
DC SYS
BAT
AC
ADAPTER
OR USB
SYSTEM
LOAD
BATTERY
GND
USB
USB
CHARGE
CURRENT
LOAD
CURRENT
LX CS
PWM
STEP-DOWN
MAX8903A
Typical Operating Circuit
*Protected by US Patent #6,507,172.
Smart Power Selector is a trademark of Maxim Integrated
Products, Inc.
Ordering Information
+ Denotes a lead(Pb)-free/RoHS-compliant package.
** EP = Exposed pad.
PART TEMP RANGE PIN-PACKAGE
MAX8903AETI+ -40°C to +85°C 28 Thin QFN-EP**