Document
MAX8903B
19-4502; Rev 1; 11/09 EVAALVUAAILTAIOBNLEKIT
2A, 1-Cell Li+ DC-DC Charger for USB and Adapter Power
General Description
The MAX8903B 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 for 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 MAX8903B 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 current can be set to 100mA or 500mA. Automatic input selection switches the system load 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 4.1V to 6.5V range of with up to 8V protection.
The MAX8903B internally blocks current from the battery and system back to the DC and USB inputs when no input supply is present. Other features include prequal charging and timer, fast charge timer, taper current detection for charge status, 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 overheating. The MAX8903B is available in a 4mm x 4mm, 28-pin thin QFN package.
Applications
PDA, Palmtop, and Wireless Handhelds
Personal Navigation Devices
Smart Cell Phones
Portable Multimedia Players
Mobile Internet Devices
Smart Power Selector is a trademark of Maxim Integrated Products, Inc.
Features
o Efficient DC-DC Converter Powers System Load and Charger
o 4MHz Switching for Tiny External Components
o Instant On—Works with No Battery or Low Battery
o Dual Current-Limiting Input Circuits—AC Adapter or USB Automatic Adapter/USB/Battery Switchover to Support Load Transients 50mΩ System-to-Battery Switch Supports USB Spec
o Thermistor Monitor
o Integrated Current-Sense Resistor
o No External MOSFETS or Diodes
o 4.1V to 16V Input Operating Voltage Range
Ordering Information
PART
TEMP RANGE PIN-PACKAGE
MAX8903BETI+
-40°C to +85°C
28 Thin QFN-EP (4mm x 4mm)
+Denotes a lead(Pb)-free/RoHS-compliant package. **EP = Exposed pad.
Typical Operating Circuit
AC ADAPTER OR USB DC
LX
CS Q1
SYS
PWM STEP-DOWN
USB USB
Q2
CHARGE CURRENT
Q3
LOAD CURRENT
CHARGE AND SYS LOAD SWITCH
SYSTEM LOAD
BAT BATTERY
MAX8903B
GND
Pin Configuration appears at end of data sheet.
________________________________________________________________ Maxim Integrated Products 1
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.
MAX8903B
2A, 1-Cell Li+ DC-DC Charger for USB and Adapter Power
ABSOLUTE MAXIMUM RATINGS
DC, LX to GND .......................................................-0.3V to +20V DCM to GND .............................................-0.3V to (VDC + 0.3V) DC to SYS .................................................................-6V to +20V BST to GND ...........................................................-0.3V to +26V BST TO LX ................................................................-0.3V to +6V USB to GND .............................................................-0.3V to +9V USB to SYS..................................................................-6V to +9V VL to GND ................................................................-0.3V to +6V THM, IDC, ISET, CT to GND .........................-0.3V to (VL + 0.3V) DOK, FLT, CEN, UOK, CHG, USUS,
BAT, SYS, IUSB, CS to GND ................................-0.3V to +6V SYS to BAT ...............................................................-0.3V to +6V PG, EP (exposed pad) to GND .............................-0.3V to +0.3V
DC Continuous Current (total in two pins)......................2.4ARMS USB Continuous Current.......................................................1.6A
LX Continuous Current (total in two pins).......................2.4ARMS CS Continuous Current (total in two pins) ......................2.4ARMS SYS Continuous Current (total in two pins) .......................3ARMS BAT Continuous Current (total in two pins) .......................3ARMS VL Short-Circuit to GND .............................................Continuous Continuous Power Dissipation (TA = +70°C)
(derate 28.6 mW/°C above +70°C) ............................2286mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature Range ....................