General Description
The MAX1645 are high-efficiency battery chargers capable of charging batteries of any chemistry type. It uses the Intel System Management Bus (SMBus) to control voltage and current charge outputs.
When charging lithium-ion (Li+) batteries, the MAX1645 automatically transition from regulating current to regulating voltage. The MAX1645 can also limit line input current so as not to exceed a predetermined current drawn from the DC source. A 175s charge safety timer prevents “runaway charging” should the MAX1645 stop receiving charging voltage/ current commands.
The MAX1645 employs a next-generation synchronous buck control circuity that lowers the minimum input-to-output voltage drop by allowing the duty cycle to exceed 99%. The MAX1645 can easily charge one to four series Li+ cells.

Features
♦ Input Current Limiting
♦ 175s Charge Safety Timeout
♦ 128mA Wake-Up Charge
♦ Charges Any Chemistry Battery: Li+, NiCd, NiMH, Lead Acid, etc.
♦ Intel SMBus 2-Wire Serial Interface
♦ Compliant with Level 2 Smart Battery Charger Spec Rev. 1.0
♦ +8V to +28V Input Voltage Range
♦ Up to 18.4V Battery Voltage
♦ 11-Bit Battery Voltage Setting
♦ ±0.8% Output Voltage Accuracy with Internal Reference
♦ 3A max Battery Charge Current
♦ 6-Bit Charge Current Setting
♦ 99.99% max Duty Cycle for Low-Dropout Operation
♦ Load/Source Switchover Drivers
♦ >97% Efficiency

Applications
   Notebook Computers
   Point-of-Sale Terminals
   Personal Digital Assistants