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