19-1566; Rev 2; 1/01
Advanced Chemistry-Independent, Level 2
Battery Chargers with Input Current Limiting
The MAX1645 are high-efficiency battery chargers capa-
ble of charging batteries of any chemistry type. It uses the
Intel System Management Bus (SMBus) to control volt-
age and current charge outputs.
When charging lithium-ion (Li+) batteries, the MAX1645
automatically transition from regulating current to regu-
lating 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.
Personal Digital Assistants
o Input Current Limiting
o 175s Charge Safety Timeout
o 128mA Wake-Up Charge
o Charges Any Chemistry Battery: Li+, NiCd,
NiMH, Lead Acid, etc.
o Intel SMBus 2-Wire Serial Interface
o Compliant with Level 2 Smart Battery Charger
Spec Rev. 1.0
o +8V to +28V Input Voltage Range
o Up to 18.4V Battery Voltage
o 11-Bit Battery Voltage Setting
o ±0.8% Output Voltage Accuracy with Internal
o 3A max Battery Charge Current
o 6-Bit Charge Current Setting
o 99.99% max Duty Cycle for Low-Dropout Operation
o Load/Source Switchover Drivers
o >97% Efficiency
-40°C to +85°C
-40°C to +85°C
Typical Operating Circuit appears at end of data sheet.
SMBus is a trademark of Intel Corp.
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.