19-2593; Rev 0; 10/02
Advanced Chemistry-Independent, Level 2
Battery Charger with Input Current Limiting
Features
o Input Current Limiting
The MAX1645B employs a next-generation synchronous buck control circuitry that lowers the minimum
input-to-output voltage drop by allowing the duty cycle
to exceed 99%. The MAX1645B can easily charge one
to four series Li+ cells.
o +8V to +28V Input Voltage Range
Applications
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 Up to 18.4V Battery Voltage
o 11-Bit Battery Voltage Setting
o ±0.8% Output Voltage Accuracy with Internal
Reference
o 3A (max) Battery Charge Current
Notebook Computers
o 6-Bit Charge-Current Setting
Point-of-Sale Terminals
o 99.99% (max) Duty Cycle for Low-Dropout
Operation
Personal Digital Assistants
o Load/Source Switchover Drivers
o >97% Efficiency
Pin Configuration
TOP VIEW
Ordering Information
PART
DCIN 1
28 CVS
LDO 2
PIN-PACKAGE
28 QSOP
26 CSSP
REF 4
TEMP RANGE
-40°C to +125°C
27 PDS
CLS 3
MAX1645BEEI
25 CSSN
CCS 5
CCI 6
24 BST
MAX1645B
23 DHI
CCV 7
22 LX
GND 8
21 DLOV
BATT 9
20 DLO
DAC 10
19 PGND
VDD 11
18 CSIP
THM 12
17 CSIN
SCL 13
16 PDL
SDA 14
15 INT
QSOP
Typical Operating Circuit appears at end of data sheet.
SMBus is a trademark of Intel Corp.
________________________________________________________________ Maxim Integrated Products
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.
1
MAX1645B
General Description
The MAX1645B is a high-efficiency battery charger
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 MAX1645B
automatically transitions from regulating current to regulating voltage. The MAX1645B 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 MAX1645B stop
receiving charging voltage/current commands.
