High Efficiency Switch Mode
Li-Ion Battery Charger
ADP3808
FEATURES
GENERAL DESCRIPTION
Selectable 3-cell or 4-cell operation
Adjustable 4.0 V to 4.5 V per cell
High end-of-charge voltage accuracy
0.4ꢀ ꢁ 25°C
0.6ꢀ ꢁ 5°C to 55°C
0.8ꢀ ꢁ 0°C to 100°C
Programmable charge current, including trickle charge
Bootstrapped synchronous drive for external N-channel
MOSFETs
The ADP3808 is a complete Li-Ion battery charging controller
for 3- or 4-cell battery packs. The device combines accurate
final battery charge voltage control with constant current
control to simplify the implementation of constant-current,
constant-voltage (CCCV) chargers.
The final battery charge voltage is programmable between 4.0 V
to 4.5 V per cell, allowing the charging of various cell types. The
charge current is programmable over a wide range from trickle
charging to full charging. The system current sense amplifier
includes an ac adapter detection output to signal that the
adapter is connected. The bootstrapped synchronous driver
controls two N-channel MOSFET transistors for high efficiency
charging at a low system cost.
Programmable oscillator frequency
APPLICATIONS
Portable computers
Portable equipment
The ADP3808 is specified over the extended commercial
temperature range of 0°C to 100°C and is available in a 24-lead
LFCSP package.
FUNCTIONAL BLOCK DIAGRAM
VCC
22
LOW-SIDE
DRIVE
REGULATOR
UVLO
AND BIAS
8
EN
DRVREG
BST
19
20
21
EN
IN
DRVH
SW
REFERENCE
OSCILLATOR
DRVREG
10
AGND
CONTROL
LOGIC
18 DRVREG
17
DRVLSD
DRVL
5
RT
CELLSEL
BAT
16
PGND
12
11
3-/4-
CELL
VTH
CSP
CSM
15
14
6
REFIN
BATTERY
VOLTAGE
ADJUST
g
m
7
9
BATADJ
COMP
g
m
CHARGE
CURRENT
SETPOINT
23
24
SYSM
SYSP
13
4
CSADJ
CMP
1V
EXTPWR
CMP
SYS+
CMP
18.25V
1
2
3
ISYS LIMSET
LIMIT
Figure 1.
Rev. 0
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