ADP3806JRU-12.6-RL Analog Devices Inc, ADP3806JRU-12.6-RL Datasheet - Page 9

• Manufacturer Part Number: ADP3806JRU-12.6-RL
• Description: IC CHARGER LI-ION 12.6V 24-TSSOP
• Manufacturer: Analog Devices Inc

Specifications of ADP3806JRU-12.6-RL

• Rohs Status: RoHS non-compliant
• Function: Charge Management
• Battery Type: Lithium-Ion (Li-Ion)
• Voltage - Supply: 13 V ~ 20 V
• Operating Temperature: 0°C ~ 100°C
• Mounting Type: Surface Mount
• Package / Case: 24-TSSOP (0.173", 4.40mm Width)
• Other names: ADP3806JRU-12.6RL

THEORY OF OPERATION
The ADP3806 combines a bootstrapped synchronous switching
driver with programmable current control and accurate final
battery voltage control in a constant-current, constant-voltage
(CCCV) Li-Ion battery charger. High accuracy voltage control
is needed to safely charge Li-Ion batteries, which are typically
specified at 4.2 V ± 1% per cell. For a typical notebook computer
battery pack, three or four cells are in series giving a total volt-
age of 12.6 V or 16.8 V. The ADP3806 is available in three
versions, a selectable 12.525 V/16.7 V output, a selectable
12.6 V/16.8 V output, and an adjustable output. The adjustable
output can be programmed for a wide range of battery voltages
using two external precision resistors.
Another requirement for safely charging Li-Ion batteries is
accurate control of the charge current. The actual charge cur-
rent depends on the number of cells in parallel within the
battery pack. Typically, this is in the range of 2 A to 3 A. The
ADP3806 provides flexibility in programming the charge cur-
rent over a wide range. An external resistor is used to sense the
charge current and this voltage is compared to a dc input volt-
age. This programmability allows the current to be changed
during charging. For example, the charge current can be reduced
for trickle charging.
REV. B
BSTREG
100k
0.1 F
7.0V
**R7
C10
SD
VIN
**R7, OPEN IF LC FUNCTION IS NOT USED.
LC
*ADP3806-12.6, ADP3806-12.5: R11 = SHORT, R12 = OPEN;
ADP3806, R11 = 412k , R12 = 102k , R14 = OPEN.
2.2 F
C14
AGND
ADP3806
VREF + VREG
VCC
10
R13
CONTROL
LOGIC
UVLO
BIAS
BST
22 F
100nF
C15
C17
REG
6.0V
100nF
DRVH
FD56990A
C9
+
–
VREF
1/2 Q1
2.5V
SD
REF
BOOTSTRAPPED
SYNCHRONOUS
SW
DRIVER
IN DRVLSD
DRVL
C7
200pF
SYNC
OSCILLATOR
PGND
180pF
1/2 Q1
FD56990A
CT
C6
+
–
Figure 1. Typical Application
DRVLSD
0.22 F
COMP
–
+
22 H
L1
C8
22 F
C16
VTH
R8
56
–
CS+
–9–
+
g m 1
g m 2
R3
249
–
+
–
+
The synchronous driver provides high efficiency when charging at
high currents. Efficiency is important mainly to reduce the amount
of heat generated in the charger but also to stay within the power
limits of the ac adapter. With the addition of a bootstrapped high
side driver, the ADP3806 drives two external power NMOS
transistors for a simple, lower cost power stage.
The ADP3806 also provides an uncommitted current sense
amplifier. This amplifier provides an analog output pin for
monitoring the current through an external sense resistor. The
amplifier can be used anywhere in the system that high side
current sensing is needed.
Charge Current Control
AMP1 in Figure 1 has a differential input to amplify the voltage
drop across an external sense resistor RCS. The input common-
mode range is from ground to VCC, allowing current control in
short circuit and low dropout conditions. The gain of AMP1 is
internally set to 25 V/V for low voltage drop across the sense
resistor. During CC mode, g
of AMP1 to be equal to the external voltage at the ISET pin.
By choosing R
charge currents can be programmed.
40m
AMP1
22nF
+
C13
R
VREF
CS
CS–
–
I
CHARGE
470nF
R4
249
C1
SYS+
=
CS
R1
2.2
102k
10m
AMP2
25
–
*R12
0.1%
R
SYS–
and V
V
SS
¥
+
REF
R
CS
R2
2.2
12.6/16.8
SELECT
ISET
2.5V
C2
470nF
ISYS
BATSEL
*R14
0
m
appropriately, a wide range of
1 forces the voltage at the output
–
+
SYSTEM
DC/DC
6.81k
R5
7.5k
ISET
BAT
LIMIT
R6
ADP3806
412k
0.1%
*R11
BATTERY
12.6V/16.8V
(1)