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參數(shù)資料
| 型號： | ADP3806 |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | Secondary Over-Voltage Protection for 2-4 cell in series Li-Ion/Poly (4.50V) 8-TSSOP -40 to 110 |
| 中文描述： | 高頻開關式鋰離子電池充電器 |
| 文件頁數(shù)： | 10/16頁 |
| 文件大?。?/td> | 274K |
| 代理商： | ADP3806 |
REV. B
–10–
ADP3806
Typical values of R
CS
range from 25 m
W
to 50 m
W
, and the
input range of ISET is from 0 V to 4 V. If, for example, a 3 A
charger is required, R
CS
could be set to 40 m
W
and V
ISET
= 3 V.
The power dissipation in R
CS
should be kept below 500 mW.
In this example, the power is a maximum of 360 mW. Once
R
CS
has been chosen, the charge current can be adjusted during
operation with V
ISET
. Lowering V
ISET
to 125 mV gives a charge
current of 125 mA for trickle charging. Components R3, R4,
and C13 provide high frequency filtering for the current
sense signal.
Final Battery Voltage Control
As the battery approaches its final voltage, the ADP3806 switches
from CC mode to CV mode. The change is achieved by the
common output node of g
m
1 and g
m
2. Only one of the two
outputs controls the voltage at the COMP pin. Both amplifiers
can only pull down on COMP, such that when either amplifier
has a positive differential input voltage, its output is not active.
For example, when the battery voltage, V
BAT
, is low, g
m
2 does
not control V
COMP
. When the battery voltage reaches the desired
final voltage, g
m
2 takes control of the loop, and the charge cur-
rent is reduced.
Amplifier g
m
2 compares the battery voltage to the internal refer-
ence voltage of 2.5 V. In the case of the ADP3806-12.5 and
ADP3806-12.6, an internal resistor divider sets the selectable
final battery voltage.
When BATSEL is high, the final battery voltage is set to three
cells (12.6 V or 12.525 V). BATSEL can be tied to REG for
this state. When BATSEL is tied to ground, V
BAT
equals four
cells (16.8 V or 16.7 V). BATSEL has a 2
m
A pull-up current as
a fail-safe to select three cells when it is left open.
The reference and internal resistor divider are referenced to the
AGND pin, which should be connected close to the negative
terminal of the battery to minimize sensing errors.
In contrast, the ADP3806 requires external, precision resistors.
The divider ratio should be set to divide the desired final voltage
down to 2.5 V at the BAT pin
R
R
V
V
BATTERY
2 5
.
11
12
1
=
–
(2)
These resistors should have a parallel impedance of approximately
80 k
W
to minimize bias current errors. When the ADP3806 is in
shutdown, an internal switch disconnects the BAT pin as shown
in Figure 2. This disconnects the resistor, R11, from the battery
and minimizes leakage. The resistance of the internal switch is
less than 200
W
.
V
REF
BATSEL
SD
BATTERY
R11
412k
0.1%
ADP3806
R12
102k
0.1%
BAT
g
m
2
Figure 2. Battery Sense Disconnect Circuit
Oscillator and PWM
The oscillator generates a triangle waveform between 1 V and
2.5 V, which is compared to the voltage at the COMP pin,
setting the duty cycle of the driver stage. When V
COMP
is below
1 V, the duty cycle is zero. Above 2.5 V, the duty cycle reaches
its maximum.
MIN
OFF
TIME
BSTREG
BST
DRVH
SW
IN
DRVL
ADP3806
BOOTSTRAPPED
SYNCHRONOUS DRIVER
CBST
PGND
1V
1V
Q1
Q2
DELAY
DRVLSD
SD
DELAY
CMP3
CMP2
CMP1
+
+
–
–
+
–
Figure 3. Bootstrapped Synchronous Driver
相關PDF資料 |
PDF描述 |
|---|---|
| ADP3806JRU | Secondary Over-Voltage Protection for 2-4 cell in series Li-Ion/Poly (4.50V) 8-TSSOP -40 to 110 |
| ADP3806JRU-12.5-R7 | High-Frequency Switch Mode Li-Ion Battery Charger |
| ADP3806JRU-12.5-RL | High-Frequency Switch Mode Li-Ion Battery Charger |
| ADP3808 | High Efficiency Switch Mode Li-Ion Battery Charger |
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相關代理商/技術參數(shù) |
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|---|---|
| ADP3806JRU | 制造商:AD 制造商全稱:Analog Devices 功能描述:High-Frequency Switch Mode Li-Ion Battery Charger |
| ADP3806JRU-12.5 | 制造商:Analog Devices 功能描述:BATTERY MANAGEMENT, 24 Pin, Plastic, TSSOP |
| ADP3806JRU-12.5-R7 | 制造商:AD 制造商全稱:Analog Devices 功能描述:High-Frequency Switch Mode Li-Ion Battery Charger |
| ADP3806JRU-12.5-RL | 制造商:AD 制造商全稱:Analog Devices 功能描述:High-Frequency Switch Mode Li-Ion Battery Charger |
| ADP3806JRU-12.6 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Analog IC |
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