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参数资料
| 型号： | LT1769CGN |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 电源管理 |
| 英文描述： | Constant-Current/ Constant-Voltage 2A Battery Charger with Input Current Limiting |
| 中文描述： | 2-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO28 |
| 封装： | 0.150 INCH, PLASTIC, SSOP-28 |
| 文件页数： | 11/16页 |
| 文件大小： | 214K |
| 代理商： | LT1769CGN |
11
LT1769
APPLICATIO
S I
FOR
ATIO
U
W
U
U
When power is on, there is about 200
μ
A of current flowing
out of the BAT and SENSE pins. If the battery is removed
during charging, and total load including R3 and R4 is less
than 200
μ
A, V
BAT
could float up to V
CC
even though the
loop has turned switching off. To keep V
BAT
regulated to
the battery voltage in this condition, R3 and R4 can be
chosen to draw 0.5mA and Q3 can be added to disconnect
them when power is off (Figure 4). R5 isolates the OVP pin
from any high frequency noise on V
IN
. An alternative method
is to use a Zener diode with a breakdown voltage two or three
volts higher than battery voltage to clamp the V
BAT
voltage.
Lithium-Ion Charging
The 2A Lithium-Ion Battery Charger (Figure 1) charges at
a constant 2A until battery voltage reaches a limit set by R3
and R4. The charger will then automatically go into a
constant-voltage mode with current decreasing to near
zero over time as the battery reaches full charge. This is the
normal regimen for lithium-ion charging, with the charger
holding the battery at “float” voltage indefinitely. In this
case no external sensing of full charge is needed.
Battery Voltage Sense Resistors Selection
To minimize battery drain when the charger is off, current
through the R3/R4 divider is set at 15
μ
A. The input current
to the OVP pin is 3nA and the error can be neglected.
With divider current set at 15
μ
A, V
BAT
= 8.4V, R4 =
2.465/15
μ
A = 162k and,
R3
R4 V
2.465
2.465
162k 8.4
2.465
2.465
390k
BAT
=
(
)
=
)
=
Li-Ion batteries typically require float voltage accuracy of
1% to 2%. Accuracy of the LT1769 OVP voltage is
±
0.5%
at 25
°
C and
±
1% over full temperature. This leads to the
possibility that very accurate (0.1%) resistors might be
needed for R3 and R4. Actually, the temperature of the
LT1769 will rarely exceed 50
°
C in float mode because
charging currents have tapered off to a low level, so 0.25%
resistors will normally provide the required level of overall
accuracy.
Figure 4. Disconnecting Voltage Divider
PWM
R
4.7k
300
PROG
C
PROG
1
μ
Q1
VN2222
5V
0V
LT1769
1769 F03
I
BAT
= (DC)(2A)
Figure 3. PWM Current Programming
R3
12k
0.25%
R4
4.99k
0.25%
OVP
V
IN
+
8.4V
V
BAT
Q3
VN2222
LT1769
1769 F04
R5
220k
Some battery manufacturers recommend terminating the
constant-voltage float mode after charge current has
dropped below a specified level (typically around 10% of
the full current) anda further time out period of 30 to 90
minutes has elapsed. This may extend battery life, so
check with the manufacturer for details. The circuit in
Figure 5 will detect when charge current has dropped
below 270mA. This logic signal is used to initiate a timeout
period, after which the LT1769 can be shut down by
pulling the V
C
pin low with an open collector or drain.
Some external means must be used to detect the need for
additional charging or the charger may be turned on
periodically to complete a short float-voltage cycle.
Current trip level is determined by the battery voltage, R1
through R3 and the sense resistor (R
S1
). D2 generates
hysteresis in the trip level to avoid multiple comparator
transitions.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT1769CGN#PBF | 功能描述:IC BATT CHARGER CONST I/V 28SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 电池管理 系列:- 其它有关文件:STC3100 View All Specifications 特色产品:STC3100 - Battery Monitor IC 标准包装:4,000 系列:- 功能:燃料，电量检测计/监控器 电池化学:锂离子（Li-Ion） 电源电压:2.7 V ~ 5.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-TSSOP，8-MSOP（0.118"，3.00mm 宽） 供应商设备封装:8-MiniSO 包装:带卷 (TR) 其它名称:497-10526-2 |
| LT1769CGN#TR | 功能描述:IC CHARGER BATT CONST V/I 28SSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 电池管理 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 功能:电池监控器 电池化学:碱性，锂离子，镍镉，镍金属氢化物 电源电压:1 V ~ 5.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-6 供应商设备封装:SOT-6 包装:带卷 (TR) |
| LT1769CGN#TRPBF | 功能描述:IC BATT CHARGER CONST I/V 28SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 电池管理 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 功能:电池监控器 电池化学:碱性，锂离子，镍镉，镍金属氢化物 电源电压:1 V ~ 5.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-6 供应商设备封装:SOT-6 包装:带卷 (TR) |
| LT1769IFE | 功能描述:IC BATT CHRGR CNSTNT I/V 20TSSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 电池管理 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 功能:电池监控器 电池化学:碱性，锂离子，镍镉，镍金属氢化物 电源电压:1 V ~ 5.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-6 供应商设备封装:SOT-6 包装:带卷 (TR) |
| LT1769IFE#PBF | 功能描述:IC BATT CHRGR CNSTNT I/V 20TSSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 电池管理 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 功能:电池监控器 电池化学:碱性，锂离子，镍镉，镍金属氢化物 电源电压:1 V ~ 5.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-6 供应商设备封装:SOT-6 包装:带卷 (TR) |
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