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| 型号： | LT1769CGN#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 11/16页 |
| 文件大小： | 0K |
| 描述： | IC BATT CHARGER CONST I/V 28SSOP |
| 标准包装： | 49 |
| 功能： | 充电管理 |
| 电池化学： | 铅酸，锂离子，镍镉，镍氢 |
| 电源电压： | 8 V ~ 25 V |
| 工作温度： | 0°C ~ 70°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 28-SSOP（0.154"，3.90mm 宽） |
| 供应商设备封装： | 28-SSOP |
| 包装： | 管件 |
| 产品目录页面： | 1340 (CN2011-ZH PDF) |
LT1769
APPLICATIO N S I N FOR M ATIO N
LT1769
PROG
R3
12k
0.25%
+
8.4V
V BAT
5V
0V
PWM
I BAT = (DC)(2A)
300 ?
R PROG
4.7k
Q1
VN2222
C PROG
1 μ F
1769 F03
LT1769
OVP
Q3
VN2222
R5
220k
R4
4.99k
0.25%
V IN
1769 F04
Figure 3. PWM Current Programming
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 BAT ? 2.465 ) = 162k ( 8.4 ? 2.465 )
2.465 2.465
= 390k
Figure 4. Disconnecting Voltage Divider
is to use a Zener diode with a breakdown voltage two or three
volts higher than battery voltage to clamp the V BAT voltage.
Battery manufacturers recommend terminating the con-
stant-voltage float mode after charge current has dropped
below a specified level (typically around 10% of the full
current) and a 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
Li-Ion batteries typically require float voltage accuracy of
1%. 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
V BAT
I BAT
R S1
0.05 ?
R S3
200 ?
R S2
200 ?
ADAPTER
OUTPUT
SENSE
LT1769
BAT
3.3V OR 5V
R1*
–
0.25% resistors will normally provide the required level of
overall accuracy.
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
BAT
C1
1.6k 0.1 μ F
3
2
8
LT1011
+
D1
1N4148
7
4
R4
470k
NEGATIVE EDGE
TO TIMER
R1(V BAT )
≈ 270mA
(560k + 430k)(0.05 ? )
duringcharging,andtotalloadincludingR3andR4isless
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
R2
560k
R3
430k
D2
1N4148
1
* TRIP CURRENT =
(R2 + R3)(R S1 )
(1.6k)(8.4V)
=
them when power is off (Figure 4). R5 isolates the OVP pin
from any high frequency noise on V IN . An alternative method
1769 F04
Figure 5. Current Comparator for Initiating Float Time Out
1769fa
11
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相关代理商/技术参数 |
参数描述 |
|---|---|
| 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) |
| LT1769IFE#TR | 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#TRPBF | 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) |
| LT1769IGN | 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) |
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