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参数资料
| 型号： | LT1769IGN |
| 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： | 10/16页 |
| 文件大小： | 214K |
| 代理商： | LT1769IGN |
10
LT1769
APPLICATIO
S I
FOR
ATIO
U
W
U
U
R5=R6(V
– V
)
V
UV
UV
IN
V
UV
= Rising lockout threshold on the UV pin
V
IN
= Charger input voltage that will sustain full load power
Example: With R6 = 5k, V
UV
= 6.7V and setting V
IN
at 12V;
R5 = 5k (12V – 6.7V)/6.7V = 4k
The resistor divider should be connected directly to the
adapter output as shown, not to the V
CC
pin, to prevent
battery drain with no adapter voltage. If the UV pin is not
used, connect it to the adapter output (not V
CC
) and
connect a resistor no greater than 5k to ground. Floating
this pin will cause reverse battery current to increase from
3
μ
A to 200
μ
A.
If connecting the unused UV pin to the adapter output is
not possible, it can be grounded. Although it would seem
that grounding the pin creates a permanent lockout state,
the UV circuitry is arranged for phase reversal with low
voltages on the UV pin to allow the grounding technique to
work.
ally, batteries will automatically be charged at the maximum
possible rate of which the adapter is capable.
This is accomplished by sensing total adapter output
current and adjusting the charge current downward if a
preset adapter current limit is exceeded. True analog
control is used, with closed-loop feedback ensuring that
adapter load current remains below the limit. Amplifier
CL1 in Figure 2 senses the voltage across R
S4
, connected
between the CLP and CLN pins. When this voltage exceeds
100mV, the amplifier will override the programmed charge
current to limit adapter current to 100mV/R
S4
. A lowpass
filter formed by 500
and 1
μ
F is required to eliminate
switching noise. If the input current limit is not used, both
CLP and CLN pins should be connected to V
CC
.
Charge Current Programming
The basic formula for charge current is (see Block
Diagram):
(
I
BAT
= I
PROG S2
= 2.465V
S1
R
PROG
R
S2
R
S1
)(
)
(
)
where R
PROG
is the total resistance from PROG pin to ground.
For the sense amplifier CA1 biasing purpose, R
S3
should
have the same value as R
S2
and SPIN should be connected
directly to the sense resistor (R
S1
) as shown in the Block
Diagram.
For example, 2A charge current is needed. For low power
dissipation on R
S1
and enough signal to drive the amplifier
CA1, let R
S1
= 100mV/2A = 0.05
. This limits R
S1
power
to 0.2W. Let R
PROG
= 5k, then:
R
S2
= R
S3
=
=
= 200
(I
BAT
)(R
PROG
)(R
S1
)
2.465V
(2A)(5k)(0.05)
2.465V
Charge current can also be programmed by pulse width
modulating I
PROG
with a switch Q1 to R
PROG
at a frequency
higher than a few kHz (Figure 3). Charge current will be
proportional to the duty cycle of the switch with full current
at 100% duty cycle.
100mV
500
CLP
CLN
V
CC
UV
1769 F02
R5
LT1769
R6
1
μ
F
+
R
S4
*
V
IN
AC ADAPTER
OUTPUT
*R
S4
=
100mV
ADAPTER CURRENT LIMIT
+
–
+
CL1
Figure 2. Adapter Input Current Limiting
Adapter Current Limiting
An important feature of the LT1769 is the ability to
automatically adjust charge current to a level which avoids
overloading the wall adapter. This allows the product to
operate at the same time the batteries are being charged
without complex load management algorithms. Addition-
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| LT1769IGN#PBF | 功能描述:IC CHARGER BATT CONST V/I 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) |
| LT1769IGN#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) |
| LT1769IGN#TRPBF | 功能描述:IC CHARGER BATT CONST V/I 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) |
| LT1775CQ5 | 制造商:Linear Technology 功能描述: |
| LT1776 | 制造商:LINER 制造商全称:Linear Technology 功能描述:50mA, 3V to 80V Low Dropout Micropower Linear Regulator |
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