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参数资料
| 型号： | LT1571EGN-5#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 9/16页 |
| 文件大小： | 0K |
| 描述： | IC CHARGER BATT CONST V/I 16SSOP |
| 标准包装： | 2,500 |
| 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 ~ 26 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-SSOP（0.154"，3.90mm 宽） |
| 供应商设备封装： | 16-SSOP |
| 包装： | 带卷 (TR) |
LT1571 Series
APPLICATIO S I FOR ATIO
I BAT = ( I PROG )( 2000 ) = ?
? ( 2000 )
is achieved with V C at 1.1V. With a 0.33μF capacitor, the
time to reach full charge current is about 9ms and it is
assumed that input voltage to the charger will reach full
value in less than 3ms. Capacitance can be increased up to
1 μ F if longer input start-up times are needed.
In any switching regulator, conventional time-based soft
starting can be defeated if the input voltage rises much
slower than the time-out period. This happens because the
switching regulators in the battery charger and the com-
puter power supply are typically supplying a fixed amount
of power to the load. If the input voltage comes up slowly
compared to the soft-start time, the regulators will try to
deliver full power to the load when the input voltage is still
well below its final value. If the adapter is current limited,
it cannot deliver full power at reduced output voltages and
The lockout voltage will be V IN = V Z + 1V.
For example, for a 24V adapter to start charging at 22V IN ,
choose V Z = 21V. When V IN is less than 22V, D1 keeps V C
low and charger off.
Charge Current Programming
The basic formula for charge current is (see Block
Diagram):
? 2 . 465 V ?
? R PROG ?
where R PROG is the total resistance from PROG pin to
ground.
For example, 1A charge current is needed.
the possibility exists for a quasi “latch” state where the
adapter output stays in a current limited state at reduced
output voltage. For instance, if maximum charger plus
R PROG =
( 2 .465V )( 2000 ) = 4 . 93 k
1 A
computer load power is 20W, a 24V adapter might be
current limited at 1A. If adapter voltage is less than (20W/1A
= 20V) when full power is drawn, the adapter voltage will be
pulled down by the constant 20W load until it reaches a lower
stable state where the switching regulators can no longer
supply full load. This situation can be prevented by utilizing
undervoltage lockout, set higher than the minimum adapter
voltage where full power can be achieved.
A fixed undervoltage lockout of 7V is built into the LT1571.
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 Q1 with full current at
100% duty cycle.
When a microprocessor DAC output is used to control
charge current, it must be capable of sinking current
at a compliance up to 2.5V if connected directly to the
PROG pin.
A higher lockout voltage can be implemented with a Zener
diode D2 (see Figure 2).
LT1571
V IN
D3
PROG
300 ?
D2
V Z
D1
1N4148
V C
V CC
LT1571
5V
R PROG
4.64k
Q1
C PROG
1 μ F
2k
GND
0V
PWM
VN2222
1571 F02
I BAT = (DC)(1A)
1571 F03
Figure 2. Undervoltage Lockout
Figure 3. PWM Current Programming
9
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相关代理商/技术参数 |
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| LT1572 | 制造商:LINER 制造商全称:Linear Technology 功能描述:100kHz, 1.25A Switching Regulator with Catch Diode |
| LT1572CS | 功能描述:IC REG MULTI CONFIG 1.25A 16SOIC RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 同步整流器:是 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
| LT1572CS#PBF | 功能描述:IC REG MULTI CONFIG 1.25A 16SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 同步整流器:是 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
| LT1572CS#TR | 功能描述:IC REG MULTI CONFIG 1.25A 16SOIC RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 同步整流器:是 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
| LT1572CS#TRPBF | 功能描述:IC REG MULTI CONFIG 1.25A 16SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 同步整流器:是 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
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