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参数资料
| 型号： | LT1571EGN-5#TR |
| 厂商： | Linear Technology |
| 文件页数： | 12/16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
[ 7 . 5 mA + ( 0 . 012 )( I BAT ) ]
( V BAT ) 2
( I BAT )( V BAT ) 2 ? ? ? 1 + V 30 ? ? ?
55 ( V IN )
C1 D1
0.22 μ F 1N5819
L1**
33 μ H
D2
1N914
SW V CC
BOOST PROG
LT1571-1
GND V C
I BAT
C IN *
10 μ F
1 μ F
300 ?
0.1 μ F
1k
D3
1N5819
R1
100k
V IN
(WALL ADAPTER)
R2
11k
Q1
VN2222
P BIAS = ( 3 . 5 mA )( V IN ) + 1 . 5 mA ( V BAT )
+
V IN
BAT
P DRIVER =
ON: I BAT = 0.5A
+
+
OFF: I BAT = 0.05A
( I BAT SW BAT ) + t V I f
( OL IN BAT )( )
)( )(
) ( 2 R )( V
P SENSE = ( 0 . 18 ? )( I BAT )
[ 7 . 5 mA + ( 0 . 012 )( I BAT ) ]
( V BAT ) 2
( I BAT )( V BAT ) 2 ? ? ? 1 + V 30 ? ? ?
55 ( V IN )
P SENSE = ( 0 . 18 ? )( I BAT )
SENSE BAT
C OUT 2V TO
* TOKIN OR MARCON CERAMIC 22 μ F 20V
SURFACE MOUNT TANT 1571 F07
** COILTRONICS CTX33-2
Figure 7. Charging NiMH or NiCd Batteries with
Constant Current (Efficiency at 0.5A ≈ 90%)
lower value and maintained as a constant trickle charge.
An intermediate “top off” current may also be used for a
fixed time period to reduce total charge time.
NiMH batteries are similar in chemistry to NiCd but have
two differences related to charging. First, the inflection
characteristic in battery voltage as full charge is
approached is not nearly as pronounced. This makes it
more difficult to use – dV/dt as an indicator of full charge,
and an increase in temperature is more often used with a
temperature sensor located in the battery pack. Secondly,
constant trickle charge may not be recommended. In-
stead, a moderate level of current is used on a pulse basis
( ≈ 1% to 5% duty cycle) with the time-averaged value
substituting for a constant low trickle.
Thermal Calculations
If the LT1571 is used for charge currents above 0.4A, a
thermal calculation should be done to ensure that junction
temperature will not exceed 125 ° C. Power dissipation in
the IC is caused by bias and driver current, switch resis-
tance, switch transition losses and the current sense
resistor. The following equations show that maximum
practical charge current for the 16-pin SSOP package
(75 ° C/W thermal resistance) is about 1.2A for an 8.4V
battery and 1.4A for a 4.2V battery. This assumes a 60 ° C
maximum ambient temperature. The 28-pin SSOP, with a
thermal resistance of 40 ° C/W, can provide a full 1.5A
charge current in many situations.
12
P SW =
V IN
2
R SW = Switch ON resistance ≈ 0.35 ?
t OL = Effective switch overlap time ≈ 10ns
f = 200kHz (500kHz for LT1571-5)
Example: V IN = 15V, V BAT = 8.4V, I BAT = 1.2A;
P BIAS = ( 3 . 5 mA )( V IN ) + 1 . 5 mA ( V BAT )
+
V IN
BAT
P DRIVER =
P SW = ( I BAT ) 2 ( R SW )( V BAT ) + ( t OL )( V IN )( I BAT )( f )
V IN
2
Total power in the IC is:
0.17 + 0.13 + 0.32+ 0.26 = 0.88W
Temperature rise will be (0.88W)(40 ° C/W) = 35 ° C. This
assumes that the LT1571 is properly heat sunk by con-
necting all fused ground pins to the expanded traces and
that the PC board has a backside or internal plane for heat
spreading.
The P DRIVER term can be reduced by connecting the boost
diode D2 to a lower system voltage (lower than V BAT )
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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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