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| 型号： | LT1512CS8#TR |
| 厂商： | Linear Technology |
| 文件页数： | 9/12页 |
| 文件大小： | 0K |
| 描述： | IC CHARGER BATT CONST V/I 8SOIC |
| 标准包装： | 2,500 |
| 功能： | 充电管理 |
| 电池化学： | 所有电池类型 |
| 电源电压： | 2.7 V ~ 25 V |
| 工作温度： | 0°C ~ 70°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 供应商设备封装： | 8-SOIC |
| 包装： | 带卷 (TR) |
LT1512
APPLICATIONS INFORMATION
With I CHRG = 0.5A, V IN = 15V and V BAT = 8.2V, I COUP = 0.43A
Average supply current (including driver current) is:
( V BAT CHRG )( 0 . 024 )
Therecommendedcapacitorisa2.2μFceramictypefrom
Marcon or Tokin. These capacitors have extremely low ESR
and high ripple current ratings in a small package. Solid
I IN = 4 mA +
)( I
V IN
+ V )( V
( I CHRG SW BAT IN BAT )
) ( R
)( V
tantalum units can be substituted if their ripple current
rating is adequate, but typical values will increase to 22μF
or more to meet the ripple current requirements.
Diode Selection
The switching diode should be a Schottky type to minimize
both forward and reverse recovery losses. Average diode
current is the same as output charging current , so this
will be under 1A. A 1A diode is recommended for most
applications, although smaller devices could be used at
reduced charging current. Maximum diode reverse voltage
will be equal to input voltage plus battery voltage.
Diode reverse leakage current will be of some concern
during charger shutdown. This leakage current is a direct
drain on the battery when the charger is not powered. High
current Schottky diodes have relatively high leakage currents
(2μA to 200μA) even at room temperature. The latest very-
low-forward devices have especially high leakage currents.
It has been noted that surface mount versions of some
Schottky diodes have as much as ten times the leakage of
their through-hole counterparts. This may be because a low
forward voltage process is used to reduce power dissipation
in the surface mount package. In any case, check leakage
speci?cations carefully before making a ?nal choice for the
switching diode. Be aware that diode manufacturers want to
specify a maximum leakage current that is ten times higher
than the typical leakage. It is very dif?cult to get them to
specify a low leakage current in high volume production.
This is an on going problem for all battery charger circuits
and most customers have to settle for a diode whose typi-
cal leakage is adequate, but theoretically has a worst-case
condition of higher than desired battery drain.
Thermal Considerations
Switch power dissipation is given by:
2
P SW =
( V IN ) 2
R SW = output switch ON resistance
Total power dissipation of the die is equal to supply current
times supply voltage, plus switch power:
P D(TOTAL) = (I IN )(V IN ) + P SW
For V IN = 10V, V BAT = 8.2V, I CHRG = 0.5A, R SW = 0.65Ω
I IN = 4mA + 10mA = 14mA
P SW = 0.24W
P D = (0.014)(10) + 0.24 = 0.38W
The S8 package has a thermal resistance of 130°C/W.
(Contact factory concerning 16-lead fused-lead pack-
age with footprint approximately same as S8 package
and with lower thermal resistance.) Die temperature rise
will be (0.38W)(130°C/W) = 49°C. A maximum ambient
temperature of 60°C will give a die temperature of 60°C +
49°C = 109°C. This is only slightly less than the maximum
junction temperature of 125°C, illustrating the importance
of doing these calculations!
Programmed Charging Current
LT1512 charging current can be programmed with a PWM
signal from a processor as shown in Figure 5. C6 and D2
form a peak detector that converts a positive logic signal
to a negative signal. The average negative signal at the
LT1512
I FB
Care should be taken to ensure that worst-case conditions
do not cause excessive die temperatures. Typical thermal
resistance is 130°C/W for the S8 package but this number
PWM
INPUT
≥1kHz
C6
1μF
R5
4.02k
D2
+
R6
4.02k
C7
10μF
R4
200Ω
C4
0.22μF
L1B
R3
will vary depending on the mounting technique (copper
area, air ?ow, etc).
1512 F05
Figure 5. Programming Charge Current
1512fa
9
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT1512I | 制造商:LINER 制造商全称:Linear Technology 功能描述:SEPIC Constant-Current/ Constant-Voltage Battery Charger |
| LT1512IGN | 功能描述:IC BATT CHRGR CONST I/V 16-SSOP 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) |
| LT1512IGN#PBF | 功能描述:IC BATT CHRGR CONST I/V 16-SSOP 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) |
| LT1512IGN#TR | 功能描述:IC CHARGER BATT CONST V/I 16SSOP 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) |
| LT1512IGN#TRPBF | 功能描述:IC BATT CHRGR CONST I/V 16-SSOP 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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