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| 型号： | LT1769CGN#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 13/16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
Example: V IN = 19V, V BAT = 12.6V, I BAT = 2A:
P BIAS = ( 3.5mA )( 19 ) + 1.5mA ( 12.6 )
C2
SW
LT1769
+
( 12.6 ) 2
19
[ 7.5mA + ( 0.012 )( 2000mA ) ] = 0.35W
L1
D2
BOOST
SPIN
P DRIVER =
( 2 )( 12.6 ) 2 ? ? ? 1 + 12 30. 6 ? ? ?
55 ( 19 )
= 0.43W
V X
I VX
+
10 μ F
1769 F07
P SW = ( 2 ) 2 ( 0.16 )( 12.6 ) + 10 ? 9 ( 19 )( 2 )( 200kHz )
19
= 0.42 + 0.08 = 0.5W
Total Power in the IC is: 0.35 + 0.43 + 0.5 = 1.3W
Temperature rise will be (1.3W)(35 ° C/W) = 46 ° C. This
assumes that the LT1769 is properly heat sunk by con-
necting the eleven fused ground pins to 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 (see Figure 7) to a lower system voltage (lower
than V BAT ) instead of V BAT .
Figure 7. Lower V BOOST
thermal resistance of the package-board combination is
dominated by the characteristics of the board in the
immediate area of the package. This means both lateral
thermal resistance across the board and vertical thermal
resistance through the board to other copper layers. Each
layer acts as a thermal heat spreader that increases the
heat sinking effectiveness of extended areas of the board.
Total board area becomes an important factor when the
area of the board drops below about 20 square inches. The
graph in Figure 8 shows thermal resistance vs board area
for 2-layer and 4-layer boards with continuous copper
Then P DRIVER =
( I BAT )( V BAT )( V X ) ? ? ? 1 + V 30 X ? ? ?
55 ( V IN )
planes. Note that 4-layer boards have significantly lower
thermal resistance, but both types show a rapid increase
for reduced board areas. Figure 9 shows actual measured
lead temperatures for chargers operating at full current.
For example, V X = 3.3V then:
Battery voltage and input voltage will affect device power
( )( )( ) V 3 . 3 ? ? 1 + 3 30 . 3 V ? ?
55 ( )
P DRIVER
=
2 A 12 . 6 V
19 V
? ?
= 0 . 09 W
dissipation, so the data sheet power calculations must be
used to extrapolate these readings to other situations.
Vias should be used to connect board layers together.
Planes under the charger area can be cut away from the
= = 28 mA
The average I VX required is:
P DRIVER 0 . 09 W
V X 3 . 3 V
The previous example shows the dramatic drop in driver
power dissipation when the boost diode (D2) is connected
to an external 3.3V source instead of the 12.6V battery.
P DRIVER drops from 0.43W to 0.09W resulting in an
approximately 12 ° C drop in junction temperature.
Fused-lead packages conduct most of their heat out the
leads. This makes it very important to provide as much PC
board copper around the leads as is practical. Total
rest of the board and connected with vias to form both a
low thermal resistance system and to act as a ground plane
for reduced EMI.
Glue-on, chip-mounted heat sinks are effective only in
moderate power applications where the PC board copper
cannot be used, or where the board size is small. They offer
very little improvement in a properly laid out multilayer
board of reasonable size.
Higher Duty Cycle for the LT1769 Battery Charger
Maximum duty cycle for the LT1769 is typically 90%, but
this may be too low for some applications. For example, if
1769fa
13
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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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