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参数资料
| 型号： | LTC3553EUD#TRPBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 电源管理 |
| 英文描述： | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PQCC20 |
| 封装： | 3 X 3 MM, 0.75 MM HEIGHT, LEAD FREE, PLASTIC, QFN-20 |
| 文件页数： | 24/36页 |
| 文件大小： | 518K |
| 代理商： | LTC3553EUD#TRPBF |
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LTC3553
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3553fa
Power-Up Sequencing
Figure 14 shows the actual power-up sequencing of the
LTC3553 with the SEQ pin held low. The regulators are
both initially disabled (0V). Once the pushbutton has been
applied (ON low) for 400ms, the buck is enabled. The buck
slews up and enters regulation. The actual slew rate is con-
trolled by the soft start function of the buck in conjunction
with output capacitance and load (see the Buck Regulator
Operation section for more information). When the buck
is within about 8% of nal regulation, the LDO is enabled
and slews up into regulation. The regulators in Figure 14
are slewing up with nominal output capacitors and no-
load. Adding a load or increasing output capacitance on
any of the outputs will reduce the slew rate and lengthen
the time it takes the regulator to achieve regulation.
Figure 15 shows how the regulator start-up sequence is
reversed with the SEQ pin tied high.
LAYOUT AND THERMAL CONSIDERATIONS
Printed Circuit Board Power Dissipation
In order to be able to deliver maximum charge current
under all conditions, it is critical that the Exposed Pad
on the backside of the LTC3553 package is soldered
to a ground plane on the board. Correctly soldered to a
2500mm2 ground plane on a double-sided 1oz copper
board, the LTC3553 has a thermal resistance (θJA) of
approximately 70°C/W. Failure to make good thermal
contact between the Exposed Pad on the backside of the
package and an adequately sized ground plane will result
in thermal resistances far greater than 70°C/W.
The conditions that cause the LTC3553 to reduce charge
current due to the thermal protection feedback can be
approximated by considering the power dissipated in the
part. For high charge currents the LTC3553 power dis-
sipation is approximately:
PD = (VBUS–BAT) IBAT + PD(REGS)
where PD is the total power dissipated, VBUS is the supply
voltage, BAT is the battery voltage, and IBAT is the battery
charge current. PD(REGS) is the sum of power dissipated
on chip by the step-down switching regulators.
The power dissipated by the buck regulator can be esti-
mated as follows:
PD(BUCK) = (BOUTx IOUT) (100 - Eff)/100
Where BOUTx is the programmed output voltage, IOUT is
the load current and Eff is the % efciency which can
be measured or looked up on an efciency table for the
programmed output voltage.
The power dissipated by the LDO regulator can be esti-
mated using:
PD(LDO) = (VINLDO – VLDO) ILDO
OPERATION
Figure 14. Power-Up Sequencing with SEQ Low,
Front Page Application Circuit
Figure 15. Power-Up Sequencing with SEQ High,
Front Page Application Circuit
BUCK OUTPUT
0.5V/DIV
LDO OUTPUT
1V/DIV
0V
3553 F14
100μs/DIV
BUCK OUTPUT
0.5V/DIV
LDO OUTPUT
1V/DIV
0V
3553 F15
100μs/DIV
相关PDF资料 |
PDF描述 |
|---|---|
| LTC3553EUD#PBF | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PQCC20 |
| LTC3554EPD#TRPB | 0.5 A BATTERY CHARGE CONTROLLER, 1295 kHz SWITCHING FREQ-MAX, PQCC20 |
| LTC3560IS6#TRPBF | 2.1 A SWITCHING REGULATOR, 2700 kHz SWITCHING FREQ-MAX, PDSO6 |
| LTC3563EDC | 1.75 A SWITCHING REGULATOR, 2700 kHz SWITCHING FREQ-MAX, PDSO6 |
| LTC3568EDD#TR | 4 A SWITCHING REGULATOR, 4000 kHz SWITCHING FREQ-MAX, PDSO10 |
相关代理商/技术参数 |
参数描述 |
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| LTC3554 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Micropower USB Power Manager with Li-Ion Charger and Two Step-Down Regulators |
| LTC3554EPD | 制造商:LINER 制造商全称:Linear Technology 功能描述:Micropower USB Power Manager with Li-Ion Charger and Two Step-Down Regulators |
| LTC3554EPD#PBF | 功能描述:IC USB POWER MANAGER 20-UTQFN RoHS:是 类别:集成电路 (IC) >> PMIC - 电源管理 - 专用 系列:- 标准包装:1 系列:- 应用:手持/移动设备 电流 - 电源:- 电源电压:3 V ~ 5.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:14-WFDFN 裸露焊盘 供应商设备封装:14-LLP-EP（4x4） 包装:Digi-Reel® 配用:LP3905SD-30EV-ND - BOARD EVALUATION LP3905SD-30 其它名称:LP3905SD-30DKR |
| LTC3554EPD#TRPBF | 功能描述:IC USB POWER MANAGER 20-UTQFN RoHS:是 类别:集成电路 (IC) >> PMIC - 电源管理 - 专用 系列:- 应用说明:Ultrasound Imaging Systems Application Note 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:37 系列:- 应用:医疗用超声波成像，声纳 电流 - 电源:- 电源电压:2.37 V ~ 6 V 工作温度:0°C ~ 70°C 安装类型:表面贴装 封装/外壳:56-WFQFN 裸露焊盘 供应商设备封装:56-TQFN-EP（8x8） 包装:管件 |
| LTC3554EPDPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Micropower USB Power Manager with Li-Ion Charger and Two Step-Down Regulators |
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