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參數(shù)資料
| 型號： | LTC3553EUD#PBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 電源管理 |
| 英文描述： | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PQCC20 |
| 封裝： | 3 X 3 MM, 0.75 MM HEIGHT, LEAD FREE, PLASTIC, QFN-20 |
| 文件頁數(shù)： | 24/36頁 |
| 文件大?。?/td> | 518K |
| 代理商： | LTC3553EUD#PBF |
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LTC3553
30
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
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
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| LTC3554 | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Micropower USB Power Manager with Li-Ion Charger and Two Step-Down Regulators |
| LTC3554EPD | 制造商:LINER 制造商全稱: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 類別:集成電路 (IC) >> PMIC - 電源管理 - 專用 系列:- 標(biāo)準(zhǔn)包裝:1 系列:- 應(yīng)用:手持/移動設(shè)備 電流 - 電源:- 電源電壓:3 V ~ 5.5 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:14-WFDFN 裸露焊盤 供應(yīng)商設(shè)備封裝:14-LLP-EP（4x4） 包裝:Digi-Reel® 配用:LP3905SD-30EV-ND - BOARD EVALUATION LP3905SD-30 其它名稱:LP3905SD-30DKR |
| LTC3554EPD#TRPBF | 功能描述:IC USB POWER MANAGER 20-UTQFN RoHS:是 類別:集成電路 (IC) >> PMIC - 電源管理 - 專用 系列:- 應(yīng)用說明:Ultrasound Imaging Systems Application Note 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:37 系列:- 應(yīng)用:醫(yī)療用超聲波成像，聲納 電流 - 電源:- 電源電壓:2.37 V ~ 6 V 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:56-WFQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:56-TQFN-EP（8x8） 包裝:管件 |
| LTC3554EPDPBF | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Micropower USB Power Manager with Li-Ion Charger and Two Step-Down Regulators |
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