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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： | 25/36页 |
| 文件大小： | 518K |
| 代理商： | LTC3553EUD#TRPBF |
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LTC3553
31
3553fa
where VINLDO is the LDO input supply voltage, VLDO is
the LDO regulated output voltage, and ILDO is the LDO
load current.
Thus the power dissipated by all regulators is:
PD(REGS) = PD(BUCK) + PD(LDO)
It is not necessary to perform any worst-case power dis-
sipation scenarios because the LTC3553 will automatically
reduce the charge current to maintain the die temperature
at approximately 110°C. However, the approximate ambi-
ent temperature at which the thermal feedback begins to
protect the IC is:
TA = 110°C – PD θJA
Example: Consider the LTC3553 operating from a wall
adapter with 5V (VBUS) providing 400mA (IBAT) to charge a
Li-Ion battery at 3.3V (BAT). Also assume PD(REGS) = 0.3W,
so the total power dissipation is:
PD = (5V – 3.3V) 400mA + 0.3W = 0.98W
The ambient temperature above which the LTC3553 will
begin to reduce the 400mA charge current, is approxi-
mately:
TA = 110°C – 0.98W 70°C/W = 41.4°C
The LTC3553 can be used above 41.4°C, but the charge
current will be reduced below 400mA. The charge current at
a given ambient temperature can be approximated by:
PD = (110°C – TA) / θJA = (VBUS – BAT) IBAT + PD(REGS)
Thus:
IBAT = [(110°C – TA) / θJA – PD(REGS)]
(VBUS – BAT)
Consider the above example with an ambient tempera-
ture of 60°C. The charge current will be reduced to
approximately:
IBAT = [(110°C – 60°C) / 70°C/W – 0.3W] / (5V – 3.3V)
IBAT = (0.71W – 0.3W) / 1.7V = 241mA
Printed Circuit Board Layout
When laying out the printed circuit board, the following
list should be followed to ensure proper operation of the
LTC3553:
1. The Exposed Pad of the package (Pin 21) should con-
nect directly to a large ground plane to minimize thermal
and electrical impedance.
2. The traces connecting the regulator input supply pins
(BVIN and VINLDO) and their respective decoupling
capacitors should be kept as short as possible. The
GND side of each capacitor should connect directly to
the ground plane of the part. This capacitor provides
the AC current to the internal power MOSFETs and their
drivers. It is important to minimize inductance from this
capacitor to the pin of the LTC3553. Connect BVIN to
VOUT and VINLDO to its input supply through short low
impedance traces.
3. The switching power trace connecting the SW pin to
its inductor should be minimized to reduce radiated
EMI and parasitic coupling. Due to the large voltage
swing of the switching node, sensitive nodes such as
the feedback nodes should be kept far away or shielded
from the switching nodes or poor performance could
result.
4. Connections between the buck regulator inductor and
its output capacitor should be kept as short as possible.
The GND side of the output capacitor should connect
directly to the thermal ground plane of the part.
5. Keep the feedback pin traces (BUCK_FB and LDO_FB)
as short as possible. Minimize any parasitic capacitance
between the feedback traces and any switching node
(i.e., SW and logic signals). If necessary, shield the
feedback nodes with a GND trace.
6. Connections between the LTC3553 PowerPath pins
(VBUS and VOUT) and their respective decoupling ca-
pacitors should be kept as short as possible. The GND
side of these capacitors should connect directly to the
ground plane of the part.
OPERATION
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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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