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参数资料
| 型号： | LTC3547BIDDB#PBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | 0.7 A DUAL SWITCHING CONTROLLER, 2700 kHz SWITCHING FREQ-MAX, PDSO8 |
| 封装： | 3 X 2 MM, 0.75 MM HEIGHT, LEAD FREE, PLASTIC, M0-229WECD-1, DFN-8 |
| 文件页数： | 3/16页 |
| 文件大小： | 248K |
| 代理商： | LTC3547BIDDB#PBF |
LTC3547B
11
3547bfb
APPLICATIO S I FOR ATIO
WU
U
Efciency Considerations
The percent efciency of a switching regulator is equal to
the output power divided by the input power times 100%.
It is often useful to analyze individual losses to determine
what is limiting the efciency and which change would
produce the most improvement. Percent efciency can
be expressed as:
%Efciency = 100% – (L1 + L2 + L3 + ...)
where L1, L2, etc., are the individual losses as a percent-
age of input power.
Although all dissipative elements in the circuit produce
losses, four sources usually account for the losses in
LTC3547B circuits: 1) VIN quiescent current, 2) switching
losses, 3) I2R losses, 4) other system losses.
1) The VIN current is the DC supply current given in the
Electrical Characteristics which excludes MOSFET
driver and control currents. VIN current results in a
small (<0.1%) loss that increases with VIN, even at
no load.
2) The switching current is the sum of the MOSFET driver
and control currents. The MOSFET driver current re-
sults from switching the gate capacitance of the power
MOSFETs. Each time a MOSFET gate is switched from
low to high to low again, a packet of charge dQ moves
from VIN to ground. The resulting dQ/dt is a current out
of VIN that is typically much larger than the DC bias cur-
rent. In continuous mode, IGATECHG = fO(QT + QB), where
QT and QB are the gate charges of the internal top and
bottom MOSFET switches. The gate charge losses are
proportional to VIN and thus their effects will be more
pronounced at higher supply voltages.
3) I2R losses are calculated from the DC resistances
of the internal switches, RSW, and external inductor,
RL. In continuous mode, the average output current
ows through inductor L, but is “chopped” between
the internal top and bottom switches. Thus, the series
resistance looking into the SW pin is a function of both
top and bottom MOSFET RDS(ON) and the duty cycle
(DC) as follows:
RSW = (RDS(ON)TOP) (DC) + (RDS(ON)BOT) (1– DC)
(5)
The RDS(ON) for both the top and bottom MOSFETs can
be obtained from the Typical Performance Character-
istics curves. Thus, to obtain I2R losses:
I2R losses = IOUT2 (RSW + RL)
4) Other “hidden” losses, such as copper trace and in-
ternal battery resistances, can account for additional
efciency degradations in portable systems. It is very
important to include these “system” level losses in
the design of a system. The internal battery and fuse
resistance losses can be minimized by making sure that
CIN has adequate charge storage and very low ESR at
the switching frequency. Other losses, including diode
conduction losses during dead-time, and inductor
core losses, generally account for less than 2% total
additional loss.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3547EDDB | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual Monolithic 300mA Synchronous Step-Down Regulator |
| LTC3547EDDB#PBF | 制造商:Linear Technology 功能描述:REG STEP DOWN 0.3A SYNCH DFN-8 制造商:Linear Technology 功能描述:REG, STEP DOWN, 0.3A SYNCH, DFN-8 |
| LTC3547EDDB#TRMPBF | 功能描述:IC REG BUCK SYNC ADJ .3A DL 8DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:250 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V 输入电压:2.05 V ~ 6 V PWM 型:电压模式 频率 - 开关:2MHz 电流 - 输出:500mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:6-UFDFN 包装:带卷 (TR) 供应商设备封装:6-SON（1.45x1） 产品目录页面:1032 (CN2011-ZH PDF) 其它名称:296-25628-2 |
| LTC3547EDDB#TRPBF | 功能描述:IC REG BUCK SYNC ADJ .3A DL 8DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:升压（升压） 输出类型:可调式 输出数:1 输出电压:1.24 V ~ 30 V 输入电压:1.5 V ~ 12 V PWM 型:电流模式，混合 频率 - 开关:600kHz 电流 - 输出:500mA 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) 供应商设备封装:8-SOIC |
| LTC3547EDDB-1 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual Monolithic 300mA Synchronous Step-Down Regulator |
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