- 您现在的位置：买卖IC网 > PDF目录1830 > LTC3549EDCB#TRPBF (Linear Technology)IC REG BUCK SYNC ADJ 0.25A 6DFN PDF资料下载
参数资料
| 型号： | LTC3549EDCB#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 11/16页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SYNC ADJ 0.25A 6DFN |
| 标准包装： | 2,500 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 0.61 V ~ 5.5 V |
| 输入电压： | 1.6 V ~ 5.5 V |
| PWM 型： | 电流模式，混合 |
| 频率 - 开关： | 2.25MHz |
| 电流 - 输出： | 250mA |
| 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-WFDFN 裸露焊盘 |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | 6-DFN-EP（2x3） |
LTC3549
APPLICATIO S I FOR ATIO
Ef?ciency Considerations
The ef?ciency 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 ef?ciency and which change would produce
the most improvement. Ef?ciency can be expressed as:
Ef?ciency = 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, two main sources usually account for most of
the losses in LTC3549 circuits: V IN quiescent current and
I 2 R losses. The V IN quiescent current loss dominates
the ef?ciency loss at very low load currents whereas the
I 2 R loss dominates the ef?ciency loss at medium to high
load currents. In a typical ef?ciency plot, the ef?ciency
curve at very low load currents can be misleading since
the actual power lost is of no consequence, as illustrated
in Figure 2.
1. The V IN quiescent current is due to two components: the
DC bias current as given in the Electrical Characteristics
and the internal main switch and synchronous switch
gate charge currents. The gate charge current results
from switching the gate capacitance of the internal power
MOSFET switches. Each time the gate is switched from
high to low to high again, a packet of charge, dQ, moves
from V IN to ground. The resulting dQ/dt is the current out
of V IN that is typically larger than the DC bias current. In
continuous mode, I GATECHG = f(Q T + Q B ) where Q T and
Q B are the gate charges of the internal top and bottom
switches. Both the DC bias and gate charge losses are
proportional to V IN and thus their effects will be more
pronounced at higher supply voltages.
2. I 2 R losses are calculated from the resistances of the
internal switches, R SW , and external inductor R L . In
continuous mode, the average output current ?owing
through inductor L is “chopped” between the main
switch and the synchronous switch. Thus, the series
resistance looking into the SW pin is a function of both
top and bottom MOSFET R DS(ON) and the duty cycle
(DC) as follows:
R SW = (R DS(ON)TOP )(DC) + (R DS(ON)BOT )
(1 – DC)
The R DS(ON) for both the top and bottom MOSFETs can be
obtained from the Typical Performance Characteristics.
Thus, to obtain I 2 R losses, simply add R SW to R L and
multiply the result by the square of the average output
current.
Other losses including C IN and C OUT ESR dissipative los-
ses and inductor core losses generally account for less
than 2% total additional loss.
1.0000
0.1000
V IN BURST
2.5V
3.6V
4.2V
V IN PULSE SKIP
2.5V
3.6V
4.2V
V OUT = 1.8V
0.0100
0.0010
0.0001
0.1
1
10 100
1000
LOAD CURRENT (mA)
3549 F02
Figure 2. Power Loss vs Load Current
3549f
11
相关PDF资料 |
PDF描述 |
|---|---|
| LTC3550EDHC-1#TRPBF | IC CHARGER BATT DUAL 16-DFN |
| LTC3552EDHC-1#TRPBF | IC CHARGER BATT LI-ION 16-DFN |
| LTC3559EUD-1#TRPBF | IC USB BATTERY CHARGER 16-QFN |
| LTC3560IS6#TRPBF | IC REG BUCK SYNC ADJ TSOT23-6 |
| LTC3561EDD#TRPBF | IC REG BUCK SYNC ADJ 1A 8DFN |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3550 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual Input USB/AC Adapter Li-Ion Battery Charger with 600mA Buck Converter |
| LTC3550-1 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual Input USB/AC Adapter Li-Ion Battery Charger with 600mA Buck Converter |
| LTC3550EDHC | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual Input USB/AC Adapter Li-Ion Battery Charger with 600mA Buck Converter |
| LTC3550EDHC#PBF | 功能描述:IC CHARGER BATT DUAL 16-DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 电池管理 系列:- 标准包装:61 系列:- 功能:电源管理 电池化学:锂离子（Li-Ion）、锂聚合物（Li-Pol） 电源电压:4.35 V ~ 5.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:22-WFDFN 裸露焊盘 供应商设备封装:22-DFN（6x3）裸露焊盘 包装:管件 |
| LTC3550EDHC#TRPBF | 功能描述:IC CHARGER BATT DUAL 16-DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 电池管理 系列:- 标准包装:61 系列:- 功能:电源管理 电池化学:锂离子（Li-Ion）、锂聚合物（Li-Pol） 电源电压:4.35 V ~ 5.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:22-WFDFN 裸露焊盘 供应商设备封装:22-DFN（6x3）裸露焊盘 包装:管件 |
发布紧急采购，3分钟左右您将得到回复。