参数资料
| 型号： | LTC3561EDD#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 10/16页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SYNC ADJ 1A 8DFN |
| 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： | 0.8 V ~ 5 V |
| 输入电压： | 2.63 V ~ 5.5 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 最高 4MHz |
| 电流 - 输出： | 1A |
| 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： | 8-WFDFN 裸露焊盘 |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | 8-DFN-EP（3x3） |
LTC3561
APPLICATIO S I FOR ATIO
The output voltage settling behavior is related to the
stability of the closed-loop system and will demonstrate
the actual overall supply performance. For a detailed
explanation of optimizing the compensation components,
including a review of control loop theory, refer to Linear
Technology Application Note 76.
Although a buck regulator is capable of providing the full
output current in dropout, it should be noted that as the
input voltage V IN drops toward V OUT , the load step capa-
bility does decrease due to the decreasing voltage across
the inductor. Applications that require large load step
capability near dropout should use a different topology
such as SEPIC, Zeta or single inductor, positive buck/
boost.
In some applications, a more severe transient can be
caused by switching in loads with large (>1uF) input
capacitors. The discharged input capacitors are effectively
put in parallel with C OUT , causing a rapid drop in V OUT . No
regulator can deliver enough current to prevent this
problem, if the switch connecting the load has low resis-
tance and is driven quickly. The solution is to limit the turn-
on speed of the load switch driver. A hot swap controller
is designed specifically for this purpose and usually incor-
porates current limiting, short-circuit protection, and soft-
starting.
Efficiency Considerations
The percent efficiency 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 efficiency and which change would
V IN
produce the most improvement. Percent efficiency can be
expressed as:
%Efficiency = 100% – (L1 + L2 + L3 + ...)
where L1, L2, etc. are the individual losses as a percentage
of input power.
Although all dissipative elements in the circuit produce
losses, four main sources usually account for most of the
losses in LTC3561 circuits: 1) LTC3561 V IN current,
2) switching losses, 3) I 2 R losses, 4) other losses.
1) The V IN current is the DC supply current given in the
electrical characteristics which excludes MOSFET driver
and control currents. V IN current results in a small
(<0.1%) loss that increases with V IN , 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 V IN to ground. The resulting dQ/dt is a current out
of V IN that is typically much larger than the DC bias
current. In continuous mode, I GATECHG = f O (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 V IN and thus their effects will be
more pronounced at higher supply voltages.
3) I 2 R Losses are calculated from the DC resistances of the
internal switches, R SW , and external inductor, R L . In
continuous mode, the average output current flowing
through inductor L is “chopped” between the internal
top and bottom switches. Thus, the series resistance
2.63V
TO 5.5V
C6
+
C IN
R6
PGND
PGND
C8
SV IN
PV IN
LTC3561
SW
L1
D1
OPTIONAL
C F
+
C OUT
C5
V OUT
PGND
I TH
V FB
PGND
PGND
C ITH
R C
SGND PGND
SHDN/R T
R1
R2
C C
R T
3561 F05
Figure 4. LTC3561 General Schematic
3561f
10
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| LTC3562 | 制造商:LINER 制造商全称:Linear Technology 功能描述:I2C Quad Synchronous Step-Down DC/DC Regulator 2 × 600mA, 2 × 400mA |
| LTC3562EUD#PBF | 功能描述:IC REG BUCK SYNC ADJ QUAD 20QFN 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:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 同步整流器:是 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
| LTC3562EUD#TRPBF | 功能描述:IC REG BUCK SYNC ADJ QUAD 20QFN 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:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 同步整流器:是 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
| LTC3562EUD-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:I2C Quad Synchronous Step-Down DC/DC Regulator 2 × 600mA, 2 × 400mA |
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