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参数资料
| 型号： | LTC3547EDDB-1#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 14/16页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SYNC ADJ .3A DL 8DFN |
| 标准包装： | 2,500 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 2 |
| 输出电压： | 0.6 V ~ 5.5 V |
| 输入电压： | 2.5 V ~ 5.5 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 2.25MHz |
| 电流 - 输出： | 300mA |
| 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（3x2） |
LTC3547
APPLICATIO S I FOR ATIO
R 2 = ? OUT ? 1 ? ? R 1 = 887 k
Design Example
As a design example, consider using the LTC3547 in a
portable application with a Li-Ion battery. The battery
provides a V IN ranging from 2.8V to 4.2V. The load on
each channel requires a maximum of 300mA in active
mode and 2mA in standby mode. The output voltages are
V OUT1 = 2.5V and V OUT2 = 1.8V.
Start with channel 1. First, calculate the inductor value
for about 40% ripple current (120mA in this example) at
maximum V IN . Using a derivation of Equation 1:
The feedback resistors program the output voltage. To
maintain high ef?ciency at light loads, the current in these
resistors should be kept small. Choosing 2μA with the
0.6V feedback voltage makes R1~300k. A close standard
1% resistor is 280k. Using Equation 4:
? V ?
? 0 . 6 ?
Anoptional10pFfeedbackcapacity(C F1 )maybeusedto
improve transient response.
? ? 1 ?
L 1 =
2 . 5 V ?
2 . 25 MHz ? ( 120 mA ) ?
2 . 5 V ?
4 . 2 V ? ?
= 3 . 7 5 μ H
Using the same analysis for channel 2 (V OUT2 = 1.8V),
the results are:
L2 = 3.81μH
For the inductor, use the closest standard value of 4.7μH.
A 4.7μF capacitor should be more than suf?cient for this
output capacitor. As for the input capacitor, a typical value
of C IN = 4.7μF should suf?ce, as the source impedance of
a Li-Ion battery is very low.
V IN
R3 = 280k
R4 = 560k
Figure 4 shows the complete schematic for this example,
along with the ef?ciency curve and transient response.
2.5V TO 5.5V
C1
4.7 μ F
RUN2 V IN RUN1
V OUT2
1.8V AT 300mA
C F2 , 10pF
L2
4.7 μ H
LTC3547
SW2 SW1
L1
4.7 μ H
C F1 , 10pF
V OUT1
2.5V AT 300mA
C OUT2
4.7 μ F
R4
562k
R3
280k
V FB2
GND
V FB1
R1
280k
R2
887k
C OUT1
4.7 μ F
3547 F04a
C1, C2, C3: TAIYO YUDEN JMK316BJ475ML
L1, L2: MURATA LQH32CN4R7M33
Figure 4a. Design Example Circuit
100
90
80
70
60
50
40
30
20
10
0
V OUT = 1.8V
V IN = 2.7V
V IN = 3.6V
V IN = 4.2V
100
90
80
70
60
50
40
30
20
10
0
V OUT = 2.5V
V IN = 2.7V
V IN = 3.6V
V IN = 4.2V
0.1
1
10 100
1000
0.1
1
10 100
1000
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
3547 F04b
Figure 4b. Ef?ciency vs Output Current
3547fa
14
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3548 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual Synchronous,400mA/800mA, 2.25MHz Step-Down DC/DC Regulator |
| LTC3548-1 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual Synchronous, Fixed Output 2.25MHz Step-Down DC/DC Regulator |
| LTC3548-2 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual Synchronous, Fixed/Adjustable Output, 2.25MHz Step-Down DC/DC Regulator |
| LTC3548A | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual Synchronous 400mA/800mA, 2.25MHz Step-Down DC/DC Regulator |
| LTC3548AEDD | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual Synchronous 400mA/800mA, 2.25MHz Step-Down DC/DC Regulator |
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