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器件描述：2.5A Synchronous Buck Regulator
器件厂商：MICREL [Micrel Semiconductor]
厂商主页：http://www.micrel.com/
文件大小：181.67KB
文件页数：16
PDF阅读：MIC2177BWM.pdf (点击阅读器件资料)
摘要：
April 1999 1 MIC2177
MIC2177 Micrel
MIC2177
2.5A Synchronous Buck Regulator
General Description
The Micrel MIC2177 is a 200kHz synchronous buck (step-
down) switching regulator designed for high-efficiency, bat-
tery-powered applications.
The MIC2177 operates from a 4.5V to 16.5V input and
features internal power MOSFETs that can supply up to 2.5A
output current. It can operate with a maximum duty cycle of
100% for use in low-dropout conditions. It also features a
shutdown mode that reduces quiescent current to less than
5m A.
The MIC2177 achieves high efficiency over a wide output
current range by switching between PWM and skip mode.
Operating mode is automatically selected according to output
conditions. Switching frequency is preset to 200kHz and can
be synchronized to an external clock signal of up to 300kHz.
The MIC2177 uses current-mode control with internal current
sensing. Current-mode control provides superior line regula-
tion and makes the regulator control loop easy to compen-
sate. The output is protected with pulse-by-pulse current
limiting and thermal shutdown. Undervoltage lockout turns
the output off when the input voltage is less than 4.5V.
The MIC2177 is packaged in a 20-lead wide power SO
package with an operating temperature range of –40 C to
+85 C.
See the MIC2178 for externally selected PWM or skip-mode
operation.
Typical Application
Features
? 4.5V to 16.5V input voltage range
? Dual-mode operation for high efficiency (up to 96%)
PWM mode for > 200mA load current
Skip mode for < 200mA load current
? 100mW internal power MOSFETs at 12V input
? 200kHz preset switching frequency
? Low quiescent current
1.0mA in PWM mode
500m A in skip mode
< 5m A in shutdown mode
? 100% duty cycle for low dropout operation
? Current-mode control
Simplified loop compensation
Superior line regulation
? Current limit
? Thermal shutdown
? Undervoltage lockout
Applications
? High-efficiency, battery-powered supplies
? Buck (step-down) dc-to-dc converters
? Cellular telephones
? Laptop computers
? Hand-held instruments
? Battery Charger
BIASSGND
EN
COMP
PGND
FB
OUT
VIN
C3
220?F
10V
V
OUT
5V/2.5A
L1, 33?H
C5
10nF
C4
0.01?F
MIC2177-5.0
AUTO
SYNC
R7
15k
V
IN
6V to 16.5V
C1
22?F
35V
U1
20
18
11
13 14–17 19
12
4–7
3,8
1,2,9
D1
MBRS140
SW
10
ENABLE
ON
C6
2.2nF
AUTO
MODE
PWM
MODE
Mode
OFF
C2
22?F
35V
C7
220?F
10V
70
75
80
85
90
95
100
10 100 1000 2500
EFFICIENCY (%)
OUTPUT CURRENT (mA)
5V Output
Efficiency
V
IN
= 6V
SKIP
PWM
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