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器件描述：1.5A Synchronous Buck Regulator
器件厂商：MICREL [Micrel Semiconductor]
厂商主页：http://www.micrel.com/
文件大小：131.2KB
文件页数：16
PDF阅读：MIC2179BSM.pdf (点击阅读器件资料)
摘要：
June 1998 1 MIC2179
MIC2179 Micrel
MIC2179
1.5A Synchronous Buck Regulator
General Description
The Micrel MIC2179 is a 200kHz synchronous buck (step-
down) switching regulator designed for high-efficiency, bat-
tery-powered applications.
The MIC2179 operates from a 4.5V to 16.5V input and
features internal power MOSFETs that can supply up to 1.5A
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
5?A.
The MIC2179 achieves high efficiency over a wide output
current range by operating in either PWM or skip mode. The
operating mode is externally selected, typically by an intelli-
gent system, which chooses the appropriate mode according
to operating conditions, efficiency, and noise requirements.
The switching frequency is preset to 200kHz and can be
synchronized to an external clock signal of up to 300kHz.
The MIC2179 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 MIC2179 and is packaged in a 20-lead SSOP package
with an operating temperature range of –40°C to +85°C.
Typical Application
BIASSGNDCOMP
PGND
FB
SW
VIN
C2
100?F
6.3V
V
OUT
3.3V/600mA
L1
22?H
C4
6.8nF
C3
0.01?F
MIC
2179-3.3
PWM
Skip Mode
PWM Mode
SYNC
EN
R2
10k
V
IN
5.4V to 16.5V
C1
10?F
20V U1
15
5
13
8 9–12 14
7
1,2,
19,20
3,4
16,17
D1
MBRM120
PWRGD
6
R1
20k
Output Good
Output Low
Pins 4 and 18 are not connected.
Pins 3 and 4 can be connected
together for a low-impedance
connection.
Features
? 4.5V to 16.5V input voltage range
? Dual-mode operation for high efficiency (up to 96%)
PWM mode for > 150mA load current
Skip mode for <150mA load current
? 150m? internal power MOSFETs at 12V input
? 200kHz preset switching frequency
? Low quiescent current
1.0mA in PWM mode
600?A in skip mode
< 5?A in shutdown mode
? Current-mode control
Simplified loop compensation
Superior line regulation
? 100% duty cycle for low dropout operation
? 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
Micrel, Inc. ? 1849 Fortune Drive ? San Jose, CA 95131 ? USA ? tel + 1 (408) 944-0800 ? fax + 1 (408) 944-0970 ? http://www.micrel.com
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