MIC2177_08 Datasheet, PDF (1/15 Pages) Micrel Semiconductor – 2.5A Synchronous Buck Regulator

MIC2177
2.5A Synchronous Buck Regulator
General Description
Features
The Micrel MIC2177 is a 200kHz synchronous buck (step-
down) switching regulator designed for high-efficiency,
battery-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
5µA.
• 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
• 100mΩ internal power MOSFETs at 12V input
• 200kHz preset switching frequency
• Low quiescent current
– 1.0mA in PWM mode
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
regulation and makes the regulator control loop easy to
compensate. 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.
– 500µA in skip mode
– < 5µA 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
The MIC2177 is packaged in a 20-pin 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.
Data sheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
Applications
• High-efficiency, battery-powered supplies
• Buck (step-down) dc-to-dc converters
• Cellular telephones
• Laptop computers
• Hand-held instruments
• Battery Charger
_________________________________________________________________________________________________________
Typical Application
V_IN
5.4V to 18V
C1
22µF
35V
ENABLE
SHUTDOWN
U1
1,2,9
VIN
20 _EN
OUT ¹⁰
18
11
SYNC
AUTO
MIC
SW
2177-5.0 _PGND
3,8
4–7
FB ¹²
L1, 50µH
D1
MBRS130L
COMP SGND BIAS
2.2
13
nF R1
14–17
19
10k
C_C
6.8nF
C3
R1
0.01µF 10k
V_OUT
5V/1A
C2
100µF
10V
5V Output
Efficiency
100
95
90
V_IN = 6V
85
80
75
70
10
SKIP
PWM
100
1000 2500
OUTPUT CURRENT (mA)
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel [phone] • fax + 1 [phone] • http://www.micrel.com
April 2008
M9999-042108