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PDF MIC2177 Data sheet ( Hoja de datos )
| Número de pieza | MIC2177 | |
| Descripción | 2.5A Synchronous Buck Regulator | |
| Fabricantes | Micrel Semiconductor | |
| Logotipo |  |
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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.
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.
• 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
– 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
VIN
5.4V to 18V
C1
22µF
35V
ENABLE
SHUTDOWN
U1 1,2,9
VIN
20
18
11
EN
SYNC
AUTO
OUT
MIC SW
2177-5.0 PGND
10
3,8
4–7
FB 12
L1, 50µH
D1
MBRS130L
COMP SGND BIAS
2.2
nF
R1 13
14–17
19
10k
CC
C3
0.01µF
6.8nF
R1
10k
VOUT
5V/1A
C2
100µF
10V
5V Output
Efficiency
100
95
90 VIN = 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 +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
April 2008
M9999-042108
1 page  
Micrel, Inc.
Symbol Parameter
Condition
ISW Output Switch Leakage
Enable Threshold
VSW = 16.5V
IEN Enable Leakage
AUTO Threshold
VEN = 0V to 5.5V
AUTO Source Current
Minimum Switch Current for
PWM Operation
VFB = 1.5V, VAUTO < 0.8V
VIN – VOUT = 0V
VIN – VOUT = 3V
General Note: Devices are ESD sensitive. Handling precautions recommended.
MIC2177
Min Typ Max Units
1 10 µA
0.8 1.6
2.2
V
–1 0.01
1
µA
0.8 1.6
V
7 11 15 µA
220 mA
420 mA
April 2008
5 M9999-042108
5 Page 
Micrel, Inc.
PWM-Mode Functional Diagram
VIN
4.5V to 16.5V
VIN 1 2 9
CIN
MIC2177
IS E N S E
Amp.
100m
P-channel
100m
N-channel
Stop S Y NC
18
200kHz
Oscillator
Corrective
Ramp
Reset
Pulse
COMP
CC RC 13
R
Q
S
PWM
Comp.
Error
Amp.
VR EF1.245V
MIC2177 [Adjustable] PWM-Mode Signal Path
S G N D 14 15 16 17
VOUT
=
1.245
(
R1
R2
+
1)
SW
3
8
L1
IL1
D COUT
VOU T
PGND
4
5
6
7
R1
FB
12
R2
VS W
Reset
Pulse
IL1 ILOAD
Error Amp.
Output
ISENSE
IL1
April 2008
11 M9999-042108
11 Page | ||
| Páginas | Total 15 Páginas | |
| PDF Descargar | [ Datasheet MIC2177.PDF ] | |
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