Buck Regulator. MIC2179 Datasheet

MIC2179 Regulator. Datasheet pdf. Equivalent

Part MIC2179
Description 1.5A Synchronous Buck Regulator
Feature Micrel, Inc. MIC2179 MIC2179 1.5A Synchronous Buck Regulator General Description The Micrel MIC.
Manufacture Micrel Semiconductor
Total Page 13 Pages
Datasheet
Download MIC2179 Datasheet



MIC2179
Micrel, Inc.
MIC2179
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 5µA.
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 intel-
ligent 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 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.
The MIC2179 and is packaged in a 20-lead SSOP package
with an operating temperature range of –40°C to +85°C.
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
• 150mΩ internal power MOSFETs at 12V input
• 200kHz preset switching frequency
• Low quiescent current
1.0mA in PWM mode
600µA in skip mode
< 5µA 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
Typical Application
VIN
5.4V to 16.5V
C1
10µF
20V
R1
20k
Output Good
Output Low
Skip Mode
PWM Mode
U1 16,17
15 EN
VIN
SW 3,4
6
5
PWRGD MIC
PWM 2179-3.3
PGND
1,2,
19,20
13 SYNC
FB 7
COMP SGND BIAS
8
9–12
14
L1
22µH
D1
MBRM120
VOUT
3.3V/600mA
C2
100µF
6.3V
C4
6.8nF
C3
0.01µF
R5
4.02k
Pins 4 and 18 are not connected.
Pins 3 and 4 can be connected
together for a low-impedance
connection.
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
June 2009
1 M9999-063009



MIC2179
Micrel, Inc.
Ordering Information
Part Number
Standard*
Pb-Free
Voltage
Temperature Range
Package
MIC2179BSM
MIC2179YSM
Adj.
-40°C to +85°C
20-Lead SSOP
MIC2179-3.3BSM MIC2179-3.3YSM
3.3V
-40°C to +85°C
20-Lead SSOP
MIC2179-5.0BSM MIC2179-5.0YSM
5.0V
-40°C to +85°C
20-Lead SSOP
* Standard product will be supported as Pb-Free IAW PCCN #040004 effective 1-1-2005 pending residual depletion.
Pin Configuration
PGND 1
PGND 2
SW 3
NC 4
PWM 5
PWRGD 6
FB 7
COMP 8
SGND 9
SGND 10
20 PGND
19 PGND
18 NC
17 VIN
16 VIN
15 EN
14 BIAS
13 SYNC
12 SGND
11 SGND
20-Lead Wide SSOP
MIC2179
Pin Description
Pin Number
1, 2, 19, 20
3
5
6
7
8
9–12
13
14
15
16, 17
4, 18
Pin Name
PGND
SW
PWM
PWRGD
FB
COMP
SGND
SYNC
BIAS
EN
VIN
NC
Pin Function
Power Ground: Connect all pins to central ground point.
Switch (Output): Internal power MOSFET output switches.
PWM/Skip-Mode Control (Input): Logic-level input. Controls regulator
operating mode. Logic low enables PWM mode. Logic high enables skip
mode. Do not allow pin to float.
Error Flag (Output): Open-drain output. Active low when FB input is 10%
below the reference voltage (VREF).
Feedback (Input): Connect to output voltage divider resistors.
Compensation: Output of internal error amplifier. Connect capacitor or
series RC network to compensate the regulator control loop.
Signal Ground: Connect all pins to ground, PGND.
Frequency Synchronization (Input): Optional. Connect an external clock
signal to synchronize the oscillator. Leading edge of signal above 1.7V
terminates switching cycle. Connect to SGND if not used.
Internal 3.3V Bias Supply: Decouple with 0.01µF bypass capacitor to
SGND. Do not apply any external load.
Enable (Input): Logic high enables operation. Logic low shuts down
regulator. Do not allow pin to float.
Supply Voltage (Input): Requires bypass capacitor to PGND. Both pins
must be connected to VIN.
not internally connected.
June 2009
2 M9999-063009





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