Buck Regulator. MIC2179 Datasheet
1.5A Synchronous Buck Regulator
The Micrel MIC2179 is a 200kHz synchronous buck (step-
down) switching regulator designed for high-efficiency, bat-
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.
• 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
• High-efficiency, battery-powered supplies
• Buck (step-down) dc-to-dc converters
• Cellular telephones
• Laptop computers
• Hand-held instruments
• Battery Charger
5.4V to 16.5V
COMP SGND BIAS
Pins 4 and 18 are not connected.
Pins 3 and 4 can be connected
together for a low-impedance
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
* Standard product will be supported as Pb-Free IAW PCCN #040004 effective 1-1-2005 pending residual depletion.
20-Lead Wide SSOP
1, 2, 19, 20
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.