500 mA Synchronous BUCK Regulator
• Input Range of 2.7V to 5.5V
• 3 Operating Modes: PWM, PFM and LDO
• Integrated BUCK and Synchronous Switches
• Ceramic or Electrolytic Input/Output Filtering
• 750 kHz Fixed Switching Frequency
• Oscillator Synchronization to 1 MHz PWM Mode
• Auto-Switching from PWM/PFM Operation
• 100% Duty Cycle Capable for Low Input Voltage
• 500 mA Continuous Output Current Capability
• Integrated Under-Voltage Lock-Out Protection
• Integrated Over-Temperature Protection
• Integrated Soft Start Circuitry
• Low Output Voltage Capability to 0.9V
• Temperature Range: -40°C to +85ºC
• Small 8-Pin MSOP Package
• Low Power Handheld CPUs and DSPs
• Cellular Phones
• Organizers and PDAs
• Digital Cameras
• +5V or +3.3V Distributed Voltages
• USB Powered Devices
The MCP1601 is a fully integrated synchronous BUCK
(step down) DC/DC converter for battery powered sys-
tems. With an input operating range of 2.7V to 5.5V, the
MCP1601 is ideal for applications being powered by
one single cell Li-Ion, 2 to 3 cell NiMH, NiCd or alkaline
sources. Output voltages can range from 0.9V to VIN to
accommodate a wide range of applications. Efficiency
can exceed 92% while operating at 750 kHz with load
current capability up to 500 mA. The MCP1601 is used
to minimize space, cost and wasted energy.
The PWM mode switching frequency is internally set to
a fixed 750 kHz allowing the use of low profile, surface
mount inductors and ceramic capacitors while
maintaining a typical efficiency of 92%.
The MCP1601 is capable of three distinct operating
modes: PWM, PFM and Low Drop Out.
When operating in PWM (pulse width modulation)
mode, the DC/DC converter switches at a single high
frequency determined by either the internal 750 kHz
oscillator or external synchronization frequency.
For applications that operate at very light to no load for
extended periods of time, the MCP1601 is capable of
operating in PFM (pulse frequency modulation mode)
to reduce the number of switching cycles/sec and
consume less energy.
The third mode of operation (LDO mode) occurs when
the input voltage approaches the output voltage and the
BUCK duty cycle approaches 100%. The MCP1601 will
enter a low drop out mode and the high-side P-Channel
BUCK switch will saturate, providing the output with the
maximum voltage possible.
The MCP1601 has integrated over-current protection,
over-temperature protection and UVLO (Under Voltage
Lockout) to provide for a fail safe solution with no
The MCP1601 is available in the 8-pin MSOP package,
with an operating temperature range of -40°C to +85°C.
2003 Microchip Technology Inc.