MCP1603-330I/MC Microchip Technology, MCP1603-330I/MC Datasheet - Page 12

• Manufacturer Part Number: MCP1603-330I/MC
• Description: IC SYNC BUCK REG 0.5A 3.3V 8DFN
• Manufacturer: Microchip Technology
• Type: Step-Down (Buck)r

Specifications of MCP1603-330I/MC

• Internal Switch(s): Yes
• Synchronous Rectifier: Yes
• Number Of Outputs: 1
• Voltage - Output: 3.3V
• Current - Output: 500mA
• Frequency - Switching: 2MHz
• Voltage - Input: 2.7 ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-DFN
• For Use With: MCP1603RD-TNY - REFERENCE DESIGN FOR MCP1603MCP1603EV - BOARD EVAL BUCK CONV MCP1603
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

MCP1603
4.0
4.1
The MCP1603 is a synchronous buck regulator that
operates in a Pulse Frequency Modulation (PFM)
mode or a Pulse Width Modulation (PWM) mode to
maximize system efficiency over the entire operating
current range. Capable of operating from a 2.7V to
5.5V input voltage source, the MCP1603 can deliver
500 mA of continuous output current.
When using the MCP1603, the PCB area required for
a complete step-down converter is minimized since
both the main P-Channel MOSFET and the synchro-
nous N-Channel MOSFET are integrated. Also while in
PWM mode, the device switches at a constant
frequency of 2.0 MHz (typ) which allow for small filter-
ing components. Both fixed and adjustable output
voltage options are available. The fixed voltage options
(1.2V, 1.5V 1.8V, 2.5V, 3.3V) do not require an external
voltage divider which further reduces the required
circuit board footprint. The adjustable output voltage
options allow for more flexibility in the design, but
require an external voltage divider.
Additionally the device features undervoltage lockout
(UVLO),
protection, and enable/disable control.
DS22042A-page 12
DETAILED DESCRIPTION
Device Overview
overtemperature
shutdown,
overcurrent
4.2
The MCP1603 has two distinct modes of operation that
allow the device to maintain a high level of efficiency
throughout the entire operating current and voltage
range. The device automatically switched between
PWM mode and PFM mode depending upon the output
load requirements.
4.2.1
During heavy load conditions, the MCP1603 operates
at a high, fixed switching frequency of 2.0 MHz (typical)
using current mode control. This minimizes output rip-
ple (10 - 15 mV typically) and noise while maintaining
high efficiency (88% typical with V
V
During normal PWM operation, the beginning of a
switching cycle occurs when the internal P-Channel
MOSFET is turned on. The ramping inductor current is
sensed and tied to one input of the internal high-speed
comparator. The other input to the high-speed compar-
ator is the error amplifier output. This is the difference
between the internal 0.8V reference and the divided-
down output voltage. When the sensed current
becomes equal to the amplified error signal, the high-
speed comparator switches states and the P-Channel
MOSFET is turned off. The N-Channel MOSFET is
turned on until the internal oscillator sets an internal RS
latch initiating the beginning of another switching cycle.
PFM-to-PWM mode transition is initiated for any of the
following conditions:
• Continuous device switching
• Output voltage has dropped out of regulation
4.2.2
During light load conditions, the MCP1603 operates in
a PFM mode. When the MCP1603 enters this mode, it
begins to skip pulses to minimize unnecessary quies-
cent current draw by reducing the number of switching
cycles per second. The typical quiescent current draw
for this device is 45 µA.
PWM-to-PFM mode transition is initiated for any of the
following conditions:
• Discontinuous inductor current is sensed for a set
• Inductor peak current falls below the transition
OUT
duration
threshold limit
= 1.8V, I
Synchronous Buck Regulator
FIXED FREQUENCY, PWM MODE
LIGHT LOAD, PFM MODE
OUT
= 300 mA).
© 2007 Microchip Technology Inc.
IN
= 3.6V,