Information
7
Portable Power Conversion Design Guide
DC/DC Conversion
Step-Down (Buck) Switch Mode Power Converters
MCP1603/L/B Synchronous Buck Regulators
The MCP1603 is a family of highly efficient, fully integrated 500 mA synchronous buck regulators. The 2.7V to 5.5V input
range makes these ideally suited for battery powered applications, including one-cell Li-ion; two- or three-cell NiMH; or two-
or three-cell NiCd power sources. With heavy loads, the MCP1603/L operates in a 2.0 MHz fixed frequency PWM mode
which provides a low-noise, low output voltage ripple, small-footprint solution. With light loads, the MCP1603/L
automatically changes operation to a PFM mode to minimize quiescent current consumption, improving battery run time.
These two modes allow the MCP1603/L to achieve the best possible efficiency over the entire load current range. The
MCP1603B, in contrast, only switches in PWM mode, maintaining a low output voltage ripple over a wide output load range
in noise-sensitive applications (audio or RF). Only three additional external components are required for a complete
converter solution when using the fixed voltage options, or a flexible output voltage can be produced with a resistive divider
on the adjustable output device options. The low-profile, small-footprint packages also enable the system solution to be
achieved with minimal size.
■ Typical efficiency over 90%
■ Supplies up to 500 mA of output current
■ Low 45 μA typical PFM quiescent current
■ Low 0.1 μA typical shutdown current
■ Adjustable output voltage range: 0.8V to 4.5V
■ Fixed output voltage options: 1.2V, 1.5V, 1.8V,
2.5V, and 3.3V
■ 2.0 MHz operation
■ Automatic PWM to PFM mode transitions (MCP1603/L)
or PWM only operation (MCP1603B)
■ 100% duty cycle operation
■ Internally compensated
■ Under-voltage lockout (UVLO) at 2.3V
■ Over-temperature protection
■ Space-saving 5-lead TSOT and 8-pin 2 × 3 DFN
packages
MCP1603 Typical Application Circuit
GND
V
IN LX
SHDN
V
OUT
4.7 μH
4.7 μF
V
OUT
1.5V @ 500 mA
V
IN
2.0V to 5.5V
4.7 μH
Typical MCP1603 Efficiency
40
50
60
70
80
90
100
E
fficiency (%)
V
IN
= 4.2V
V
IN
= 3.6V
0
10
20
30
0.1 1 10 100 1000
E
Output Current (mA)
V
OUT
= 3.3
V
PFM/PWM
PWM Only