February 2006
FAN5631/FAN5632
Regulated Step-Down Charge Pump DC/DC Converter
Features
■ 90% Peak Efficiency
■ Low EMI
■ Low Ripple
■ Selectable Output Voltage 1.2V/1.5V for FAN5631
■ Efficiency Optimizer Feature for FAN5632
■ Input Voltage Range: 2.2V to 5.5V
■ Output Current: Up to 250mA
■ ±5% Output Voltage Accuracy
■ 30µA Operating Current
■ ICC < 1µA in Shutdown Mode
■ 1.7MHz Operating Frequency
■ Shutdown Isolates Output from Input
■ Soft-Start Limits In-Rush Current
■ Short Circuit and Over Temperature Protection
■ Minimum External Component Count
■ Available in a 3x3mm 10-Lead MLP Package
Applications
■ Cell Phones
■ Handheld Computers
■ Portable Electronic Equipment
■ Core Supply to Next Generation Processors
■ Low Voltage DC Bus
■ Digital Cameras
■ DSP Supplies
Description
The FAN5631/FAN5632 is an advanced, third-generation
switched capacitor step-down DC/DC converter utilizing Fair-
child's proprietary ScalarPump™ technology. This innovative
architecture utilizes scalar switch re-configuration and fractional
switching techniques to produce low output ripple, lower ESR
spikes, and improve efficiency over a wide load range.
The FAN5631/FAN5632 produces a fixed regulated output volt-
age from an input voltage of 2.2V to 5V. Customized output volt-
ages are available in 100mV increments from 1V to 1.8V.
Contact a Fairchild sales representative for customized output
voltage options.
In order to maximize efficiency, the FAN5631/5632 achieves
regulation by skipping pulses. Depending upon load current, the
size of the switches are scaled dynamically; consequently,
current spikes and EMI are minimized. An internal soft-start
circuitry prevents excessive current drawn from the supply. The
device is internally protected against short circuit and over
temperature conditions.
The FAN5631 has a dual output voltage feature. When VSEL is
high, VOUT is 1.5V and when VSEL is low, VOUT is 1.2V. Other
output voltage options are available upon request.
In addition, the FAN5632 has an efficiency optimizer feature
that, when enabled, changes the switch mode configuration
from 2:1 to 1:1 at the lower threshold of VIN. The efficiency is
then maintained at its peak level over a wider range of input volt-
ages. In addition, VOUT will vary between 1.2V to 1.5V as a
result of this efficiency optimization. If the efficiency optimizer is
not enabled, VOUT is regulated to 1.5V.
Both the FAN5631 and FAN5632 are available in a 3x3mm
10-lead MLP package.
Ordering Information
Product Number
FAN5631
FAN5632
Package Type
3x3mm 10-Lead MLP
3x3mm 10-Lead MLP
Order Code
FAN5631MPX
FAN5632MPX
©2006 Fairchild Semiconductor Corporation
1
FAN5631/FAN5632 Rev. 1.0.2
www.fairchildsemi.com