2005 Fairchild Semiconductor Corporation
FAN5631/FAN5632 Rev. 1.0.0
1
www.fairchildsemi.com
October 2005
F
FAN5631/FAN5632
Regulated Step-Down Charge Pump DC/DC Converter
Features
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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
I
CC
< 1μA in Shutdown Mode
1.5MHz 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
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Applications
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Cell Phones
Handheld Computers
Portable Electronic Equipment
Core Supply to Next Generation Processors
Low Voltage DC Bus
Digital Cameras
DSP Supplies
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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 V
high, V
OUT
is 1.5V and when V
output voltage options are available upon request.
SEL
is
SEL
is low, V
OUT
is 1.2V. Other
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 V
then maintained at its peak level over a wider range of input volt-
ages. In addition, V
OUT
will vary between 1.2V to 1.5V as a
result of this efficiency optimization. If the efficiency optimizer is
not enabled, V
OUT
is regulated to 1.5V.
IN
. The efficiency is
Both the FAN5631 and FAN5632 are available in a 3x3mm
10-lead MLP package.
Ordering Information
Product Number
Package Type
Order Code
FAN5631
3x3mm 10-Lead MLP
FAN5631MPX
FAN5632
3x3mm 10-Lead MLP
FAN5632MPX