FAN5631 / FAN5632 — Regulated Step Down Charge Pump DC/DC Converter
October 2007
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
I
CC
<1mA in Shutdown Mode
1.5MHz Operating Frequency
Shutdown Isolates Output from Input
Soft-Start Limits Inrush Current
Short-Circuit and Over-Temperature Protection
Minimum External Component Count
10-Lead 3x3mm MLP Package
Description
The FAN5631/FAN5632 is an advanced, third-
generation switched capacitor step-down DC/DC
converter utilizing Fairchild'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 voltage from an input voltage of 2.2V to 5V.
To maximize efficiency, the FAN5631/5632 achieves
regulation by skipping pulses. Depending on 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
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
SEL
is high, V
OUT
is 1.5V; and when V
SEL
is low, V
OUT
is
1.2V.
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
IN
. The
efficiency is maintained at its peak level over a wider
range of input voltages. In addition, V
OUT
varies from
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.
Both the FAN5631 and FAN5632 are available in a 10-
lead 3x3mm MLP package.
Applications
Cell Phones
Handheld Computers
Portable Electronic Equipment
Core Supply to Next-Generation Processors
Low-Voltage DC Bus
Digital Cameras
DSP Supplies
Ordering Information
Part Number
FAN5631MPX
FAN5632MPX
Package
10-Lead 3x3mm Molded Leadless Package (MLP)
10-Lead 3x3mm Molded Leadless Package (MLP)
Packing Method
Tape and Reel
Tape and Reel
All packages are lead free per JEDEC: J-STD-020B standard.
© 2006 Fairchild Semiconductor Corporation
FAN5631/FAN5632 Rev. 1.0.2
www.fairchildsemi.com
FAN5631 / FAN5632 — Regulated Step Down Charge Pump DC/DC Converter
Typical Application
V
SEL
ON
OFF
C
B
+
C
B
-
EN
GND
1
2
3
4
5
10
9
8
7
6
NC
NC
NC
NC
C
OUT
10µF
C
IN
10µF
V
IN
= 2.7V to 5.5V
V
OUT
= 1.2V to 1.5V
I
OUT_max
= 250mA
Figure 1. Typical Application
FAN5631
FAN5632 with
optimization
Average Efficiency (over V
IN
=2.7V to 5V) = 66%, with optimization = 77%
Average Efficiency (over V
IN
=2.7V to 4.2V) = 67%, with optimization = 84%
Figure 2. Typical Efficiency Graph
© 2006 Fairchild Semiconductor Corporation
FAN5631/FAN5632 Rev. 1.0.2
www.fairchildsemi.com
2
FAN5631 / FAN5632 — Regulated Step Down Charge Pump DC/DC Converter
Pin Configuration
Top View
V
SEL
EN
C
B
+
GND
C
B
-
1
2
3
4
5
10
9
8
7
6
NC
V
IN
NC
NC
V
OUT
Figure 3. Pin Assignments
Pin Definitions
Pin #
Name
Description
Output Voltage Select Logic Input Pin.
The V
SEL
pin cannot be left floating and must be
connected to either a logic high or logic low level.
1
V
SEL
FAN5631:
If a logic low is applied to the V
SEL
pin, V
OUT
is 1.2V; if a logic high is
applied, V
OUT
is 1.5V.
FAN5632:
If a logic low is applied to the V
SEL
pin, the efficiency optimization mode is enabled
and the output voltage accuracy is relaxed to meet optimum efficiency. If a logic high is
applied, the device operates like a typical charge pump converter.
2
3
4
5
6
7
8
9
10
EN
C
B
+
GND
C
B
-
V
OUT
NC
NC
V
IN
NC
Enable Input Pin.
If a logic high is applied to the EN pin, the device is enabled. If a logic low is
applied, the device is disabled and the supply current is reduced to less than 1µA. The EN pin
cannot be left floating and must be connected to a logic high or logic low level.
Bucket Capacitor Positive Pin.
Ground Pin.
This pin is connected to the internal MOSFET switches. This pin must be
externally connected to GND.
Bucket Capacitor Negative Pin.
Output Voltage Pin.
Not Connected.
This pin is not internally connected.
Not Connected.
This pin is not internally connected.
Supply Voltage Input.
Not Connected.
This pin is not internally connected.
© 2006 Fairchild Semiconductor Corporation
FAN5631/FAN5632 Rev. 1.0.2
www.fairchildsemi.com
3
FAN5631 / FAN5632 — Regulated Step Down Charge Pump DC/DC Converter
Absolute Maximum Ratings
Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be
operable above the recommended operating conditions and stressing the parts to these levels is not recommended.
In addition, extended exposure to stresses above the recommended operating conditions may affect device
reliability. The absolute maximum ratings are stress ratings only.
Symbol
V
CC
I
LOAD
Θ
JC
T
L
T
J
T
STG
ESD
(2)
Parameter
V
IN
to GND
All other pins to GND
Load Current
Thermal Resistance Junction-to-Tab
Junction Temperature
Storage Temperature
Human Body Model, JESD22-A114
Charged Device Model, JESD22-C101
(1)
Min.
-0.3
-0.3
Max.
6.0
V
IN
+ 0.3
0.5
8
+260
Unit
V
A
°C/W
°C
°C
°C
kV
Lead Temperature, Soldering 10 Seconds
-40
-65
2.5
0.2
+150
+150
Notes:
1. Junction-to-ambient thermal resistance,
θ
JA
,
is a strong function of PCB material, board thickness, thickness and
number of copper planes, number of via used, diameter of via used, available copper surface, and attached heat
sink characteristics. The estimated value for zero air flow at 0.5W is 60°C/W.
2. Using Mil Std. 883E, method 3015.7 (Human Body Model) and EIA/JESD22C101-A (Charged Device Model).
Recommended Operating Conditions
The Recommended Operating Conditions table defines the conditions for actual device operation. Recommended
operating conditions are specified to ensure optimal performance to the datasheet specifications. Fairchild does not
recommend exceeding them or designing to Absolute Maximum Ratings.
Symbol
V
CC
I
OUT
T
A
Parameter
Supply Voltage Range
Output Current (V
IN
> 2.V)
Operating Ambient Temperature Range
Min.
2.2
-40
Typ.
Max.
5.5
250
Unit
V
mA
°C
+25
+85
© 2006 Fairchild Semiconductor Corporation
FAN5631/FAN5632 Rev. 1.0.2
www.fairchildsemi.com
4
FAN5631 / FAN5632 — Regulated Step Down Charge Pump DC/DC Converter
Electrical Characteristic
V
IN
= 2.2V to 5.5V, I
OUT
= 1mA, C
IN
= 10µF, C
OUT
= 10µF, C
B
= 1µF, T
A
= -40°C to +85°C, unless otherwise noted.
Typical values are at T
A
= 25°C.
Symbol
V
UVLO
Parameter
Input Under-voltage Lockout
No-load Supply Current
Conditions
No Switching
FAN5631, SEL to High
FAN5631, SEL to Low
FAN5632, SEL to High
FAN5632, SEL to Low
Min.
Typ.
2
Max.
60
Units
V
µA
1.5
1.2
1.5
Variable
between
1.5 and 1.2
-5
0.25
0.2
0.1
25
90
2.22xV
OUT
1.5
150
15
1.3
0.4
-1
1.3
0.4
-1
1.6
1
1
4.0
1.0
+5
%
mV/mA
mV/V
µA
mA
%
V
MHz
°C
°C
V
V
µA
V
V
µA
ms
V
V
OUT
Output Voltage
Output Voltage Accuracy
R
LOAD
R
LINE
I
SD
I
SC
Load Regulation
Line Regulation
Shutdown Supply Current
Output Short-circuit Current
Peak Efficiency
V
IN
at Configuration Change
F
OSC
TSD
TSD
HYS
V
IH
V
IL
I
EN
V
IH
V
IL
I
IN
t
ON
Oscillator Frequency
Thermal Shutdown Threshold
Thermal Shutdown Threshold
Hysteresis
Enable Logic Input High
Voltage
Enable Logic Input Low
Voltage
Enable Logic Input Current
V
SEL
Logic Input High Voltage
V
SEL
Logic Input Low Voltage
V
SEL
Logic Input Current
V
OUT
Turn-On Time
(3)
1mA
≤
I
OUT
≤
150mA, V
IN
=2.7V to
5.5V
0mA
≤
I
OUT
≤
150mA, V
IN
=3.6V
I
OUT
=0.1mA
V
EN
=0V
V
OUT
≤
150mA
V
IN
Decreasing
Note:
3. The short-circuit protection is designed to protect against pre-existing short-circuit conditions, such as assembly
shorts, that exist prior to device power-up. The short-circuit current limit is 25mA
Average
. Short-circuit currents in
normal operation are inherently limited by the on resistance of the internal FET. Since this resistance is in the
range of 1Ω, in some cases, thermal shutdown may occur. Immediately following the first thermal shutdown
event, the short-circuit condition is treated as pre-existing and the load current reduces to 25mA
Average
.
© 2006 Fairchild Semiconductor Corporation
FAN5631/FAN5632 Rev. 1.0.2
www.fairchildsemi.com
5
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