www.fairchildsemi.com
REV. 1.0.2 6/22/04
Features
95% Efficiency, Synchronous Operation
Adjustable Output Voltage Option from 0.7V to V
IN
2.5V to 5.5V Input Voltage Range
Customized Fixed Output Voltage Options
Up to 300mA Output Current
Fixed Frequency 1MHz PWM Operation
High Efficiency Power Save Mode
100% Duty Cycle Low Dropout Operation
Soft Start
Dynamic Output Voltage Positioning
15
A Quiescent Current
Excellent Load Transient Response
5-Lead SOT-23 Package
6-Lead MLP 3x3mm Package
Applications
Pocket PCs, PDAs
Cell Phones
Battery-Powered Portable Devices
Digital Cameras
Low Power DSP Supplies
Description
The FAN5307, a high efficiency low noise synchronous
PWM current mode and Pulse Skip (Power Save) mode
DC-DC converter is designed for battery-powered applica-
tions. It provides up to 300mA of output current over a wide
input range from 2.5V to 5.5V. The output voltage can be
either internally fixed or externally adjustable over a wide
range of 0.7V to 5.5V by an external voltage divider. Custom
output voltages are also available.
At moderate and light loads pulse skipping modulation is
used. Dynamic voltage positioning is applied, and the output
voltage is shifted 0.8% above nominal value for increased
headroom during load transients. At higher loads the system
automatically switches to current mode PWM control,
operating at 1 MHz. A current mode control loop with fast
transient response ensures excellent line and load regulation.
In Power Save mode, the quiescent current is reduced to
15
A in order to achieve high efficiency and to ensure long
battery life. In shut-down mode, the supply current drops
below 1
A. The device is available in 5-lead SOT-23 and
6-lead MLP 3x3mm packages.
Typical Application
EFFICIENCY vs. LOAD CURRENT
V
OUT
= 1.8V
Load Current [mA]
0.01
0.1
1
10
100
1000
Efficiency [%]
65
70
75
80
85
90
95
100
V
IN
=2.5V
V
IN
=3.6V
V
IN
=5.5V
FAN5307
High-Efficiency Step-Down DC-DC Converter
PRODUCT SPECIFICATION
FAN5307
2
REV. 1.0.2 6/22/04
Pin Assignment
Pin Description
5SOT-23
Pin Description 6-Lead 3x3mm MLP
Pin No.
Pin Name
Pin Description
1
V
IN
Supply voltage input.
2
GND
Ground.
3
EN
Enable Input. Logic high enables the chip and logic low disables the chip and reduces
supply current to <1
A. Do not float this pin.
4
FB
Feedback Input. In case of fixed voltage options, connect this pin directly to the output.
For an adjustable voltage option, connect this pin to the resistor divider.
5
L
X
Inductor pin. This pin is connected to the internal MOSFET switches.
Pin No.
Pin Name
Pin Description
1
EN
Enable Input. Logic high enables the chip and logic low disables the chip and reduces
supply current to <1
A. Do not float this pin.
2
GND
Reference ground.
3
V
IN
Supply voltage input.
4 L
X
Inductor pin. This pin is connected to the internal MOSFET switches.
5
PGND
Power ground. Internal N-channel MOSFET is connected to this pin.
6
FB
Feedback Input. In case of fixed voltage options, connect this pin directly to the output.
For an adjustable voltage option, connect this pin to the resistor divider.
FAN5307
PRODUCT SPECIFICATION
REV. 1.0.2 6/22/04
3
Absolute Maximum Ratings
Recommended Operating Conditions
Notes:
1. Junction to ambient thermal resistance,
JA
, is a strong function of PCB material, board thickness, thickness and number of
copper planes, number of vias used, diameter of via used, available copper surface, and attached heat sink characteristics.
2. Using Mil Std. 883E, method 3015.7(Human Body Model) and EIA/JESD22C101-A (Charge Device Model).
3. Refer to the applications section for further details.
Parameter
Min
Max
Unit
V
IN
-0.3
6.5
V
Voltage on any other pin
GND-0.3
V
IN
+ 0.3
V
Thermal Resistance (Note 1)
Junction to case, SOT-23
130
C/W
Junction to tab, MLP 3x3
8
Lead Soldering Temperature (10 seconds)
260
C
Storage Temperature
-65
150
C
Electrostatic Discharge (ESD) Protection
Level (Note 2)
HBM
4
kV
CDM
1
Parameter
Min
Typ
Max
Unit
Supply Voltage Range
2.5
5.5
V
Output Voltage Range, Adjustable Version
0.7
V
IN
V
Output Current
300
mA
Inductor (Note 3)
10
H
Input Capacitor (Note 3)
4.7
F
Output Capacitor (Note 3)
10
F
Operating Ambient Temperature Range
-40
+85
C
Operating Junction Temperature Range
-40
+125
C
PRODUCT SPECIFICATION
FAN5307
4
REV. 1.0.2 6/22/04
General Electrical Characteristics
Electrical Characteristics For Adjustable Version
V
IN
= 2.5V to 5.5V, I
OUT
= 200mA, EN = V
IN
, C
IN
= 4.7F, C
OUT
= 22F, L
X
= 10H, T
A
= -40C to +85C, unless
otherwise noted. Typical values are at T
A
= 25C.
Parameter
Conditions
Min.
Typ.
Max.
Units
Input Voltage
2.5
5.5
V
Quiescent Current
I
OUT
= 0mA, Device is not
switching
15
30
A
Shutdown Supply Current
EN = GND
0.1
1
A
Enable High Input Voltage
1.3
V
Enable Low Input Voltage
0.4
V
En Input Bias Current
EN = V
IN
or GND
0.01
0.1
A
PMOS On Resistance
V
IN
= V
GS
= 3.6V
530
690
m
V
IN
= V
GS
= 2.5V
670
850
NMOS On Resistance
V
IN
= V
GS
= 3.6V
430
540
m
V
IN
= V
GS
= 2.5V
530
660
P-channel Current Limit
2.5V < V
IN
< 5.5V
400
520
700
mA
N-channel Leakage Current
V
DS
= 5.5V
0.1
1
A
P-channel Leakage Current
V
DS
= 5.5V
0.1
1
A
Switching Frequency
800
1000
1200
kHz
Line Regulation
V
IN
= 2.5 to 5.5V,
I
OUT
= 10mA
0.16
%/V
Load Regulation
6-Lead 3x3mm MLP
0.0014
%/mA
Load Regulation
5-Lead SOT-23
0.0022
%/mA
Output Voltage Accuracy (5SOT-
23)
V
IN
= 2.5 to 4.5V,
-3
3
%
V
IN
= 2.5 to 5.5V,
-4
3
%
Leakage Current into SW Pin
V
IN
> V
OUT
, 0.1
1
A
Reverse Leakage Current into pin
SW
V
IN
= Open, EN = GND,
V
sw
= 5.5V
0.1
1
A
Output Voltage Accuracy
(6-Lead 3x3mm MLP)
V
IN
= 2.5 to 5.5V,
-3
3
%
V
IN
= 2.5V to 5.5V, I
OUT
= 200mA, EN = V
IN
, C
IN
= 4.7F, C
OUT
= 22F, L
X
= 10H, T
A
= 25C.
Parameter
Conditions
Min.
Typ.
Max.
Units
Feedback (FB) Voltage
0.5
V
100 m A
I
O U T
300 m A
100 m A
I
O U T
300 m A
0
m A
I
O U T
300 m A
0
m A
I
O U T
300 m A
0 V
V
s w
V
I N
0
m A
I
O U T
300 m A
FAN5307
PRODUCT SPECIFICATION
REV. 1.0.2 6/22/04
5
Electrical Characteristics for Fixed V
OUT
= 1.8V Version
Note:
4. Transition voltage is defined as the difference between the output voltage measured at 0.1m A (PFM mode) and 300mA
(PWM mode), respectively.
5.
6. These limits also apply to any mode transition caused by any kind of load transition within specified output current range.
V
IN
= 2.5V to 5.5V, I
OUT
= 200mA, EN = V
IN
, C
IN
= 4.7F, C
OUT
= 22F, L
X
= 10H, T
A
= -40C to +85C, unless
otherwise noted. Typical values are at T
A
= 25C.
Parameter
Conditions
Min.
Typ.
Max.
Units
PFM to PWM Transition Voltage
(Note 4)
V
IN
= 3.7V, T
A
= 25C,
72
mV
PFM to PWM Transition Voltage
(Note 4)
V
IN
= 4.2V, T
A
= 25C,
72
mV
Output Voltage during Mode
Transition (Note 5, 6)
1.7
1.93
V
Over Voltage Clamp Threshold
Incl. line, load, load transients,
and temperature
1.878
1.93
V
0.1 m A
I
O U T
300 m A
0.1 m A
I
O U T
300 m A
0.01
0.587 0.589
Time (mSec)
I
LO
AD
(mA)
ss
0
4.6
2
200
Load Transient Response Test Waveform
tr = 10S
tf = 2S
PRODUCT SPECIFICATION
FAN5307
6
REV. 1.0.2 6/22/04
Typical Performance Characteristics
(T
A
= 25C, C
in
= C
out
= 10F, L = 10H, V
OUT
= 1.8V, unless otherwise noted.)
EFFICIENCY vs. LOAD CURRENT
V
OUT
= 1.8V
Load Current [mA]
0.01
0.1
1
10
100
1000
Efficiency [%]
65
70
75
80
85
90
95
100
NO LOAD QUIESCENT CURRENT
vs. INPUT VOLTAGE
Input Voltage [V]
2.5
3.0
3.5
4.0
4.5
5.0
5.5
No Load Quiescent Current [
A]
14
16
18
20
22
24
26
TA=+85C
TA=+25C
TA=-40C
V
IN
=2.5V
V
IN
=3.6V
V
IN
=5.5V
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80
Temperature [C]
Frequency [kHz]
880
900
920
940
960
980
1000
1020
1040
1060
FREQUENCY vs. TEMPERATURE
V
IN
=2.5V
V
IN
=3.6V
V
IN
=5.5V
POWER SAVE (PFM) MODE OPERATION
START-UP
LINE TRANSIENT RESPONSE
LOAD TRANSIENT RESPONSE
PRODUCT SPECIFICATION
FAN5307
7
REV. 1.0.2 6/22/04
Detailed Operation Description
The FAN5307 is a step-down converter operating in a
current-mode PFM/PWM architecture with a typical switch-
ing frequency of 1MHz. At moderate to heavy loads, the con-
verter operates in pulse-width-modulation (PWM) mode. At
light loads the converter enters a power-save mode (PFM
pulse skipping) to keep the efficiency high.
PWM Mode
In PWM mode, the device operates at a fixed frequency of
1MHz. At the beginning of each clock cycle, the P-channel
transistor is turned on. The inductor current ramps up and is
monitored via an internal circuit. The P-channel switch is
turned off when the sensed current causes the PWM compar-
ator to trip when the output voltage is in regulation or when
the inductor current reaches the current limit (set internally
to typically 520mA). After a minimum dead time the N-
channel transistor is turned on and the inductor current ramps
down. As the clock cycle is completed, the N-channel switch
is turned off and the next clock cycle starts.
PFM (Power Save) Mode
As the load current decreases and the peak inductor current
no longer reaches the typical threshold of 80mA, the con-
verter enters pulse-frequency-modulation (PFM) mode. In
PFM mode the device operates with a variable frequency and
constant peak current thus reducing the quiescent current to
minimum. Consequently, the high efficiency is maintained at
light loads. As soon as the output voltage falls below a
threshold, set at 0.8% above the nominal value, the P-chan-
nel transistor is turned on and the inductor current ramps up.
The P-channel switch turns off and the N-channel turns on
as the peak inductor current is reached (typical 140mA).
The N-channel transistor is turned off before the inductor
current becomes negative. At this time the P-channel is
switched on again starting the next pulse. The converter
continues these pulses until the high threshold (typical 1.6%
above nominal value) is reached. A higher output voltage in
Block Diagram
FB
ERROR
AMPLIFIER
REF
FB
REF
IS
IS
CURRENT
SENSE
NEG. LIMIT
SENSE
DIGITAL
SOFT START
UNDER VOLTAGE
LOCKOUT
LOGIC
CONTROL
MOSFET
DRIVER
OSC
SLOPE COMPENSATION
PFM
COMPARATOR
COMPARATOR
OVER
VOLTAGE
COMPARATOR
NEG. LIMIT
COMPARATOR
IS
GND
LX
VIN
EN
GND
0.5V
PRODUCT SPECIFICATION
FAN5307
8
REV. 1.0.2 6/22/04
PFM mode gives additional headroom for the voltage drop
during a load transient from light to full load. The voltage
overshoot during this load transient is also minimized due to
active regulation during turning on the N-channel rectifier
switch. The device stays in sleep mode until the output
voltage falls below the low threshold. The FAN5307 enters
the PWM mode as soon as the output voltage can no longer
be regulated in PFM with constant peak current.
100% Duty Cycle Operation
As the input voltage approaches the output voltage and the
duty cycle exceeds the typical 95%, the converter turns the
P-channel transistor continuously on. In this mode the output
voltage is equal to the input voltage minus the voltage drop
across the P-channel transistor:
V
OUT
= V
IN
I
LOAD
(R
ds
ON
+ R
L
), where
R
ds
ON
= P-channel switch ON resistance
I
LOAD
= Output current
R
L
= Inductor DC resistance
Soft Start
The FAN5307 has an internal soft-start circuit that limits the
inrush current during start-up. This prevents possible voltage
drops of the input voltage and eliminates the output voltage
overshoot. The soft-start is implemented as a digital circuit
increasing the switch current in four steps to the P-channel
current limit (520mA). Typical start-up time for a 10F out-
put capacitor and a load current of 200mA is 500s.
Short-Circuit Protection
The switch peak current is limited cycle by cycle to a typical
value of 520mA. In the event of a output voltage short circuit
the device operates at minimum duty cycle, therefore the
average input current is typically 100mA.
FAN5307
PRODUCT SPECIFICATION
REV. 1.0.2 6/22/04
9
Application Information
Adjustable Output Voltage Version
The output voltage for the adjustable version is set by the
external resistor divider, as shown below:
and is calculated as:
To reduce noise sensitivity, R1 + R2 should not exceed
800k
.
Inductor Selection
The inductor parameters directly related to device perfor-
mances are saturation current and dc resistance. The
FAN5307 operates with a typical inductor value of 10H.
The lower the dc resistance, the higher the efficiency. For
saturation current, the inductor should be rated higher than
the maximum load current plus half of the inductor ripple
current that is calculated as follows:
where:
f = Switching Frequency
L = Inductor Value
I
L
= Inductor Ripple Current
Input Capacitor Selection
For best performances, a low ESR input capacitor is
required. A ceramic capacitor of at least 4.7F, placed as
close to the input pin of the device is recommended.
Output Capacitor Selection
The FAN5307's switching frequency of 1MHz allows the
use of a low ESR ceramic capacitor with a value of 10F to
22F. This provides low output voltage ripple. In power save
mode the output voltage ripple is independent of the output
capacitor value and the ripple is determined by the internal
comparator thresholds. The typical output voltage ripple at
light load is 1% of the nominal output voltage.
PCB Layout Recommendations
The inherently high peak currents and switching frequency
of the power supplies require a careful PCB layout design.
Therefore, use wide traces for the high current path and
place the input capacitor, the inductor, and the output capaci-
tor as close as possible to the integrated circuit terminals. For
the adjustable version the resistor divider should be routed
away from the inductor to avoid electromagnetic interfer-
ence.
The 6-lead MLP version of the FAN5307 separates the high
current ground from the reference ground, therefore it is
more tolerant to the PCB layout design and shows better per-
formance.
Inductor
Value
Vendor
Part Number
Performance
10H
Sumida
CDRH5D28-100
High
Efficiency
CDRH5D18-100
CDRH4D28-100
Murata
LQH66SN100M
01L
6.8H
Sumida
CDRH3D16-6R8
Smallest
Solution
10H
CDRH4D18-100
CR32-100
CR43-100
Murata
LQH4C100K04
Table 1: Recommended Inductors
10
H
10F
4.7
F
F
AN5307SX
1
3
4
5
2
V
IN
V
OUT
GND
EN
FB
L
X
C
f
R1
R2
4.7pF
V
O U T
0.5 V
1
R
1
R
2
------
+
=
I
L
V
O U T
1
V
O U T
V
I N
/
(
)
L
f
--------------------------------------------------
=
Capacitor
Value
Vendor
Part Number
4.7F
Taiyo
Yuden
JMK212BY475MG
10F
JMK212BJ106MG
JMK316BJ106KL
TDK
C12012X5ROJ106K
C3216X5ROJ106M
22F
Murata
GRM32DR60J226K
Table 2: Recommended Capacitors
PRODUCT SPECIFICATION
FAN5307
10
REV. 1.0.2 6/22/04
Mechanical Dimensions
6-Lead 3x3mm MLP Package
0.15 C
2X
3.0
2.6
2.6
0.15 C
2X
0.10 C
2X
0.10 C
2X
0.10 C
0.08 C
1.0 MAX
SEATING
PLANE
0~12
(0.20)
2.25
0.2 MIN
0.95
1.90
1.65
0.30~0.45
0.10
M
C
C
A B
1
3
6
4
A
3.0
1.85
2.15
(0.65)
RECOMMENDED LAND PATTERN
2.45
3.45
0.65 TYP
0.95 TYP
TOP VIEW
1.00
0.65
0.05
0.00
0.45
0.20
SIDE VIEW
NOTES:
A. CONFORMS TO JEDEC REGISTRATION MO-229,
VARIATION VEEA, DATED 11/2001
B. DIMENSIONS ARE IN MILLIMETERS.
C. DIMENSIONS AND TOLERANCES PER
ASME Y14.5M, 1994
BOTTOM VIEW
B
C
0.05
M
FAN5307
PRODUCT SPECIFICATION
REV. 1.0.2 6/22/04
11
Mechanical Dimensions
5-Lead SOT-23 Package
Symbol
Inches
Millimeters
Notes
Min
Max
Min
Max
A
.035
.057
.90
1.45
A1
.000
.006
.00
.15
B
.008
.020
.20
.50
c
.003
.010
.08
.25
D
.106
.122
2.70
3.10
E
.059
.071
1.50
1.80
e
.037 BSC
.95 BSC
e1
.075 BSC
1.90 BSC
H
.087
.126
2.20
3.20
L
.004
.024
.10
.60
0
10
0
10
e
B
D
e1
E
H
A
A1
L
c
Notes:
1. Package outline exclusive of mold flash &
metal burr.
2. Package outline exclusive of solder plating.
3. EIAJ Ref Number SC_74A
PRODUCT SPECIFICATION
FAN5307
LIFE SUPPORT POLICY
FAIRCHILD'S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES
OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR
CORPORATION. As used herein:
1. Life support devices or systems are devices or systems
which, (a) are intended for surgical implant into the body, or
(b) support or sustain life, and (c) whose failure to perform
when properly used in accordance with instructions for use
provided in the labeling, can be reasonably expected to
result in a significant injury of the user.
2. A critical component in any component of a life support
device or system whose failure to perform can be
reasonably expected to cause the failure of the life support
device or system, or to affect its safety or effectiveness.
www.fairchildsemi.com
6/22/04 0.0m 000
Stock#DS30005307
2004 Fairchild Semiconductor Corporation
DISCLAIMER
FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO
ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. FAIRCHILD DOES NOT ASSUME
ANY LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN;
NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS.
Ordering Information
Product Number
V
OUT
(V)
Package Type
Order Code
FAN5307
1.8
5-Lead SOT-23 Tape and Reel
FAN5307S18X
1.8
6-Lead 3x3mm MLP Tape and Reel
FAN5307MP18X
Adjustable
5-Lead SOT-23 Tape and Reel
FAN5307SX
Adjustable
6-Lead 3x3mm MLP Tape and Reel
FAN5307MPX
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