FAN2001/FAN2002 Rev. 1.0.2
1
www.fairchildsemi.com
April 2005
©2005 Fairchild Semiconductor Corporation
FAN2001/FAN2002 1A High-Efficiency Step-Down DC-DC Converter
FAN2001/FAN2002
1A High-Efficiency Step-Down DC-DC Converter
Features
■
96% Efficiency, Synchronous Operation
■
Adjustable Output Voltage Options from 0.8V to V
IN
■
2.5V to 5.5V Input Voltage Range
■
Up to 1A Output Current
■
Fixed Frequency 1.3MHz PWM Operation
■
High Efficiency Power Save Mode
■
100% Duty Cycle Low Dropout Operation
■
Soft Start
■
Output Over-Voltage Protection
■
Dynamic Output Voltage Positioning
■
25
µ
A Quiescent Current
■
Thermal Shutdown and Short Circuit Protection
■
Pb-Free 3x3mm 6-Lead MLP Package
Applications
■
Pocket PCs, PDAs
■
Cell Phones
■
Battery-Powered Portable Devices
■
Digital Cameras
■
Hard Disk Drives
■
Set-Top-Boxes
■
Point-of-Load Power
■
Notebook Computers
■
Communications Equipment
Description
Designed for use in battery-powered applications, the FAN2001/
FAN2002 is a high-efficiency, low-noise synchronous PWM cur-
rent mode and Pulse Skip (Power Save) mode DC-DC con-
verter. It can provide up to 1A of output current over a wide input
range from 2.5V to 5.5V. The output voltage can be externally
adjusted over a wide range of 0.8V to 5.5V by means of an
external voltage divider.
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 dur-
ing load transients. At higher loads the system automatically
switches over to current mode PWM control, operating at 1.3
MHz. A current mode control loop with fast transient response
ensures excellent line and load regulation. To achieve high effi-
ciency and ensure long battery life, the quiescent current is
reduced to 25µA in Power Save mode, and the supply current
drops below 1µA in shut-down mode. The FAN2001/FAN2002 is
available in a 3x3mm 6-lead MLP package.
Typical Application
Figure 1. Typical Application
1
2
3
6
5
4
FB
PGND
SW PV
IN
V
IN
EN
P1
(AGND)
L1
R2
R1
V
OUT
2 x 10µF
3.3µH10µF
10K
Ω
5K
Ω
1.2V (1A)
FAN2002
2 x 10µF
10µF
V
OUT
EN
SW
CIN COUT
1.2V (1A)
1
2
3
6
5
4FB
PGND
VIN
NC
P1
(AGND)
3.3µH
R1
10KΩ
5KΩ
R2
FAN2001
2
www.fairchildsemi.com
FAN2001/FAN2002 Rev. 1.0.2
FAN2001/FAN2002 1A High-Efficiency Step-Down DC-DC Converter
Pin Assignment
Figure 2. Pin Assignment
Pin Description
FAN2001 (3x3mm 6-Lead MLP)
FAN2002 (3x3mm 6-Lead MLP)
Pin No. Pin Name Pin Description
P1 AGND Analog Ground.
P1 must be soldered to the PCB ground.
1V
IN
Supply Voltage Input.
2PGND Power Ground.
This pin is connected to the internal MOSFET switches. This pin must be
externally connected to AGND.
3ENEnable Input.
Logic high enables the chip and logic low disables the chip, reducing the supply
current to less than 1µA. Do not float this pin.
4 FB Feedback Input.
Adjustable voltage option, connect this pin to the resistor divider.
5NCNo Connection Pin.
6SWSwitching Node.
This pin is connected to the internal MOSFET switches.
Pin No. Pin Name Pin Description
P1 AGND Analog Ground.
P1 must be soldered to the PCB ground.
1FBFeedback Input.
Adjustable voltage option, connect this pin to the resistor divider.
2PGND Power Ground.
This pin is connected to the internal MOSFET switches. This pin must be exter-
nally connected to AGND.
3SWSwitching Node.
This pin is connected to the internal MOSFET switches.
4 PV
IN
Supply Voltage Input.
This pin is connected to the internal MOSFET switches.
5V
IN
Supply Voltage Input.
6ENEnable Input.
Logic high enables the chip and logic low disables the chip, reducing the supply
current to less than 1µA. Do not float this pin.
VIN
PGND
EN FB
SW
NC
1
2
3
6
5
4
P1
(AGND)
FB
PGND
SW PVIN
EN
VIN
1
2
3
6
5
4
P1
(AGND)
Top View
3x3mm 6-Lead MLP
FAN2001 FAN2002
3
www.fairchildsemi.com
FAN2001/FAN2002 Rev. 1.0.2
FAN2001/FAN2002 1A High-Efficiency Step-Down DC-DC Converter
Absolute Maximum Ratings
(Note1)
Recommended Operating Conditions
Notes:
1. Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional
operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure
to absolute maximum rating conditions for extended periods may affect device reliability. Absolute maximum ratings apply individually only, not in
combination. Unless otherwise specified, all other voltages are referenced to AGND.
2. 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.
3. Using Mil Std. 883E, method 3015.7(Human Body Model) and EIA/JESD22C101-A (Charge Device Model).
4. Refer to the applications section for further details.
Parameter Min Max Unit
V
IN
, PV
IN
-0.3 7 V
Voltage On Any Other Pin -0.3 V
IN
V
Lead Soldering Temperature (10 seconds) 260 °C
Junction Temperature 150 °C
Storage Temperature -65 150 °C
Thermal Resistance-Junction to Tab
(
θ
JC
)
,
3x3mm 6-lead MLP (Note 2) 8 °C/W
Electrostatic Discharge Protection (ESD) Level (Note 3) HBM 4 kV
CDM 1
Parameter Min Typ Max Unit
Supply Voltage Range 2.5 5.5 V
Output Voltage Range, Adjustable Version 0.8 V
IN
V
Output Current 1A
Inductor (Note 4) 3.3
µ
H
Input Capacitor (Note 4) 10 µF
Output Capacitor (Note 4) 2 x 10 µF
Operating Ambient Temperature Range -40 +85 °C
Operating Junction Temperature Range -40 +125 °C
4
www.fairchildsemi.com
FAN2001/FAN2002 Rev. 1.0.2
FAN2001/FAN2002 1A High-Efficiency Step-Down DC-DC Converter
Electrical Characteristics
Notes:
5. Refer to the application section for further details.
6. For output voltages
≤
1.2V a 40
µ
F output capacitor value is required to achieve a maximum output accuracy of 3% while operating in power save
mode (PFM mode).
V
IN
= V
OUT
+ 0.6V(min. 2.5V) to 5.5V, I
OUT
= 350mA, V
OUT
=1.2V, EN = V
IN
, T
A
= -40°C to +85°C,
Unless otherwise noted. Typical values are at T
A
= 25°C.
Symbol Parameter Conditions Min. Typ. Max. Units
V
IN
Input Voltage 0 mA
≤
I
OUT
≤
600 mA 2.5 5.5 V
0 mA
≤
I
OUT
≤
1000 mA 2.7 5.5 V
I
Q
Quiescent Current I
OUT
= 0mA, Device is not switching 20 35
µ
A
I
OUT
= 0mA, Device is
switching (Note 5)
R2 =10K
Ω
50
µ
A
R2 =100K
Ω
25
µ
A
Shutdown Supply Current EN = GND 0.1 1
µ
A
Undervoltage Lockout
Threshold
V
IN
Rising 1.9 2.1 2.3 V
Hysteresis 150 mV
V
ENH
Enable High Input Voltage 1.3 V
V
ENL
Enable Low Input Voltage 0.4 V
I
EN
EN input bias current EN = V
IN
or GND 0.01 0.1
µ
A
R
DS-ON
PMOS On Resistance V
IN
= V
GS
= 5.5V 250 350 m
Ω
V
IN
= V
GS
= 2.5V 300 400
NMOS On Resistance V
IN
= V
GS
= 5.5V 200 300 m
Ω
V
IN
= V
GS
= 2.5V 250 350
I
LIM
P-channel current limit 2.5V < V
IN
< 5.5V 1300 1500 2000 mA
Oscillator frequency 1000 1300 1500 KHz
I
lkg_(N)
N-channel leakage current V
DS
= 5.5V 0.1 1
µ
A
I
lkg_(P)
P-channel leakage current V
DS
= 5.5V 0.1 1
µ
A
Line regulation I
OUT
≤
10 mA 0.16 %/V
Load regulation 350 mA
≤
I
OUT
≤
1000 mA 0.15 %
Vref Reference Voltage 0.8 V
Output DC Voltage Accuracy
(Note 6)
0 mA
≤
I
OUT
≤
1000 mA -3 +3 %
Over-Temperature Protection PWM Mode Only
350 mA
≤
I
OUT
≤
1000 mA
Rising
Temperature
150 °C
Hysteresis 20 °C
Start-Up Time I
OUT
= 1000 mA, C
OUT
= 20 µF 800 µS
5
www.fairchildsemi.com
FAN2001/FAN2002 Rev. 1.0.2
FAN2001/FAN2002 1A High-Efficiency Step-Down DC-DC Converter
Typical Performance Characteristics
T
A
= 25°C, CIN = 10µF, COUT = 20µF, L = 3.3µH, R2 = 10KΩ, unless otherwise noted.
1101001000
60
65
70
75
80
85
90
95
100
VIN = 5V
VOUT = 3.3V VIN = 3.6V
V
OUT = 1.2V
VIN = 3.6V
VOUT = 3V
0.1 1 10 100 1000
35
40
45
50
55
60
65
70
75
80
85
90
95
100
VIN = 5.5V
VOUT = 3.3V
VIN = 3.9V
0.1 1 10 100 1000
30
40
50
60
70
80
90
100
Load Current (mA) Load Current (mA)
Load Current (mA) Load Current (mA)
Efficiency (%)
Efficiency (%)
Efficiency (%)
Efficiency vs. Load Current
Efficiency vs. Load Current Efficiency vs. Load Current
VOUT = 1.2V
VIN = 5.5V
VIN = 3.6V
VIN = 2.5V
0200 400 600 800 1000
1.192
1.194
1.196
1.198
1.200
1.202
1.204
1.206
1.208
1.210
1.212
1.214
Output Voltage (V)
Quiescent Current (µA)
Oscillator Frequency (kHz)
VIN = 5V
Output Voltage vs. Load Current
2.5 3.0 3.5 4.0 4.5 5.0 5.5
0
10
20
30
40
50
60
70
80
Input Voltage (V)
R2 = 100KΩ
R2 = 10KΩ
Quiescent Current vs. Input Voltage
-40 -20 0 20 40 60 80 100
1200
1220
1240
1260
1280
1300
1320
1340
1360
1380
1400
Temperature (°C)
Frequency vs. Temperature
VIN = 2.5V
VIN = 3.6V
VIN = 5.5V
VOUT = 1.2V
R2 = 100KΩ
R2 = 100KΩ
6www.fairchildsemi.com
FAN2001/FAN2002 Rev. 1.0.2
FAN2001/FAN2002 1A High-Efficiency Step-Down DC-DC Converter
Typical Performance Characteristics (Contd.)
TA = 25°C, CIN = 10µF, COUT = 20µF, L = 3.3µH, R2 = 10KΩ, unless otherwise noted.
PWM Mode Power Save Mode
Time (1
µ
s/div)
SW Node
(2V/div)
Voltage
Inductor
(200mA/div)
Current
Output
(5mV/div)
Voltage
Time (5
µ
s/div)
SW Node
(2V/div)
Voltage
Output
(20mV/div)
Voltage
Inductor
(200mA/div)
Current
Time (10
µ
s/div)
Load Transient Response
Output
(50mV/div)
Voltage
Inductor
(500mA/div)
Current
600mA
100mA
Load Transient Response
Time (10
µ
s/div)
Output
(50mV/div)
Voltage
Inductor
(500mA/div)
Current
Voltage at
Enable Pin
600mA 100mA
VOUT = 1.2V
Start-Up Response
Output
(500mV/div)
Voltage
Inductor
(200mA/div)
Current
Time (100
µ
s/div)
(5V/Div)
Load Current
Step
Load Current
Step
Start-Up Response
Time (200
µ
s/div)
Output
(500mV/div)
Voltage
Inductor
(500mA/div)
Current
Voltage at
Enable Pin
(5V/Div)
VOUT = 1.2V
VOUT = 1.2V
IOUT = 10mA
VOUT = 1.2V
IOUT = 1000mA
7www.fairchildsemi.com
FAN2001/FAN2002 Rev. 1.0.2
FAN2001/FAN2002 1A High-Efficiency Step-Down DC-DC Converter
Block Diagram
Figure 3. Block Diagram
Detailed Operation Description
The FAN2001/FAN2002 is a step-down converter operating in a
current-mode PFM/PWM architecture with a typical switching
frequency of 1.3MHz. At moderate to heavy loads, the converter
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
1.3MHz. 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 comparator to trip
when the output voltage is in regulation or when the inductor
current reaches the current limit (set internally to typically
1500mA). 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 inductor current reaches
negative value, the converter enters pulse-frequency-modula-
tion (PFM) mode. The transition point for the PFM mode is given
by the equation:
The typical output current when the device enters PFM mode is
150mA for input voltage of 3.6V and output voltage of 1.2V. 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 thresh-
old, set at 0.8% above the nominal value, the P-channel transis-
tor 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 450mA).
The N-channel transistor is turned off before the inductor cur-
rent 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 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 turn
on of the N-channel rectifier switch. The device stays in sleep
mode until the output voltage falls below the low threshold. The
FAN2001/FAN2002 enters the PWM mode as soon as the out-
put 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-chan-
nel transistor continuously on. In this mode the output voltage is
equal to the input voltage minus the voltage drop across the P-
channel transistor:
VOUT = VIN – ILOAD × (RdsON + RL), where
RdsON = P-channel switch ON resistance
ILOAD = Output current
RL = Inductor DC resistance
FB
ERROR
AMP
NEG.
LIMIT
COMP
PFM
COMP
LOGIC
CONTROL
OVER
VOLTAGE
COMP
UNDER-VOLTAGE
LOCKOUT
MOSFET
DRIVER
OSC
SLOPE COMPENSATION
REF FB
REF
IS
IS
CURRENT
SENSE
NEG.
LIMIT
SENSE
DIGITAL
SOFT START
IS
GND
SW
V
IN
EN
GND
0.8V
COMP
IOUT VOUT
1V
OUT VIN
⁄()–
2Lf××
------------------------------------------
×=
8www.fairchildsemi.com
FAN2001/FAN2002 Rev. 1.0.2
FAN2001/FAN2002 1A High-Efficiency Step-Down DC-DC Converter
UVLO and Soft Start
The reference and the circuit remain reset until the VIN crosses
its UVLO threshold.
The FAN2001/FAN2002 has an internal soft-start circuit that
limits the in-rush current during start-up. This prevents possible
voltage drops of the input voltage and eliminates the output volt-
age overshoot. The soft-start is implemented as a digital circuit
increasing the switch current in four steps to the P-channel cur-
rent limit (1500mA). Typical start-up time for a 20µF output
capacitor and a load current of 1000mA is 800µs.
Short Circuit Protection
The switch peak current is limited cycle-by-cycle to a typical
value of 1500mA. In the event of an output voltage short circuit,
the device operates with a frequency of 400kHz and minimum
duty cycle, therefore the average input current is typically
200mA.
Thermal Shutdown
When the die temperature exceeds 150°C, a reset occurs and
will remain in effect until the die cools to 130°C, at that time the
circuit will be allowed to restart.
Applications Information
Setting the Output Voltage
The internal reference is 0.8V (Typical). The output voltage is
divided by a resistor divider, R1 and R2 to the FB pin. The out-
put voltage is given by:
Where R1 + R2 < 800KΩ.
According to this equation, and assuming desired output volt-
age of 1.5096V, and given R2 = 10KΩ, the calculated value of
R1 is 8.87KΩ. If quiescent current is a key design parameter a
higher value feedback resistor can be used (e.g. R2 = 100KΩ)
and a small bypass capacitor of 10pF is required in parallel with
the upper resistor as shown in Figure 4.
Figure 4. Setting the Output Voltage
Inductor Selection
The inductor parameters directly related to the device’s perfor-
mances are saturation current and dc resistance. The FAN2001/
FAN2002 operates with a typical inductor value of 3.3µH. 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.
This is calculated as follows:
where:
∆IL = Inductor Ripple Current
f = Switching Frequency
L = Inductor Value
Some recommended inductors are suggested in the table
below:
Table 1: Recommended Inductors
Capacitors Selection
For best performances, a low ESR input capacitor is required. A
ceramic capacitor of at least 10µF, placed as close to the VIN
and AGND pins of the device is recommended. The output
capacitor determines the output ripple and the transient
response.
Table 2: Recommended Capacitors
PCB Layout Recommendations
The recommended PCB layout is shown in Figures 5 and 6. The
inherently high peak currents and switching frequency of power
supplies require a careful PCB layout design.
Figure 5. Recommended PCB Layout (FAN2001)
VOUT VREF 1R1
R2
-------+
=
Cf
2 x 10µF
10µF
VOUT
EN
SW
CIN COUT
1.2V (1A)
1
2
3
6
5
4FB
PGND
VIN
NC
P1
(AGND)
3.3µH
R1
100KΩ
50KΩ
R2
Inductor Value Vendor Part Number
3.3µH Panasonic ELL6PM3R3N
3.3µH Murata LQS66C3R3M04
Capacitor
Value
Vendor Part Number
10µF Taiyo Yuden JMK212BJ106MG
JMK316BJ106KL
TDK C2012X5ROJ106K
C3216X5ROJ106M
Murata GRM32ER61C106K
∆ILVOUT
1V
OUT VIN
⁄()–
Lf×
-----------------------------------------
×=
9www.fairchildsemi.com
FAN2001/FAN2002 Rev. 1.0.2
FAN2001/FAN2002 1A High-Efficiency Step-Down DC-DC Converter
Figure 6. Recommended PCB Layout (FAN2002)
Therefore, use wide traces for high current paths and place the
input capacitor, the inductor, and the output capacitor as close
as possible to the integrated circuit terminals. In order to mini-
mize voltage stress to the device resulting from ever present
switching spikes, use an input bypass capacitor with low ESR.
Note that the peak amplitude of the switching spikes depends
upon the load current; the higher the load current, the higher the
switching spikes. The resistor divider that sets the output volt-
age should be routed away from the inductor to avoid RF cou-
pling. The ground plane at the bottom side of the PCB acts as
an electromagnetic shield to reduce EMI.
For more board layout recommendations download the applica-
tion note “PCB Grounding System and FAN2001/FAN2011 High
Performance DC-DC Converters” (AN-42036).
10 www.fairchildsemi.com
FAN2001/FAN2002 Rev. 1.0.2
FAN2001/FAN2002 1A High-Efficiency Step-Down DC-DC Converter
Mechanical Dimensions
3x3mm 6-Lead MLP
Ordering Information
Product Number Output Voltage Package Type Order Code
FAN2001 Adjustable 3x3mm 6-Lead MLP FAN2001MPX
FAN2002 Adjustable 3x3mm 6-Lead MLP FAN2002MPX
11 www.fairchildsemi.com
FAN2001/FAN2002 Rev. 1.0.2
FAN2001/FAN2002 1A High-Efficiency Step-Down DC-DC Converter
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.
TRADEMARKS
The following are registered and unregistered trademarks Fairchild Semiconductor owns or is authorized to use and is
not intended to be an exhaustive list of all such trademarks.
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 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, or (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 significant injury to the
user.
2. A critical component is 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.
PRODUCT STATUS DEFINITIONS
Definition of Terms
Datasheet Identification Product Status Definition
Advance Information
Preliminary
No Identification Needed
Obsolete
This datasheet contains the design specifications for
product development. Specifications may change in
any manner without notice.
This datasheet contains preliminary data, and
supplementary data will be published at a later date.
Fairchild Semiconductor reserves the right to make
changes at any time without notice in order to improve
design.
This datasheet contains final specifications. Fairchild
Semiconductor reserves the right to make changes at
any time without notice in order to improve design.
This datasheet contains specifications on a product
that has been discontinued by Fairchild semiconductor.
The datasheet is printed for reference information only.
Formative or
In Design
First Production
Full Production
Not In Production
IntelliMAX™
ISOPLANAR™
LittleFET™
MICROCOUPLER™
MicroFET™
MicroPak™
MICROWIRE™
MSX™
MSXPro™
OCX™
OCXPro™
OPTOLOGIC
OPTOPLANAR™
PACMAN™
FAST
FASTr™
FPS™
FRFET™
GlobalOptoisolator™
GTO™
HiSeC™
I2C™
i-Lo™
ImpliedDisconnect™
Rev. I15
ACEx™
ActiveArray™
Bottomless™
CoolFET™
CROSSVOLT™
DOME™
EcoSPARK™
E2CMOS™
EnSigna™
FACT™
FACT Quiet Series™
POP™
Power247™
PowerEdge™
PowerSaver™
PowerTrench
QFET
QS™
QT Optoelectronics™
Quiet Series™
RapidConfigure™
RapidConnect™
µSerDes™
SILENT SWITCHER
SMART START™
SPM™
Stealth™
SuperFET™
SuperSOT™-3
SuperSOT™-6
SuperSOT™-8
SyncFET™
TinyLogic
TINYOPTO™
TruTranslation™
UHC™
UltraFET
UniFET™
VCX™
Across the board. Around the world.™
The Power Franchise
Programmable Active Droop™
