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FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator
April 2006
FAN2011/FAN2012
1.5A Low Voltage Current Mode Synchronous PWM Buck
Regulator
Features
95% Efficiency, Synchronous Operation
■
■
Adjustable Output Voltage from 0.8V to V
4.5V to 5.5V Input Voltage Range
■
■
Up to 1.5A Output Current
Fixed Frequency 1.3 MHz PWM Operation
■
■
100% Duty Cycle Low Dropout Operation (LDO)
Soft Start
■
■
Excellent Load Transient Response
3x3mm 6-lead MLP Package
■
IN
Applications
Hard Disk Drive
■
■
Set T op Box
Point of Load Power
■
■
Notebook Computers
Communications Equipment
■
Description
The FAN2011/FAN2012 is a high-efficiency, low-noise
synchronous Pulse Width Modulated (PWM) current
mode DC-DC converter, designed for low voltage applications. It provides up to 1.5A continuous load current
from the 4.5V to 5.5V input. The output voltage is adjustable over a wide range of 0.8V to V
external voltage divider.
The FAN2011 is always on, while the FAN2012 has an
“Enable Input,” and the device can be put in the shutdown mode, in which the ground current falls below 1µA.
A current mode control loop with a fast transient
response ensures excellent line and load regulation. The
fixed 1.3MHz switching frequency enables the user to
choose a small, inexpensive external inductor and
capacitor. Filtering is also easily accomplished with very
small components.
Protection features include input under-voltage lockout,
short circuit protection and thermal shutdown. Soft-start
limits in-rush current during start-up conditions.
The device is av ailab le in a 3x3mm 6-lead MLP package,
making it possible to build a 1.5A complete DC-DC converter in a tiny space on the PCB.
by means of an
IN
Ordering Information
Product Number Output Voltage Package Type
FAN2011 Adjustable 3x3mm 6-Lead MLP 0°C to 85°C FAN2011MPX
FAN2012 Adjustable 3x3mm 6-Lead MLP 0°C to 85°C FAN2012MPX
FAN2011I Adjustable 3x3mm 6-Lead MLP -40°C to 85°C FAN2011EMPX
FAN2012I Adjustable 3x3mm 6-Lead MLP -40°C to 85°C FAN2012EMPX
FAN2011/FAN2012 Rev. 1.0.4
©2006 Fairchild Semiconductor Corporation
Ambient Operating
Temperature Order Code
1
www.fairchildsemi.com
Page 2
Typical Application
FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator
10KΩ
V
OUT
R2
R1
4 x 10µF
PGND
L1
3.3µH
Pin Assignment
SW
FB
1
P1
2
(A
3
GND)
6
NC
V
5
PV
4
+5V
IN
V
IN
10µF
OUT
R2
R1
4 x 10µF
10KΩ
L1
3.3µH
FB
PGND
SW
FAN2011 FAN2012
Figure 1. Typical Application
Top View
1
FB
P1
2
PGND
SW
(AGND)
3
FAN2011
3x3mm 6-Lead MLP
6
NC
V
5
IN
4
PV
IN
1
FB
P1
2
PGND
SW
(AGND)
3
FAN2012
3x3mm 6-Lead MLP
EN
6
V
5
IN
4
PV
IN
Figure 2. Pin Assignment
1
P1
2
(A
GND)
3
EN
6
V
5
PV
4
+5V
IN
IN
10µF
Pin Description
FAN2011 (3x3mm 6-Lead MLP)
Pin No. Pin Name Pin Description
P1 AGND
1FB
2 PGND
3SW
4 PV
5V
IN
IN
6NC
FAN2012 (3x3mm 6-Lead MLP)
Pin No. Pin Name Pin Description
P1 AGND
1 FB
2 PGND
3SW
4PV
5V
6EN
IN
IN
Analog Ground. P1 must be soldered to the PCB ground.
Feedback Input. Adjustable voltage option; connect this pin to the resistor divider.
Power Ground. This pin is connected to the internal MOSFET switches. This pin
must be externally connected to AGND.
Switching Node. This pin is connected to the internal MOSFET switches.
Supply V oltage Input. This pin is connected to the internal MOSFET switches.
Supply V oltage Input.
Not Connected. This pin is not internally connected.
Analog Ground. P1 must be soldered to the PCB ground.
Feedback Input. Adjustable voltage option; connect this pin to the resistor divider.
Power Ground. This pin is connected to the internal MOSFET switches. This pin
must be externally connected to AGND.
Switching Node. This pin is connected to the internal MOSFET switches.
Supply V oltage Input. This pin is connected to the internal MOSFET switches.
Supply V oltage Input.
Enable 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.
FAN2011/FAN2012 Rev. 1.0.4
2
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Page 3
µ
µ
Absolute Maximum Ratings
Stresses above those listed under “Absolute Maxim um 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.
Parameter Min. Max. Unit
V
IN
PV
and any other pin -0.3 V
IN
Thermal Resistance-Junction to Tab ( θ
), 3mm x 3mm 6-lead MLP
JC
(1)
Lead Soldering Temperature (10 seconds) – 260 °C
Storage Temperature -65 150 °C
Junction Temperature -40 150 °C
Electrostatic Discharge (ESD) Protection Level
(2)
HBM 4 – kV
CDM 2 –
-0.3 7 V
IN
–8°C/W
V
FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator
Recommended Operating Conditions
Parameter Min. Typ. Max. Unit
Supply Voltage Range 4.5 – 5.5 V
Output Voltage Range, Adjustable Version 0.8 – V
Output Current – – 1500 mA
Inductor
Input Capacitor
Output Capacitor
Operating Ambient Temperature
Range
(3)
(3)
(3)
– 3.3 –
–10– µ F
–4 x 10 –
FAN2011 and FAN2012 0 – +85 °C
FAN2011I and FAN2012I -40 – +85
Notes:
1. Junction to ambient thermal resistance, θ
, is a strong function of PCB material, board thickness, thickness and
JA
number of copper planes, number of via 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.
IN
V
H
F
FAN2011/FAN2012 Rev. 1.0.4
3
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Page 4
≤
≤
Electrical Characteristics
V
= 4.5V to 5.5V, V
IN
otherwise noted. Typical values are at T
Parameter Conditions Min. Typ. Max. Units
Input V oltage 4.5 – 5.5 V
Quiescent Current I
UVLO Threshold V
PMOS On Resistance V
NMOS On Resistance V
P-channel Current Limit 4.5V < V
Over-Temperature Protection Rising Temperature – 150 – °C
Switching Frequency 1000 1300 1600 kHz
Line Regulation V
Load Regulation 0mA ≤ I
OUT
= 1.2V, I
= 200mA, C
OUT
A
= 10µF, C
IN
= 4 x 10µF, L = 3.3µH, T
OUT
= 0°C to +85°C, unless
A
= 25°C.
= 0mA – 7 10 mA
OUT
Rising 3.4 3.7 4 V
IN
Hysteresis – 150 – mV
= V
IN
IN
= 5V – 150 290 m Ω
GS
= V
= 5V – 150 290 m Ω
GS
< 5.5V 2200 2600 3500 mA
IN
Hysteresis – 20 – °C
= 4.5 to 5.5V, I
IN
OUT
1500mA – 0.2 0.5 %
= 100mA – 0.16 – % /V
OUT
FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator
Output Voltage During Load Transition
Output Voltage During Load Transition
Reverse Leakage Current Into Pin SW V
Reference V oltage , V
REF
Output V oltage Accuracy V
(4)
(4)
I
from 700mA to 100mA – – 5 %
OUT
I
from 100mA to 700mA -5 – – %
OUT
= Open, EN = GND, V
IN
= 5.5V – 0.1 1 µA
sw
– 0.8 V
= 4.5 to 5.5V
IN
0mA ≤ I
OUT
1500mA
FAN2011
FAN2012
FAN2011I
-2 – 2 %
-3 – 3 %
FAN2012I
-40°C to +85°C
Notes:
4. Load transient response test waveform.
Additional Electrical Characteristics for FAN2012
T
= 0°C to +85°C, V
A
= 4.5 to 5.5V. Typical values are at T
IN
= 25°C.
A
Parameter Conditions Min. Typ. Max. Units
Shutdown Mode Supply Current V
EN Bias Current – – 0.1 µA
EN High Voltage 1.3 – – V
EN Low Voltage – – 0.4 V
= 0V – 0.1 1 µA
EN
700
(mA)
LOAD
I
100
FAN2011/FAN2012 Rev. 1.0.4
tr = 67nS tf = 67nS
0
Figure 3. Load Transient Response Test Waveform
s
s
0.6
4
4.6
Time (mSec)
www.fairchildsemi.com
Page 5
Typical Performance Characteristics
T
= 25°C, C
A
= 10µF, C
IN
= 40µF, L = 3.3µH, V
OUT
IN
= 5V, unless otherwise noted.
FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator
Output Vo ltage vs. Ambient Temperature
1.
214
1.212
1.210
1.208
1.206
1.204
1.202
1.200
1.198
Output Voltage (V)
1.196
1.194
-40 -20 0 20 406080100 120
Temp (∞C) vs Vout@ 0 mA
Temp (∞C) vs Vout@ 100mA
Temp (∞C) vs Vout@ 500 mA
Temp (∞C) vs Vout@ 1000 mA
Temp (∞C) vs Vout@ 1500 mA
Ambient Temperature (°C)
Efficiency vs. Load Current
100
V
90
80
70
60
50
Power Efficiency (%)
40
30
VIN = 5.5V
10 100 1000 10000
VIN = 4.5V
VIN = 5V
Load Current (mA)
OUT
V
OUT
= 3.3V
= 1.2V
Switching Frequency vs. Ambient Temperature
12
60
Switching Frequency (KHz)
1255
1250
1245
1240
1235
1230
020406080100120
Ambient Temperature (°C)
FAN2011/FAN2012 Rev. 1.0.4
5
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FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator
Typical Performance Characteristics
T
= 25°C, C
A
Input
Voltage
(5V/div)
SW Node
Voltage
(5V/div)
Inductor
Current
(200mA/div)
Output
Voltage
(500mV/div)
Input
Voltage
(5V/div)
SW Node
Voltage
(5V/div)
Inductor
Current
(500mA/div)
= 10µF, C
IN
= 40µF, L = 3.3µH, V
OUT
Start-up Response
V
OUT
I
OUT
Time (50µs/div)
Start-up Response
IN
= 1.2V
= 100mA
(Continued)
= 5V, unless otherwise noted.
Input
Voltage
(5V/div)
SW Node
Voltage
(5V/div)
Inductor
Current
(200mA/div)
Output
Voltage
(1V/div)
Input
Voltage
(5V/div)
SW Node
Voltage
(5V/div)
Inductor
Current
(500mA/div)
Start-up Response
V
OUT
I
OUT
Time (100µs/div)
Start-up Response
= 3.3V
= 100mA
Output
Voltage
(500mV/div)
Load
Current
SW Node
Voltage
(5V/div)
Output
Voltage
(20mV/div)
Inductor
Current
(200mA/div)
100mA
V
OUT
I
= 1500mA
OUT
Time (100µs/div)
Transient Response
700mA
V
OUT
Time (5µs/div)
= 1.2V
= 1.2V
Output
Voltage
(1V/div)
Load
Current
SW Node
Voltage
(5V/div)
Output
Voltage
(20mV/div)
Inductor
Current
(200mA/div)
700mA
V
= 3.3V
OUT
= 1500mA
I
OUT
Time (100µs/div)
Transient Response
100mA
V
OUT
Time (5µs/div)
= 1.2V
FAN2011/FAN2012 Rev. 1.0.4
6
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Page 7
Block Diagram
FB
SOFT START
0.8V
DIGITAL
ERROR
AMP
COMP
EN
UNDER VOLTAGE
LOCKOUT
LOGIC
CONTROL
MOSFET
DRIVER
IS
V
IN
CURRENT
SENSE
FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator
SW
GND
IS
OSC
SLOPE COMPENSATION
OVER
VOLTAGE
COMP
REF FB
Figure 4. Block Diagram
Detailed Operation Description
The FAN2011 is a step-down pulse width modulated
(PWM) current mode converter with a typical switching
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, typically
2600mA). 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. The
duty cycle is solely given by the ratio of output voltage
and input voltage. Therefore, the conver ter runs with a
minimum duty cycle when output voltage is at minimum
and input voltage is at maximum.
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
= VIN – I
OUT
R
I
R
= P-channel switch ON resistance
DS_ON
= Output current
LOAD
= Inductor DC resistance
L
LOAD
× (R
DS_ON
+ RL), where
GND
UVLO and Soft Start
The reference and the circuit remain reset until the V
crosses its UVLO threshold.
The FAN2011 has an inter nal 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 voltage overshoot. The soft-start is implemented
as a digital circuit, increasing the switch current in four
steps to the P-channel current limit (2600mA). Typical
start-up time for a 40µF output capacitor and a load current of 1500mA is 800µs.
Short Circuit Protection
The switch peak current is limited cycle by cycle to a typical value of 2600mA. 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 350mA.
Thermal Shutdown
When the die temperature exceeds 150°C, a reset
occurs and remains in effect until the die cools to 130°C,
at which point, the circuit restarts.
IN
FAN2011/FAN2012 Rev. 1.0.4
7 www.fairchildsemi.com
Page 8
FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator
Applications Information
Setting the Output Voltage
The internal reference is 0.8V. The output is divided
down by a voltage divider, R1 and R2 to the FB pin. The
output voltage is:
R
1
=
V
OUTVREF
According to this equation, and assuming desired output
voltage of 1.5096V, and given R2 = 10KΩ, the calculated
value of R1 is 8.87KΩ.
Inductor Selection
The inductor parameters directly related to device performances are saturation current and DC resistance. The
FAN2011/FAN2012 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 calculated as follows:
where:
∆I
= Inductor Ripple Current
L
f = Switching Frequency
L = Inductor Value
Some recommended inductors are suggested in the
table below:
+
1
-------
R
2
∆I
LVOUT
1V
OUTVIN
------------------------------------------
×=
×
Lf
⁄()–
PCB Layout Recommendations
The inherently high peak currents and switching frequency of power supplies require a careful PCB layout
design. 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. To minimize voltage stress to the device
resulting from ever-present switching spikes, use an
input bypass capacitor with low ESR. Use of an external
Schottky diode, with its anode connected to SW node
and cathode connected to PV
ing spikes. 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 voltage should
be routed away from the inductor to avoid RF coupling.
The ground plane at the bottom side of the PCB acts as
an electromagnetic shield to reduce EMI. The recommended PCB layout is shown below in Figure 5
further reduces switch-
IN,
.
Table 1. Recommended Inductors
Inductor Value Vendor Part Number
3.3µH Panasonic ELL6PM3R3N
3.3µH Murata LQS66C3R3M04
3.3µH Coiltronics SD-3R3-R
Capacitors Selection
For best performances, a low ESR input capacitor is
required. A ceramic capacitor of at least 10µF, placed as
close to the V
and AGND pins of the device is recom-
IN
mended. The output capacitor determines the output ripple and the transient response.
Table 2. Recommended Capacitors
Capacitor
Vendor Part Number
Value
10µF Taiyo
Yuden
TDK C2012X5ROJ106K
Murata GRM32ER61C106K
JMK212BJ106MG
JMK316BJ106KL
C3216X5ROJ106M
Figure 5. Recommended PCB Layout
FAN2011/FAN2012 Rev. 1.0.4
8 www.fairchildsemi.com
Page 9
Mechanical Dimensions
3x3mm 6-Lead MLP
FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator
FAN2011/FAN2012 Rev. 1.0.4
9 www.fairchildsemi.com
Page 10
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.
ACEx™
ActiveArray™
Bottomless™
FPS™
Build it Now™
CoolFET™
CROSSVOLT™
DOME™
EcoSPARK™
2
E
CMOS™
EnSigna™
FACT™
FACT Quiet Series™
Across the board. Around the world.™
The Power Franchise
Programmable Active Droop™
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.
LIFE SUPPORT POLICY
®
FAST
FASTr™
LittleFET™
FRFET™
GlobalOptoisolator™
GTO™
HiSeC™
2
I
C™
i-Lo™
ImpliedDisconnect™
IntelliMAX™
®
ISOPLANAR™
MICROCOUPLER™
MicroFET™
MicroPak™
MICROWIRE™
MSX™
MSXPro™
OCX™
OCXPro™
OPTOLOGIC
®
OPTOPLANAR™
PACMAN™
POP™
Power247™
PowerEdge™
PowerSaver™
PowerTrench
®
QFET
®
QS™
QT Optoelectronics™
Quiet Series™
RapidConfigure™
RapidConnect™
µSerDes™
ScalarPump™
SILENT SWITCHER
SMART START™
SPM™
Stealth™
SuperFET™
SuperSOT™-3
SuperSOT™-6
SuperSOT™-8
SyncFET™
TCM™
TinyLogic
TINYOPTO™
TruTranslation™
UHC™
UltraFET
UniFET™
®
VCX™
Wire™
®
®
FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator
FAIRCHILDíS 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.
PRODUCT STATUS DEFINITIONS
Definition of Terms
Datasheet Identification Product Status Definition
Advance Information
Preliminary
No Identification Needed
Formative or
In Design
First Production
Full Production
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.
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.
Obsolete
FAN2011/FAN2012 Rev. 1.0.4
Not In Production
This datasheet contains specifications on a product
that has been discontinued by Fairchild semiconductor.
The datasheet is printed for reference information only.
Rev. I18
10 www.fairchildsemi.com
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