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FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator
November 2004
FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator
Features
I I I I I I I I I 95% Efficiency, Synchronous Operation Adjustable Output Voltage from 0.8V to VIN 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 Soft Start Excellent Load Transient Response 3x3mm 6-lead MLP Package
Description
The FAN2011/FAN2012 is a high-efficiency, low-noise synchronous 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 VIN by means of an 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 1A. 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 available 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.
Applications
I I I I I Hard Disk Drive Set Top Box Point of Load Power Notebook Computers Communications Equipment
Typical Application
FB 1 R2 R1 VOUT L1 10K PGND SW 3 3.3H 4 x 10F 2 P1 (AGND)
6 5 4
NC VIN PVIN 10F +5V R1 VOUT 4 x 10F L1 R2 10K
FB 1 PGND SW 2 3 P1 (AGND)
EN 6 5 4 VIN PVIN 10F +5V
3.3H
FAN2011 Figure 1. Typical Application
FAN2012
FAN2011/FAN2012 Rev. 1.0.2
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FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator
Pin Assignment
Top View
FB PGND SW
1 2 3
6
NC VIN PVIN
FB PGND SW
1 2 3
6
EN VIN PVIN
P1 (AGND)
5 4
P1 (AGND)
5 4
FAN2011 3x3mm 6-Lead MLP
FAN2012 3x3mm 6-Lead MLP
Figure 2. Pin Assignment
Pin Description
FAN2011 (3x3mm 6-Lead MLP)
Pin No.
P1 1 2 3 4 5 6
Pin Name
AGND FB PGND SW PVIN VIN NC
Pin Description
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 Voltage Input. This pin is connected to the internal MOSFET switches. Supply Voltage Input. Not Connected. This pin is not internally connected.
FAN2012(3x3mm 6-Lead MLP)
Pin No.
P1 1 2 3 4 5 6
Pin Name
AGND FB PGND SW PVIN VIN EN
Pin Description
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 Voltage Input. This pin is connected to the internal MOSFET switches. Supply Voltage Input. Enable Input. Logic high enables the chip and logic low disables the chip, reducing the supply current to less than 1A. Do not float this pin.
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FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator
Absolute Maximum Ratings (Note1)
Parameter
VIN PVIN and any other pin Thermal Resistance-Junction to Tab (JC), 3mmx3mm 6-lead MLP (Note 2) Lead Soldering Temperature (10 seconds) Storage Temperature Junction Temperature Electrostatic Discharge (ESD) Protection Level (Note 3) HBM CDM -65 -40 4 2
Min
-0.3 -0.3
Max
7 VIN 8 260 150 150
Unit
V V C/W C C C kV
Recommended Operating Conditions
Parameter
Supply Voltage Range Output Voltage Range, Adjustable Version Output Current Inductor (Note 4) Input Capacitor (Note 4) Output Capacitor (Note 4) Operating Ambient Temperature Range FAN2011 and FAN2012 FAN2011I and FAN2012I 0 -40 3.3 10 4 x 10 +85 +85
Min
4.5 0.8
Typ
Max
5.5 VIN 1500
Unit
V V mA H F F C
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, 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.
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FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator
Electrical Characteristics
VIN = 4.5V to 5.5V, VOUT = 1.2V, IOUT = 200mA, CIN = 10F, COUT = 4 x 10F, L = 3.3H, TA = 0C to +85C, unless otherwise noted. Typical values are at TA = 25C. Parameter
Input Voltage Quiescent Current UVLO Threshold PMOS On Resistance NMOS On Resistance P-channel Current Limit Over-Temperature Protection Switching Frequency Line Regulation Load Regulation Output Voltage During Load Transition (Note 5) Output Voltage During Load Transition (Note 5) Reverse Leakage Current Into Pin SW Reference Voltage, VREF Output Voltage Accuracy VIN = 4.5 to 5.5V 0mA IOUT 1500mA FAN2011 FAN2012 FAN2011I FAN2012I -40C to +85C -2 -3 VIN = 4.5 to 5.5V, IOUT = 100mA 0mA IOUT 1500mA IOUT from 700mA to 100mA IOUT from 100mA to 700mA VIN = Open, EN = GND, Vsw = 5.5V -5 0.1 0.8 2 3 1 IOUT = 0mA VIN rising Hysteresis VIN = VGS = 5V VIN = VGS = 5V 4.5V < VIN < 5.5V Rising temperature Hysteresis 1000 2200 3.5
Conditions
Min.
4.5
Typ.
7 3.7 150 150 150 2600 150 20 1300 0.16 0.2
Max.
5.5 10 3.9 290 290 3500
Units
V mA V mV m m mA C C
1600 0.5 5
kHz %/V % % % A V % %
Additional Electrical Characteristics for FAN2012 TA = 0C to +85C, VIN = 4.5 to 5.5V. Typical values are at TA = 25C. Parameter
Shutdown Mode Supply Current EN Bias Current EN High Voltage EN Low Voltage 1.3 0.4 VEN = 0V
Conditions
Min.
Typ.
0.1
Max.
1 0.1
Units
A A V V
Notes: 5. Load transient response test waveform.
ILOAD (mA)
700
t r = 67nS t f = 67nS
100 0
ss
0.6 4.6 Time (mSec)
Figure 3. Load Transient Response Test Waveform
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FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator
Typical Performance Characteristics
TA = 25C, CIN = 10F, COUT = 40F, L = 3.3H, VIN = 5V, unless otherwise noted.
Output Voltage vs. Ambient Temperature
1.214 1.212
Temp Temp Temp Temp Temp ( C) ( C) ( C) ( C) ( C) vs vs vs vs vs Vout@ 0 mA Vout@ 100mA Vout@ 500 mA Vout@ 1000 mA Vout@ 1500 mA
Switching Frequency vs. Ambient Temperature
1260
Switching Frequency (KHz)
120
Output Voltage (V)
1.210 1.208 1.206 1.204 1.202 1.200 1.198 1.196 1.194 -40 -20 0 20 40
1255 1250 1245 1240 1235 1230 0 20 40 60 80 100 120
60
80
100
Ambient Temperature (C)
Ambient Temperature (C)
Efficiency vs. Load Current
100
Power Efficiency (%)
90 80 70 60 50 40
VIN = 5.5V VIN = 5V
VOUT = 3.3V
VOUT = 1.2V VIN = 4.5V
30 10 100 1000 10000
Load Current (mA)
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FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator
Typical Performance Characteristics (Continued)
TA = 25C, CIN = 10F, COUT = 40F, L = 3.3H, VIN = 5V, unless otherwise noted.
Start-up Response
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 (200mA/div) Output Voltage (1V/div)
Start-up Response
VOUT = 1.2V IOUT = 100mA Time (50s/div)
VOUT = 3.3V IOUT = 100mA Time (100s/div)
Start-up Response
Input Voltage (5V/div) SW Node Voltage (5V/div) Inductor Current (500mA/div) Output Voltage (500mV/div) Input Voltage (5V/div) SW Node Voltage (5V/div) Inductor Current (500mA/div) Output Voltage (1V/div)
Start-up Response
VOUT = 1.2V IOUT = 1500mA Time (100s/div)
VOUT = 3.3V IOUT = 1500mA Time (100s/div)
Transient Response
700mA
Transient Response
Load Current SW Node Voltage (5V/div) Output Voltage (20mV/div) VOUT = 1.2V Inductor Current (200mA/div)
700mA 100mA
Load Current SW Node Voltage (5V/div) Output Voltage (20mV/div) Inductor Current (200mA/div)
100mA
VOUT = 1.2V Time (5s/div) Time (5s/div)
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FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator
Block Diagram
EN VIN
DIGITAL SOFT START UNDER VOLTAGE LOCKOUT
IS
CURRENT SENSE
FB ERROR AMP
COMP
LOGIC CONTROL
MOSFET DRIVER
SW
0.8V
GND
IS OVER VOLTAGE COMP OSC SLOPE COMPENSATION REF FB
GND
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 1.3 MHz. 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 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 converter runs with a minimum duty cycle when output voltage is at minimum and input voltage is at maximum.
The FAN2011 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 (2600mA). Typical start-up time for a 40F output capacitor and a load current of 1500mA is 800s.
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 150C, a reset occurs and will remain in effect until the die cools to 130C, at that time the circuit will be allowed to restart.
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 Pchannel transistor: VOUT = VIN - ILOAD x (RDS_ON + RL), where RDS_ON = P-channel switch ON resistance ILOAD = Output current RL = Inductor DC resistance
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: R1 V OUT = V REF 1 + ------ R
2
UVLO and Soft Start
The reference and the circuit remain reset until the VIN crosses its UVLO threshold.
According to this equation, and assuming desired output voltage of 1.5096V, and given R2 = 10K, the calculated value of R1 is 8.87K.
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FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator
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 3.3H. 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: I L = V OUT where: IL = Inductor Ripple Current f = Switching Frequency L = Inductor Value Some recommended inductors are suggested in the table below: 1 - ( V OUT V IN ) x -----------------------------------------Lxf
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.
Figure 5. Recommended PCB Layout
Inductor Value
3.3H 3.3H
Vendor
Panasonic Murata
Part Number
ELL6PM3R3N LQS66C3R3M04
Table 1: Recommended Inductors Capacitors Selection
For best performances, a low ESR input capacitor is required. A ceramic capacitor of at least 10F, 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.
Capacitor Value
10F
Vendor
Taiyo Yuden
Part Number
JMK212BJ106MG JMK316BJ106KL
TDK
C2012X5ROJ106K C3216X5ROJ106M
Murata
GRM32ER61C106K
Table 2: Recommended Capacitors 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. In order 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 PVIN further reduces switching 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
FAN2011/FAN2012 Rev. 1.0.2
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FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator
Mechanical Dimensions
3x3mm 6-Lead MLP
Ordering Information
Product Number
FAN2011 FAN2012 FAN2011I FAN2012I
Output Voltage
Adjustable Adjustable Adjustable Adjustable
Package Type
3x3mm 6-Lead MLP 3x3mm 6-Lead MLP 3x3mm 6-Lead MLP 3x3mm 6-Lead MLP
Ambient Operating Temperature
0C to 85C 0C to 85C -40C to 85C -40C to 85C
Order Code
FAN2011MPX FAN2012MPX FAN2011IMPX FAN2012IMPX
FAN2011/FAN2012 Rev. 1.0.2
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FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator
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.
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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 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: 2. A critical component is any component of a life 1. Life support devices or systems are devices or support device or system whose failure to perform can systems which, (a) are intended for surgical implant into be reasonably expected to cause the failure of the life the body, or (b) support or sustain life, or (c) whose support device or system, or to affect its safety or failure to perform when properly used in accordance with instructions for use provided in the labeling, can be effectiveness. reasonably expected to result in significant injury to the user. PRODUCT STATUS DEFINITIONS Definition of Terms Datasheet Identification Advance Information Product Status Formative or In Design Definition 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.
Preliminary
First Production
No Identification Needed
Full Production
Obsolete
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. I14
FAN2011/FAN2012 Rev. 1.0.2
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