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FAN5307
High-Efficiency Step-Down DC-DC Converter
Features
* * * * * * * * * * * * * * 95% Efficiency, Synchronous Operation Adjustable Output Voltage Option from 0.7V to VIN 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 15A Quiescent Current Excellent Load Transient Response 5-Lead SOT-23 Package 6-Lead MLP 3x3mm Package
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 applications. 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 15A in order to achieve high efficiency and to ensure long battery life. In shut-down mode, the supply current drops below 1A. The device is available in 5-lead SOT-23 and 6-lead MLP 3x3mm packages.
Applications
* * * * * Pocket PCs, PDAs Cell Phones Battery-Powered Portable Devices Digital Cameras Low Power DSP Supplies
Typical Application
EFFICIENCY vs. LOAD CURRENT VOUT = 1.8V 100 95 90 Efficiency [%] 85 80 75 70 65 0.01 0.1 1 10 100 1000
VIN=3.6V VIN=5.5V VIN=2.5V
Load Current [mA]
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PRODUCT SPECIFICATION
FAN5307
Pin Assignment
Pin Description 5SOT-23
Pin No. 1 2 3 4 5 Pin Name Pin Description VIN GND EN FB LX Supply voltage input. Ground. Enable Input. Logic high enables the chip and logic low disables the chip and reduces supply current to <1A. Do not float this pin. 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. Inductor pin. This pin is connected to the internal MOSFET switches.
Pin Description 6-Lead 3x3mm MLP
Pin No. 1 2 3 4 5 6 Pin Name Pin Description EN GND VIN LX PGND FB Enable Input. Logic high enables the chip and logic low disables the chip and reduces supply current to <1A. Do not float this pin. Reference ground. Supply voltage input. Inductor pin. This pin is connected to the internal MOSFET switches. Power ground. Internal N-channel MOSFET is connected to this pin. 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.
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FAN5307
PRODUCT SPECIFICATION
Absolute Maximum Ratings
Parameter VIN Voltage on any other pin Thermal Resistance (Note 1) Lead Soldering Temperature (10 seconds) Storage Temperature Electrostatic Discharge (ESD) Protection Level (Note 2) HBM CDM -65 4 1 Junction to case, SOT-23 Junction to tab, MLP 3x3 Min -0.3 GND-0.3 Max 6.5 VIN + 0.3 130 8 260 150 C C kV Unit V V C/W
Recommended Operating Conditions
Parameter Supply Voltage Range Output Voltage Range, Adjustable Version Output Current Inductor (Note 3) Input Capacitor (Note 3) Output Capacitor (Note 3) Operating Ambient Temperature Range Operating Junction Temperature Range -40 -40 10 4.7 10 +85 +125 Min 2.5 0.7 Typ Max 5.5 VIN 300 Unit V V mA H F F C C
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.
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PRODUCT SPECIFICATION
FAN5307
General Electrical Characteristics
VIN = 2.5V to 5.5V, IOUT = 200mA, EN = VIN, CIN = 4.7F, COUT = 22F, LX = 10H, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = 25C. Parameter Quiescent Current Shutdown Supply Current Enable High Input Voltage Enable Low Input Voltage En Input Bias Current PMOS On Resistance NMOS On Resistance P-channel Current Limit N-channel Leakage Current P-channel Leakage Current Switching Frequency Line Regulation Load Regulation 6-Lead 3x3mm MLP Load Regulation 5-Lead SOT-23 Output Voltage Accuracy (5SOT23) VIN = 2.5 to 5.5V, IOUT = 10mA 100 m A I O U T 300 m A 100 m A I O U T 300 m A VIN = 2.5 to 4.5V, 0 m A I O U T 300 m A VIN = 2.5 to 5.5V, 0 m A I O U T 300 m A Leakage Current into SW Pin VIN > VOUT, 0 V Vs w VI N VIN = Open, EN = GND, Vsw = 5.5V VIN = 2.5 to 5.5V, 0 m A I O U T 300 m A -3 -3 -4 0.1 EN = VIN or GND VIN = VGS = 3.6V VIN = VGS = 2.5V VIN = VGS = 3.6V VIN = VGS = 2.5V 2.5V < VIN < 5.5V VDS = 5.5V VDS = 5.5V 800 400 0.01 530 670 430 530 520 0.1 0.1 1000 0.16 0.0014 0.0022 3 3 1 Conditions Input Voltage IOUT = 0mA, Device is not switching EN = GND 1.3 0.4 0.1 690 850 540 660 700 1 1 1200 mA
A A
Min. 2.5
Typ. 15 0.1
Max. 5.5 30 1
Units V
A A
V V
A
m m
kHz %/V %/mA %/mA % %
A
Reverse Leakage Current into pin SW Output Voltage Accuracy (6-Lead 3x3mm MLP)
0.1
1 3
A
%
Electrical Characteristics For Adjustable Version
VIN = 2.5V to 5.5V, IOUT = 200mA, EN = VIN, CIN = 4.7F, COUT = 22F, LX = 10H, TA = 25C. Parameter Feedback (FB) Voltage Conditions Min. Typ. 0.5 Max. Units V
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FAN5307
PRODUCT SPECIFICATION
Electrical Characteristics for Fixed VOUT = 1.8V Version
VIN = 2.5V to 5.5V, IOUT = 200mA, EN = VIN, CIN = 4.7F, COUT = 22F, LX = 10H, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = 25C. Parameter PFM to PWM Transition Voltage (Note 4) PFM to PWM Transition Voltage (Note 4) Output Voltage during Mode Transition (Note 5, 6) Over Voltage Clamp Threshold Incl. line, load, load transients, and temperature Conditions VIN = 3.7V, TA = 25C, 0.1 m A I O U T 300 m A VIN = 4.2V, TA = 25C, 0.1 m A I O U T 300 m A 1.7 1.878 Min. Typ. Max. 72 72 1.93 1.93 Units mV mV V V
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.
ILOAD (mA) 200
tr = 10S tf = 2S
2 0 0.01
ss
0.587 0.589
4.6
Time (mSec)
Load Transient Response Test Waveform
6. These limits also apply to any mode transition caused by any kind of load transition within specified output current range.
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PRODUCT SPECIFICATION
FAN5307
Typical Performance Characteristics
(TA = 25C, Cin = Cout = 10F, L = 10H, VOUT = 1.8V, unless otherwise noted.)
LINE TRANSIENT RESPONSE START-UP
LOAD TRANSIENT RESPONSE
EFFICIENCY vs. LOAD CURRENT VOUT = 1.8V 100
No Load Quiescent Current [A]
NO LOAD QUIESCENT CURRENT vs. INPUT VOLTAGE 26
95 90
Efficiency [%]
VIN=2.5V VIN=3.6V VIN=5.5V
24 22 20 18 16 14 2.5
TA=+85C
85 80 75 70 65 0.01 0.1
TA=+25C
TA=-40C
1
10
100
1000
3.0
Load Current [mA]
3.5 4.0 4.5 Input Voltage [V]
5.0
5.5
FREQUENCY vs. TEMPERATURE 1060 1040 1020
Frequency [kHz]
VIN=5.5V
POWER SAVE (PFM) MODE OPERATION
1000 980 960 940 920 900 880 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 Temperature [C]
VIN=2.5V VIN=3.6V
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PRODUCT SPECIFICATION
FAN5307
Block Diagram
EN VIN
DIGITAL SOFT START IS
PFM COMPARATOR
UNDER VOLTAGE LOCKOUT
IS
CURRENT SENSE
REF
FB
ERROR AMPLIFIER COMPARATOR
LOGIC CONTROL
MOSFET DRIVER
LX
0.5V
GND IS
OVER VOLTAGE COMPARATOR
REF OSC SLOPE COMPENSATION
FB NEG. LIMIT SENSE
NEG. LIMIT COMPARATOR
GND
Detailed Operation Description
The FAN5307 is a step-down converter operating in a current-mode PFM/PWM architecture with a typical switching frequency of 1MHz. 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.
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 converter 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-channel 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
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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 comparator 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 Nchannel transistor is turned on and the inductor current ramps down. As the clock cycle is completed, the N-channel switch
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PRODUCT SPECIFICATION
FAN5307
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.
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 output capacitor and a load current of 200mA is 500s.
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: VOUT = VIN - ILOAD x (RdsON + RL), where
RdsON = P-channel switch ON resistance ILOAD = Output current RL = Inductor DC resistance
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.
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FAN5307
PRODUCT SPECIFICATION
Application Information
Adjustable Output Voltage Version
The output voltage for the adjustable version is set by the external resistor divider, as shown below:
VIN FAN5307SX 1 4.7F GND 2 3 EN 5 LX 10H R1 4 FB R2 Cf 4.7pF VOUT 10F
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. Capacitor Value 4.7F 10F Vendor Taiyo Yuden Part Number JMK212BY475MG JMK212BJ106MG JMK316BJ106KL TDK 22F Murata C12012X5ROJ106K C3216X5ROJ106M GRM32DR60J226K Table 2: Recommended Capacitors
and is calculated as:
V O U T = 0.5 V x R1 1 + -----R2
To reduce noise sensitivity, R1 + R2 should not exceed 800k.
Inductor Selection
The inductor parameters directly related to device performances 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:
1 - ( VO U T VI N ) I L = V O U T x -------------------------------------------------Lxf
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 capacitor 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 interference. 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 performance.
where: f = Switching Frequency L = Inductor Value IL = Inductor Ripple Current Inductor Vendor Part Number Value 10H Sumida CDRH5D28-100 CDRH5D18-100 CDRH4D28-100 Murata 6.8H 10H LQH66SN100M 01L CDRH4D18-100 CR32-100 CR43-100 Murata LQH4C100K04 Table 1: Recommended Inductors Smallest Solution Performance High Efficiency
Sumida CDRH3D16-6R8
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PRODUCT SPECIFICATION
FAN5307
Mechanical Dimensions
6-Lead 3x3mm MLP Package
0.15 C 2X 0.10 C 2X 2.6 3.0 1.85 2.15 3.45 3.0 A B 2.45
(0.65) 0.10 C 2X TOP VIEW 1.0 MAX 0.10 C 0~12
1.00 0.65
2.6
0.15 C 2X 0.95 TYP 0.65 TYP
RECOMMENDED LAND PATTERN
0.08 C 0.05
0.00 SEATING PLANE
(0.20) SIDE VIEW 2.25 0.95
C
1
0.45 0.20
3
1.65
0.2 MIN
6 1.90
4
0.30~0.45
O0.10 M C A B O0.05 M C
BOTTOM 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
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FAN5307
PRODUCT SPECIFICATION
Mechanical Dimensions
5-Lead SOT-23 Package
B e c E H e1 D A A1 L
Symbol A A1 B c D E e e1 H L
Inches Min .035 .000 .008 .003 .106 .059 Max .057 .006 .020 .010 .122 .071
Millimeters Min .90 .00 .20 .08 2.70 1.50 Max 1.45 .15 .50 .25 3.10 1.80
Notes
Notes: 1. Package outline exclusive of mold flash & metal burr. 2. Package outline exclusive of solder plating. 3. EIAJ Ref Number SC_74A
.037 BSC .075 BSC .087 .004 0 .126 .024 10
.95 BSC 1.90 BSC 2.20 .10 0 3.20 .60 10
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PRODUCT SPECIFICATION
FAN5307
Ordering Information
Product Number VOUT (V) 1.8 FAN5307 1.8 Adjustable Adjustable Package Type 5-Lead SOT-23 Tape and Reel 6-Lead 3x3mm MLP Tape and Reel 5-Lead SOT-23 Tape and Reel 6-Lead 3x3mm MLP Tape and Reel Order Code FAN5307S18X FAN5307MP18X FAN5307SX FAN5307MPX
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 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

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