FAN5307MP15X - Fairchild Semiconductor Corporation

August 2009

FAN5307 • Rev. 1.0.5

FAN5307 — High-Efficiency Step-Down DC-DC Converter

FAN5307

High-Efficiency Step-Down DC-DC Converter

Features

 95% Efficiency, Synchronous Operation

 Adjustable Output Voltage Option: 0.7V to 0.8VIN

 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

 15µA 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 Ca meras

 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

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 0.8VIN by an

external voltage divider. Custom output voltages are

also available. Contact a Fairchild sales representative

for customized output voltage options.

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 15µA to achieve

high efficiency and ensure long battery life. In shutdown

mode, the supply current drops below 1µA.

The device is available in 5-lead SOT-23 and 6-lead

MLP 3x3mm packages.

Ordering Information

Part Number Operating

Temperature

Range VOUT (V) Package Eco

Status Packing

Method

FAN5307S18X -40 to +85°C 1.8 5-Lead SOT-23 RoHS Tape and Reel

FAN5307MP18

X -40 to +85°C 1.8 6-lead 3x3mm Molded

Leadless Package (MLP) Green Tape and Reel

FAN5307S15X -40 to +85°C 1.5 5-Lead SOT-23 RoHS Tape and Reel

FAN5307MP15

X -40 to +85°C 1.5 6-lead 3x3mm Molded

Leadless Package (MLP) Green Tape and Reel

FAN5307SX -40 to +85°C Adjustable 5-Lead SOT-23 RoHS Tape and Reel

FAN5307MPX -40 to +85°C Adjustable 6-lead 3x3mm Molded

Leadless Package (MLP) Green Tape and Reel

For Fairchild’s defini t i on of Eco St atus, pleas e visit: http://www.fairchildsemi.com/company/green/rohs_green.html.

FAN5307 • Rev. 1.0.5 2

FAN5307 — High-Efficiency Step-Down DC-DC Converter

Typical Applications

10µH C

OUT

=10µF

= 4.7µF

OUT

GND

EN FB

PGND

Figure 1. 6-Lead 3x3mm (MLP) Figure 2. 5-Lead SOT-23

Load Current [mA]

0.01 0.1 1 10 100 1000

Efficiency [ %]

100

=2.5V

=3.6V

=5.5V

Figure 3. Efficiency vs. Load Current (VOUT=1.8V)

FAN5307 • Rev. 1.0.5 3

FAN5307 — High-Efficiency Step-Down DC-DC Converter

Pin Configuration

Figure 4. 5-Lead SOT-23 Figure 5. 6-Lead 3x3mm MLP

Pin Definitions

5-Lead SOT-23

Pin # Name Description

1 VIN Supply Voltage Input.

2 GND

Ground.

3 EN

Enable Input. Logic HIGH enables the chip; logic LOW disables the chip and reduces supply

current to <1µA. Do not float this pin. If the EN pin is tied to VIN, VIN must be ramped up faster

than 5V/ms for VOUT to enter regulation.

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 LX Inductor Pin. This pin is connected to the internal MOSFET switches.

6-Lead 3x3mm MLP

Pin # Name Description

1 EN

Enable Input. Logic HIGH enables the chip; logic LOW disables the chip and reduces supply

current to <1μA. Do not float this pin. If the EN pin is tied to VIN, VIN must be ramped up faster

than 5V/ms for VOUT to enter regulation.

2 GND

Reference Ground.

3 VIN Supply Voltage Input.

4 LX Inductor Pin. This pin is connected to the internal MOSFET switches

5 PGND

Power Ground. The 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 • Rev. 1.0.5 4

FAN5307 — High-Efficiency Step-Down DC-DC Converter

Absolute Maximum Ratings

Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be

operable above the recommended operating conditions and stressing the parts to these levels is not recommended.

In addition, extended exposure to stresses above the recommended operating conditions may affect device

reliability. The absolute maximum ratings are stress ratings only.

Symbol Parameter Min. Max. Unit

Supply Voltage -0.3 6.5 V

VIN Input Voltage on PVIN and Any Other Pin GND-0.2 VIN+0.3 V

Junction-to-Case, SOT-23 130

θJC Thermal Resistance(1) Junction-to-Tab, MLP 3x3 8 °C/W

TL Lead Soldering Temperature, 10 Seconds +260 °C

TSTG Storage Temperature -65 +150 °C

Human Body Model, JESD22-A114 4

ESD(2) Charged Device Model, JESD22-C101 1 kV

Notes:

1. Junction-to-ambient thermal resistance, θJA, 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.

2. Using Mil Std. 883E, method 3015.7 (Human Body Model) and EIA/JESD22C101-A (Charged Device Model).

Recommended Operating Conditions

The Recommended Operating Conditions table defines the conditions for actual device operation. Recommended

operating conditions are specified to ensure optimal performance to the datasheet specifications. Fairchild does not

recommend exceeding them or designing to Absolute Maximum Ratings.

Symbol Parameter Min. Typ. Max. Unit

VIN Supply Voltage Range 2.5 5.5 V

VOUT Output Voltage Range, Adjustable Version 0.7 0.8VIN V

IOUT Output Current 300 mA

L Inductor(3) 10 µH

CIN Input Capacitor(3) 4.7 µF

COUT Output Capacitor(3) 10 µF

TA Operating Ambient Temperature Range -40 +85 °C

TJ Operating Junction Temperature Range -40 +125 °C

Note:

3. Refer to the Applications section for details.

FAN5307 • Rev. 1.0.5 5

FAN5307 — High-Efficiency Step-Down DC-DC Converter

Electrical Characteristics

VIN=2.5V to 5.5V, IOUT=200mA, EN=VIN, CIN=4.7µF, COUT=22µF, LX=10µH, TA=-40°C to +85°C, unless otherwise

noted. Typical values are at TA=25°C.

Symbol Parameter Conditions Min. Typ. Max. Units

VIN Input Voltage 2.5 5.5 V

IQ Quiescent Current IOUT=0mA, Device is

not switching 15 30 µA

ISD Shutdown Supply Current EN=GND 0.1 1.0 µA

VENH Enable High Input Voltage 1.3 V

VENL Enable Low Input Voltage 0.5 V

IEN En Input Bias Current EN=VIN or GND 0.01 0.10 µA

VIN=VGS=3.6V 530 690

PMOS On Resistance VIN=VGS=2.5V 670 850

mΩ

VIN=VGS=3.6V 430 540

RDS-ON NMOS On Resistance VIN=VGS=2.5V 530 660

mΩ

ILIM P-channel Current Limit 2.5V < VIN < 5.5V 400 520 700 mA

IIkg_(N) N-channel Leakage Current VDS=5.5V 0.1 1.0 µA

IIkg_(P) P-channel Leakage Current VDS=5.5V 0.1 1.0 µA

Switching Frequency 800 1000 1200 kHz

RLINE Line Regulation VIN=2.5 to 5.5,

IOUT=10mA 0.16 % / V

6-Lead MLP 100mA ≤ IOUT

≤ 300mA 0.0014 % / mA

RLOAD Load

Regulation 5-Lead SOT-23 100mA ≤ IOUT

≤ 300mA 0.0022 % / mA

6-Lead MLP VIN=2.5 to 5.5V,

0mA ≤ IOUT ≤ 300mA -4 4

VIN=2.5 to 4.5V,

0mA ≤ IOUT ≤ 300mA -4 4

VOUT Output Voltage

Accuracy 5-Lead SOT-23 VIN=2.5 to 5.5V,

0mA ≤ IOUT ≤ 300mA -5 4

ILEAK Leakage Current into Pin SW VIN>VOUT,

0V ≤ VSW ≤ VIN 0.1 1.0 µA

ILEAK_R Reverse Leakage Current into Pin SW VIN=Open, EN=GND,

VSW=5.5 0.1 1.0 µA

Electrical Characteristics for Adjustable Version

VIN=2.5V to 5.5V, IOUT = 200mA, EN=VIN, CIN=4.7µF, COUT=22µF, LX=10µH, TA=25°C.

Symbol Parameter Min. Typ. Max. Units

VFB Feedback Voltage 0.5 V

FAN5307 • Rev. 1.0.5 6

FAN5307 — High-Efficiency Step-Down DC-DC Converter

Electrical Characteristics for Fixed VOUT=1.8 Version

VIN=2.5V to 5.5V, IOUT=200mA, EN=VIN, CIN=4.7µF, COUT=22µF, LX=10µH, TA=-40°C to +85°C, unless otherwise

noted. Typical values are at TA=25°C.

Symbol Parameter Conditions Min. Typ. Max. Units

VIN=3.7V, TA=25°C,

0.1mA ≤ IOUT ≤ 300mA

VPFM_PWM PFM to PWM Transition

Voltage(4) VIN=4.2V, TA=25°C,

0.1mA ≤ IOUT ≤ 300mA

72 mV

VOUT_TRANS Output Voltage During Mode Transition(5,6) 1.70 1.93 V

VOUT_CLAMP Over-Voltage Clamp Threshold Includes Line, Load, Load

Transients, and Temperature 1.878 1.930 V

Note:

4. Transition voltage is defined as the difference between the output voltage measured at 0.1mA (PFM mode) and

300mA (PWM mode), respectively.

5. See Figure 6.

6. These limits also apply to any mode transition caused by any kind of load transition within specified output

current range.

0.01 0.587 0.589 Time

(

)

ILOAD (mA)

04.6

200

tr = 10µs tf = 2µs

Figure 6. Load Transient Response Test Waveform

FAN5307 • Rev. 1.0.5 7

FAN5307 — High-Efficiency Step-Down DC-DC Converter

Typical Performance Characteristics

TA=25°C, CIN=COUT=10µF, L=10µH, VOUT=1.8V, unless otherwise noted.

Figure 7. Line Transient Response Figure 8. Startup

Figure 9. Load Transient Response Figure 10. Load Transient Response

Load Current [mA]

0.01 0.1 1 10 100 1000

Efficiency [%]

100

=2.5V

=3.6V

=5.5V

Input Voltage [V]

2.5 3.0 3.5 4.0 4.5 5.0 5.5

No Load Quiescent Current [µA]

TA=+85ºC

TA=+25ºC

TA=-40ºC

Figure 11. Efficiency vs. Load Current (VOUT=1.8V) Figure 12. No-Load Quiescent Current vs. VIN

-40-30-20-100 1020304050607080

Temperature [ºC]

Frequency [kHz]

880

900

920

940

960

980

1000

1020

1040

1060

=2.5V

=3.6V

=5.5V

Figure 13. Frequency vs. Temperature Figure 14. Power Save (PRM) Mode Operation

FAN5307 • Rev. 1.0.5 8

FAN5307 — High-Efficiency Step-Down DC-DC Converter

Block Diagram

ERROR

AMPLIFIER

REF FB

REF

CURRENT

SENSE

NEG. LIMIT

SENSE

DIGITAL

SOFT START

UNDER-VOLTAGE

LOCKOUT

LOGIC

CONTROL

MOSFET

DRIVER

OSC

SLOPE COMPENSATION

PFM

COMPARATOR

OVER-

VOLTAGE

COMPARATOR

NEG. LIMIT

COMPARATOR

GND

VIN

GND

0.5V

Figure 15. Block Diagram

FAN5307 • Rev. 1.0.5 9

FAN5307 — High-Efficiency Step-Down DC-DC Converter

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.

PWM Mode

In PW M 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 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.

FM (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, reducing

the quiescent current to a minimum and maintaining

high efficiency 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 is reached (typically 1.6% above nominal

value). 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 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. FAN5307 enters

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 90%, 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 × (RDSON + RL), where (1)

RDSON = P-channel switch on resistance

ILOAD = Output current

RL = Inductor DC resistance

Soft Star t

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 10µF output

capacitor and a load current of 200mA is 500µs.

Short-Circui t Prot ection

Switch peak current is limited, cycle by cycle, to a

typical value of 520mA. In an output voltage short

circuit, the device operates at minimum duty cycle;

therefore, the average input current is typically 100mA.

FAN5307 • Rev. 1.0.5 10

FAN5307 — High-Efficiency Step-Down DC-DC Converter

Application Information

Adjustable Output Voltage Version

The output voltage for the adjustable version is set by

the external resistor divider, as shown below:

100k

Figure 16. External Resistor Divider

calculated as:

⎥

⎦

⎤

⎢

⎣

⎡+×= 2

OUT R

1V5.0V (2)

To reduce noise sensitivity, R1 + R2 should not exceed

1MΩ.

Inductor Select i on

The inductor parameters directly related to device

performance are saturation current and DC resistance.

The FAN5307 operates with a typical inductor value of

10µH. 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:

(

)

fL V/V1

VI INOUT

OUTL ×

−

×=Δ (3)

where:

f = Switching frequency

L = Inductor value

ΔIL = Inductor ripple current

Table 1. Recommended Inductors

Inductor

Value Vendor Part Number Perfor-

mance

CDRH5D28-100

CDRH5D18-100

Sumida

CDRH4D28-100

10µH

Murata LQH66SN100M01L

Highest

Efficiency

6.8µH CDRH3D16-6R8

CDRH4D18-100

CR32-100

Sumida

CR43-100

Murata LQH4C100K04

10µH

Cooper

Bussmann CTX01-17327

Smallest

Solution

Input Capacit or Sel ect ion

For best performances, a low-ESR input capacitor is

required. A ceramic capacitor of at least 4.7µF, placed

as close to the input pin of the device, is recommended.

Output Capaci t or Sel ection

The FAN5307’s switching frequency of 1MHz allows the

use of a low-ESR ceramic capacitor with a value of

10µF to 22µF. 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.

Table 2. Recommended Capacitors

Capacitor

Value Vendor Part Number

4.7µF JMK212BY475MG

JMK212BJ106MG

Taiyo Yuden JMK316BJ106KL

C12012X5ROJ106K

10µF TDK C3216X5ROJ106M

22µF Murata GRM32DR60J226K

PCB Layout Recommendations

The inherently high peak currents and switching

frequency of the power supplies require careful PCB

layout design. 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.

Figure 17. Possible Layout

FAN5307 • Rev. 1.0.5 11

FAN5307 — High-Efficiency Step-Down DC-DC Converter

Physical Dimensions

Figure 18. 3x3mm 6-Lead Molded Leadless Package (MLP)

Pack age drawings are provided as a service to customers consideri ng Fai rchild components . Drawings may c hange i n any manner

without notice. P l ease note the revi sion and/or date on t he drawing and contac t a Fairchild S emiconductor representative to verify

or obtain the most recent revision. Package specifications do not expand the terms of Fairchild’s worldwide terms and conditions, specifically

the warranty therein, which covers Fairchild products.

Always visit Fairchild Semiconductor’ s online packaging area for the most recent package drawings:

http://www.fairchildsemi.com/packaging/.

FAN5307 • Rev. 1.0.5 12

FAN5307 — High-Efficiency Step-Down DC-DC Converter

Physical Dimensions

LAND PATTERN RECOMMENDATION

0.10 C

0.20 CAB

0.60 REF

0.55

0.35 SEATING PLANE

0.25

GAGE PLANE

8°

0°

NOTES: UNLESS OTHEWISE SPECIFIED

A) THIS PACKAGE CONFORMS TO JEDEC

MO-178, ISSUE B, VARIATION AA,

B) ALL DIMENSIONS ARE IN MILLIMETERS.

1.45 MAX

1.30

0.90

0.15

0.05

1.90

0.95 0.50

0.30

3.00

2.60

1.70

1.50

3.00

2.80

SYMM

C0.950.95

2.60

0.70

1.00

SEE DETAIL A

0.22

0.08

C) MA05Brev5

TOP VIEW

(0.30)

Figure 19. 5-Lead SOT-23 Package

Pack age drawings are provi ded as a servic e to customers considering Fairc h i l d components. Drawi ngs may change in any manner

without notice. P l ease note the revi sion and/or date on t he drawing and contac t a Fairchild S emic onductor representative to v er ify

or obtain the most recent revision. Package specifications do not expand the terms of Fairchild’s worldwide terms and conditions, specifically

the warranty therein, which covers Fairchild products.

Always visit Fairchild Semiconductor’ s online packaging area for the most recent package drawings:

http://www.fairchildsemi.com/packaging/.

FAN5307 • Rev. 1.0.5 13

FAN5307 — High-Efficiency Step-Down DC-DC Converter