Fairchild FAN5354 service manual

March 2011

FAN5354

3MHz, 3A Synchronous Buck Regulator

FAN5354 — 3MHz, 3A Synchronous Buck Regulator

Features



3MHz Fixed-Frequency Operation

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Best-in-Class Load Transient

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3A Output Current Capability

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2.7V to 5.5V Input Voltage Range

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Adjustable Output Voltage: 0.8 to VIN•0.9

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PFM Mode for High Efficiency in Light Load (Forced PWM Available on MODE Pin)

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Minimum PFM Frequency Avoids Audible Noise

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270µA Typical Quiescent Current in PFM Mode

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External Frequency Synchronization

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Low Ripple Light-Load PFM Mode with Forced PWM Control

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Power Good Output

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Internal Soft-Start

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Input Under-Voltage Lockout (UVLO)

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Thermal Shutdown and Overload Protection

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12-Lead 3x3.5mm MLP

Applications

Description

The FAN5354 is a step-down switching voltage regulator that delivers an adjustable output from an input voltage supply of

2.7V to 5.5V. Using a proprietary architecture with synchronous rectification, the FAN5354 is capable of delivering 3A at over 85% efficiency, while maintaining a very high efficiency of over 80% at load currents as low as 2mA. The regulator operates at a nominal fixed frequency of 3MHz, which reduces the value of the external components to 470nH for the output inductor and 10µF for the output capacitor. Additional output capacitance can be added to improve regulation during load transients without affecting stability and inductance up to 1.2µH may be used with additional output capacitance.

At moderate and light loads, pulse frequency modulation (PFM) is used to operate the device in power-save mode with a typical quiescent current of 270µA. Even with such a low quiescent current, the part exhibits excellent transient response during large load swings. At higher loads, the system automatically switches to fixed-frequency control, operating at 3MHz. In shutdown mode, the supply current drops below 1µA, reducing power consumption. PFM mode can be disabled if constant frequency is desired. To avoid audible noise, the regulator limits its minimum PFM frequency. The FAN5354 is available in 12-lead 3x3.5mm MLP package.

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Set-Top Box

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Hard Disk Drive

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Communications Cards

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DSP Power

Figure 1. Typical Application

Ordering Information

Part Number Temperature Range Package Packing Method

FAN5354MPX -40 to 85°C MLP-12, 3x3.5mm Tape and Reel

Table 1. Recommended External Components for 3A Maximum Load Current

Component Description Vendor Parameter Typ. Units

IHLP1616ABER47M01 (Vishay)

SD12-R47-R (Coiltronics)

L1 470nH Nominal

VLC5020T-R47N (TDK)

(TDK)

LQH55PNR47NT0 (Murata)

C

R3

OUT

IN

IN1

VCC

10nF, 25V, X7R, 0402

(1)

4.7µF, 6.3V, X5R, 0603

2 Pieces

10µF, 6.3V, X5R, 0805 10µF, 6.3V, X5R, 0805

Resistor: 1Ω 0402

GRM21BR60J106M (Murata)

C2012X5R0J106M (TDK)

GRM155R71E103K (Murata)

C1005X7R1E103K (TDK)

GRM188R60J475K (Murata)

C1608X5R0J475K (TDK)

Any R 1

Note:

1. R3 is optional and improves IC power supply noise rejection. See Layout recommendations for more information.

L 0.47

DCR 20

C 10.0

C 10 nF

C 4.7

µH

mΩ

µF

Ω

Pin Configuration

FAN5354 — 3MHz, 3A Synchronous Buck Regulator

FB

VOU T

PGN D

SW

1

2

3

4

5

P1

(GND)

12

11

10

9

8

7

MODE

PGO OD

EN

VCC

PVIN

PVIN6

Figure 2. 12-Pin, 3x3.5mm MLP (Top View)

Pin Definitions

Pin # Name Description

1 FB

2 VOUT

3, 4 PGND

5, 6 SW

P1 GND

7, 8 PVIN

9 VCC

10 EN

11 PGOOD

12 MODE

Note:

2. P1 is the bottom heat-sink pad. Ground plane should flow through pins 3, 4, and P1 and can be extended through pin 11 if PGOOD’s function is not required, and through pin 12 if MODE is to be grounded, to improve IC cooling.

FB. Connect to resistor divider. The IC regulates this pin to 0.8V.

VOUT. Sense pin for VOUT. Connect to COUT.

Power Ground. Low-side MOSFET is referenced to this pin. CIN and COUT should be returned with a minimal path to these pins.

Switching Node. Connect to inductor.

Ground. All signals are referenced to this pin.

Power Input Voltage. Connect to input power source. Connect to CIN with minimal path.

IC Bias Supply. Connect to input power source. Use a separate bypass capacitor CVCC from this pin

to the P1 GND terminal between pins 1 and 12.

Enable. The device is in shutdown mode when this pin is LOW. Do not leave this pin floating.

Power Good. This open-drain pin pulls LOW if the output falls out of regulation or is in soft-start.

MODE / Sync. A logic 0 allows the IC to automatically switch to PFM during light loads. When held

HIGH, the IC to stays in PWM mode. The regulator also synchronizes its switching frequency to the frequency provided on this pin. Do not leave this pin floating.

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. Units

VIN

SW, PVIN, VCC Pins

Other Pins -0.3 VCC + 0.3

V

INOV_SLEW

R

PGOOD

ESD

Maximum Slew Rate of VIN Above 6.5V when PWM is Switching 15 V/ms

Pull-Up Resistance from PGOOD to VCC 1

Electrostatic Discharge Protection Level

TJ Junction Temperature –40 +150 °C

T

Storage Temperature –65 +150 °C

STG

TL Lead Soldering Temperature, 10 Seconds +260 °C

Note:

3. Lesser of 7V or VCC+0.3V.

IC Not Switching -0.3 7.0

IC Switching -0.3 6.5

Human Body Model per JESD22-A114 2

Charged Device Model per JESD22-C101 2

V

(3)

V

KΩ

KV

FAN5354 — 3MHz, 3A Synchronous Buck Regulator

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. Units

V

Supply Voltage Range 2.7 5.5 V

CC, VIN

V

Output Voltage Range 0.8 90% Duty Cycle V

OUT

I

Output Current 0 3 A

OUT

L Inductor 0.47 µH

CIN Input Capacitor 10 µF

C

Output Capacitor 20 µF

OUT

TA Operating Ambient Temperature -40 +85 °C

TJ Operating Junction Temperature -40 +125 °C

Thermal Properties

Symbol Parameter Min. Typ. Max. Units

θJA

Junction-to-Ambient Thermal Resistance

Note:

4. Junction-to-ambient thermal resistance is a function of application and board layout. This data is measured with four-layer 1s2p boards in accordance to JESD51- JEDEC standard. Special attention must be paid not to exceed junction temperature T

at a given ambient temperate TA.

J(max)

(4)

46 °C/W

Electrical Characteristics

Minimum and maximum values are at VIN=2.7V to 5.5V, TA=-40°C to +85°C, unless otherwise noted. Typical values are at TA=25°C, VIN=5V.

Symbol Parameter Conditions Min. Typ. Max. Units

Power Supplies

I

=0, MODE=0 270

IQ Quiescent Current

I

Shutdown Supply Current EN=GND 0.1 3.0

SD

V

Under-Voltage Lockout Threshold

UVLO

V

Under-Voltage Lockout Hysteresis 530 mV

UVHYST

LOAD

I

=0, MODE=1 (Forced PWM) 14 mA

LOAD

VIN Rising 2.83 2.95 V

VIN Falling 2.10 2.30 2.40 V

Logic Pins

VIH HIGH-Level Input Voltage 1.05 V

VIL LOW-Level Input Voltage 0.4 V

V

Logic Input Hysteresis Voltage 100 mV

LHYST

IIN Input Bias Current Input Tied to GND or VIN 0.01 1.00

I

PGOOD Pull-Down Current V

OUTL

I

PGOOD HIGH Leakage Current V

OUTH

V

Regulation

OUT

V

∆

IV∆

∆

Output Reference DC Accuracy

REF

Measured at FB Pin

REG

OUT

LOAD

OUT

VV∆

IN

V

DC Accuracy

OUT

Load Regulation I

Line Regulation 2.7V ≤ VIN ≤ 5.5V, I

Transient Response I

=0.4V 1 mA

PGOOD

PGOOD=VIN

0.01 1.00

TA=25°C 0.792 0.800 0.808 V

0.788 0.800 0.812 V

At V

Pin W.R.T. Calculated Value,

OUT

I

=500mA

LOAD

=1 to 3A –0.03 %/A

OUT(DC)

=1.5A 0.01 %/V

OUT(DC)

Step 0.1A to 1.5A, tr=tf=100ns, V

LOAD

=1.2V +40 mV

OUT

1.6 +1.6 %

Power Switch and Protection

R

DS(ON)P

R

DS(ON)N

I

LIMPK

T

V

SDWN

P-Channel MOSFET On Resistance 60 mΩ N-Channel MOSFET On Resistance 40 mΩ

P-MOS Peak Current Limit 3.75 4.55 5.50 A

Thermal Shutdown 150 °C

LIMIT

Thermal Shutdown Hysteresis 20 °C

HYST

Input OVP Shutdown

Rising Threshold 6.2 V

Falling Threshold 5.50 5.85 V

Frequency Control

fSW Oscillator Frequency 2.7 3.0 3.3 MHz

f

MODE Pin Synchronization Range External Square-Wave, 30% to 70% Duty Cycle 2.7 3.0 3.3 MHz

SYNC

f

Minimum PFM Frequency TA = 25°C, V

PFM(MIN)

= 5.0V 17 26 36 kHz

IN

Soft-Start

tSS Regulator Enable to Regulated V

V

Soft-Start V

SLEW

Slew Rate 10 V/ms

REF

OUT

R

> 5Ω, to V

LOAD

R

> 5Ω, to V

LOAD

OUT

=1.2V

=1.8V

210 250

340 420

µA

µs µs

FAN5354 — 3MHz, 3A Synchronous Buck Regulator

OUT

Figure

3. Efficiency vs. I

LOAD

at V

OUT

=1.2V

Figure

4.

Efficiency vs. I

LOAD

at

V

OUT

=

1.8V

Figure

5.

Efficiency vs. I

LOAD

at

V

OUT

=

2.5V Figure

6.

Efficiency vs. I

LOAD

at

V

OUT

=

3.3V

Typical Characteristics

Unless otherwise specified, VIN=5V, V

100%

90%

80%

70%

60%

50%

40%

Efficiency

30%

20%

10%

0%

1 10 100 1000 10000

I

Output Current (mA)

LOAD

100%

90%

80%

70%

60%

50%

40%

Efficiency

30%

20%

10%

0%

1 10 100 1000 10000

I

Output Current (mA)

LOAD

=1.2V, circuit of Figure 1, and components per Table 1.

100%

90%

80%

70%

60%

50%

40%

VIN = 3.3V, Mode=0

VIN = 3.3V, Mode=1

VIN = 5V, Mode=0

VIN = 5V, Mode=1

VIN = 3.3V, Mode = 0

VIN = 3.3V, Mode = 1

VIN = 5V, Mode = 0

VIN = 5V, Mode = 1

Efficiency

30%

20%

10%

0%

1 10 100 1000 10000

I

Output Current (mA)

LOAD

100%

90%

80%

70%

60%

50%

40%

Efficiency

30%

20%

10%

0%

1 10 100 1000 10000

I

Output Current (mA)

LOAD

VIN = 3.3V, Mode = 0

VIN = 3.3V, Mode = 1

VIN = 5V, Mode = 0

VIN = 5V, Mode = 1

VIN = 4.2V, Mode = 0

VIN = 4.2V, Mode = 1

VIN = 5V, Mode = 0

VIN = 5V, Mode = 1

1

0.9

0.8

0.7

A)

µ

0.6

0.5

0.4

0.3

Supply Current (

0.2

0.1

0

2.7 3.2 3.7 4.2 4.7 5.2

Input Voltage(V)

85°C

25°C

-40°C

400

375

350

325

300

275

250

PFM, No load supply Current(µA)

225

200

VOUT = 1.2

2.7 3.2 3.7 4.2 4.7 5.2

Input Voltage(V)

VOUT = 3.3

85°C

25°C

–40°C

Figure 7. Shutdown Supply Current vs VIN, EN=0 Figure 8. Quiescent Current in PFM vs. VIN, No Load