FAN5336_技术文档

January 2007

FAN5336

tm

1.5MHz Boost Regulator with 33V Integrated FET Switch

Features

Description

■ 1.5MHz Switching Frequency

■ Low Noise

The FAN5336 is a high-efficiency, low-noise, fixed-fre-

quency PWM, current-mode, DC-DC boost regulator. It

is designed for small LCD bias supply and white LED

backlight supply applications. Depending on the applica-

tion, a FAN5336 regulator can output up to 33V at up to

50mA output current. With output voltage up to 21V, the

output current can be up to 100mA. FAN5336 can be

used for power conversion as low as 9V output voltage.

■ Adjustable Output Voltage

■ Up to 1.5A Peak Switch Current

■ Low Shutdown Current: <1µA

■ Cycle-by-Cycle Current Limit

■ Over-Voltage Protection at the Feedback Pin

■ Fixed-Frequency PWM Operation

■ Soft-Start Capability

A current-mode control loop has a fast transient

response that provides excellent load regulation within

0.2% of output voltage. The FAN5336 switches at fixed

1.5MHz frequency, allowing the use of small, low-cost

external components. Constant frequency switching

results in low input noise and small output capacitors.

FAN5336 provides cycle-by-cycle current limiting up to

1.5A peak current.

■ Internal Compensation

■ Thermal Shutdown

■ Excellent Load Regulation: 0.2%

■ Low Ripple

■ 6-Lead 3x3mm MLP

The FAN5336 may be used to drive a serial flash LED

with up to 100mA current at 21V for a maximum of

400ms on-time and 10% duty cycle.

Applications

■ Portable Displays

■ Mobile Phone / Smart Phone LED Backlights

■ Display Bias

A low-EMI mode reduces interference and radiated elec-

tromagnetic energy caused by the ringing of the inductor.

■ PDA, DVD, Camcorder Backlights

■ Pager and Cordless Phone Displays

■ Portable Medical Diagnostic Equipment

■ Remote Controls

Additional features include thermal shutdown, over-volt-

age protection, cycle-by-cycle current limit, low ripple,

and soft-start support.

The device is available in a 3x3mm 6-lead MLP, 0.8mm

thickness package.

■ MP3 or PMP or DSC Players

■ Serial Flash LED Drivers

Application Diagram

D1

L1

V_IN

V_OUT

6.8µH

C_OUT

4.7µF

C_IN

C_F

10µF

1

6

5

V

SW

NC

IN

180pF

R1

R2

2

P1

GND

3

4

ON

FB

SHDN

OFF

Figure 1. Typical Application Diagram

FAN5336 Rev. 1.0.0

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Ordering Information

Part Number

Package

6-Lead 3x3mm MLP

Temperature Range

Pb-Free

Packing Method

FAN5336MPX

-40°C to +85°C

Yes

Tape and Reel

Pin Assignments

VIN

1

2

3

6

5

4

SW

NC

FB

GND

SHDN

P1

Figure 2. 6-Lead, 3x3mm MLP (Top View)

Pin Descriptions

Pin #

Name

Description

P1

1

GND

V_IN

Analog and Power Ground. P1 must be soldered to the PCB ground.

Input Voltage Pin.

2

GND

SHDN

FB

Ground.

3

Shutdown Control Pin. Logic HIGH enables, logic LOW disables the device.

4

Feedback Pin. Feedback node that connects to an external voltage divider.

5

NC

No Connect.

6

SW

Switching Node.

FAN5336 Rev. 1.0.0

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2

Absolute Maximum Ratings

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

ble above the recommended operating conditions and stressing the parts to these levels is not recommended. In addi-

tion, extended exposure to stresses above the recommended operating conditions may affect device reliability. The

absolute maximum ratings are stress ratings only.

Symbols

Parameter

Min.

Max.

6.0

Unit

V

V_IN

V_INto GND

FB, SHDN to GND

SW to GND

-0.3

V_IN+ 0.3

35

V

T_L

T_J

Lead Soldering Temperature (10 seconds)

Junction Temperature

300

°C

150

°C

T_STG

Θ_JA

Storage Temperature

-55

150

°C

Thermal Resistance

265

°C/W

HBM

CDM

2

1

ESD

Electrostatic Discharge Protection Level⁽¹⁾

kV

Note:

1. Using EIA/JESD22A114B (Human Body Model) and EIA/JESD22C101-A (Charge 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.

Symbols

V_IN

Parameter

Min.

2.7

Typ.

Max.

5.5

33

Unit

V

Input Voltage

V_OUT

T_A

Output Voltage

9

V

Ambient Operating Temperature

Output Capacitance

-40

2.2⁽²⁾

25

85

°C

µF

C_OUT

10

Note:

2. This load capacitance value is required for loop stability. Tolerance, temperature variation, and voltage dependency

of the capacitance must be considered. Typically a 4.7µF ceramic capacitor is required to achieve the specified

value at V_OUT= 33V.

FAN5336 Rev. 1.0.0

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3

Electrical Characteristics

V_IN= 2.7 to 5.5V, V_SHDN= V_IN, and T_A= -40°C to +85°C. Typical values are at T_A= 25°C and V_IN= 3.6V unless

otherwise noted.

Parameter

Conditions

Min.

Typ.

Max.

Units

Refer to the Test Circuit in Figure 3.

Output Voltage Accuracy

Switch Current Limit

V_IN= 3.6V

V_IN= 3.2V

-3

1.1

75

+3

%

A

1.5

1.8

V_OUT= 21V ±5%, V_IN≥ 3.0V

Load Current

mA

V_OUT= 21V ±5%, V_IN≥ 3.2V,

T_ON< 0.4s, T_OFF> 3.6s

100

Switch On-Resistance

Quiescent Current

V_IN= 3.6V

0.4

0.7

6.5

0.1

Ω

mA

µA

V

No Switching, V_FB≥ 1.27V

Switching

OFF Mode Current

V

_SHDN= 0V

3.0

Device ON

1.5

Shutdown Threshold

Shutdown Pin Bias Current

Device OFF

0.5

10

V_SHDN= 0V or V_SHDN= 5.5V

I_Load= 0mA, V_IN= 3.6V at 25°C

1

1.230

1

nA

V

Feedback Voltage (V_REF

)

1.205

1.255

10

Feedback Pin Bias Current

nA

Feedback Voltage Line

Regulation⁽³⁾

3.0V < V_IN< 5.5V, I_LOAD= 0mA

0.4

1.5

%/V

Switching Frequency

Maximum Duty Cycle

Start-up Turn-on Time

Load Regulation

1.15

87

1.50

93

1.85

MHz

%

V_IN= 3.0V, I_OUT= 75mA

3.0

0.2

5.0

1

ms

%

V_IN= 3.6V, 1mA < I_Load<100mA

No Switching, V_IN= 5.5V

Switch Leakage Current

µA

Note:

ΔV_OUT

------------------ --------------

1

3.The line regulation is calculated based on

.

×

ΔV_IN

V_OUT

Test Circuit

BAT54

2.7V to 5.5V

L

V_IN

V_OUT

6.8µH

C_OUT

C_IN

4.7µF

C_F

10µF

1

2

6

V

SW

NC

FB

IN

180pF

R1

R2

160k

10k

5

4

P1

GND

3

ON

SHDN

OFF

Figure 3. Test Circuit

FAN5336 Rev. 1.0.0

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4

Typical Performance Characteristics

V

=3.6V, V

=21V, T =25°C, C =10µF, C

=4.7µF, L=6.8µH, C =180pF, R =160kΩ, R =10kΩ unless otherwise noted.

IN

OUT

A

IN

OUT

F

1

2

Load Regulation

Efficiency vs. Load Current

21.5

21.3

21.1

20.9

20.7

20.5

90

85

80

75

70

65

60

55

50

45

40

Vin=2.7V

Vin=3.6V

Vin=5.5V

Vin=2.7V

Vin=3.6V

Vin=5.5V

10

20

30

40

50

60

70

80

90

100

10

20

30

40

50

60

70

80

90

100

Load Current (mA)

Figure 4. Efficiency vs. Load Current

Line Regulation at No Load

Figure 5. Load Regulation

22

21.8

21.6

21.4

21.2

21

20.8

20.6

20.4

20.2

20

2.5

3

3.5

4

4.5

5

5.5

Battery Voltage(V)

Figure 6. Line Regulation at No Load

Figure 7. 100mA Load Current Operation

Figure 8. Start-up Response

Figure 9. Load Transient Response

FAN5336 Rev. 1.0.0

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5

Block Diagram

V

IN

SHDN

3

SW

6

1

Shutdown

Circuitry

FB

+

Comp

-

1.15 x V

REF

Thermal

Shutdown

R

-

4

FB

Error

Amp

n

+

Q

Driver

Comp

R

+

-

S

Ramp

Generator

Current Limit

Comparator

-

+

Oscillator

+

Amp

0.03

-

Reference

Soft-Start

5

2

NC

GND

Figure 10. Block Diagram

Circuit Description

The FAN5336 is a pulse-width modulated (PWM)

current-mode boost converter. The FAN5336 improves

the performance of battery-powered equipment by

significantly minimizing the spectral distribution of noise

at the input caused by the switching action of the regula-

tor. To facilitate effective noise filtering, the switching

frequency was chosen to be high, 1.5MHz. An internal

soft-start circuit minimizes in-rush currents. The timing of

the soft-start circuit was chosen to reach 95% of the

nominal output voltage within 5ms following an enable

command when V_IN= 2.7V, V_OUT= 21V, I_LOAD= 35mA

and C_{OUT (EFFECTIVE)}= 4.7µF.

comparator consists of the sum of two components: the

amplified control signal received from the 30mΩ current

sense resistor and the ramp generator voltage derived

from the oscillator. The oscillator sets the latch and the

latch turns on the FET switch. Under normal operating

conditions, the PWM comparator resets the latch and

turns off the FET, terminating the pulse. Since the com-

parator input contains information about the output volt-

age and the control loop is arranged to form a negative

feedback loop, the value of the peak inductor current is

adjusted to maintain regulation.

Every time the latch is reset, the FET is turned off and

the current flow through the switch is terminated. The

latch can be reset by other events as well, such as over-

current and over-voltage conditions. Over-current condi-

tion is monitored by the current-limit comparator, which

resets the latch and turns off the switch within each clock

cycle. An over-voltage condition at the feedback (FB) pin

is detected by a fast comparator limiting the duty cycle in

a similar manner to over-current monitoring.

The device architecture is a current-mode controller with

an internal sense resistor connected in series with the N-

channel switch. The voltage at the feedback pin tracks

the output voltage at the cathode of the external Schottky

diode (shown in the test circuit in Figure 3). The error

amplifier amplifies the difference between the feedback

voltage and the internal bandgap reference. The ampli-

fied error voltage serves as a reference voltage to the

PWM comparator. The inverting input of the PWM

FAN5336 Rev. 1.0.0

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6

Applications Information

Table 3: Recommended Capacitors

Setting the Output Voltage

Cap. Value

10µF

Vendor

Murata

Part Number

The internal feedback voltage reference (V_REF) is 1.23V

(typical). The output voltage is divided by a resistor

divider, R₁and R₂to the FB pin. The output voltage is

calculated by:

GRM31CR70J106KA01B

GRM32RR61E475KC31B

4.7µF

A feedforward capacitor (C_F) is required for stability. The

recommended value is around 180pF.

R₁

⎛

⎞

⎟

⎠

------

⎜

V_OUT= V_REF1 +

EQ 1

⎜

R₂

Diode Selection

⎝

The external diode used for rectification is usually a

Schottky diode. Its average forward current should

exceed the load current and its reverse voltage maxi-

mum ratings should exceed the voltage at the output of

the converter. A barrier Schottky diode, such as BAT54,

is preferred due to its low reverse current over the

temperature range.

The maximum output current depends on the output volt-

age settings. Table 1 provides the recommended voltage

for several steady-state configurations:

Table 1: Recommended Voltages

V_OUT

(V)

I_LOADMax.

(mA)

R₁(kΩ) for

R₂= 10kΩ

V_INRange

(V)

Care should be taken to avoid any short circuit of V_OUT

to GND, even with the IC disabled, since the diode can

be instantly damaged by the excessive current.

9

50

170

125

75

63.2

87.5

160

258

2.7 to 5.5

2.9 to 4.7

2.7 to 5.5

3.6 to 5.5

4.0 to 5.5

2.7 to 5.5

9

12

21

33

Flash LED Driver

The FAN5336 may be used to drive a serial flash LED

with up to 100mA current at 21V for a maximum of

400ms on-time and 10% duty cycle.

50

10

Thermal Shutdown

Inductor Selection

When the die temperature exceeds 150°C, a reset

occurs and remains in effect until the die cools to 130°C,

when the circuit is allowed to restart.

The inductor parameters directly related to device perfor-

mance are saturation current and DC resistance. The

FAN5336 operates with a typical inductor value of 6.8µH.

The lower the DC resistance, the higher the efficiency.

Balancing inductor size, cost, and overall efficiency

allows optimum choice.

PCB Layout Recommendations

The inherently high peak currents and switching fre-

quency of power supplies require careful PCB layout

design. For best results, 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. The resistor divider that sets the output

voltage should be routed away from the inductor to avoid

RF coupling. A four-layer PCB, with at least one ground

plane connected to Pin 2 of the IC, is recommended. The

ground plane acts as an electromagnetic shield to

reduce EMI and parasitic coupling between components.

The inductor saturation current should be rated around

1.5A, which is the threshold of the internal current limit

circuit. This limit is reached only during the start-up and

with heavy load conditions. When this occurs, the con-

verter can shift into discontinuous conduction mode due

to the automatic turn-off of the switching transistor,

resulting in higher ripple and reduced efficiency.

Table 2: Recommended Inductors

Inductor

Value

Vendor

Part Number

Comment

Lower

Profile

6.8µH

TDK SLF7028T6R8M1R3

Murata LQS66C6R8M04

Higher

Efficiency

6.8µH

Capacitors Selection

For best performance, low-ESR input and output capaci-

tors are required. Ceramic capacitors of C_IN= 10µF and

C_OUT= 4.7µF, placed as close as possible to the IC pins,

are recommended for the lower input and output ripple.

The output capacitor voltage rating should be selected

according to the V_OUTsetting.

Figure 11. Recommended PCB Layout

FAN5336 Rev. 1.0.0

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7

Mechanical Dimensions

Dimensions are in millimeters unless otherwise noted.

Figure 12. 6-Lead 3x3 MLP

FAN5336 Rev. 1.0.0

www.fairchildsemi.com

8

FAN5336 Rev. 1.0.0

www.fairchildsemi.com

9


型号：	FAN5336
厂家：	FAIRCHILD SEMICONDUCTOR
描述：	1.5MHz Boost Regulator with 33V Integrated FET Switch 1.5MHz的升压稳压器与33V集成FET开关稳压器开关
文件：	总9页 (文件大小：697K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

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