Fairchild FAN5333A, FAN5333B service manual

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FAN5333A/FAN5333B High Efficiency, High Current Serial LED Driver with 30V Integrated Switch

August 2005

FAN5333A/FAN5333B
High Efficiency, High Current Serial LED Driver with 30V
Integrated Switch

Features

1.5MHz Switching Frequency

Low Noise

Adjustable Output Voltage

Up to 1.5A Peak Switch Current

1.5W Output Power Capability

Low Shutdown Current: <1µA

Cycle-by-Cycle Current Limit

Low Feedback Voltage

Over-Voltage Protection

Fixed-Frequency PWM Operation

Internal Compensation

FAN5333A has 110mV Feedback Voltage

FAN5333B has 315mV Feedback Voltage

Thermal Shutdown

5-Lead SOT23 Package

Applications

Cell Phones

PDAs

Handheld Equipment

Display Bias

LED Bias

Flash LED

Description

The FAN5333A/FAN5333B is a general purpose LED driver that
features fixed frequency mode operation and an integrated FET
switch. The device’s high output power makes it suitable to drive
flash LEDs in serial connections. This device is designed to
operate at high switching frequencies in order to minimize
switching noise measured at the battery terminal of hand-held
communications equipment. Quiescent current in both normal
and shutdown mode is designed to be minimal in order to
extend battery life. Normal or shutdown mode can be selected
by a logic level shutdown circuitry.

The low ON-resistance of the internal N-channel switch ensures
high efficiency and low power dissipation. A cycle-by-cycle cur­rent limit circuit keeps the peak current of the switch below a
typical value of 1.5A. The FAN5333A/FAN5333B is available in
a 5-lead SOT23 package.

Typical Application

VIN

©2005 Fairchild Semiconductor Corporation

FAN5333A/FAN5333B Rev. 1.0.1

4.7µF
to
10µF

ON

C

OFF

L

5

6.8µH to 10µH

V

IN

SW

FB

IN

BAT54

C

OUT

0.1µF
to

2.2µF

1

3

I

LED

I

LED1

I

LED2

V

OUT

FAN5333

4

SHDN

GND

2

R

R1

R2

Figure 1. Typical Application Diagram

1

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Pin Assignment

FAN5333A/FAN5333B High Efficiency, High Current Serial LED Driver with 30V Integrated Switch

Top View

SW

GND

FB

V

IN

SHDN

5-Lead SOT-23

Figure 2. Pin Assignment

Pin Description

Pin No. Pin Name Pin Description

1SW

2 GND

3FB

4 SHDN

5V

IN

Switching Node .

Analog and Power Ground .

Feedback Pin. Feedback node that connects to an external current set resistor.

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

Input Voltage Pin .

FAN5333A/FAN5333B Rev. 1.0.1

2

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FAN5333A/FAN5333B High Efficiency, High Current Serial LED Driver with 30V Integrated Switch

Absolute Maximum Ratings (

Note1)

Parameter Min Max Unit

V

to GND 6.0 V

IN

FB, SHDN

SW to GND -0.3 35 V

Lead Soldering Temperature (10 seconds) 300 °C

Junction Temperature 150 °C

Storage Temperature -55 150 °C

Thermal Resistance ( Θ

Electrostatic Discharge Protection (ESD) Level (Note 2) HBM 2 kV

to GND -0.3 V

) 210 °C/W

JA

CDM 1

+ 0.3 V

IN

Recommended Operating Conditions

Parameter Min Typ Max Unit

Input Voltage 1.8 5.5 V

Output Voltage V

Operating Ambient Temperature -40 25 85 °C

Output Capacitance Rated at the Required Output (Note 3) for maximum load
current

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.

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

3. This load capacitance value is required for the loop stability. Tolerance, temperature variation, and voltage dependency of the
capacitance must be considered. Typically a 1µF ceramic capacitor is required to achieve specified value at V

IN

0.47 µF

30 V

= 30V.

OUT

FAN5333A/FAN5333B Rev. 1.0.1

3

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≤

Ω

Ω

µ

≤

µ

Electrical Characteristics

Unless otherwise noted, V
T

= 25°C, Test Circuit, Figure 3.

A

Parameter Conditions Min. Typ. Max. Units

Feedback Voltage FAN5333A 99 110 121 mV

Switch Current Limit V

Load Current Capability V

Switch On-resistance V

Quiescent Current V

OFF Mode Current V

Shutdown Threshold Device ON 1.5 V

Shutdown Pin Bias Current V

Feedback Pin Bias Current 1 300 nA

Feedback Voltage Line Regulation 2.7V < V

Switching Frequency 1.2 1.5 1.8 MHz

Maximum Duty Cycle 87 93 %

Switch Leakage Current No Switching, V

OVP 15 %

Thermal Shutdown Temperature 150 °C

= 3.6V, V

IN

OUT

= 20V, I

= 20mA, T

LED

= -40°C to 85°C, Typical values are at

A

FAN5333B 299 315 331 mV

= 3.2V 1.1 1.5 A

IN

20V, V

OUT

= 5V 0.6

IN

V

= 3.6V 0.7

IN

= 3.6V, No Switching 0.6 mA

SHDN

= 0V 0.1 3

SHDN

= 3.2V 65 mA

IN

Device OFF 0.5 V

SHDN

= 0V or V

< 5.5V, V

IN

= 5.5V 1 300 nA

SHDN

20V 0.3 %

OUT

= 5.5V 1

IN

FAN5333A/FAN5333B High Efficiency, High Current Serial LED Driver with 30V Integrated Switch

A

A

Test Circuit

VIN

C

10µF

ON

L

IN

5

10µH

SW

V

IN

FB

BAT54

C

OUT

1µF

I

1

3

LED

V

OUT

Electronic Load

FAN5333

R

OFF

4

SHDN

GND

Figure 3. Test Circuit

2

FAN5333A/FAN5333B Rev. 1.0.1

4

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Typical Performance Characteristics

T

= 25°C, C

A

= 4.7µF, C

IN

= 0.47µF, L = 10µH, unless otherwise noted.

OUT

FAN5333A/FAN5333B High Efficiency, High Current Serial LED Driver with 30V Integrated Switch

Efficiency vs. Input Voltage

100

V

= 9V

90

80

70

Efficiency (%)

60

I

LED

50

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

I

LED

= 20mA

I

LED

= 30mA

= 40mA

OUT

I

LED

= 10mA

Input Voltage(V)

Maximum Load Current vs. Input Voltage

300

I

<5%

LED

I

250

200

150

100

50

Maximum Load Current (mA)

0

<5%

LED

CIN = 10µF
CIN = 10µF

= 1µF

C

OUT

C

= 1µF

OUT

TA = 25°C

TA = -40°C

2345

V

= 15V

OUT

TA = 85°C

Input Voltage (V)

Efficiency vs. Input Voltage

100

V

= 15V

90

80

70

Efficiency (%)

60

50

I

I

= 10mA

LED

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

LED

I

= 30mA

LED

= 20mA

I

LED

= 40mA

OUT

Input Voltage(V)

Maximum Load Current vs.Input Voltage

200

∆I

<5%

LED

= 10µF

C

150

100

50

Maximum Load Current (mA)

0

= 9.3V

V

OUT

2.0 2.5 3.0 3 .5 4.0

Input Voltage (V)

IN

C

= 1µF

OUT

V

= 12.3V

OUT

V

OUT

= 14.2V

LED Current vs Temperature

10.8

10.6

)

10.4

mA

10.2

10.0

LED Current (

FAN5333A/FAN5333B Rev. 1.0.1

VIN = 5.5V

9.8

9.6

-40 -20 0 20406080

Tem pe ra ture (°C)

VIN = 2.2V

VIN = 3.6V

SW Frequency vs Temperature

2.0

V

V

= 15V

OUT

1.8

1.6

1.4

SW Frequency (MHz)

1.2

5

= 15V

OUT

VIN = 5.5V

VIN = 3.6V

VIN = 2.2V

-40 -20 0 20406080

Tem per ature (°C)

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FAN5333A/FAN5333B High Efficiency, High Current Serial LED Driver with 30V Integrated Switch

Typical Performance Characteristics

T

= 25°C, C

A

25

20

15

10

Load Current (mA)

5

0

= 4.7µF, C

IN

= 0.47µF, L = 10µH, unless otherwise noted.

OUT

Load Current vs.Input Voltage

V

= 15V

OUT

2 345

Input Voltage (V)

(Contd.)

Output

EN

Vol tage

(5V/div)

Battery

Current

(0.5A/div)

Vol tage

(5V/div)

Start-Up Response

Time (100µs/div)

L = 10µH
C

= 10µF

IN

C

= 1µF

OUT

V

= 2.7V

IN

FAN5333A/FAN5333B Rev. 1.0.1

6

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Block Diagram

V

SHDN

45

IN

FAN5333A/FAN5333B High Efficiency, High Current Serial LED Driver with 30V Integrated Switch

SW

1

FB

3

Shutdown

Circuitry

Reference

1.15 x V

REF

-

Error

Amp

+

Ramp

Generator

Oscillator

FB

+

Over
Voltage
Comp

-

Thermal

Shutdown

S

+

Comp

-

Current Limit
Comparator

Figure 4. Block Diagram

Circuit Description

The FAN5333A/FAN5333B is a pulse-width modulated (PWM)
current-mode boost converter. The FAN5333A/FAN5333B
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 regulator. In order to facilitate
effective noise filtering, the switching frequency was chosen to be
high, 1.5MHz. The device architecture is that of 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). The error amplifier amplifies the
difference between the feedback voltage and the internal band­gap reference. The amplified error voltage serves as a refer­ence voltage to the PWM comparator. The inverting input of the
PWM comparator consists of the sum of two components: the
amplified control signal received from the 30m Ω 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, thus terminating the
pulse. Since the comparator input contains information about
the output voltage and the control loop is arranged to form a
negative feedback loop, the value of the peak inductor current
will be 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. Over-current condition is moni­tored by the current limit comparator which resets the latch and
turns off the switch instantaneously within each clock cycle.

R

Amp

n

+

30mΩ

-

2

GND

Driver

Q

R

R

S

+-

Over-Voltage Protection

The voltage on the feedback pin is sensed by an OVP Compar­ator. When the feedback voltage is 15% higher than the nominal
voltage, the OVP Comparator stops switching of the power tran­sistor, thus preventing the output voltage from going higher.

Open-circuit protection

As in any current regulator, if the feedback loop is open, the out­put voltage increases until it is limited by some additional exter­nal circuitry. In the particular case of the FAN5333, the output
voltage is limited by the switching transistor breakdown at
around 45V, typically (assuming that C

and the Schottky

OUT

diode rating voltage are higher). Since at such high output volt­age the output current is inherently limited by the discontinuous
conduction mode, in most cases, the switching transistor enters
non-destructive breakdown and the IC survives.

However, to ensure 100% protection for LED disconnection, we
recommend limiting V

with an external Zener diode or stop-

OUT

ping the boost switching with an external voltage supervisory
circuit.

Applications Information

Setting the Output Current

The internal reference (V
and 315mV (Typical) for FAN5333B. The output current is set by
a resistor divider R connected between FB pin and ground. The
output current is given by

) is 110mV (Typical) for FAN5333A

REF

V

FB

LED

----------=
R

I

FAN5333A/FAN5333B Rev. 1.0.1

7

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SHDN

FAN5333

FAN5333A/FAN5333B High Efficiency, High Current Serial LED Driver with 30V Integrated Switch

Inductor Selection

The inductor parameters directly related to device performances
are saturation current and dc resistance. The FAN5333A/
FAN5333B operates with a typical inductor value of 10µH. The
lower the dc resistance, the higher the efficiency. Usually a
trade-off between inductor size, cost and overall efficiency is
needed to make the optimum choice.

The inductor saturation current should be rated around 1A, in
an application having the LED current near the maximum cur­rent as indicated in “Typical Performance Characteristics”. The
peak inductor current is limited to 1.5A by the current sense
loop. This limit is reached only during the start-up and with
heavy load condition; when this event occurs the converter can
shift over in discontinuous conduction mode due to the auto­matic turn-off of the switching transistor, resulting in higher rip­ple and reduced efficiency.

Some recommended inductors are suggested in the table
below:

Inductor

Value Vendor Part Number

10µH TDK SLF6025&-100M1R0

10µH MURATA LQH66SN100M01C Highest

10µH COOPER SD414-100 Small

Com­ment

Efficiency

Size

Brightness Control

1. Dimming Using PWM Logic Signal

A PWM signal applied to SHDN
the LED’s brightness in direct dependence with the duty cycle.
The maximum frequency should not exceed 1kHz to ensure a
linear dependence of the LED’s average current. The amplitude
of the PWM signal should be suitable to turn the FAN5333 ON
and OFF.

Alternatively, a PWM logic signal can be used to switch a FET
ON/OFF to change the resistance that sets the LED’s current
Ta ble 6 on page 8. Adjusting the duty cycle from 0% to 100%
results in varying the LED’s current between I

Where

V

I

MIN

FB

-------------= and I
R

MIN

Ta b le 5 on page 8 can control

MAX

MIN

V

FB

--------------------------------=
R

MINRSET

and I

MAX

.

Table 1: Recommended Inductors

Capacitors Selection

For best performance, low ESR input and output capacitors are
required. Ceramic capacitors of C
placed as close to the IC pins, are required for the maximum

= 10µF and C

IN

OUT

= 1µF

load(65mA). For the lighter load ( ≤ 20mA ) the capacitances may
be reduced to C

= 4.7µF and C

IN

= 0.47µF or even to 0.1µF,

OUT

if higher ripple is acceptable. The output capacitor voltage rating
should be according to the V

OUT

setting.

Some capacitors are

suggested in the table below.

Capacitor

Value Vendor Part Number

0.47µF Panasonic ECJ-3YB1E474K

1µF Murata GRM21BR61E105K

10µF Murata GRM21BR61A106K

Table 2: Recommended Capacitors

Diode Selection

The external diode used for rectification is usually a Schottky
diode. Its average forward current and reverse voltage maxi­mum ratings should exceed the load current and the voltage at
the output of the converter respectively. A barrier Schottky diode
such as BAT54 is preferred, due to its lower reverse current over
the temperature range.

Care should be taken to avoid any short circuit of V
even with the IC disabled, since the diode can be instantly dam­aged by the excessive current.

OUT

to GND,

Figure 5. Dimming Using a PWM Signal

FAN5333

FB

R

SET

R

MIN

Figure 6. Dimming Using a PWM Logic Signal

2. Dimming Using DC Voltage

An external adjustable DC voltage Table 7 on page 8 between
0V to 2V can control the LED’s current from 15mA to 0mA,
respectively.

FAN5333A

FB

1.6KΩ

5Ω

90KΩ

V

DC

15Ω

FAN5333B

4.7KΩ

FB

90KΩ

V

DC

Figure 7. Dimming Using DC Voltage

FAN5333A/FAN5333B Rev. 1.0.1

8

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FAN5333A/FAN5333B High Efficiency, High Current Serial LED Driver with 30V Integrated Switch

3. Dimming Using Filtered PWM Signal

This method allows the use of a greater than 1kHz PWM fre­quency signal with minimum impact on the battery ripple. The
filtered PWM signal Table 8 on page 9 acts as an adjustable DC
voltage as long as its frequency is significantly higher than the
corner frequency of the RC low pass filter.

FAN5333A

FB

20KΩ

15KΩ

5Ω

15Ω

1.6KΩ

FAN5333B

4.7KΩ

0.1µF

FB

20KΩ

15KΩ

0.1µF

Figure 8. Dimming Using Filtered PWM Signal

Thermal Shutdown

When the die temperature exceeds 150°C, a reset occurs and
will remain in effect until the die cools to 130°C, at that time the
circuit will be allowed to restart.

PCB Layout Recommendations

The inherently high peak currents and switching frequency of
power supplies require 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. The FB pin connec­tion should be routed away from the inductor proximity to pre­vent RF coupling. A PCB with at least one ground plane
connected to pin 2 of the IC is recommended. This ground plane
acts as an electromagnetic shield to reduce EMI and parasitic
coupling between components.

FAN5333A/FAN5333B Rev. 1.0.1

9 www.fairchildsemi.com

Mechanical Dimensions

5-Lead SOT-23

FAN5333A/FAN5333B High Efficiency, High Current Serial LED Driver with 30V Integrated Switch

B

e

H

E

e1

D

A

A1

c

L

α

Symbol Inches Millimeters Notes

Min Max Min Max

A .035 .057 .90 1.45

A1 .000 .006 .00 .15

B .008 .020 .20 .50

c .003 .010 .08 .25

D .106 .122 2.70 3.10

E .059 .071 1.50 1.80

e .037 BSC .95 BSC

e1 .075 BSC 1.90 BSC

H .087 .126 2.20 3.20

L .004 .024 .10 .60

α

0º 10º 0º 10º

Ordering Information

Product Number Package Type Order Code

FAN5333A 5-Lead SOT23 FAN5333ASX

FAN5333B 5-Lead SOT23 FAN5333BSX

FAN5333A/FAN5333B Rev. 1.0.1

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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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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.

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FAN5333A/FAN5333B High Efficiency, High Current Serial LED Driver with 30V Integrated Switch

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:

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, or (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 significant injury to the
user.

PRODUCT STATUS DEFINITIONS

Definition of Terms

Datasheet Identification Product Status Definition

Advance Information

Preliminary

No Identification Needed

Formative or
In Design

First Production

Full Production

2. A critical component is 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.

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.

Obsolete

FAN5333A/FAN5333B Rev. 1.0.1

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. I16

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