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Электронный компонент: FAN5333ASX

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2005 Fairchild Semiconductor Corporation
1
www.fairchildsemi.com
August 2005
FAN5333A/FAN5333B Rev. 1.0.1
F
AN5333A/F
AN5333B High Efficienc
y
,
High Current Serial LED Driver with 30V Integrated Switc
h
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: <1A
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 cur-
rent 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
Figure 1. Typical Application Diagram
SHDN
V
IN
V
OUT
R
GND
V
IN
FB
SW
C
IN
6.8H to 10H
1
3
2
4
5
4.7
F
to
10
F
C
OUT
L
BAT54
I
LED
0.1
F
to
2.2
F
ON
OFF
I
LED2
I
LED1
R1
R2
FA
N5333
2
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FAN5333A/FAN5333B Rev. 1.0.1
F
AN5333A/F
AN5333B High Efficienc
y
,
High Current Serial LED Driver with 30V Integrated Switc
h
Pin Assignment
Figure 2. Pin Assignment
Pin Description
Pin No.
Pin Name
Pin Description
1
SW
Switching Node
.
2
GND
Analog and Power Ground
.
3
FB
Feedback Pin.
Feedback node that connects to an external current set resistor.
4
SHDN
Shutdown Control Pin.
Logic HIGH enables, logic LOW disables the device.
5
V
IN
Input Voltage Pin
.
Top View
5-Lead SOT-23
SW
GND
FB
V
IN
SHDN
3
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FAN5333A/FAN5333B Rev. 1.0.1
F
AN5333A/F
AN5333B High Efficienc
y
,
High Current Serial LED Driver with 30V Integrated Switc
h
Absolute Maximum Ratings
(
Note1)
Recommended Operating Conditions
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 1F ceramic capacitor is required to achieve specified value at V
OUT
= 30V.
Parameter
Min
Max
Unit
V
IN
to GND
6.0
V
FB, SHDN to GND
-0.3
V
IN
+ 0.3
V
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 (
JA
)
210
C/W
Electrostatic Discharge Protection (ESD) Level (Note 2)
HBM
2
kV
CDM
1
Parameter
Min
Typ
Max
Unit
Input Voltage
1.8
5.5
V
Output Voltage
V
IN
30
V
Operating Ambient Temperature
-40
25
85
C
Output Capacitance Rated at the Required Output (Note 3) for maximum load
current
0.47
F
4
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FAN5333A/FAN5333B Rev. 1.0.1
F
AN5333A/F
AN5333B High Efficienc
y
,
High Current Serial LED Driver with 30V Integrated Switc
h
Electrical Characteristics
Test Circuit
Figure 3. Test Circuit
Unless otherwise noted, V
IN
= 3.6V, V
OUT
= 20V, I
LED
= 20mA, T
A
= -40C to 85C, Typical values are at
T
A
= 25C, Test Circuit, Figure 3.
Parameter
Conditions
Min.
Typ.
Max.
Units
Feedback Voltage
FAN5333A
99
110
121
mV
FAN5333B
299
315
331
mV
Switch Current Limit
V
IN
= 3.2V
1.1
1.5
A
Load Current Capability
V
OUT
20V, V
IN
= 3.2V
65
mA
Switch On-resistance
V
IN
= 5V
0.6
V
IN
= 3.6V
0.7
Quiescent Current
V
SHDN
= 3.6V, No Switching
0.6
mA
OFF Mode Current
V
SHDN
= 0V
0.1
3
A
Shutdown Threshold
Device ON
1.5
V
Device OFF
0.5
V
Shutdown Pin Bias Current
V
SHDN
= 0V or V
SHDN
= 5.5V
1
300
nA
Feedback Pin Bias Current
1
300
nA
Feedback Voltage Line Regulation
2.7V < V
IN
< 5.5V, V
OUT
20V
0.3
%
Switching Frequency
1.2
1.5
1.8
MHz
Maximum Duty Cycle
87
93
%
Switch Leakage Current
No Switching, V
IN
= 5.5V
1
A
OVP
15
%
Thermal Shutdown Temperature
150
C
SHDN
V
IN
V
OUT
R
GND
V
IN
FB
SW
C
IN
10
H
1
3
2
4
5
10
F
C
OUT
L
BAT54
I
LED
1
F
ON
OFF
Electronic Load
FA
N5333
5
www.fairchildsemi.com
FAN5333A/FAN5333B Rev. 1.0.1
F
AN5333A/F
AN5333B High Efficienc
y
,
High Current Serial LED Driver with 30V Integrated Switc
h
Typical Performance Characteristics
T
A
= 25C, C
IN
= 4.7F, C
OUT
= 0.47F, L = 10H, unless otherwise noted.
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
50
60
70
80
90
100
50
60
70
80
90
100
Efficiency vs. Input Voltage
Input Voltage(V)
Ef
f
i
ci
en
cy (
%
)
I
LED
= 10mA
V
OUT
= 9V
I
LED
= 20mA
I
LED
= 30mA
I
LED
= 40mA
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
Efficiency vs. Input Voltage
Input Voltage(V)
Ef
f
i
ci
en
cy (
%
)
V
OUT
= 15V
I
LED
= 20mA
I
LED
= 30mA
I
LED
= 40mA
I
LED
= 10mA
2
3
4
5
0
50
100
150
200
250
300
Maximum Load Current vs. Input Voltage
Max
im
u
m
L
o
a
d
C
u
rren
t
(
m
A)
Input Voltage (V)
T
A
= -40C
T
A
= 25C
T
A
= 85C
2.0
2.5
3.0
3.5
4.0
0
50
100
150
200
Maximum Load Current vs.Input Voltage
Input Voltage (V)
Max
im
u
m
L
o
a
d

Cu
rren
t

(mA
)
V
OUT
= 14.2V
V
OUT
= 9.3V
V
OUT
= 12.3V
-40
-20
0
20
40
60
8 0
9 .6
9 .8
10 .0
10 .2
10 .4
10 .6
10 .8
LED Current vs Temperature
LE
D
Cu
rren
t
(
mA
)
Temperature (C)
V
IN
= 2.2V
V
IN
= 3.6V
V
IN
= 5.5V
V
OUT
= 15V
I
LED
<5%
C
IN
= 10F
V
OUT
= 15V
I
LED
<5%
C
IN
= 10F
C
OUT
= 1F
I
LED
<5%
C
IN
= 10F
C
OUT
= 1F
-40
-20
0
20
40
60
80
1.2
1.4
1.6
1.8
2.0
SW Frequency vs Temperature
Temperature (C)
SW F
r
eq
u
e
n
c
y (
M
Hz
)
V
IN
= 2.2V
V
OUT
= 15V
V
IN
= 3.6V
V
IN
= 5.5V
C
OUT
= 1F
6
www.fairchildsemi.com
FAN5333A/FAN5333B Rev. 1.0.1
F
AN5333A/F
AN5333B High Efficienc
y
,
High Current Serial LED Driver with 30V Integrated Switc
h
Typical Performance Characteristics
(Contd.)
T
A
= 25C, C
IN
= 4.7F, C
OUT
= 0.47F, L = 10H, unless otherwise noted.
2
3
4
5
0
5
10
15
20
25
V
OUT
= 15V
Load Current vs.Input Voltage
Input Voltage (V)

Loa
d C
u
r
r
e
nt (
m
A)
Start-Up Response
Time (100s/div)
(5V/di
v)
Vo
l
t
age
Out
put
Vo
l
t
ag
e
Battery
Current
(5
V/d
iv)
(0.5
A/d
iv)
EN
L = 10H
C
IN
= 10F
C
OUT
= 1F
V
IN
= 2.7V
7
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FAN5333A/FAN5333B Rev. 1.0.1
F
AN5333A/F
AN5333B High Efficienc
y
,
High Current Serial LED Driver with 30V Integrated Switc
h
Block Diagram
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 signif-
icantly 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 band-
gap reference. The amplified error voltage serves as a refer-
ence 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
current sense
resistor and the ramp generator voltage derived from the oscilla-
tor. The oscillator sets the latch, and the latch turns on the FET
switch. Under normal operating conditions, the PWM compara-
tor 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 cur-
rent flow through the switch is terminated. The latch can be
reset by other events as well. Over-current condition is moni-
tored by the current limit comparator which resets the latch and
turns off the switch instantaneously within each clock cycle.
Over-Voltage Protection
The voltage on the feedback pin is sensed by an OVP Compar-
ator. When the feedback voltage is 15% higher than the nominal
voltage, the OVP Comparator stops switching of the power tran-
sistor, thus preventing the output voltage from going higher.
Open-circuit protection
As in any current regulator, if the feedback loop is open, the out-
put voltage increases until it is limited by some additional exter-
nal 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
OUT
and the Schottky
diode rating voltage are higher). Since at such high output volt-
age 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
OUT
with an external Zener diode or stop-
ping the boost switching with an external voltage supervisory
circuit.
Applications Information
Setting the Output Current
The internal reference (V
REF
) is 110mV (Typical) for FAN5333A
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
Reference
Oscillator
n
FB
FB
Amp
Driver
Comp
-
-
+
+
S
Ramp
Generator
R
R
R
Q
S
Current Limit
Comparator
30m
1.15 x V
REF
Shutdown
Circuitry
Thermal
Shutdown
SHDN
GND
SW
V
IN
Amp
Error
4
5
1
2
3
+
Over
Voltage
Comp
+
-
-
+
-
I
LED
V
FB
R
----------
=
8
www.fairchildsemi.com
FAN5333A/FAN5333B Rev. 1.0.1
F
AN5333A/F
AN5333B High Efficienc
y
,
High Current Serial LED Driver with 30V Integrated Switc
h
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 10H. 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 cur-
rent 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 auto-
matic turn-off of the switching transistor, resulting in higher rip-
ple and reduced efficiency.
Some recommended inductors are suggested in the table
below:
Table 1: Recommended Inductors
Capacitors Selection
For best performance, low ESR input and output capacitors are
required. Ceramic capacitors of C
IN
= 10F and C
OUT
= 1F
placed as close to the IC pins, are required for the maximum
load(65mA). For the lighter load (
20mA
)
the capacitances may
be reduced to C
IN
= 4.7F and C
OUT
= 0.47F or even to 0.1F,
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.
Table 2: Recommended Capacitors
Diode Selection
The external diode used for rectification is usually a Schottky
diode. Its average forward current and reverse voltage maxi-
mum 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
OUT
to GND,
even with the IC disabled, since the diode can be instantly dam-
aged by the excessive current.
Brightness Control
1. Dimming Using PWM Logic Signal
A PWM signal applied to SHDN Table 5 on page 8 can control
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
Table 6 on page 8. Adjusting the duty cycle from 0% to 100%
results in varying the LED's current between I
MIN
and I
MAX
.
Where
Figure 5. Dimming Using a PWM Signal
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.
Figure 7. Dimming Using DC Voltage
Inductor
Value
Vendor
Part Number
Com-
ment
10H
TDK
SLF6025&-100M1R0
10H
MURATA
LQH66SN100M01C
Highest
Efficiency
10H
COOPER
SD414-100
Small
Size
Capacitor
Value
Vendor
Part Number
0.47F
Panasonic
ECJ-3YB1E474K
1F
Murata
GRM21BR61E105K
10F
Murata
GRM21BR61A106K
I
MIN
V
FB
R
MIN
-------------
=
and I
MAX
V
FB
R
MIN
R
SET
--------------------------------
=
SHDN
FAN5333
FB
FAN5333
R
MIN
R
SET
FB
V
DC
90K
5
1.6K
FAN5333A
FB
V
DC
90K
15
4.7K
FAN5333B
9
www.fairchildsemi.com
FAN5333A/FAN5333B Rev. 1.0.1
F
AN5333A/F
AN5333B High Efficienc
y
,
High Current Serial LED Driver with 30V Integrated Switc
h
3. Dimming Using Filtered PWM Signal
This method allows the use of a greater than 1kHz PWM fre-
quency 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.
Figure 8. Dimming Using Filtered PWM Signal
Thermal Shutdown
When the die temperature exceeds 150C, a reset occurs and
will remain in effect until the die cools to 130C, 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 connec-
tion should be routed away from the inductor proximity to pre-
vent 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.
FB
20K
15K
5
1.6K
FAN5333A
0.1
F
FB
20K
15K
15
4.7K
FAN5333B
0.1
F
10
www.fairchildsemi.com
FAN5333A/FAN5333B Rev. 1.0.1
F
AN5333A/F
AN5333B High Efficienc
y
,
High Current Serial LED Driver with 30V Integrated Switc
h
Mechanical Dimensions
5-Lead SOT-23
Ordering Information
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
0
10
0
10
Product Number
Package Type
Order Code
FAN5333A
5-Lead SOT23
FAN5333ASX
FAN5333B
5-Lead SOT23
FAN5333BSX
D
e1
e
B
E
H
A
A1
L
c
11
www.fairchildsemi.com
FAN5333A/FAN5333B Rev. 1.0.1
F
AN5333A/F
AN5333B High Efficienc
y
,
High Current Serial LED Driver with 30V Integrated Switc
h
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.
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.
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 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.
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.
PRODUCT STATUS DEFINITIONS
Definition of Terms
Datasheet Identification
Product Status
Definition
Advance Information
Preliminary
No Identification Needed
Obsolete
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.
This datasheet contains specifications on a product
that has been discontinued by Fairchild semiconductor.
The datasheet is printed for reference information only.
Formative or
In Design
First Production
Full Production
Not In Production
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