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Электронный компонент: FAN5332ASX

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2004 Fairchild Semiconductor Corporation
1
www.fairchildsemi.com
August 2005
FAN5332A Rev. 1.0.1
F
AN5332A High Efficienc
y
,
High Current Serial LED Driver and OLED Suppl
y with 30V Integrated Switc
h
FAN5332A
High Efficiency, High Current Serial LED Driver and OLED
Supply 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
Over-Voltage Protection
Fixed -Frequency PWM Operation
Soft Start
Internal Compensation
Thermal Shutdown
5-lead SOT-23 Package
Applications
Cell Phones
PDAs
Handheld Equipment
Display Bias
LED Bias
Flash LED
Description
The FAN5332A is an 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 switch-
ing 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 cir-
cuitry.
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 FAN5332A is available in a 5-lead
SOT23 package.
Typical Application
Figure 1. Typical Application Diagram
SHDN
V
IN
V
OUT
R1
R2
GND
V
IN
FB
SW
C
F
C
IN
6.8H
1
3
2
4
5
10
F
82pF
C
OUT
L
BAT54
2.2
F
2.7V to 5.5V
ON
OFF
F
AN5332A
2
www.fairchildsemi.com
FAN5332A Rev. 1.0.1
F
AN5332A High Efficienc
y
,
High Current Serial LED Driver and OLED Suppl
y 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 voltage divider.
4
SHDN
Shutdown Control Pin.
Logic HIGH enables, logic LOW disables the device.
5
V
IN
Input Voltage Pin.
5-Lead SOT-23
Top View
SW
GND
FB
SHDN
V
IN
3
www.fairchildsemi.com
FAN5332A Rev. 1.0.1
F
AN5332A High Efficienc
y
,
High Current Serial LED Driver and OLED Suppl
y 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. Junction to ambient thermal resistance,
JA
,
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.
3. Using EIA/JESD22A114B (Human Body Model) and EIA/JESD22C101-A (Charge Device Model).
4. This load capacitance value is required for the loop stability. Tolerance, temperature variation, and voltage
dependency of the capacitance must be considered. Typically a 2.2F 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
) (Note 2)
200
C/W
Electrostatic Discharge Protection (ESD) Level (Note 3)
HBM
2
kV
CDM
1
Parameter
Min
Typ
Max
Unit
Input Voltage
2.7
5.5
V
Output Voltage
12
30
V
Operating Ambient Temperature
-40
25
85
C
Output Capacitance (Note 4)
1.6
F
4
www.fairchildsemi.com
FAN5332A Rev. 1.0.1
F
AN5332A High Efficienc
y
,
High Current Serial LED Driver and OLED Suppl
y with 30V Integrated Switc
h
Electrical Characteristics
Test Circuit
Figure 3. Test Circuit
Unless otherwise noted, V
IN
= 3.6V, No external load,T
A
= -40C to +85C, Typical values are at T
A
= 25C,
Test Circuit, Figure 3.
Parameter
Conditions
Min.
Typ.
Max.
Units
Output Voltage Accuracy
-3
+3
%
Switch Current Limit
V
IN
= 3.2V
1.1
1.5
A
Load Current Capability
V
OUT
> 18.5V, V
IN
2.7V
50
mA
V
OUT
> 19.7V, V
IN
3.2V, T
ON
< 0.4Sec.
75
mA
Switch On-resistance
V
IN
= 5V
0.6
V
IN
= 3.6V
0.7
Quiescent Current
V
SHDN
= 3.6V, No Switching
0.7
mA
V
SHDN
= 3.6V, Switching, V
OUT
= 20.7V
4.5
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
100
nA
Feedback Voltage
T
A
= 25C
1.205
1.230
1.255
V
Feedback Pin Bias Current
1
100
nA
Line Regulation
3.2V < V
IN
< 5.5V, V
OUT
= 20.7V, T
A
= 25C
0.5
1.5
%
Load Regulation
0mA < I
Load
< 75mA, V
OUT
= 20.7V
0.8
%
Switching Frequency
1.2
1.5
1.8
MHz
Maximum Duty Cycle
87
93
%
Enable Delay
V
IN
= 2.7V, I
OUT
= 50mA, V
OUT
= 20.7V
1.5
5
mS
Power on Delay
V
IN
= 2.7V, I
OUT
= 50mA, V
OUT
= 20.7V
1.5
5
mS
Switch Leakage Current
No Switching, V
IN
= 5.5V
1
A
160K
10K
SHDN
V
IN
V
OUT
R1
R2
GND
V
IN
FB
SW
C
F
C
IN
6.8H
1
3
2
4
5
10
F
82pF
C
OUT
L
BAT54
2.2
F
2.7V to 5.5V
ON
OFF
FA
N5332A
5
www.fairchildsemi.com
FAN5332A Rev. 1.0.1
F
AN5332A High Efficienc
y
,
High Current Serial LED Driver and OLED Suppl
y with 30V Integrated Switc
h
Typical Performance Characteristics
T
A
= 25C, C
IN
= 10F, C
OUT
= 2.2F, L = 6.8H, unless otherwise noted.
Battery Voltage (V)
Battery Voltage (V)
Battery Voltage (V)
Battery Voltage (V)
2.5
3.0
3.5
4.0
4.5
5.0
5.5
18
19
20
21
22
Output Voltage (V)
T
A
= 85
C
T
A
= 25
C
T
A
= -40
C
Line Regulation
2.5
3.0
3.5
4.0
4.5
5.0
5.5
50
60
70
80
90
Full Load Efficiency
Efficiency (%)
Efficiency (%)
T
A
= 85
C
T
A
= 25
C
T
A
= -40
C
2.5
3.0
3.5
4.0
4.5
5.0
5.5
0
1
2
3
4
5
6
Battery Current (mA)
T
A
= 25
C
T
A
= -40
C
T
A
= 85
C
Tim e (500
s/div)
Output
Voltage
(5V/
div
)
ENABLE
Vo
l
t
ag
e
Inductor
(50
0
m
A
/di
v
)
Current
(5
V/d
i
v
)
V
IN
= 3.6V
R
OUT
= 275
Start-Up Response
Load Transient Response
Output
(5
00m
V/d
i
v
)
Voltage
Load Current
St
e
p
Tim e (100
s/div )
V
IN
= 3.6V
75 mA
0mA
R
OUT
= 275
R
OUT
= 275
2.5
3.0
3.5
4.0
4.5
5.0
5.5
60
65
70
75
80
85
No Load Battery Current vs. Battery Voltage
Light Load Efficiency
I
Load
= 10mA
I
Load
= 20mA
V
OUT
= 20.7V
Load Regulation
6
www.fairchildsemi.com
FAN5332A Rev. 1.0.1
F
AN5332A High Efficienc
y
,
High Current Serial LED Driver and OLED Suppl
y with 30V Integrated Switc
h
Block Diagram
Figure 4. Block Diagram
Circuit Description
The FAN5332A is a pulse-width modulated (PWM) current-mode
boost converter. The FAN5332A improves the performance of bat-
tery-powered equipment by significantly minimizing the spectral
distribution of noise at the input caused by the switching action of
the regulator. To facilitate effective noise filtering, the switching fre-
quency was chosen to be high, 1.6MHz. An internal soft start cir-
cuitry minimizes in-rush currents. The timing of the soft start circuit
was chosen to reach 95% of the nominal output voltage within
maximum 5mS following an enable command when V
IN
= 2.7V,
V
OUT
= 20.7V, I
LOAD
= 35mA and C
OUT (EFFECTIVE)
=2.2
F.
The device architecture is that of a current mode controller with
an internal sense resistor connected in series with the N-chan-
nel 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 refer-
ence. The amplified error voltage serves as a reference voltage
to the PWM comparator. The inverting input of the PWM com-
parator 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 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 out-
put 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 condition is detected by a fast comparator limiting
the duty cycle in a similar manner to over-current monitoring
described above. Dimming may be accomplished by PWM mod-
ulating the SHDN input at a frequency around 100Hz.
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.
Applications Information
Setting the Output Voltage
The internal reference (V
REF
) is 1.23V (Typical). The output volt-
age is divided by a resistor divider, R1 and R2 to the FB pin.
The output voltage is given by
According to this equation, and assuming desired output volt-
age of 20.7V, good choices for the feedback resistors are,
R
1
=160k
and R
2
=10k
.
Inductor Selection
The inductor parameters directly related to device performances
are saturation current and dc resistance. The FAN5332A oper-
ates with a typical inductor value of 6.8H. The lower the dc
resistance, the higher the efficiency. Usually a trade-off between
Reference
Oscillator
Soft-Start
n
FB
FB
Amp
Comp
Over
Voltage
Comp
-
-
+
+
Ramp
Generator
R
R
R
Q
S
Current Limit
Comparator
0.03
W
1.15 x V
REF
Shutdown
Circuitry
Thermal
Shutdown
SHDN
GND
SW
V
IN
Amp
Error
4
5
1
2
3
+
+
-
-
+
-
Driver
V
OUT
V
REF
1
R
1
R
2
-------
+
=
7
www.fairchildsemi.com
FAN5332A Rev. 1.0.1
F
AN5332A High Efficienc
y
,
High Current Serial LED Driver and OLED Suppl
y with 30V Integrated Switc
h
inductor size, cost and overall efficiency is needed to make the
optimum choice.
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
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:
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
= 2.2F
placed as close to the IC pins, are recommended for the lower
input and output ripple. 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
A feed forward capacitor C
F
, is required for stability. The recom-
mended value (R
1
x C
F
) is around 13S.
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.
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.
Heavy Load Limitations
In heavy load applications (P
OUT
>1.5W) the power dissipated
in steady state at high ambient temperature can increase the
die temperature to the point where the thermal shutdown kicks
in. To prevent this, a limited time operation should be consid-
ered in applications such as a flash LED driver. An operation
time of 0.4Sec. at maximum load, followed by a 3.6Sec. OFF
time ensures stable operation even in the worst case, provided
that the IC heat dissipation is optimized to lower the junction to
ambient thermal resistance.
The external passive components and the layout of the PCB
play an important role in reaching the highest efficiency of the
boost converter. For best results, the data sheet recommenda-
tions regarding external components and PCB layout should be
followed closely.
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 resistor divider
that sets the output voltage should be routed away from the
inductor to avoid RF coupling. A two layer PCB with the bottom
layer as ground plane connected to the pin 2 of the IC is recom-
mended. This ground plane acts as an electromagnetic shield to
reduce EMI and parasitic coupling between components.
Figure 5. Recommended PCB Layout
Inductor
Value
Vendor
Part Number
Comment
6.8H
TDK
SLF7028T6R8M1R3
Low Profile
6.8H
MURATA
LQ566C6R8M04
High
Efficiency
6.8H
COOPER
SD414-6R8
Small Size
Capacitor
Value
Vendor
Part Number
10F
Murata
GRM31CR70J106KA01B
2.2F
Murata
GRM32RR71E225KC01B
8
www.fairchildsemi.com
FAN5332A Rev. 1.0.1
F
AN5332A High Efficienc
y
,
High Current Serial LED Driver and OLED Suppl
y with 30V Integrated Switc
h
Mechanical Dimensions
5-Lead SOT-23Package
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
FAN5332A
5-Lead SOT23
FAN5332ASX
D
e1
e
B
E
H
A
A1
L
c
9
www.fairchildsemi.com
FAN5332A Rev. 1.0.1
F
AN5332A High Efficienc
y
,
High Current Serial LED Driver and OLED Suppl
y 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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