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Электронный компонент: FAN5609MTCX

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www.fairchildsemi.com
REV. 1.0.2 5/30/03
Features
Parallel LED Driver Supports All Forward Voltages
Adaptive V
OUT
Adjustment to the Highest Diode Voltage
Internally Matched LED Current Sources
No External Components Needed to Set LED Current
Built-in Charge Pump has Three Modes of Operation:
Linear Regulation V
IN
> 4.2V
3/2 DC-DC Converter and Regulation 3.6V<V
IN
<4.2V
2/1 DC-DC Converter and Regulation 2.7V<V
IN
<3.6V
Up to 86% Efficiency
Low EMI, Low Ripple
Up to 80mA Output Current (4
20mA)
Built-in DAC for Digital or PWM Brightness Control
Can be Duty Cycle Modulated between 0 to 18mA
2.7V to 5.5V Input Voltage Range
I
CC
< 2A in Shutdown Mode
1MHz Operating Frequency
Shutdown Isolates Output from Input
Soft-Start Limits Inrush Current
Short Circuit Protection
Minimal External Components Needed
Available in a 14-lead TSSOP Package
Available in a 16-lead MLP Package
Applications
Cell Phones
Handheld Computers
PDA, DSC, MP3 Players
Keyboard Backlight
LED Displays
Description
The FAN5609 generates regulated output current from a
battery with input voltage varying between 2.7V to 5.5V.
Switch reconfiguration and fractional switching techniques
are utilized to achieve high efficiency over the entire input
voltage range. A proprietary internal circuitry continuously
monitors each LED current loop and automatically adjusts
the generated output DC voltage to the lowest minimum
value required by the LED having the highest forward
voltage. This adaptive nature of the FAN5609 eliminates the
need for LED pre-selection (matching) and ensures opera-
tion at high efficiency. When the input voltage is sufficiently
high to sustain the programmed current level in the LEDs,
the FAN5609 re-configures itself to operate as a linear
regulator, and the DC-DC converter is turned off. An internal
two-bit digital to analog converter provides programmability
of the output currents. Only two 0.1F bucket capacitors and
two 4.7F input/output capacitors are needed for proper
operation.
Soft-start circuitry prevents excessive current draw during
power on. The device has built-in short circuit protection.
FAN5609
LED Driver with Adaptive Charge Pump DC/DC
Converter
Typical Application
CAP1
CAP2
C
OUT
C
IN
LED-
LED-
LED-
LED-
V
OUT
V
OUT
V
IN
V
IN
GND
FAN5609
IN B
IN A
D
A
C
CAP+
CAP+
CAP-
CAP-
FAN5609
PRODUCT SPECIFICATION
2
REV. 1.0.2 5/30/03
Pin Assignments
Pin Descriptions
Test Circuit
Pin No.
FAN5609
Pin Function Description
14L-TSSOP
4mmX4mm 16L-MLP
1
V
IN
V
IN
Input
2
V
OUT
V
OUT
Output to LEDs Anode
3
GND
GND
Ground
4
B
B
DAC B
5
A
A
DAC A
6
LED -
LED -
4th LED Cathode
7
LED -
LED -
3rd LED Cathode
8
LED -
LED -
2nd LED Cathode
9
LED -
LED -
1st LED Cathode
10
NC
NC
No Connection
11
CAP1-
CAP1-
Bucket capacitor negative terminal
12
CAP1+
CAP1+
Bucket capacitor positive connection
13
CAP2+
CAP2+
Bucket capacitor positive terminal
14
CAP2-
CAP2-
Bucket capacitor negative connection
15
NC
No Connection
16
NC
No Connection
GND
V
IN
LED-
LED-
V
OUT
B
A
CAP1+
CAP2+
CAP1-
CAP2-
LED-
LED-
NC
FAN5609
14-Lead TSSOP
FAN5609
4x4mm 16-Lead MLP
FAN5609
Top-View
CAP1+
CAP1-
LED-
GND
V
IN
V
OUT
B
LED-
LED-
LED-
A
CAP2+
CAP2-
NC
NC
NC
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
V
IN
= 2.7V to 5.5V
V
OUT
NC
4 White LEDs
Fairchild QTLP670C-IW
Super Bright LED
NC
NC
C
IN
CAP2
CAP1
C
OUT
V
H
V
H
V
L
V
L
1
4
5
8
9
16
13
12
FAN5609
0.1
F
0.1
F
4.7
F
4.7
F
All capacitors are Ceramic chip capacitor
PRODUCT SPECIFICATION
FAN5609
REV. 1.0.2 5/30/03
3
Absolute Maximum Ratings
Recommended Operating Conditions
DC Electrical Characteristics
Note:
1. Using Mil Std. 883E, method 3015.7(Human Body Model) and EIA/JESD22C101-A (Charge Device Model)
Parameter
Min
Max
Unit
V
IN
, V
OUT
, A, B Voltage to GND
-0.3
6.0
V
CAP+, CAP-, to GND
-0.3
V
IN
+ 0.3
V
V
OUT
Short Circuit Duration
INDEFINITE
Lead Soldering Temperature (10 seconds)
300
C
Operating Junction Temperature Range
150
C
Storage Temperature
-55
150
C
Electrostatic Discharge Protection Level (Note 1)
HBM
4
kV
CDM
2
Parameter
Min
Typ
Max
Unit
Input Voltage Range, V
IN
2.7
5.5
V
Operating Ambient Temperature Range
-40
25
85
C
Unless otherwise noted, V
IN
=3V to 5.5V, T
A
= 25C. Refer to "Test Circuit".
Boldface
values indicate specifications
over the ambient operating temperature range.
Parameter
Conditions
Min.
Typ.
Max.
Units
Quiescent Current
V
OUT
= 5.5V,
No Load
1.5
4
mA
Output Current Accuracy
I
NOM
= 20mA
A = High
B = High
17
20
23
mA
LED to LED Current Matching
V
IN
= 5.5V
A = B = High
-5
+5
%
Efficiency
V
IN
= 4.5V
85 to75
%
V
IN
= 3V
65 to 55
Input A, B Threshold
Low
0
0.3
V
IN
V
High
0.6
V
IN
V
IN
V
IN
at Configuration
Change
From 1:1 to 3:2
4.2
V
From 3:2 to 2:1
3.6
Oscillator Frequency
0.80
1
1.2
MHz
Supply Current, "OFF Mode"
2
A
FAN5609
PRODUCT SPECIFICATION
4
REV. 1.0.2 5/30/03
Block Diagram
Linear
Regulator
Oscillator
Analog
Detector
Power
Good
Bandgap
Reference
Reference
D
R
I
V
E
R
S
P
U
M
P
Voltage
Selector
1
F
1
F
V
IN
V
OUT
GND
Ref1
Ref3
Ref4 (BG)
Regulator
Low Battery Ref.
Range Selection
Mode Change
Ref2
5
F
I.
LIM.
I.
LIM.
I.
LIM.
I.
LIM.
V
IN
On Off
And
Current Range
DAC
A
B
Circuit Description
The FAN5609's switched capacitor DC/DC converter auto-
matically configures its internal switches to achieve high effi-
ciency and to provide tightly regulated output currents for
the LEDs. An analog detector determines which diode
requires the highest voltage in order to sustain the pre-set
current levels, and adjusts the pump regulator accordingly.
Every diode has its own linear current regulator. In addition,
a voltage regulator controls the output voltage when the bat-
tery voltage is within a range where linear regulation can
provide maximum possible efficiency. If the battery voltage
is too low to sustain the diode current in the linear mode,
a fractional 3:2 charge pump is enabled. When the battery
voltage drops further and this mode is no longer sufficient to
sustain proper operation, the pump is automatically reconfig-
ured to operate in 2:1 mode. As the battery discharges and
the voltage decays, the FAN5609 switches between modes to
maintain a constant current through LED throughout the bat-
tery life. The transition has hysteresis to prevent toggling.
Supply Voltage
The internal supply voltage for the device is automatically
selected from V
IN
or V
OUT
pins, whichever is higher.
Soft Start
The soft-start circuit limits inrush current when the device is
initially powered up and enabled. The reference voltage con-
trols the rate of the output voltage ramp-up to its final value.
Typical start-up time is 1ms. The rate of the output voltage
ramp-up is controlled by an internally generated slow ramp,
and an internal variable resistor limits the input current.
PRODUCT SPECIFICATION
FAN5609
REV. 1.0.2 5/30/03
5
Shutdown and Short Circuit Current Limit
Set both DAC inputs low to shut down the device. Built-in
short circuit protection limits the supply current to a maxi-
mum of 50mA.
Digital Control
A digital-to-analog converter (DAC) allows selection of the
following modes: OFF, 7mA, 14mA, 20mA, per diode.
By turning the IN B pin ON and OFF, the current can be
modulated between 7 to 20mA to achieve any I
Average
value
(PWM). In PWM mode, the modulating frequency has to be
set sufficiently high in order to avoid a flickering effect
(100Hz to 1kHz).
Digital Control with PWM
Any input can be modulated by a pulse train of variable duty
cycle (
). By turning ON and OFF DAC inputs A or B, the
current can be continuously modulated to any average value
between 1 to 19mA. For a maximum range of LED current,
both A&B can be modulated at the same time.
A
0
1
0
1
B
0
0
1
1
I
LED
OFF
7mA
14mA
20mA
Switch Configuration
Figure 1
Step-up, 2:1 configuration.
Switch positions shown in charge phase.
Reverse all switches for pump phase.
CAP1
GND
V
OUT
V
IN
GND
CAP2
Figure 2
Step-up
3:2 configuration
Switch positions shown in charge phase.
Reverse all switches for pump phase.
C
OUT
V
OUT
=
2 X V
IN
+
+
-
-
V
IN