FAN5609 Fairchild Semiconductor, FAN5609 Datasheet - Page 5

• Manufacturer Part Number: FAN5609
• Description: LED Driver with Adaptive Charge Pump DC/DC Converter
• Manufacturer: Fairchild Semiconductor

PRODUCT SPECIFICATION
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
(PWM). In PWM mode, the modulating frequency has to be
set sufficiently high in order to avoid a flickering effect
(100Hz to 1kHz).
REV. 1.0.2 5/30/03
Switch Configuration
I
LED
A
B
V
IN
Figure 1
Step-up, 2:1 configuration.
Switch positions shown in charge phase.
Reverse all switches for pump phase.
OFF
GND
0
0
7mA
1
0
14mA
0
1
V
Average
OUT
=
20mA
2 X V
1
1
value
IN
Digital Control with PWM
Any input can be modulated by a pulse train of variable duty
cycle ( δ ). 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.
CAP2
CAP1
GND
+
+
-
-
V
IN
Figure 2
Step-up
3:2 configuration
Switch positions shown in charge phase.
Reverse all switches for pump phase.
V
C
OUT
OUT
FAN5609
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