SP6683 Datasheet, PDF (8/14 Pages) Sipex Corporation – High Power LED Driver for Parallel Configuration

Configuring the SP6683 as Voltage or
Current Source
The white LED load configuration used by
customers can be discrete white LEDs or a white
LED module. Inside the white LED module,
there may or may not be resistors in series with
the white LEDs. According to the different
application requirements, the SP6683 can be
configured as either a voltage source or a current
source to provide solutions for these different
applications, as shown below. The figure shows
the SP6683 driving discrete white LEDs as a
current source.
V_OUT
1
SP6683
5
FB
Rb
Rb
GND
2.2uF
8
Driving discrete white LEDs as current source
APPLICATION INFORMATION
Anode
FB
3-wire W-LED module
GND
3-wire white LED module
V_{OUT 1}
Anode
SP6683
5
V_FB
GND
8
2-wire W-LED module
Cathode
Rb
The current in one white LED current is set by
the ratio of the feedback pin voltage (315mV)
and the bias resistor R_B. To set the operating
current, R_B can be selected by:
R_B = ^VFB
I_LED
The current of the remaining white LEDs is set
according to the similarity of the white LEDs.
3-wire white LED modules with internal series
resistors (as shown in figure below) can also be
driven in this way.
Driving 2-wire white LED module as current source
In the figure above, the SP6683 was used to
drive a 2-wire white LED module (without
internal series resistors) as a current source. The
bias resistor R_B is selected to regulate the total
current of the white LED module instead of the
current of a single LED as in the figure showing
the 3 wire white LED module.
V_{OUT 1}
SP6683
V_FB
5
GND
8
R5
2.2uF
R6
Anode
2-wire W-LED
module
Cathode
Date: 3/31/06 RevG
Driving 2-wire white LED module as voltage source
SP6683 1X/1.5X Charge Pump LED Driver for Flash or Backlight
8
© Copyright 2006 Sipex Corporation