QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 629
MULTI-DISPLAY LED CONTROLLER
LTC3205
DESCRIPTION
Demonstration circuit 629 is a multi-display LED con-
troller featuring the LTC3205.
The LTC3205 is a highly integrated multi-display LED
controller. This device contains a high efficiency, low
noise fractional step-up/step-down charge pump to pro-
vide power for a main and sub white LED display, plus
an RGB color LED display. The LTC3205 requires only
four small ceramic capacitors plus two resistors to form
a complete 3-panel LED power supply and a current
controller.
Maximum currents for the main/sub and RGB displays
are set independently with a single resistor. Current for
each LED is controlled with an internal current source.
Dimming and ON/OFF control for all displays is achieved
via a 3-wire serial interface. Four dimming states exist
for the main and sub panel displays and 16 dimming
states are available via internal PWM for the red, green,
and blue LEDs resulting in up to 4096 color combina-
tions.
The LTC3205 charge pump optimizes efficiency based
on V
IN
and LED forward voltage conditions. The part
powers up in step-down mode and automatically
switches to step-up mode once the first LED current
source begins to enter dropout. Internal circuitry pre-
vents inrush current and excess input noise during start-
up and mode switching.
QUICK START PROCEDURE
Demonstration circuit 629 is easy to set up to evaluate
the performance of the LTC3205. Refer to Figure 1 for
proper measurement equipment setup and follow the
procedure below:
1.
Connect DC629 to the DC590 USB Serial Controller
using the supplied 14-conductor ribbon cable as
shown in Figure 1. Refer to the DC590 Quick Start
guide for software installation details.
2.
Attach the supplied USB cable into your computer and
then into the DC590 controller board.
3.
Run the QuickEval
™
program. The program detects
the DC629 and displays the LTC3205 control window
(shown in Figure 2).
4.
Attach a 2.7V–4.5V power source to the Vin and GND
turrets of the DC629 demo board. This is the V
IN
power supply for the LTC3205 (see attached sche-
matic).
NOTE:
The LTC3205’s maximum current settings for
Main, Sub, and RGB are set by R2 and R3 (see the at-
tached DC629 schematic.) R2 = R3 = 32.4k, which set
the maximum current to 15mA.
1