Linear Technology 824, LTC3208 Quick Start Manual

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 824

MULTIDISPLAY LED CONTROLLER

LTC3208

WARNING: The LEDs on this demo board produce very bright light. Do not look directly at LEDs when power is
applied. Serious eye damage may occur.

DESCRIPTION

Demonstration circuit 824 is a multi-display LED
controller featuring the LTC3208.

The LTC3208 is a highly integrated multi-display
LED controller. This device contains a high effi­ciency, low noise charge pump to provide power
for a MAIN, SUB, and auxiliary (AUX) white LED
displays, an RGB color display, and a camera
(CAM) display with flash capabilities. The four aux­iliary LEDs may be individually configured to the
MAIN, SUB, CAM, or AUX display. The LTC3208
requires only four small ceramic capacitors plus
one resistor to form a complete 5-panel LED
power supply and current controller.

The maximum display currents are set with a sin­gle 24.3K ohm resistor. Current for each LED is
controlled with a precision internal current source.
Dimming and ON/OFF control for all displays are
achieved via a 2-wire I2C interface. The RGB or
SUB panel may be disabled via the ENRGB/S pin.

256 dimming states exist for the MAIN and SUB
panels. 16 states are available for the RGB, CAM,
and AUX displays. The RGB LED may display up
to 4096 color combinations.

The LTC3208 charge pump optimizes efficiency
based on the voltage across the LED current
sources. The part powers up in 1X mode and will
automatically switch to boost mode whenever any
enabled LED current source begins to drop out.
The first dropout switches the part to 1.5X mode
and a subsequent dropout switches the part into
2X mode. The charge pump can also be pro­grammed to 1.5X mode or 2X mode via the I2C
interface.

Design files for this circuit board are available. Call
the LTC factory.

, LTC and LT are registered trademarks of Linear Technology Corporation.

QUICK START PROCEDURE

Demonstration circuit 824 is easy to setup to evalu­ate the performance of the LTC3208. Refer to Figure
1 and Figure 2 for proper measurement equipment
setup and follow the procedure below.

1. Refer to the DC590 Quick Start guide for DC590
and QuickEvalTM setup and software installation
details.

2. Make sure the USB cable is connected between
the computer and the DC590 controller board.

3. Connect DC824 to the DC590 USB Serial Con­troller using the supplied 14-conductor ribbon
cable as shown in Figure 1.

4. Attach a 2.9 – 4.5V power source to the Vin and
GND turrets of the DC824 demo circuit as shown
in Figure 2. This is the Vin power supply for the
LTC3208 (see application schematic). DC824 has
an extra 4.7uF de-coupling capacitor on Vin to
help accommodate long lead lengths. DC590
gets its power from the USB cable.

5. Run the QuickEvalTM program. The program
detects the DC824 and displays the LTC3208
control window (shown in Figure 3).

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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 824

MULTIDISPLAY LED CONTROLLER

Figure 1. Proper Serial Interface Connection

Figure 2. Proper Measurement and Equipment Setup

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MULTIDISPLAY LED CONTROLLER

USING THE LTC3208 QUICKEVAL SOFTWARE

The program provides brightness controls for the
MAIN, SUB, CAM, AUX, and RGB LEDs. The

UPDATE ALL REG

in the LTC3208 to the current settings on the
LTC3208 demo panel. The
flashes the CAM LEDs from the CAM Low regis­ter to the CAM High register for the time se­lected in the FLASH TIME drop-down window.
The

FLASH TIME

user to select the flash time from 50ms to 200ms
in 50ms increments. The
option buttons allow the user to flash the CAM
LEDs using the CAMHL pin or via the I2C port.
The

Enable RGB AUX4

user to enable the RGB and AUX4 dropout sig­nals when checked and disable these dropout
signals when not checked.

Mode

option buttons allow the user to select be­tween
Charge Pump modes. The
tons allow the user to select either the RGB or
SUB panel to be disabled with the ENRGB/S pin.
The
trols the ENRGB/S pin. The
option buttons are used to configure the AUX
LEDs to the MAIN, SUB, CAM, or AUX displays.
There are two demo buttons that briefly illustrate
how the LTC3208 may be used. A CIE Chroma­ticity diagram allows direct selection of colors.
The
stops and resets any demonstration in progress.

VIEW LTC3208 PRODUCT PAGE Button –

button opens an internet browser and searches
the Linear Technology Corporation web site for
information on the LTC3208 when an internet
connection is available.

MAIN and SUB Control –

slide controls that adjust the MAIN and SUB dis­plays from 0 to 25mA in 256 steps. This is ac­complished by clicking on the up and down ar­rows to increment by one LSB, by clicking and
dragging the slide pointer, or by clicking in the

Auto

switching,

ENRGBS

LEDS OFF

button updates all registers

CAM FLASH

drop-down window allows the

CAM FLASH Select

check box allows the

The Charge Pump

Force 1.5X

ENRGBS

button on the DC824A board con-

AUX1

button resets all LEDs to zero,

, or

through

These are vertical

button

Force 2X

option but-

AUX4

This

vertical scroll bar to increment by 10 hex LSBs.
The hex code is displayed in the box below each
slider.

AUX Control –

the AUX display from 0 to 27mA in 16 steps. The
LED intensity may be adjusted by clicking on the
up and down arrows to increment by one LSB or
by clicking and dragging the slide pointer. The
hex code is displayed in the box below each
slider.

CAMH and CAML Controls –

cal slide control adjusts the CAM display from 0
to 100mA in 16 steps when the CAMH register is
selected. Since the Nichia NSCW100 is limited
to 30mA continuous current, the CAML vertical
slide control is limited in software to 25mA. In
normal operation the CAM display illuminates at
the intensity set by the CAML register. When the
CAM FLASH button is selected, the CAM display
illuminates at the intensity set by the CAMH reg­ister on the release of the mouse button for the
length of time selected in the FLASH TIME drop­down window. The LED intensity may be ad­justed by clicking on the up and down arrows to
increment by one LSB or by clicking and drag­ging the slide pointer. The hex code is displayed
in the box below the slider.

RED, GREEN, and BLUE Controls –

vertical slide controls which allow individual ad­justment of the RED, GREEN, and BLUE LEDs
from 0 to 27mA each in 16 exponential steps to
make any of the 4096 available colors. The hex
code and color are displayed in small boxes be­low each of the sliders. They are adjusted by
clicking on the up and down arrows or by clicking
and dragging the slide pointer.

CIE Chromaticity Diagram –

lected by clicking on a specific color in the dia­gram. The Gamut box, when checked, displays
the Chromaticity coordinates or gamut of all the

This vertical slide control adjust

The CAMH verti-

These are

Colors can be se-

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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 824

MULTIDISPLAY LED CONTROLLER

colors that can be produced by the Nichia
NSCM315C RGB diode.

UPDATE ALL REG Button –

is selected, all seven of the LTC3208 registers
are updated to the present settings on the demo
control window. This is beneficial when power is
initially applied to the demo board, the ribbon
cable has been disconnected, or when the
RESET push button has been depressed.

CAM FLASH Select Option Buttons –

buttons allow the user to select the method in
which the CAM display is flashed. When the
CAMHL PIN option button is selected, the CAM
display is flashed by applying a pulse on the
CAMHL Pin. If the I2C option button is selected,
the CAM display is flashed by momentarily set­ting the S
bus.

CAMHL FLASH Button –

selected and released, the CAM LEDs will flash
at the intensity selected in the CAMH register for
a period selected in the FLASH TIME drop-down
window. This is accomplished by applying a
pulse on the CAMHL pin or by setting the S
bit in the G register via the I2C interface.

FLASH TIME Drop-Down Window –

dow allows the user to select a flash time from
50ms to 200ms in 50ms increments. The flash
time is the time the program selects the CAMH
register when the CAMHL FLASH button is se­lected.

Enable RGB AUX4 Dropout Check Box –

When this box is selected, the RGB and AUX4
dropout signals are enabled. When it is dese­lected, the RGB and AUX4 dropout signals are
disabled and these outputs may then be used as
open drain logic signals.

bit in the G register via the I2C

CAMHILO

When this button

These

When this button is

CAMHILO

This win-

LEDS OFF Button –

the LEDs and will turn off and reset any active
demo.

Force Charge Pump Option Buttons –

buttons allow the user to select between auto
switching, forced 1.5X, or forced 2X Charge
Pump modes.

ENRGBS Option Buttons –

selected, the RGB display will be disabled until
the ENRGBS push button on the DC824A board
is depressed. If the SUB Control is selected, the
SUB panel will be disabled until the ENRGBS
push button on the DC824A board is depressed.

AUX1 - AUX4 Option Buttons –

allow the user to configure each of the AUX
LEDs to the MAIN, SUB, CAM or AUX displays.
The intensity of each LED will be controlled by
the corresponding register and slide control se­lected. If the MAIN button is selected, the corre­sponding LED will change illumination with the
MAIN brightness control.

REGA – REGG Hex Display Boxes –

boxes display the hex value last written to the
corresponding register from the DC590A board.

ENRGBS Push Button –

on the DC824A board and enables either the
RGB display or the SUB display when de­pressed, depending on which ENGRBS option
button is selected on the demo control window.

RESET Push Button –

the DC824A board and clears the seven regis­ters in the LTC3208 when depressed. The reset
button will not update or change the demo con­trol window. The UPDATE ALL REG button may
be used to update the registers to the current
demo control window settings.

This button will turn off all

These

If RGB Control is

These buttons

These

This button is located

This button is located on

Demo Buttons –

to run 2 different demonstrations. Demo 1 cy­cles through the RGB colors. Demo 2 cycles
through the brightness levels of all the LEDs and
flashes between various CAMH and CAML in­tensities using the I2C serial port.

These buttons can be selected

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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 824

MULTIDISPLAY LED CONTROLLER

Figure 3. LTC3208 Control Window

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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 824

MULTIDISPLAY LED CONTROLLER

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