Linear Technology LTC3210 User manual

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 914
MAIN/CAM LED CONTROLLER
LTC3210
1
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 914 is a multi-display LED con-
troller featuring the LTC3210.
The LTC3210 is a low noise charge pump designed to
drive four MAIN LEDs and one high current CAM
LED. The LTC3210 requires only four small ceramic
capacitors plus two resistors to form a complete LED
power supply and current controller.
The maximum display currents are set with a 30.1K
ohm resistor for the Main display and a 24.3K ohm
resistor for the CAM display. Current for each LED is
controlled with a precision internal current source.
The intensity of the displays are adjusted by strobing
the ENM and ENC pins. See the LTC3210 data sheet
for more information on this process. The DC914
uses a PIC controller to interface between the DC590
board and the LTC3210 via a 2-wire I
2
C serial inter-
face. There are 8 dimming states available for the
MAIN and CAM displays.
The 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 part resets to 1X
mode whenever the part is shut down.
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 914 is easy to setup. Refer to
Figure 1 for proper measurement equipment setup
and follow the procedure below.
1. Refer to the DC590 Quick Start guide for
QuikEval
TM
setup and software installation details.
2. Make sure the USB cable is connected between
the computer and the DC590 controller board.
3. Connect DC914 to the DC590 USB Serial Control-
ler 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 DC914 demo board. This is
the Vin power supply for the LTC3210 (see appli-
cation schematic). The DC914 has an extra 4.7uF
de-coupling capacitor between Vin and GND to
help accommodate long lead lengths. The DC590
board gets its power from the USB cable.
5. Run the QuikEval
TM
program. The program de-
tects the DC914 and displays the LTC3210 con-
trol window (shown in Figure 2).

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 914
MAIN/CAM LED CONTROLLER
LTC3210
2
Figure 1. Proper Measurement Equipment Setup for DC914
USING THE LTC3210 QUICKEVAL SOFTWARE
The program provides brightness controls for
the MAIN and CAM LEDs. The UPDATE but-
ton updates the PIC controller and the LED
displays to the current settings on the
LTC3210 demo control window. The FLASH
button flashes the CAM LED from the ENCT
(Torch) setting to the ENCF (Flash) setting for
the time selected in the FLASH TIME drop-
down window. The FLASH TIME drop-down
window allows the user to select the flash time
from 50ms to 1000ms in various increments.
The GRADATION Cycle button briefly illus-
trates how the LTC3210 may increment and
decrement the displays. The LEDS OFF but-
ton resets all LEDs to zero, and stops the
gradation cycle.
VIEW LTC3210 PRODUCT PAGE Button –
This button opens an internet browser and
searches the Linear Technology Corporation
web site for information on the LTC3210 when
an internet connection is available.
ENM Control – This vertical slide control ad-
justs the MAIN display from 0 to 20mA in 8

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 914
MAIN/CAM LED CONTROLLER
LTC3210
3
steps. This is accomplished by clicking on the
up or down arrows to change it by one LSB,
by clicking and dragging the slide pointer, or
by clicking in the vertical scroll bar. The indi-
vidual LED current and the number of pulses
required to achieve this current are displayed
in the two text boxes below the slider.
ENCT Control – This vertical slide control ad-
justs the CAM display from 0 to 162mA in 4
steps. The current is limited in software be-
cause some LEDs can not handle large con-
tinuous currents. The LED intensity may be
adjusted by clicking on the up or down arrows
to change it by one LSB, by clicking and drag-
ging the slide pointer, or by clicking in the ver-
tical scroll bar. The LED current and the num-
ber of pulses required to achieve this current
are displayed in the two text boxes below the
slider.
ENCF Control – This vertical slide control
sets the CAM display intensity during a flash
condition from 0 to 378mA in 8 steps. When
the FLASH button is selected, the CAM dis-
play illuminates at the intensity set by the
ENCF control on the release of the mouse
button for the length of time selected in the
FLASH TIME drop-down window. The LED
flash intensity may be adjusted by clicking on
the up or down arrows to change it by one
LSB, by clicking and dragging the slide
pointer, or by clicking in the vertical scroll bar.
The LED flash current and the number of
pulses required to achieve this current are
displayed in the two text boxes below the
slider.
FLASH Button – When this button is selected
and released, the CAM LED will flash at the
intensity selected in the ENCF register for a
period selected in the FLASH TIME drop-
down window. This is accomplished by reset-
ting the internal counter and DAC by holding
ENC low for the set PULSE TSD time then
applying the set number of pulses on the ENC
pin when the mouse button is released. After
the flash time has elapsed, the CAM display is
set back to the ENCT setting by holding ENC
low for set PULSE TSD time then applying the
set number of pulses on the ENC pin.
FLASH TIME Drop-Down Window – This
window allows the user to select a flash time
from 50ms to 1000ms in various increments.
The flash time is the time the program sets
the CAM display to the ENCF setting on the
release of the mouse button after the FLASH
button was selected.
PULSE TON Drop-Down Window – This win-
dow allows the user to select a pulse ON time
for the ENM and ENC pulses. The ON time
may be adjusted from 5us to 75us in various
increments.
PULSE TOFF Drop-Down Window – This
window allows the user to select a pulse OFF
time for the ENM and ENC pulses. The OFF
time may be adjusted from 5us to 100us in
various increments.
PULSE TSD (RESET) Drop-Down Window –
This window allows the user to select a pulse
TSD time for the ENM and ENC pulses. This
is the time the ENM and ENC pins are held
low to reset the internal counters and DACs
prior to sending the pulses to the enable pins.
This time may be adjusted from 250us to
1000us in various increments.
GRADATION STEP TIME Drop-Down Win-
dow – This window allows the user to select
the length of time for each gradation step
while running the GRADATION Cycle. See
GRADATION Cycle button for more details on
this function. The gradation step time may be
adjusted from 10ms to 242ms in various in-
crements.
UPDATE Button – When this button is se-
lected, the PIC is updated with the timing and
ENM and ENC information and the LED dis-
plays are updated to the present settings on
the demo control window. This is beneficial
when power is initially applied to the demo

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 914
MAIN/CAM LED CONTROLLER
LTC3210
4
board, the ribbon cable has been discon-
nected, or when the PIC RESET push button
has been depressed.
GRADATION Cycle Button – This button
may be selected to start or stop the
GRADATION Cycle. The GRADATION Cycle
cycles through the brightness levels of all the
LEDs starting from the lowest to the highest
intensity and then back to the lowest. To in-
crease the LED intensity, the enable pins are
held low for the set PULSE TSD time prior to
the first pulse of each step. After the highest
intensity is reached, the intensity is then de-
creased by a single low pulse equal to the
PULSE TOFF time for each step. This decre-
ments the internal counter by one from the
previous setting. This is done until the lowest
setting is reached. This cycle is repeated until
the GRADATION Cycle button is selected
again or until the LEDS OFF button is se-
lected.
LEDS OFF Button – This button turns off all
of the LEDs and turns off GRADATION Cycle.
PIC RESET Push Button – This button is lo-
cated on the DC914 demo board. It Resets
the PIC when depressed. The reset button will
not update or change the demo control win-
dow. The UPDATE button may be used to up-
date the PIC to the current demo control win-
dow settings.

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 914
MAIN/CAM LED CONTROLLER
LTC3210
5
Figure 2. LTC3210 Control Window

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 914
MAIN/CAM LED CONTROLLER
LTC3210
6

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