Linear Technology 1055 User manual

LTC3219
DESCRIPTION
Demo Circuit 1055
QUICK START GUIDE
LTC3219
250mA Universal Nine
Channel LED Driver
WARNING!
Do not look directly at operating LED.
This circuit produces light that can damage eyes.
Demonstration circuit 1055 is a 250mA Universal Nine
Channel LED Driver with two RGB displays and three
white LEDs featuring the LTC3219.
The LTC3219 is a low noise charge pump designed to
drive nine universal LED current sources. The LTC3219
requires only five small ceramic capacitors to form a
complete LED power supply and current controller.
The maximum display currents are set with an internal
precision current reference. On/Off blinking, gradation,
and intensity are achieved via an I
2
C serial interface. See
the LTC3219 data sheet for more information on this
process. There are 64 dimming states available for the
universal LEDs.
The charge pump optimizes efficiency based on the volt-
age 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 a data byte is up-
dated via the I
2
C port.
Design files for this circuit board are available. Call
the LTC factory.
L, LTC, LTM, LT are registered trademarks of Linear Technology Corporation. Other product
names may be trademarks of the companies that manufacture the products.
QUICK START PROCEDURE
Demonstration circuit 1055 is easy to set up to evaluate
the performance of the LTC3219. Refer to Figure 1 for
proper measurement equipment setup and follow the
procedure below:
NOTE. When measuring the input or output voltage ripple, care must be
taken to avoid a long ground lead on the oscilloscope probe. Measure the
input or output voltage ripple by touching the probe tip directly across the
VBAT and GND terminals. See Figure 2 for proper scope probe technique.
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.
NOTE. If using the DC590B board, a specific DVCC voltage level
may be selected. This is done by setting the VCCIO jumper on the
DC590 board to one of the following settings: 3.3V, 5V, removed
for 2.7V or set to external if use of an external supply is desired.
3. Connect DC1055 to the DC590 USB Serial Controller
using the supplied 14-conductor ribbon cable as
shown in Figure 1.
4. With power off, connect the input power supply to
VBAT and GND with a series ammeter and a voltmeter
as shown in Figure 1.
5.
Turn on and set the input power supply between 2.9 –
5.5V. The DC1055 has an extra 4.7uF de-coupling ca-
pacitor between VBAT and GND to help accommodate
long VBAT source lead lengths. The DC590 board gets
its power from the USB cable.
NOTE. Make sure that the input voltage does not exceed 6V.
6. Run the QuikEval program. The program detects the
DC1055 and displays the LTC3219 control window
(shown in Figure 3).
1
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LTC3219
Figure 1. Proper Measurement Equipment Setup
Figure 2. Measuring Input or Output Ripple
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LTC3219
3
USING THE LTC3219 QUIKEVAL SOFTWARE
The LTC3219 program provides brightness controls for
the universal LEDs. It also allows the user to gradate the
universal LEDs up or down and blink at a selected on-
time and period. The LTC3219 also controls the LEDs
from an external enable pin. The intensity of the universal
LEDs may be set by 1) Selecting the check box for the
desired LED, 2) Setting the intensity in the associated
vertical slider, 3) Selecting the SET ULEDs button.
VIEW LTC3219 PRODUCT PAGE button opens an inter-
net browser and searches the Linear Technology Corpo-
ration web site for information on the LTC3219 when an
internet connection is available.
REG 0 through REG 11 text box windows display the
hexadecimal value that has been written to the corre-
sponding registers.
SELECT ALL selects all universal LEDs to change when
the SET ULEDs, CLEAR ULEDs, or other LED control but-
tons are selected.
DESELECT ALL deselects all selected universal LEDs and
prevents the universal LEDs from changing intensity or
modes.
ULED1 through ULED9 check boxes are used to indi-
vidually select or deselect the universal LEDs.
ULEDs 1-3 vertical slide control adjusts the intensity for
selected universal LEDs U1 through U3 from 0 to 28mA
in 64 steps. The SET ULEDs, BLINK ULEDs, or other LED
control buttons need to be selected to illuminate the se-
lected LEDs. The LED intensity slider may be adjusted by
clicking on the up or 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 vertical slide control adjusts the intensity for se-
lected universal LEDs U4 and U7 from 0 to 28mA in 64
steps. The SET ULEDs, BLINK ULEDs, or other LED con-
trol buttons need to be selected to illuminate the selected
LEDs. The LED intensity slider may be adjusted by click-
ing on the up or 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.
GREEN vertical slide control adjusts the intensity for se-
lected universal LEDs U5 and U8 from 0 to 28mA in 64
steps. The SET ULEDs, BLINK ULEDs, or other LED con-
trol buttons need to be selected to illuminate the selected
LEDs. The LED intensity slider may be adjusted by click-
ing on the up or 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.
BLUE vertical slide control adjusts the intensity for se-
lected universal LEDs U6 and U9 from 0 to 28mA in 64
steps. The SET ULEDs , BLINK ULEDs, or other LED con-
trol buttons need to be selected to illuminate the selected
LEDs. The LED intensity slider may be adjusted by click-
ing on the up or 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.
SET ULEDs button sets all selected LEDs to the selected
intensity settings.
QUICK WRITE button sets all LEDs to the intensity and
mode of ULED1 using the LTC3219 Quick Write feature.
The intensity of ULED1 is updated to the value indicated
on the ULEDs 1-3 vertical slider. All vertical sliders and
register text boxes on the LTC3219 control window are
updated to match the IC settings. The ULED1 check box
does not need to be selected for this button to work.
CLEAR ULEDs button turns off and clears the register of
all selected LEDs.
ENU OUTPUT SELECT button sets or unsets the ENU
control for the selected LEDs. When a LED ENU output is
selected, the ULED register label below the ULED register
text box is highlighted in blue. If gradation with ENU con-
trol is desired, use the START GRADATION WITH ENU
control button.
SET ENU PIN HI button sets the ENU pin high or low and
turns on or off the LEDs under ENU control. If the LED is
set for gradation or blinking with ENU control, the LED
will gradate up/down, or start/stop blinking at the se-
lected intensity.
GRADATION TIME option buttons set the desired time to
gradate up to or down from the selected LED intensity
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LTC3219
when the GRADATE UP, GRADATE DOWN, START
GRADATION WITH ENU or DEMO 1 button is selected. If
the DISABLED option button is selected, the universal
LEDs will not gradate when any of the GRADATION con-
trol buttons are selected.
GRADATE UP button gradates the selected LEDs up to
the set intensity at the selected gradation time. Gradation
is disabled when done. The ULED check box is high-
lighted purple to indicate that gradation mode has been
enabled.
GRADATE DOWN button gradates the selected LEDs
down from the set intensity at the selected gradation
time. Gradation is disabled when done. The ULED check
box is highlighted purple to indicate that gradation mode
has been enabled.
START GRADATION WITH ENU button gradates the se-
lected LEDs up to the set intensity when the ENU pin is
high (SET ENU PIN HI button is selected) and down
when the ENU pin is low. If this button is selected while
in gradation with ENU mode and with the ENU PIN high,
gradation and ENU control will be relinquished with the
LEDs set. If this button is selected while in gradation with
ENU mode and with the ENU PIN low, gradation and ENU
control will be relinquished with the LEDs off. During
gradation with ENU control, all other ULEDs must remain
off and the charge pump must remain in Auto mode (not
forced to any mode). The ULED check box is highlighted
purple to indicate that gradation mode has been enabled.
NOTE. The gradation time must be set to something other than
DISABLED to gradate the LEDs.
BLINK ONt/PERIOD option buttons set the desired blink-
ing on-time and period to blink after the BLINK ULEDs
button has been selected.
BLINK ULEDs button blinks or stop blinking the selected
LEDs at the on-time and period selected by the BLINK
ONt/PERIOD option buttons and at the selected LED in-
tensity. The ULED check box is highlighted green to indi-
cate that blink mode has been enabled.
CHARGE PUMP MODE option buttons allow the user to
select between Auto (not forced to any mode), Force 1x,
Force 1.5x, and Force 2x charge pump modes.
GPO MODE button disables or enables dropout for the
selected LEDs. When dropout is disabled the LEDs will
not cause the charge pump to switch into 1.5x or 2x
modes and the pin may be used as a general-purpose
output (GPO mode). The ULED check box is highlighted
orange to indicate that GPO MODE has been selected.
UPDATE ALL REG button updates the data registers to
the data displayed in the register text boxes.
LEDs OFF button turns off and resets all LEDs and LED
modes, plus stops and resets all demos.
DEMO 1-Rainbow button may be selected to start or
stop DEMO 1. This demo cycles through the different
colors that the two RGB LEDs can produce using the
LTC3219’s gradation feature. The default gradation time
for this demo is 0.96s, however the 0.48s or 0.24s gra-
dation times may be used by selecting the desired grada-
tion time prior to starting the demo.
DEMO 2-Light Cycle button may be selected to start or
stop DEMO 2. This demo gradates up and blinks all uni-
versal LEDs starting with ULED1 to ULED9. After all
LEDs are up and blinking, the LEDs are gradated off
starting with ULED1 to ULED9. This is accomplished us-
ing the LTC3219’s gradation and blinking modes.
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LTC3219
Figure 3. LTC3219 Control Window
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LTC3219
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LTC3219
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