Linear Technology DC2218A Demo Manual

DESCRIPTION
Demonstration circuit DC2218A is a matrix LED dimmer
system featuring the LT3965
mer IC. There are 16 500mA LEDs that can be individually
turned on, off, or PWM dimmed with two 8-switch LED
dimmer LT3965 ICs. The two strings of LEDs are driven
with two buck LED driver outputs of the LT3797 triple LED
controller IC. The third channel of the LT3797 serves as a
30V pre-boost voltage regulator to provide a proper input
voltage to the two buck LED driver channels. DC2218A
can be driven from a 9V to 30V input and can survive
transients up to 36V.
A pre-programmed DC2026C Linduino™ One demo circuit
is attached to the DC2218A matrix LED dimmer shield to
create a full matrix LED dimmer system. With the Linduino
One attached as an under-shield microcontroller board, the
entire system can be powered from either a 9V to 36V lab
power supply or battery connected to the EMIVIN banana
jacks or from a 12V 4A+ AC/DC converter connected to
the J7 barrel jack connector.
PERFORMANCE SUMMARY
PARAMETER
Input Voltage (EMIVIN or J7 Barrel Connector)
RTCLK Switching Frequency
PWM Dimming Frequency
I
LED
30V LT3797 CH3 Pre-Boost Voltage
OUT
2
I C Serial Communications Frequency
Barrel Jack Connector Size (for 12V 4A+ Supply)
8-switch matrix LED dim-
Specifications are at T
CONDITIONS
Set by LTC6900
Switching Frequency Divided by 2048
16 LEDs, 8 LEDs Each LT3965
PJ-002AH Power Jack Connector J7
DEMO MANUAL DC2218A
8-Switch Matrix LED Dimmer
DC2218A can be operated by connecting 12V power to the
input and selecting 7 pre-programmed patterns with rotary
switch S1. When connected to a PC through a USB cable,
an eighth setting of S1 (position 7) allows DC2218A to be
operated with a graphical user interface (GUI).
The LT3965 data sheet gives a complete description of
the part, operation and applications information. The data
sheet must be read in conjunction with this demo manual
for demonstration circuit DC2218A. The LT3965EFE is
assembled in a 28-lead plastic TSSOP (FE) package with
a thermally enhanced ground pad. Proper board layout
is essential for maximum thermal performance. See the
data sheet section Layout Considerations.
Design files for this circuit board are available at
http://www.linear.com/demo/DC2218A
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
Linduino and QuikEval are trademarks of Linear Technology Corporation. All other trademarks
are the property of their respective owners.
= 25°C
A
LT3965EFE
MIN TYP MAX
8 36
350
170
500
30
400
2.1
UNITS
V
kHz
Hz
mA
V
kHz
mm ID
dc2218af
1