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Introduction
1.1
Requirements
1.1.1
Software
1.1.2
Host Computer
1.1.3
Power Supply Requirements
Introduction
www.ti.com
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Available Settings
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HPA357A Bill of Materials
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HPA358A Bill of Materials
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The Texas Instruments TLC5944 is a 16-channel, constant-current LED driver that is capable of driving up
to 60 mA per channel. The TLC5944 has several features including 6-bit Dot Correction, 12-bit grayscale
PWM dimming, Pre-Charge FET, LED failure and overtemperature detection. For more information on
PWM dimming, see the TLC5944 data sheet (
), a Dot Correction technical paper (
and a PWM Dimming technical paper (
) on the TI Web site. This EVM contains three TLC5944
integrated circuits (IC) connected in series. The three ICs drive 16 light-emitting diodes (LED), each
having a red, green, and blue LED in the same package.
Multiplexing, Ghosting, and Pre-Charge FETs
The EVM is also configured to demonstrate LED multiplexing, which is connecting more than one LED to
an LED driver output. The EVM demonstrates multiplexing by connecting an additional row of red LEDs to
one of the LED driver ICs. The practice of multiplexing LEDs often generates a phenomenon known as
Ghosting. This phenomenon is also called Phantom Noise or Spike Noise. Ghosting occurs when an LED
is programmed to be off, but is visually illuminated. The LED is illuminated because of stray currents
flowing through it that are generated by switching the rows of LEDs in and out of the circuit, stray board
capacitance, and mismatches in diode forward voltages. The TLC5944 contains Pre-Charge FETs that
shunt these currents around the LEDs so they do not produce light. The EVM GUI software allows the
user to easily demonstrate multiplexing both with and without the Pre-Charge FETs to see the ghosting
effect.
In order to operate this EVM, the following components must be connected and properly configured. All
components, software, and connectors are supplied in the EVM except for the host computer and the dc
power supply
Texas Instruments provides a compact disk (CD) in the EVM kit that contains the software necessary to
evaluate the TLC5944EVM. Check the TLC5944 product folder on the TI Web site (
) for
updates to the software.
A computer with a USB port is required to operate this EVM. The TLC5944 software runs on the personal
computer (PC) and communicates with the EVM via the PC’s USB port.
PC Requirements:
•
Windows™ 2000 or Windows XP operating system
•
USB port
•
Minimum of 30 MB of free hard disk space (100 MB recommended)
•
Minimum of 256 MB of RAM
A dc power supply capable of delivering 5 V at 1 A is required to power the EVM.
controlCARD is a trademark of Texas Instruments.
Windows, Internet Explorer are trademarks of Microsoft Corporation.
VeriSign is a trademark of VeriSign, Inc.
ZigBee is a trademark of ZigBee Alliance.
TLC5944EVM-358
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SLVU306 – April 2009
