24th Feb 09
Leadis LED IP block temperature
compensation engine can be licensed
Leadis Technology has announced that its proprietary LED-Sense
Temperature Sensing and Compensation Engine, implemented
in their semiconductor device LDS8160, is now available
for licensing to third parties as an embedded, stand-alone
IP block. This IP engine, suitable for enhancing the performance
of LED Driver, Light Management Unit and Power Management
Unit ICs, directly measures the junction temperature of
an LED in the system at its precise physical location. Based
on the measurement, the LED drive current is then optimized
according to a user-programmed profile. The engine continuously
monitors the LED, with each measurement cycle taking less
than 200 microseconds per LED.
Because the engine directly measures the junction temperature
of the diode, it achieves accuracies up to +/- 1C, which
roughly doubles the accuracy obtainable with incumbent indirect
solutions that measure the junction temperature of the silicon
in the IC and then extrapolate the temperature at the LED.
Alternatively, for solutions that rely on an external temperature
sensor, the LED-Sense reduces system cost and complexity.
In today's power-hungry environment, LEDs are growing as
a green, higher-efficiency alternative used to light our
world. Regardless of the application, a critical factor
to the adoption of LEDs is its reliability, which degrades
with self-heating. Preventing excessive heating on the device
is one of the most significant challenges system designers
face today. This is especially the case for High Brightness
LEDs in automotive and general illumination. The first step
in preventing excessive self-heating of LEDs is to accurately
and continuously monitor their junction temperature and
quickly react to changes. In this context, Leadis' LED-Sense
Temperature Sensing and Compensation Engine is a unique
tool that can be added to every system designer's tool box.
"We are pleased to bring to the market our patent
pending LED-Sense Temperature Sensing and Compensation Engine
IP," said Donato Montanari, Vice President at Leadis
Technology. "The modular structure of this IP engine
and its small gate count of approximately twenty thousand
gates make it economical and flexible for system designers
to adopt. Our IP can be used in systems where the LEDs are
connected in either series or parallel."
About the LED-Sense Temperature Sensing and Compensation
Engine IP
The LED-Sense Temperature Sensing and Compensation Engine
is comprised of three independent IP blocks. The Sensing
and Acquisition block is a mixed-signal block that outputs
10-bit codes representing sequential readings of the Threshold
Voltage of the different LEDs. The Digital Temperature Processing
block is a hardwired digital signal processor that transforms
the 10-bit voltage codes into 5-bit Temperature codes. The
Temperature Compensation block is the last block of the
pipe and consists of a Look-Up Table that takes the Temperature
codes as address and produces an adjustment value that is
summed to the PWM signal controlling the current of the
LED.
Leadis' LED-Sense Temperature Sensing and Compensation
Engine has been proven on the LDS8160, a backlight driver
for portable applications, and is now being made available
as a stand-alone IP for embedded use. Both the LDS8160 and
its evaluation board are available for sampling.
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