Semtech launches first smart current sink LED backlighting platform
1 min read
Semtech has announced what it claims to be the industry's first smart current sink LED backlighting platform. The new platform has on chip digital lighting effects for high end handheld displays and incorporates Semtech's Automatic Dropout Prevention (ADP) technology. According to the analogue and mixed signal semiconductor specialist, this enables current sink drivers that can replace boost converters and charge pumps in high end handhelds, while providing high quality display backlighting.
Semtech's ADP topology has been designed to address the problem of current sinks' inability to be optimal for high end devices. This is because line transients caused by the heavy system loads produced display flicker when these loads were enabled and disabled. ADP eliminates this problem via automatic and simultaneous monitoring of each current sink to avoid dropout as the system loads turn on and off. Each time a current sink with ADP approaches dropout, the digital logic reduces the current setting for all of the backlight LEDs in small increments that are imperceptible to the human eye.
This process continues until all current sinks have sufficient headroom to regulate their current at the reduced setting. When this point is reached, the ADP circuitry locks the current setting, thereby eliminating any display flicker. The SC667 and SC668 are the first current sinks to incorporate Semtech's ADP technology.
Semtech claims the new SC667 and SC668 current sinks reduce the total parts count and extend battery life compared to boost converters or charge pumps, and offer 'far superior' illumination quality compared to conventional current sink drivers. On chip digital lighting effects enable users to incorporate fade, breathe and blink effects without changing the firmware.
"With current sink topologies, the supply voltage available to the white LEDs is reduced toward the end of the battery discharge cycle," said Athar Zaidi, director of Marketing in Semtech's Power Management Group. "Semtech's ADP technology ensures that the LEDs dim in uniform and imperceptible steps as the battery voltage declines. The current sink approach also extends battery life, because there are no boost converters to draw higher current as in conventional implementations."
The devices also integrate a number of functions to enable high end features on portables, including an ambient light sensing/control circuit that sets backlight brightness based on surrounding lighting conditions.
