New Holtek HT7938A/HT7939A White-light LED Drivers

04/27/2012

Following the successful release of the HT7938 and HT7939, and in order to increase the application coverage of WLED backlight small-size panels, Holtek is now delighted to announce the release of two new devices, the HT7938A and HT7939A. Supporting a PWM dimming frequency of up to 200kHz, this series of new LED driver devices will expand the range of suitable WLED backlight applications.

The HT7938A and the previous HT7938 both use a 40V high voltage process and are able to drive up to 10 WLEDs in series. Using LEDs in series means that the individual LED currents are identical resulting in the same generated illumination level from each WLED. Two feedback voltages of 200mV or 300mV provide a variety of design options. Compared with the HT7939, the HT7939A now upgrades the previous internal MOSFET drive current of 950mA up to a value of 1200mA, which can also drive up to 39 LEDs, in a combination of 3-series and 13-parallel. Both the HT7938A and HT7939A also include over-temperature and over-current protection circuits as well as an under voltage lockout (UVLO) function.