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General Description
The Supertex HV9910DB3v.3 demo board is a complete
high current, High-Brightness LED power driver to supply a
string of LED(s) using the HV9910 IC from a low DC voltage.
The demo board can be used to test the performance of the
HV9910 as a constant current driver to power LEDs.
The HV9910DB3v.2 (constant frequency HV9910
demoboard) was not capable of driving LED strings whose
voltage was greater than one-half the input voltage. The
HV9910DB3v.3 rectifi es this drawback by operating in a
constant off-time mode as compared to a constant frequency
mode. The constant off-time mode enables regulation of the
LED current even when the LED voltage string is greater than
one half the input voltage. (Please refer to the application
note AN-H50 on the Supertex website for more information
on the constant off-time mode of operation.)
The HV9910DB3v.3 can supply a maximum output current
of 900mA to drive LED strings from a 9VDC to 30VDC
input. It achieves an overall effi ciency above 85%. The
HV9910DB3v.3 is ideally suited to drive two 1Watt or 3Watt
LEDs from a 12V or 24V input voltage.
The power conversion stage of the HV9910DB3v.3 consists
of a current-controlled buck converter operating at an off-
time of about 5.8µs. The nominal output current of the demo
board can be adjusted to any value less than 900mA using
the on-board trimming potentiometer. PWM dimming can be
achieved by applying a pulse-width-modulated square wave
signal between the PWMD and GND pins.
Board Layout and Connections
HV9910DB3v3
Low Voltage, High Brightness
LED Driver Demo Board
Specifi cations
Input Voltage:
8V – 30V DC
LED string voltage:
See instructions
Load current:
900mA maximum
Switching Frequency:
variable
Effi ciency:
>85%
Dimensions:
82mm X 28mm
8
to
30V
DC
PWM Dimming
(optional)
Enable
Connection
3 2 1
(Board Size: 53mm x 18mm)