
Supertex inc.
Supertex inc.
 www.supertex.com
HV9931DB1
Doc.# DSDB-HV9931DB1
A032713
The HV9931 LED driver is primarily targeted at low to 
medium power LED lighting applications where galvanic 
isolation of the LED string is not an essential requirement. 
The driver provides near unity power factor and constant 
current regulation using a two stage topology driven by 
a single MOSFET and control IC. Triac dimming of this 
design is possible with the addition of some components for 
preloading and inrush current shaping.
The DB1 and DB2 Demoboards were designed for a xed 
string current of 350mA and a string voltage of 40V for a load 
power of about 14W. The boards will regulate current for an 
output voltage down to 0V.
Nominal input voltage for the DB1 is 120VAC, for the DB2 
230VAC. Design for universal input (85 to 265VAC) is by 
all means possible but does increase cost and size while 
lowering efciency.
The input EMI lter was designed to suppress the differential 
mode switching noise to meet CISPR15 requirements. 
No  specic  components  were  added  to  suppress  currents 
of common mode nature. Common mode current can be 
controlled in many ways to satisfy CISPR 15 requirements.
The  board  is  tted  with  a  number  of  optional  circuits;  a 
schematic of a simplied driver is given as well. The circuits 
featured are output current soft start and protections from 
line overvoltage, load overvoltage and open circuit. The 
driver is inherently short circuit proof by virtue of the peak 
current regulation method.
Board Layout and Connections
LED Driver Demoboard
Input 120VAC // Output 350mA, 40V (14W)
Specications
Input voltage: 100V
RMS
 to 135V
RMS
, 60Hz
Output voltage: 0 to 40V
Output current: 350mA +/-5%
Output power: 14W, Max
Power factor 98%
Total harmonic distortion EN61000-3-2 Class C
EMI limits CISPR 15 (see text)
Efciency 83%
Output current ripple 30%
PP
Input overvoltage 
protection
140V
RMS
, Latching
Output overvoltage 
protection
43V, Latching
Switching frequency 73kHz
Dimensions:  3.5” x 3.0” x 1.25”
General Description
V
A
V
A