HV9921DB1 Datasheet, PDF (1/2 Pages) Supertex, Inc – Universal Off-line LED Driver Demoboard

Supertex inc.
Universal Off-line
LED Driver Demoboard
Introduction
The Supertex HV9921DB1 demoboard is a complete LED
power driver to supply a string of LEDs using the HV9921,
an integrated 3-pin high input voltage constant-current
buck regulator IC. The HV9921 integrates a 500V switching
MOSFET and can operate directly from the rectified universal
AC line voltage range of 80 to 265VAC.
The current in the LED string is internally programmed to
20mA ±15%. The HV9921DB1 is ideally suited for driving
strings of LEDs having forward voltage from 20 to 50V at
high efficiency (typically 80% at 120VAC).
Specifications
Parameter
Input voltage range
Load current
LED string voltage
Conducted EMI
Efficiency
The HV9921DB1 is a peak current-controlled buck converter
operating with fixed off-time of 10.5us. Its fixed off-time
control scheme provides good stability and tight regulation of
the LED current throughout the input AC line voltage range.
As its switching frequency varies over the AC line cycle, the
HV9921 inherently introduces frequency dither and simplifies
the compliance with EMI regulations.
HV9921DB1
Value
80 to 265VAC
20mA ± 15%
20 ~ 50V
CISPR15
80% typ.
Board Layout and Connection Diagram
LED-
C0
LED+
D1
L1
HV9921
U1
LED String
LIN
V_F = 20 to 50V
I_F = 20mA
CIN
CDD
D5
+
D3
D4
C2
D2
CIN2
AC Line
80 - 265VAC
Connections
LED+: Connect the Anode of the LED string to this pin.
LED-: Connect the Cathode of the LED string to this pin.
AC1, AC2: Connect AC Line to these pins.
Note:
The demoboard is not protected from output open/
short circuit condition. Damage to the demoboard may
occur if the output load is not properly connected.
Doc.# DSDB-HV9921DB1
A032913
Supertex inc.
www.supertex.com