HV9910DB6 Datasheet, PDF (1/5 Pages) Supertex, Inc – Supertex Driver Evaluation Board for OSRAM OSTAR™ LED

HV9910DB6
Supertex Driver Evaluation Board for
OSRAM OSTAR™ LED
General Description
Specifications
The Supertex HV9910DB6 is a simple, constant-current,
LED driver evaluation board designed to drive OSRAM’s
6-chip or 4-chip OSTAR™ from a 24V supply.
The board uses the Supertex HV9910B in a buck
configuration in a constant off-time mode. The peak current
control scheme enables fairly accurate control of the LED
current with a very simple control scheme and a low part
count.
The information in this datasheet also applies to the
demoboards which have the Supertex HV9910.
Parameter
Input voltage
LED string voltage
Output current
Switching frequency
Efficiency@ 24V input
Open LED protection
Output short circuit
protection
Board dimensions
Value
24V ± 10%
12 - 20V
700mA ± 10% for 6-chip OSTAR
750mA ± 10% for 4-chip OSTAR
Variable
94% for 6-chip OSTAR
91% for 4-chip OSTAR
Yes
No
42mm x 16mm
Connection Diagram
24V
+
-
Connections
1.Connect the input voltage source between VIN and
GND as shown.
2.Connect the LED load between VO+ and VO- as
shown (anode to VO+ and cathode to VO-).
Operation of the LED Driver
The Supertex HV9910B LED Driver is a constant off-time,
peak current-controlled buck converter. Constant off-time
mode of operation is necessary to ensure stability of the
peak current mode control since the duty cycle of operation
is greater than 50%. The constant off-time operation gives
a very good line regulation, making the LED current almost
independent of the input voltage. However, constant off-time
operation increases the variation of the LED current with the
LED string voltage, since the inductor current ripple is highly
dependent on the load voltage. This is typically not a prob-
lem since the LED voltage variation for a given load is fairly
small.