HV9982DB1 Supertex, HV9982DB1 Datasheet - Page 3

• Manufacturer Part Number: HV9982DB1
• Manufacturer: Supertex

Specifications of HV9982DB1

• Lead Free Status / Rohs Status: Supplier Unconfirmed

Testing the Demoboard
Normal Operation – Connect the board as shown in the
connection diagram. Ensure that switches S1 and S2 are
LO. Turn on the clock, 24V supply and the reference volt-
age. Connect any of the PWMD pins to VDD. The LEDs of
the corresponding channel will light up. Measure the LED
current using an ammeter and the reference voltage using a
voltmeter. The current will be:
Current matching – Without changing the reference volt-
age, enable each channel individually and measure the cur-
rent (or, if possible, enable all channels and the three output
currents simultaneously). The error will be ≤ ± 3%.
Linear Dimming – Vary the reference voltage between 0
– 500mV and measure the LED current.
The current will vary as per Eqn.1. This variation is fairly lin-
ear until the REF voltage gets very low. As the voltage goes
below 50mV, the current will not match the reference voltage
as linearly.
PWM Dimming – With the reference voltage fi xed at 0.5V,
apply a TTL compatible square wave signal (≤ 1kHz). The
LED current will dim based on the duty cycle of the PWM
input.
I
LED
= V
4.99
REF
± 3.0%
(1)
3
Analog Control of PWM Dimming – Change S1 and S2 as
required using Table 1. Connect the analog 0-2V source at
the PWMD terminal and turn on the demoboard. The LEDs
will dim and the LED current can be adjusted by varying the
analog voltage.
Open LED protection – Connect a voltage probe between
the VO+ terminal of any channel and GND and disconnect
the LED string. The output voltage will rise up to 92V and
trip the over voltage protection. At this point, all three chan-
nels will shut down and the output voltage of the channel
with the open LED condition will be maintained hysteretically
between 92V and 82V until the output voltage of the fauly
channel falls below 82V or till the LED string is reconnected.
Once the LED string is reconnected, all three channels will
turn back on.
Short Circuit Protection – Short the output terminals of any
one channel using a jumper. All three channels shut down
and the IC tries restarting every 1.0ms. Once the short circuit
is removed, all three channels come back into regulation.
HV9982DB1