HV9982DB1 Supertex, HV9982DB1 Datasheet - Page 4

• Manufacturer Part Number: HV9982DB1
• Manufacturer: Supertex

Specifications of HV9982DB1

• Lead Free Status / Rohs Status: Supplier Unconfirmed

Typical Results
Normal Operation – Fig.1 shows the waveforms during normal operation at full load and 24V input. The smaller pulses in
the drain waveforms represent the ringing between the input inductor of the boost converter and the parasitic capacitance
at the drain pin of the switching FET. This is a normal occurrence in any discontinuous mode converter.
Fig. 1: Waveforms for Normal Operations
Startup – Fig. 2 shows the startup waveforms. These waveforms were obtained by connecting the PWMD pins to VDD and
applying a step waveform at the 24V input. There is a 500μs delay before the ramp voltage starts rising. This delay is due
to the time required to charge the capacitors at the VDD pins plus the internal power-on-reset time. The other part of the
delay is the time required by the ramp capacitor to charge to 5V. Once the RAMP voltage reaches 5V, the converter starts
switching and the LED current starts up slowly without any overshoots.
Fig. 2: Startup Waveforms
Open LED Protection – Figs.3-6 show the over voltage protection in operation. Fig. 3 shows the open circuit condition
occurring when the LED current goes to zero. At this point, the output voltage starts increasing since the energy from the
input is used to charge the output capacitors. Once the output voltage reaches 92V, all three channels are shut down (Note:
Fig. 3: Over Voltage Trigger
C2 (Pink):
C4 (Green): Output Current for Channel 1 (50mA/div)
C1 (Yellow): Input Voltage (10V/div)
Time Scale: 500μs/div
C1 (Yellow): Output Voltage of Channel 1(20V/div)
C4 (Green): Output Current for Channel 1 (50mA/div)
Time Scale: 20μs/div
C1 (Yellow): Drain Waveform for Channel 1 (50V/div)
C2 (Pink):
C3 (Blue):
C4 (Green): Output Current for Channel 1 (100mA/div)
Time Scale: 1μs/div
RAMP waveform (2V/div)
Drain Waveform for Channel 2 (50V/div)
Drain Waveform for Channel 3 (50V/div)
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HV9982DB1