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HV9910DB6中文资料

General Description

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.

con? guration 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.

Connection Diagram

Supertex Driver Evaluation Board for

OSRAM OSTAR? LED

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.

Speci? cations

Typical Results

Full Load Efficiency vs. Input Voltage

9293

Input Voltage (V)

E f f i c i e n c y (%)

Fig. 1. Full Load Efficiency Plot

Fig. 1 shows the full load ef? ciency of the LED driver over the input voltage range of the driver.

Fig. 2. Line Regulation of Output Current

Line Regulation of LED Current

-1-0.5

0.5

Input Voltage (V)

% c h a n g e i n c u r r e n t

Fig. 2 shows the line regulation of the driver over the input voltage range.

Typical Results

Load Regulation of LED Current

(@V IN = 24V)

0.7

0.71

0.72

0.73

0.74

0.750.76

Output Voltage (V)

L E D C u r r e n t (A )

Fig. 3. Load Regulation of Output Current

Fig. 3 shows the variation of the output current with output voltage.

Switching Frequency vs. Input Voltage

(@V O = 19V)

02040608010012021

252627

Input Voltage (V)

S w i t c h i n g F r e q u e n c y (k H z )

Fig. 4a. Switching Frequency Variation with Input

Voltage

Fig. 4a shows the variation of the switching frequency over the entire input voltage range.

Typical Results

LED Current Drain Voltage Fig. 5a. Steady State Waveforms for a 6-chip OSTAR LED Current

Drain Voltage

Fig. 5b. Steady State Waveforms for a 4-chip OSTAR

Switching Frequency vs. Load Voltage

(@V IN = 24V)

040

120

160

200

Output Voltage (V)

S w i t c h i n g F r e q u e n c y (k H z )

Fig. 4b. Switching Frequency Variation with Output

Voltage

Fig. 4b shows the variation of the switching frequency with the load voltage.

Fig. 5 shows the steady state waveforms of the LED driver driving the OSTAR loads.

Schematic

VO+