SP4425QDS/12

SP4425Q Electroluminescent Lamp Driver

© Copyright 1998 Sipex Corporation

9

The following scope photos show the affect the tuning resistors (QR1 and QR2) have on the output

waveform. Figure 11 implements only 5K

Ω of series resistance introducing only a slight amount of

filtering of the discharge edge. Figure 12 shows that if the values are increased to 10K

Ω the discharge

edge is reduced even further. A 20K

Ω example is shown in Figure 14 and represents the most amount

of filtering needed. Again, the balance in light output and audible noise must be observed for each

application.

Figure 11.

QR1=QR2=5K

Ω

V

Low noise suppression level

Figure 12.

QR1=QR2=10K

Ω

V

Low noise suppression level

Figure 13.

QR1=QR2=15K

Ω

V

High noise suppression level

Figure 14.

QR1=QR2=20K

Ω

V

High noise suppression level

V

BATTERY

V

DD

C

C

QR1=5K-20K

Ω

QR2=5K-20K

Ω

SP4425Q

Coil=Toko 1.2mH/19Ohm

EL Lamp