WT8043

Weltrend

Semiconductor,

Inc.

2F., No. 24, Industry E. 9th Rd.

Science-Based Industrial Park

Hsin-Chu, Taiwan, R.O.C.

Tel:

886-35-780241

Fax: 886-35-770419

16

Horizontal Frequency Discriminator

There are 3 horizontal frequency discriminator pins on 20 pin type package:

36.2kHz, 45kHz, 52kHz (for N20P1), 33kHz, 36.2kHz, 45kHz (for N20P4); 2

frequency discriminator pins on 16 pin type package: 33kHz, 36.2kHz and 6

frequency discriminator pins on 24 pin type package: 33kHz, 36.2kHz, 45kHz,

52kHz, 62kHz and 72kHz.

Please refer to table 3 for the logical truth table of

these pins. These frequency discriminator pins can pull up to +12V through a

resistor, sink current to the open drain structure must keep under 6mA (ref. P4

Electrical Characteristics). These frequency discriminator pins output can be used

for CS Capacitor Control directly as well as other application.

Table 3: Truth table of Frequency discriminator

Signal

Hsync

F33K F36.2K

F45K

F52K

F62K

F72K

Hs

< 33k

1

1

1

1

1

1

36.2k > Hs > 33k

0

1

1

1

1

1

45k > Hs > 36.2k

0

0

1

1

1

1

52k > Hs > 45k

0

0

0

1

1

1

62k > Hs > 52k

0

0

0

0

1

1

72k > Hs > 62k

0

0

0

0

0

1

Hs

> 72k

0

0

0

0

0

0

SYNC Output State Description

Both H_out / V_out duplicate Hsin/Vsin in the same frequency and pulse width,

but are fixed at negative polarity. And H_out/ V_out have their own cut-off

frequency: 15kHz for H_Sync and 30Hz for V_Sync. While the frequency of input

signal is less than the cut-off frequency, the output will keep in low state. Please

refer to the Table 4.

Table 4:

Hsin

Vsin

H_out

V_out

>15kHz

>30Hz

Negative polarity Hsin

Negative polarity Vsin

>15kHz

<30Hz

Negative polarity Hsin

Low state

<15kHz

>30Hz

Low state

Negative polarity Vsin

<15kHz

<30Hz

Low state

Low state