28LF-94H - Sharp TV Service Manual (repair manual). Page 13

• 

Black-Current Stabilization (BCS) circuit

• 

Thermal protection

 

V

i(1)

1 

inverting input 1 

V

i(2)

2 

inverting input 2 

V

i(3)

3 

inverting input 3 

GND 4 

ground 

(fin) 

I

om

5 

black current measurement output 

V

DD

6 supply 

voltage 

V

oc(3)

7 

cathode output 3 

V

oc(2)

8 

cathode output 2 

V

oc(1)

9 

cathode output 1 

The PNX3000 is an analog front end for digital video processors. It contains an IF circuit for both analog and digital
broadcast signals, and input selectors and A to D converters for analog video and audio signals. The digital output
signals are made available via three serial data links.
The IC has a supply voltage of 5V. The supply voltage of the analog audio part can be 5V or 8V, depending on the
maximum signal amplitudes that are required.

 

• Multi-standard vision IF circuit with alignment-free PLL demodulator without external components
• Internal (switchable) time-constant for the IF-AGC circuit
• DTV IF circuit for gain control of digital broadcast TV signals.
• Sound IF amplifier with separate AGC circuit for quasi split sound
• IF circuit can also be used for intercarrier sound
• Analog demodulator for AM sound
• Integrated sound trap and group delay correction
• Video ident function detects the presence of a video signal
• Video source selector with 4 external CVBS or YC inputs and 2 analog CVBS outputs with independent source
selection for each output
• Two linear inputs for 1fH or 2fH RGB signals with source selector. The RGB signals are converted to YUV before A to
D conversion. Both inputs can also be used as YPB PR input for DVD or set top box
• Integrated anti-alias filters for video A to D converters