PCA84C441 PHILIPS [NXP Semiconductors], PCA84C441 Datasheet - Page 15

• Manufacturer Part Number: PCA84C441
• Description: 8-bit microcontrollers with OSD and VST
• Manufacturer: PHILIPS [NXP Semiconductors]

Philips Semiconductors
10 AFC INPUT
The AFC input is used to measure the level of the
Automatic Frequency Control signal. This is achieved by
comparing the AFC input signal with the output of a 3-bit
DAC as shown in Fig.14. DAC analog switches select one
of 8 resistor taps connected between V
Consequently, eight different voltages may be selected
(see Table 4). The compare signal AFCC, can be tested to
determine whether the AFC input is higher or lower than
the DAC level.
The AFC input shares the same pin as the Derivative Port
line DP1.7. Setting the enable bit AFCE to:
1996 Nov 29
handbook, full pagewidth
Logic 1, selects the AFC function
Logic 0, selects the Derivative Port DP1.7 function.
8-bit microcontrollers with OSD and VST
DP1.7/AFC
DD
AFC2
and V
SS
COMPARATOR
3-BIT DAC
Fig.14 AFC circuit.
.
DP1.7
AFC1
15
Table 4 Selection of V
EN
AFC2 AFC1 AFC0
0
0
0
0
1
1
1
1
EN
AFC0
0
0
1
1
0
0
1
1
84C44X; 84C64X; 84C84X
AFCE
0
1
0
1
0
1
0
1
MCD178
internal bus
AFCC
ref
V
V
V
V
V
V
V
DD
DD
DD
DD
DD
DD
DD
inner latches
V
V
DD
ref
0.125
0.250
0.375
0.500
0.625
0.750
0.875
Product specification
(for V
0.625 V
1.250 V
1.875 V
2.500 V
3.125 V
3.750 V
4.375 V
5.000 V
DD
V
ref
= 5.0 V)