tda8433 NXP Semiconductors, tda8433 Datasheet - Page 5

• Manufacturer Part Number: tda8433
• Description: Deflection Processor For Computer Controlled Tv Receivers
• Manufacturer: NXP Semiconductors

Philips Semiconductors
PIN FUNCTIONS
Pin 1 - Ao subaddress
The Ao bit is the least significant bit
of the bus-address. It enables two
TDA8433s, with different
addresses, to be connected to the
same bus.
Pin 2 - Vertical sync input
Positive trigger pulses of
sufficient to exceed the internal
threshold of the ramp generator.
Flyback and blanking will then start
and, during the blanking period, the
circuit will be inhibited for further
input pulses (see Fig.3). It should be
noted that the TDA8433 has no
vertical oscillator therefore, the sync
processor, which is used in this
combination, has to provide trigger
pulses as well when the video input
is absent.
Pin 3 - Vertical blanking
The positive going blanking pulse is
fed from a current source. The
blanking period is fixed by the
capacitor connected to pin 5 and the
resistor connected to pin 4 (see
Fig.3).
Pins 4 and 5 - Reference/flyback
timing
The external resistor connected
between pin 4 and ground provides
a reference current for the triangle
generator circuit. This circuit
generates the triangle waveform at
pin 5. The width of the blanking
pulse is set by the external
capacitor connected to pin 5.
August 1991
Deflection processor for computer
controlled TV receivers
3 V are
Table 1 Sync processor time constants
Pin 6 - DACC (tau switching)
The output voltage, which depends
on the VTRA and VTRC bits in the
I
to the coincidence detector of the
sync processor. In this way the time
constants of the horizontal PLL (in the
sync processor) can be set. If the
TDA2579 is used (see Fig.6) the
effect will be as listed in Table 1.
Pin 7 - DACB (horizontal phase)
The voltage at pin 7 is fed to the
horizontal pulse modulator in the sync
processor. This voltage, together with
the signal produced by the phase 2
detector during horizontal flyback,
sets the phase of the horizontal
output with respect to the flyback
pulse in the horizontal output stage.
The voltage range is variable
between 0.05 V and 10 V.
Pin 8 - DACA (horizontal
frequency)
The frequency of the horizontal
oscillator in the external sync
processor is adjusted by the voltage
level at pin 8. The voltage is variable
in 63 steps from 0.05 V to 10 V (i.e.
0.158 V per step).
Pin 9 - OUT (video switch)
The output at pin 9 is controlled by the
CVBS bit from the control register
where
CVBS = logic 0; the output is HIGH
(open collector)
2
'0'
'0'
'1'
'1'
C-bus control register, is connected
VTRA
'0'
'1'
'0'
'1'
VTRC
5
12 V
5.3 V
1.5 V
0.2 V
OUTPUT
automatic operation
medium
fast (video recorder)
not to be used
CVBS = logic 1; the output is LOW
(saturation voltage)
An external video selector can be
controlled by means of this switching
function.
Pins 10 and 17 - I/O and Voltage
reference
Pin 10 is connected to the output of
the phase 1 detector in the sync
processor. Whether the pin is used as
an input or an output is dependent on
the PHI1 bit of the horizontal
frequency (HFREQ) register. When
PHI = logic 0 (output transistor open)
pin 10 is used as an input. The DC
information at this pin is compared
with the reference voltage at pin 17
and is reflected in the HCENT of the
status register.
HCENT = logic 0; input
HCENT = logic 1; input
In this way the free running frequency
can be adjusted by computer while
the oscillator is locked. Alternatively,
when PHI1 = logic 1, pin 10 is
switched to ground. The free running
frequency of the oscillator can the be
adjusted while watching the screen
provided that pin 10 is connected to
the video input of the sync processor.
Pin 11 -IN (HLOCKN and 50/60 Hz)
This pin is connected to the combined
MUTE and 50/60 Hz pin of the sync
processor. The various DC levels
define the state of the HLOCKN and
50/60 Hz bits in the status register
(see Table 2.)
TIME CONSTANT
Product specification
TDA8433
V
V
ref
ref
at V
at V
17
17