TDA9847 datasheet(8/28 Pages) PHILIPS

8 / 28 page

1995 May 23

Philips Semiconductors

Preliminary speciﬁcation

TV and VTR stereo/dual sound processor

with digital identiﬁcation

TDA9847

When the microcontroller has only open drain ports

available for the C1, C2 and C3 control line, external

pull-up resistors must be connected to these control lines.

Figure 7 shows an example of a timing diagram to program

the main and SCART register of the TDA9847 with a

microcontroller via the control lines C1, C2, C3 and C4.

Both registers are programmed with the same control line

levels: C1 = LOW, C2 = HIGH and C3 = LOW. The dual

identification frequency is detected and the dual LED is

switched-on. The A-signal (dual mode) is fed to all

AF outputs (see Tables 1 and 2). This is shown in the

beginning of this timing diagram.

The second period of time shows the programming of the

external mode (C3 goes to HIGH: CC-signal) for the main

channel. The switch positions are immediately changed to

the external AF source, because the C4 level is LOW. The

dual LED is switched-off by the logic (see Section

“External mode”).

The next periods of time show the way to change the

switch positions for the SCART channel to route B-signals

to the AF outputs (dual mode: BB). At first the control

output Port of the microcontroller for the C4 line goes into

the high ohmic state. The changing of the C1, C2 or C3

level has no influence on the register data. In the timing

diagram the C1 level changes from LOW-to-HIGH and the

C3 level goes from HIGH-to-LOW. In the next steps the C4

line goes from 3-state-to-HIGH, and the level of the other

control lines are valid for the SCART channel, and the

B-signals are fed (dual mode: BB) to the AF outputs of the

main channel.

After some time in this example the C1 and C2 levels

change from HIGH-to-LOW and the C3 level goes from

LOW-to-HIGH (sound mute). The SCART channel is

immediately muted, because the level of the C4 line is

HIGH.

The last period of time shows the programming of the dual

mode (AA) for the main channel. At first the control output

Port of the microcontroller for the C4 line goes into the high

ohmic state. The changing of the C1, C2 or C3 level has

no influence on the register data. The switch positions of

the SCART channel stay in the sound mute.

In the 3-state mode the C2 level changes from

LOW-to-HIGH, and the C3 level goes from HIGH-to-LOW.

When the C4 level is LOW, the level of the other control

lines are valid for the main channel. The A-signal (dual

mode) is fed to the main outputs.

The operation mode mute (see Table 1) can be achieved

from any position of the C4 control line without going via

3-state.

Figure 5 shows the hold and set-up time of the C1,

C2 and C3 control line in the 3-state mode,

see Chapter “Characteristics”.

MICROCONTROLLER WITH LOW/HIGH OUTPUT PORTS

Figure 11 shows an example of an application circuit for

TDA9847 (VP = 4.5 to 8.8 V) in conjunction with a

microcontroller, which has open drain output ports to

control the main and SCART channel. Four resistors and

two output ports of the microcontroller are necessary to

generate the 3-state voltage. The other control lines have

a pull-up resistor (10 k

Ω) in the event of open drain output

stages. These resistors are not necessary for LOW/HIGH

output ports of the microcontroller having internal pull-up

or push-pull stages. The values and tolerances of these

components are given in this figure. Table 4 shows the

conversion logic truth table.

For information about programming the different operation

mode selections see Section “Operating mode selection”.

Power supply

The different supply voltages and currents required for the

analog and digital circuits are derived from an internal

band-gap reference circuit. The AF reference voltage is

⁄2VP. For a fast setting to 1⁄2VP an internal start-up circuit

is added. A good ripple rejection is achieved with the

external capacitor Cref = 100 µF/16 V in conjunction with

the high ohmic input of the 1

⁄2VP pin (pin 8). No additional

DC load on this pin is allowed.

Power-On Reset (POR)

When a POR is activated by switching on the supply

voltage or because of a supply voltage breakdown, the

117/274 Hz DPLL, the 117/274 Hz integrator and the logic

will be reset. Both AF channels (main and SCART) are

muted (

≤1 ms).

ESD protection

All pins are ESD protected. The protection circuits

represent the latest state of the art.

Internal circuit

The internal pin configuration is given in Fig.7.

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