TDA9855WP Philips Semiconductors, TDA9855WP Datasheet - Page 37

• Manufacturer Part Number: TDA9855WP
• Description: I2C-bus controlled BTSC stereo/SAP decoder and audio processor
• Manufacturer: Philips Semiconductors

Philips Semiconductors
APPLICATION HINTS
Selection of input signals by using the zero-crossing mute mode (see Fig.11)
A selection between the internal signal path and the external input LIL/LIR produces a modulation click depending on the
difference of the signal values at the time of switching.
At t
detector no modulation click is audible.
For example: The selection is enabled at t
bit (GMU = 1) via the I
activates mute.
After a fixed delay time before t
zero-crossing mode (TZCM = 1) to be sure that mute is enabled.
The output signal remains muted until the next signal zero-crossing of input B occurs, and then follows that signal.
The delay time t
1997 Nov 04
handbook, full pagewidth
I
decoder and audio processor
1
(1) Input A (internal signal).
(2) Output.
(3) Input B (external input signal).
2
C-bus controlled BTSC stereo/SAP
the maximum possible difference between signals is 7 V (p-p) and gives a large click. Using the zero-crossing
2
t
V
1
4
3
2
1
0
1
2
3
4
is e.g. 40 ms. The zero-crossing function is working at the lowest frequency of 40 Hz.
2
C-bus. The output signal follows the input A signal, until the next zero-crossing occurs and then
2
Fig.11 Zero-crossing function; only one channel shown.
, the microcontroller has to send the forced mute mode (TZCM = 0) and the return to the
1
t 1
, the microcontroller sets the zero-crossing bit (TZCM = 1) and then the mute
37
t 2
(1)
(2)
(3)
MED436
Product specification
t
TDA9855