Features And Diagnostics; The Mode Select Pin; The Status I/O Pin - Philips TDA1562Q Application Note

Philips Semiconductors

2. Features and Diagnostics

The TDA 1562Q is equipped with three pins with which a number of functions and
features can be controlled and which can give information about the status of the device.

2.1 The Mode select pin

First of all, the Mode Select pin controls switching on and off of the device.
By controlling the voltage at the mode select pin, the device can be switched into the
mute condition and into the operating condition.
The transition levels (thresholds) specified in the data sheet are maximum and minimum
values. For instance when the threshold for stand-by to mute is specified at 2V
(maximum) and the threshold for mute to stand-by is specified at 1V (minimum), the
actual values will be between 1 and 2 V. Between the two threshold levels there is a
hysteresis of 200 mV. For example, when the device switches from stand-by to mute at
1.6 V, switching from mute to stand-by will occur when the mode select voltage drops
below 1.4 V (see also fig.7 of the data sheet). This hysteresis is built in to prevent that
the device will come into an undefined state when the mode select voltage is increased
or decreased very slowly.
With the maximum and minimum values for the different thresholds, the mode select
voltage ranges where the device is guaranteed to be in a certain condition, can be
determined.
-The device is guaranteed in stand-by when the mode select voltage is below 1V
-When the mode select voltage is between 2V and 3.3V, the device is in the mute
condition.
-When the mode select voltage is between 4.2V and Vp, the device is in the operating
condition.
The mute function which is controlled by the mode select voltage is a zero-cross mute.
The mute function will only engage or disengage when the signal passes through 0V.
This way, the mute operation will cause as little unwanted noise as possible.

2.2 The Status I/O pin

The Status I/O pin (pin 16) can be used as an input pin as well as an output pin.
Using the Status I/O pin as an input pin is done by forcing an external voltage on this pin.
The levels and thresholds at pin 16 are the same as those for the mode select pin, only
the functions controlled by the status I/O voltage are different.
-When the voltage at pin 16 is 0V to 1V, the device is muted. This mute function is a fast
mute, so it will cut off the signal, regardless of the output level at the moment of muting.
The fast mute may cause a plop-like sound when it is engaged at a high output level, but
in some situations a fast mute is required.
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Application note Rev. 01.02 — 05 May 2006
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TDA1562Q application note
© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
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