YDA131 Datasheet, PDF (9/18 Pages) YAMAHA CORPORATION – D- 1 STEREO 2.5W DIGITAL AUDIO POWER AMPLIFIER

YDA131
●Pop noise reduction function
This IC includes pop noise reduction function that works when turning on and shutting off the power supply, and
controlling the mute or sleep functions.
・When turn on the power supply
This IC is in mute state immediately after turning on the power supply.
The starting process is performed at the power on (sleep cancellation), and after the internal operation stabilizes, the mute
state is cancelled. This operation minimizes the generation of pop noise at turning on the power supply.
To make this function operate effectively, it is necessary to use the input resistor "RI" of the first stage inversion
operational amplifier, the input AC coupling capacitor "CI" of the first stage inversion operational amplifier, and
reference voltage stabilizing capacitor "CR1" under the following condition.
These values must be same for both channels.
Condition: CR1 > (RI * CI)/5000
To make the pop noise reduction function operate effectively when turning on the power supply, the capacitors (CR1) of
VREFL and VREFR terminals must be discharged sufficiently before turning on the power supply again. If you turn on
the power supply again without discharged sufficiently these capacitors, this function does not operate effectively, and
there is a possibility that pop noise generates.
・Starting time
Starting time is a period for each reference voltage to reach the specified potential (for charging capacitors (CR1) of
VREFL and VREFR terminals) when the power supply is turned on or is turned on again. This period varies in relation to
the capacitance (CR1) of VREFL and VREFR terminals.
The table of starting time is as follows:
Table: Starting time
CR1capacitor(µF)
2
10
30
50
Starting time (sec)
0.13
0.33
0.85
1.40
・When shutting off the power supply
This IC performs muting processing internally when the power supply voltage has changed by more than10% in a very
short period or when the power supply voltage is reduced below 3.0V to reduce the pop noise when the IC is shut off.
To make this function operate efficiently, it is necessary to fall the power voltage quickly when shutting off the power
supply.
When the power is supplied to the IC through a voltage regulator and a large capacitance is connected after the regulator,
such as the case shown in "Figure 5: Power supply fall acceleration circuit example", the voltage of VDD can be reduced
quicker if a diode is connected to it.
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