THS4521_10 Datasheet, PDF (30/48 Pages) Texas Instruments – VERY LOW POWER, NEGATIVE RAIL INPUT, RAIL-TO-RAIL OUTPUT, FULLY DIFFERENTIAL AMPLIFIER

THS4521
THS4522
THS4524
SBOS458D – DECEMBER 2008 – REVISED AUGUST 2010
Audio On/Off Pop Performance
The THS4521 was tested to show on and off pop
performance by connecting a speaker between the
differential outputs and switching the power supply on
and off, and also by using the PD function of the
THS4521. Testing was done with and without tones.
During these tests, no audible pop could be heard.
With no tone input, Figure 72 shows the pop
performance when switching power on to the
THS4521 and Figure 73 shows the device
performance when turning the power off. The
transients during power on and off illustrate that no
audible pop should be heard
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
0
POWER-SUPPLY TURN-ON POP PERFORMANCE
Power
Supply
Outputs
50
100
150
200
Time (ms)
Figure 72. THS4521 Power-Supply Turn-On Pop
Performance
POWER-SUPPLY TURN-OFF POP PERFORMANCE
5.0
4.5
4.0
3.5
Outputs
3.0
Power
Supply
2.5
2.0
1.5
1.0
0.5
0
0
50
100
150
200
Time (ms)
Figure 73. THS4521 Power-Supply Turn-Off Pop
Performance
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With no tone input, Figure 74 shows the pop
performance using the PD pin to enable the
THS4521, and Figure 75 shows performance using
the PD pin to disable the device. Again, the transients
during power on and off show that no audible pop
should be heard. It should also be noted that the turn
on/off times are faster using the PD pin technique.
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
0
PD ENABLE POP PERFORMANCE
PD
Outputs
50
100
150
200
Time (ms)
Figure 74. THS4521 PD Pin Enable Pop
Performance
PD DISABLE POP PERFORMANCE
5.0
4.5
PD
4.0
3.5
Outputs
3.0
2.5
2.0
1.5
1.0
0.5
0
0
50
100
150
200
Time (ms)
Figure 75. THS4521 PD Pin Disable Pop
Performance
The power on/off pop performance of the THS4521,
whether by switching the power supply or when using
the power-down function built into the chip, shows
that no special design should be required to prevent
an audible pop.
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