THS4531A Datasheet, PDF (35/51 Pages) Texas Instruments – Ultra Low Power, Rail-to-Rail Output, Fully-Differential Amplifier

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THS4531A
SLOS823A – DECEMBER 2012 – REVISED JANUARY 2013
5
2.5
Power Down
V_OUT +
4
V_OUT −
2
V_S = 5 V
3
G = 2 V/V ^1.5
R_F = 2 kΩ
R_L = 200 Ω
2
1
1
0.5
0
0
0
50m
100m
150m
200m
Time (s)
G074
Figure 87. PD Enable Pop Performance
AUDIO ADC DRIVER PERFORMANCE: THS4531A AND PCM4204 COMBINED PERFORMANCE
To show achievable performance with a high performance audio ADC, the THS4531A is tested as the drive
amplifier for the PCM4204. The PCM4204 is a high-performance, four-channel analog-to-digital (A/D) converter
designed for professional and broadcast audio applications. The PCM4204 architecture utilizes a 1-bit delta-
sigma modulator per channel incorporating an advanced dither scheme for improved dynamic performance, and
supports PCM output data. The PCM4204 provides flexible serial port interface and many other advanced
features. Please refer to its data sheet for more information.
The PCM4204 EVM is used to test the audio performance of the THS4531A as a drive amplifier. The standard
PCM4204 EVM is provided with 4x OPA1632 fully differential amplifiers, which use the same pin out as the
THS4531A. For testing, one of these amplifiers is replaced with a THS4531A device in same package (MSOP),
gain changed to 1V/V, and power supply changed to single supply +5V. Figure 88 shows the circuit. With single
supply +5V supply the output common-mode of the THS4531A defaults to +2.5V as required at the input of the
PCM4204. So the resistor connecting the V_OCM input of the THS4531A to the input common-mode drive from the
PCM4204 is optional and no performance change was noted with it connected or removed. The EVM power
connections were modified by connecting positive supply inputs, +15V, +5VA and +5VD, to a +5V external power
supply (EXT +3.3 was not used) and connecting -15V and all ground inputs to ground on the external power
supply so only one external +5V supply was needed to power all devices on the EVM.
2k
2k
V_IN±
From Analyzer
V_IN+
0.22 F
2k
1 nF
40.2
5V
V_OUT±
+
V_OCM
±
THS4531A
V_OUT+
1 nF
40.2
2k
100 pF
2.7 nF
To Analyzer
PCM4204
100 pF
Figure 88. THS4531A and PCM4204 Test Circuit
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