THS4531_14 Datasheet, PDF (38/56 Pages) Texas Instruments – Ultra Low Power, Rail-to-Rail Output, Fully-Differential Amplifier

THS4531
SLOS358B – SEPTEMBER 2011 – REVISED MARCH 2012
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 85. PD Enable Pop Performance
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AUDIO ADC DRIVER PERFORMANCE: THS4531 AND PCM4204 COMBINED PERFORMANCE
To show achievable performance with a high performance audio ADC, the THS4531 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 THS4531 as a drive amplifier. The standard
PCM4204 EVM is provided with 4x OPA1632 fully differential amplifiers, which use the same pin out as the
THS4531. For testing, one of these amplifiers is replaced with a THS4531 device in same package (MSOP), gain
changed to 1V/V, and power supply changed to single supply +5V. Figure 86 shows the circuit. With single
supply +5V supply the output common-mode of the THS4531 defaults to +2.5V as required at the input of the
PCM4204. So the resistor connecting the V_OCM input of the THS4531 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.
2 kΩ
V_IN–
2 kΩ
From Analyzer
V_IN+
0.22 μF
2 kΩ
1 nF
40.2 Ω
5V
+
V_OCM
–
V_OUT–
THS4531
1 nF
V_OUT+
40.2 Ω
2 kΩ
100 pF
2.7 nF
To Analyzer
PCM4204
100 pF
Figure 86. THS4531 and PCM4204 Test Circuit
38
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