THS4524-EP Datasheet, PDF (36/48 Pages) Texas Instruments – VERY LOW POWER, NEGATIVE RAIL INPUT, RAIL-TO-RAIL OUTPUT, FULLY DIFFERENTIAL AMPLIFIER

THS4524-EP
SBOS609 – JUNE 2012
ADC Driver Performance:
THS4524 and ADS1278 Combined
Performance
The THS4524 provides excellent performance when
driving high-performance ΔΣ and successive
approximation register (SAR) ADCs in audio and
industrial applications using a single 3-V to 5-V power
supply. To show achievable performance, the
THS4524 is tested as the drive amplifier for the
ADS1278 24-bit ADC. The ADS1278 offers excellent
ac and dc performance, with four selectable operating
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modes from 10 kSPS to 128 kSPS to enable the user
to fine-tune performance and power for specific
application needs. The circuit shown in Figure 82 was
used to test the performance. Data were taken using
the High-Resolution mode (52 kSPS) of the ADS1278
with input frequencies at 1 kHz and 10 kHz and
signal levels 1/2 dB below full-scale (–0.5 dBFS). FFT
plots showing the spectral performance are given in
Figure 83 and Figure 84; tabulated ac analysis results
are shown in Table 6 and compared to the ADS1278
data sheet typical performance specifications.
1 kW
1.5 nF
5V
0
-20
-40
-60
-80
-100
-120
-140
-160
0
V_IN+
V_IN-
1 kW
1 kW
49.9 W
THS4524
49.9 W
V_OCM
0.1 mF
1.5 nF
2.2 nF
AINN1
ADS1278 (CH 1)
AINP1 V_COM
x1
1/2
OPA2350
0.1 mF
1 kW
Figure 82. THS4524 and ADS1278 (Ch 1) Test Circuit
1-kHz FFT
G=1
R_F = R_G = 1 kW
C_F = 1.5 nF
V_S = 5 V
Load = 2 x 49.9 W + 2.2 nF
4
8
12
16
20
Frequency (kHz)
Figure 83. 1-kHz FFT
24 26
0
-20
-40
-60
-80
-100
-120
-140
-160
0
10-kHz FFT
G=1
R_F = R_G = 1 kW
C_F = 1.5 nF
V_S = 5 V
Load = 2 x 49.9 W + 2.2 nF
4
8
12
16
20
Frequency (kHz)
Figure 84. 10-kHz FFT
24 26
Configuration
THS4524 and
ADS1278
ADS1278 Data
sheet (typ)
Tone
1 kHz
10 kHz
1 kHz
Table 6. AC Analysis
Signal (dBFS)
–0.5
–0.5
SNR (dBc)
109
102
THD (dBc)
–108
–110
–0.5
110
–108
SINAD (dBc)
105
101
—
SFDR (dBc)
114
110
109
36
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