OPA1688 Datasheet, PDF (27/41 Pages) Texas Instruments – OPA168x SoundPlus 36-V, Single-Supply, 10-MHz, Rail-to-Rail Output Operational Amplifiers

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OPA1688, OPA1689
SBOS724 – SEPTEMBER 2015
Typical Application (continued)
Table 4. Maximum Output Power and THD+N Before Clipping for Different Load Impedances
LOAD IMPEDANCE (Ω)
16
32
600
MAXIMUM OUTPUT POWER BEFORE
CLIPPING (mW)
32
50
16
THD+N AT MAXIMUM OUTPUT POWER
(dB)
–104.1
–109.5
–117.8
Figure 52, Figure 53, and Figure 54 further illustrate the exceptional performance of the OPA1688 as a
headphone amplifier.
Figure 52 shows the THD+N over frequency for a 500-mV_RMS output signal into the same three load impedances
previously tested.
Figure 53 and Figure 54 show the output spectrum of the OPA1688 at low (1 mW) and high (50 mW) output
power levels into a 32-Ω load. The distortion harmonics in both cases are approximately 120 dB below the
fundamental.
0
0
±20
±40
±60
±80
±100
±120
10
100
1000
10000
Frequency (Hz)
C003
Figure 52. THD+N Measured over Frequency (90-kHz
Measurement Bandwidth) for a 500-mV_RMS Output Level
±20
±40
±60
±80
±100
±120
±140
±160
0
5000
10000
15000
20000
Frequency (Hz)
C001
Figure 53. Output Spectrum of a
1-mW, 1-kHz Tone into a 32-Ω Load
(The third harmonic is dominant at a level of –117.6 dB
relative to the fundamental.)
0
±20
±40
±60
±80
±100
±120
±140
±160
0
5000
10000
15000
20000
Frequency (Hz)
C001
Figure 54. Output Spectrum of a 50-mW, 1-kHz Tone Into a
32-Ω Load, Immediately Below the Onset of Clipping
(The highest harmonic is the second harmonic at
–119 dB below the fundamental.)
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