Texas Instruments DEM-PCM2912 EVM, User Manual, Page: 34 / 43

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4.1 Measurements for Dynamic Characteristics
4.2 Playback Performance
PC
Playing test data at f = 44.1 kHz by application software
(for example, Sound Recorder, Media Player, etc.)
S
USB
Connector
D2 D1
SW1
JP1
J1
JP2
J2
100 mA
0 dB
PCM2912
PCM2912-EVM
Mic
Headphone
Audio Precision
SYS-2722
Analog Analyzer
Left ch
Right ch
R
L
Measurements for Dynamic Characteristics
Typical dynamic performance graphs for playback and recording devices generally represent three
performance characteristics (in addition to other specifications): total harmonic distortion and noise
(THD+N); signal-to-noise ratio (SNR); and dynamic range (DR). For playback devices, channel separation
is also a performance characteristic. These graphs also specify the test environment and measurement
conditions required in order to meet typical performance values defined in the product data sheet.
For the DEM-PCM2912 EVM, the evaluation environment specifications are:
•
Equipment used: Audio Precision, System Two Cascade Plus
•
Power supply: V
BUS
= 5.0 V (Bus power setting)
•
Temperature: Room/ambient
The DEM-PCM2912 EVM performance presented in this section was obtained under the following
conditions:
•
f
S
= 44.1 kHz
•
Output PGA (Speaker output volume): 0 dB
•
Sidetone from microphone PGA: –76 dB (mute)
•
R
L
= 10 k
Ω
/ 32
Ω
/ 16
Ω
are inserted into headphone jack J2 for headphone output
•
Jumper setting: set JP1 to 100 mA and JP2 to 0 dB
•
Application software for playback: Sound Recorder, Media Player and ITunes for Windows Vista/XP;
QuickTime and ITunes for Mac OS X.
•
Equipment: AP2 Analog Analyzer (SYS-2722)
Configure the equipment as shown in Figure 4-1 .
Figure 4-1. DEM-PCM2912 EVM Configuration for Playback Performance Measurement
34 Evaluation and Measurements SBAU132 – March 2008
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