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Measurements for Dynamic Characteristics
4.1
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
• Temperature: Room/ambient
4.2
Playback Performance
The DEM-PCM2912 EVM performance presented in this section was obtained under the following
conditions:
• f
= 44.1 kHz
S
• Output PGA (Speaker output volume): 0 dB
• Sidetone from microphone PGA: –76 dB (mute)
• R
= 10 kΩ / 32 Ω / 16 Ω are inserted into headphone jack J2 for headphone output
L
• 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
PC
Playing test data at f = 44.1 kHz by application software
(for example, Sound Recorder, Media Player, etc.)
USB
Connector
Figure 4-1. DEM-PCM2912 EVM Configuration for Playback Performance Measurement
34
Evaluation and Measurements
= 5.0 V (Bus power setting)
BUS
Figure
S
D2
D1
SW1
4-1.
Mic
J1
PCM2912
Headphone
100 mA
JP1
J2
0 dB
JP2
PCM2912-EVM
www.ti.com
Audio Precision
SYS-2722
Analog Analyzer
Left ch
Right ch
R
L
SBAU132 – March 2008
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