Evaluation Module User's Guide

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
PCM2912A
PCM2912A-EVM
Mic
Headphone
AudioPrecision
SYS-2722
AnalogAnalyzer
Leftch
Rightch
R
L
Measurements for Dynamic Characteristics www.ti.com
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-PCM2912A 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-PCM2912A 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-PCM2912A EVM Configuration for Playback Performance Measurement
34 Evaluation and Measurements SBAU141 – January 2009
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