Texas Instruments DEM-PCM2912A EVM Measurements for Dynamic Characteristics, Playback Performance

Measurements for Dynamic Characteristics www.ti.com

4.1Measurements 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-PCM2912A EVM, the evaluation environment specifications are:

∙Equipment used: Audio Precision, System Two Cascade Plus

∙Power supply: VBUS = 5.0 V (Bus power setting)

∙Temperature: Room/ambient

4.2Playback Performance

The DEM-PCM2912A EVM performance presented in this section was obtained under the following conditions:

∙fS = 44.1 kHz

∙Output PGA (Speaker output volume): 0 dB

∙Sidetone from microphone PGA: –76 dB (mute)

∙RL = 10 kΩ / 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.

PC

Playing￿test￿data￿at￿fS =￿44.1￿kHz￿by￿application￿software (for￿example,￿Sound￿Recorder,￿Media￿Player,￿etc.)

			Mic
			J1
	PCM2912A
			Headphone
D2	D1	100￿mA
USB	SW1	JP1	J2
		0￿dB
Connector
		JP2
	PCM2912A-EVM

Audio￿Precision

SYS-2722

Analog￿Analyzer

Left￿ch

Right￿ch

RL

Figure 4-1. DEM-PCM2912A EVM Configuration for Playback Performance Measurement

34 Evaluation and Measurements SBAU141–January 2009

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