WM8775

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PP Rev 1.8, June 2004

6

ELECTRICAL CHARACTERISTICS

Test Conditions

PARAMETER

SYMBOL

TEST CONDITIONS

MIN

TYP

MAX

UNIT

Digital Logic Levels (TTL Levels)

Input LOW level

0.8

V

Input HIGH level

2.0

V

Output LOW

0.1 x DVDD

V

Output HIGH

0.9 x DVDD

V

Analogue Reference Levels

Reference voltage

AVDD/2

V

Potential divider resistance

50k

Ω

ADC Performance

Input Signal Level (0dB)

1.0 x

AVDD/5

Vrms

SNR (Note 1,2)

A-weighted, 0dB gain

@ fs = 48kHz

93

102

dB

SNR (Note 1,2)

A-weighted, 0dB gain

@ fs = 96kHz

64xOSR

99

dB

Dynamic Range (note 2)

A-weighted, -60dB

full scale input

102

dB

1 kHz, 0dBFs

-90

dB

Total Harmonic Distortion (THD)

1kHz, -3dBFs

-95

-85

dB

ADC Channel Separation

1kHz Input

90

dB

Programmable Gain Step Size

0.25

0.5

0.75

dB

Programmable Gain Range

(Analogue)

1kHz Input

-21

+24

dB

Programmable Gain Range

(Digital)

1kHz Input

-82

+0

dB

Mute Attenuation (Note 5)

1kHz Input, 0dB gain

76

dB

1kHz 100mVpp

50

dB

Power Supply Rejection Ratio

PSRR

20Hz to 20kHz

100mVpp

45

dB

Supply Current

Analogue supply current

AVDD = 5V

48

mA

Digital supply current

DVDD = 3.3V

4.5

mA

Notes:

1.

Ratio of output level with 1kHz full scale input, to the output level with all zeros into the digital input, measured ‘A’

weighted.

2.

All performance measurements done with 20kHz low pass filter, and where noted an A-weight filter. Failure to use

such a filter will result in higher THD+N and lower SNR and Dynamic Range readings than are found in the Electrical

Characteristics. The low pass filter removes out of band noise; although it is not audible it may affect dynamic

specification values.

3.

VMID decoupled with 10uF and 0.1uF capacitors (smaller values may result in reduced performance).

4.

All performance measurement done using certain timing conditions (please refer to section ‘Digital Audio Interface’).

5.

A better MUTE Attenuation can be achieved if the ADC gain is set to minimum.