Advanced Information

WM8740

WOLFSON MICROELECTRONICS LTD

AI Rev 1.7 July 2000

5

TEST CONDITIONS

PARAMETER

SYMBOL

TEST CONDITIONS

MIN

TYP

MAX

UNIT

Analogue Output Levels

Into 10kohm, full scale 0dB,

(5V supply)

2

Output level differential

Into 10kohm, full scale 0dB,

(3.3V supply)

1.32

To midrail or AC coupled

(5V supply)

1

kohms

Minimum resistance load

To midrail or AC coupled

(3.3V supply)

600

ohms

Maximum capacitance load

5V or 3.3V

100

pF

Output DC level

AVDD/2

V

Reference Levels

Potential divider resistance

AVDD to VMIDL/VMIDR and

VMIDL/VMIDR to AGND

10

kohms

Voltage at VMIDL/VMIDR

AVDD/2

POR

POR threshold

2.2

V

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 over a 20Hz to 20kHz bandwidth.

2.

All performance measurements done with 20kHz low pass 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.

BCKIN

DIN

LRCIN

t

BCH

t

BCL

t

BL

t

LB

t

BCY

t

DS

t

DH

Figure 1 Audio Data Input Timing

Test Conditions

PARAMETER

SYMBOL

TEST CONDITIONS

MIN

TYP

MAX

UNIT

Audio Data Input Timing Information

BCKIN pulse cycle time

100

ns

BCKIN pulse width high

40

ns

BCKIN pulse width low

40

ns

BCKIN rising edge to

LRCIN edge

20

ns

LRCIN rising edge to

BCKIN rising edge

20

ns