WM9705 datasheet(10/55 Pages) WOLFSON

10 / 55 page

WM9705

Production Data

PD Rev 4.4 August 2006

Test Characteristics:

AVDD = 3.3V, DVDD = 3.3V, MCLK = 24.576MHz, TA = 25

oC, unless otherwise stated.

PARAMETER

SYMBOL

TEST CONDITIONS

MIN

TYP

MAX

UNIT

PEN and AUXILIARY INPUT ADC

Resolution

Bits

Differential non-linearity error

DNL

+/-0.25

LSB

Integral non-linearity error

INL

+/-2

LSB

Offset error

+/-4

LSB

Gain error

+/-4

LSB

Noise

500

µVrms

Conversion time

20.8

µsec

Acquisition time

µsec

Throughput rate

kHz

Multiplexer settling time

500

nsec

X conversion

X+ pin

Y conversion

Y+ pin

ADC positive reference

auxiliary conversion

AVDD1

X conversion

X- pin

Y conversion

Y- pin

ADC negative reference

auxiliary conversion

AGND1

ADC sampling capacitance

AUXADC input range (fullscale)

AGND1

AVDD1

AUXADC input leakage current

+/-0.5

µA

BMON input range

AGND1

6.5V

BMON input impedance

at sampling time

Ω

BMON effective input

impedance (Note 3)

93.75Hz sample rate

7.7

Ω

BMON input gain

1/3

PEN INTERFACE

Full scale input range

AVDD

Positive input

AVDD

Absolute input range

Negative input

Capacitance

Leakage current

+/-0.5

µA

Screen switch on resistance

Ω

PIL = 0

200

Pressure measurement current

PIL = 1

400

µA

External Pen-detect pull up

resistor value

100

Ω

Pen Detect Comparator

Threshold DAC Range

PDDACR

0.1

1.65

Pen Detect Comparator

Threshold DAC step size

PDDACLSB

0.1

Note:

Harmonic distortion on the headphone output decreases with output power – see Figure 3.

SNR is the ratio of 0dB signal amplitude to noise floor with no signal present (all 0s input code to DACs).

The input impedance of the BMON input is 30k to ground when the ADC is sampling and hi-Z when it is not. The effective

input resistance is calculated dependant on how often the battery is sampled by the user. 7.7M

Ω is the effective

impedance if the battery is sampled once every 512 frames. For a fuller description of this and information on how to

calculate the effect input impedance please see the section on auxiliary conversions on pages 46.

ADC sampling capacitance allows the user to calculate the minimum external capacitance required for a stable ADC value.

WM9705 Datasheet(PDF) 10 Page - Wolfson Microelectronics plc

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