Wolfson Microelectronics

10

WM0831, WM0832

Pin Descriptions

WM0831

Pin

Name

Type

Function

1

CS

Digital

Chip Select

(active low)

2

IN+

Analogue input

Positive differential

input

3

IN-

Analogue input

Negative differential

input

4

GND

Supply

Analogue and digital

ground

Analogue input

Voltage reference

input

6

DO

Digital input

Data Output

7

CLK

Digital input

Clock input

Supply

Positive supply

voltage

WM0832

Pin

Name

Type

Function

1

CS

Digital

Chip Select

(active low)

2

CH0

Analogue input

Channel 0 input to

multiplexer (MUX)

3

CH1

Analogue input

Channel 1 input to

multiplexer (MUX)

4

GND

Supply

Analogue and

digital ground

5

DI

Digital input

Data input

6

DO

Digital input

Data Output

7

CLK

Digital input

Clock input

voltage and

voltage(ratiometric)

reference input

Multiplexer / Package Options

Device

Number of Analogue Channels

Number of

No

Single Ended

Differential

Package Pins

WM0831

1

1

8

WM0832

2

1

8

Functional Description

Input and Multiplexer Operation and Addressing

WM0831 has two inputs IN+ and IN- configured for

differential operation, single ended operation is achieved

by grounding IN- to an analogue common or GND.

WM0832 uses an input multiplexer scheme with two input

channels, configurable for single-ended or differential

operation. The single ended input uses the GND pin as its

analogue ground reference.

WM0831/2 uses a successive approximation routine to

perform A/D conversion and employs a sample data

comparator structure which always performs conversion

on a differential voltage. Conversion takes place on the

voltage difference between assigned “+” and “-” inputs and

the converter expects the “+” input to be the most positive,

if the “+” input is more negative than “-” then the converter

gives an all zeros output. Assignment of WM0832 inputs

is made for a single-ended signal between an “+” input

and (analogue) ground (GND), or for a differential input

between CH0 and CH1 inputs of either polarity.

For WM0832 prior to the start of every conversion the input

configuration is assigned during the MUX addressing

sequence by serially shifting data into the Data Input (DI) on

the second and third rising edges of the clock input. The

MUX address selects which analogue inputs are enabled,

either single-ended or differential. For differential inputs the

polarity of the inputs are also assigned. The MUX

addressing table gives full details of input assignments.

Because WM0831 has only one differential input of fixed

polarity it does not require addressing.

WM0832 MUX Addressing

MUX Address

Channel Number

SGL/DIF

ODD/EVEN

0

1

Differential MUX Mode

00

+-

01

-+

Single Ended MUX Mode

10

+

11

+