Low-Cost, 2-Channel, ±14-Bit Serial ADCs

16

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X = Don't Care

Table 3. Procedure to Calibrate the ADC

0

0

1

0

0

or

1

00

XX

No

Change

00

1

Performs an offset-null conversion with the

internal ADC inputs shorted to the selected

input channel's negative input (IN1- or IN2-).

The next operation performs the first signal

conversion with the new setup.

3

0

0

0

1

X

00

XX

No

Change

00

1

Performs a gain-calibration conversion with

the null register contents as the starting value.

The result is stored in the calibration register.

2

0

0

1

1

X

00

XX

New

Data

00

1

Sets the new conversion speed (if required)

and performs an offset correction conversion

with the internal ADC inputs shorted to REF-.

The result is stored in the null register.

(This step also selects the speed/resolution

for the ADC.)

1

PD

PDX

NUL

CAL

CHS

Not

Used

DV2 &

DV4

CONV1-

CONV4

Not

Used

N

NO

O--O

OP

P

DESCRIPTION

STEP

CONTROL WORD

X = Don't Care

Table 2. Allowable Input Multiplexer Configurations

Input control word is not transferred to the control register. ADC

configuration remains unchanged and no new conversion starts when CS

returns high.

No

Change

No

Change

0

X

X

X

REF+ and REF- connected to the ADC inputs; gain-calibration mode

selected. Autocal conversion begins when CS returns high, and the results are

stored in the 16-bit I/O register.

REF-

REF+

1

X

0

1

REF- connected to the ADC inputs; offset-null mode selected. Autonull conversion

begins when CS returns high, and the results are stored in the null register.

REF-

REF-

1

X

1

1

IN2- connected to the ADC inputs; offset-null mode selected. Autonull conversion

begins when CS returns high, and the results are stored in the null register.

IN2-

IN2-

1

1

1

0

IN1- connected to the ADC inputs; offset-null mode selected. Autonull conversion

begins when CS returns high, and the results are stored in the null register.

IN1-

IN1-

1

0

1

0

Channel 2 connected to ADC inputs. Conversion begins when CS returns high.

IN2-

IN2+

1

1

0

0

Channel 1 connected to ADC inputs. Conversion begins when CS returns high.

IN1-

IN1+

1

0

0

0

DESCRIPTION

ADC IN-

ADC IN+

N

NO

O--O

OP

P

CHS

NUL

CAL