Low-Power, 8-Channel,

Serial 10-Bit ADC

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9

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

(MSB)

(LSB)

START

SEL2

SEL1

SEL0

UNI/BIP

SGL/DIF

PD1

PD0

Bit

Name

Description

7(MSB)

START

The first logic “1” bit after CS goes low defines the beginning of the control byte.

6

SEL2

These three bits select which of the eight channels are used for the conversion.

5

SEL1

See Tables 1 and 2.

4

SEL0

3

UNI/BIP

1 = unipolar, 0 = bipolar. Selects unipolar or bipolar conversion mode. In unipolar

mode, an analog input signal from 0V to VREF can be converted; in differential bipolar

mode, the differential signal can range from -VREF / 2 to +VREF / 2. Select differential

operation if bipolar mode is used.

2

SGL/DIF

1 = single ended, 0 = differential. Selects single-ended or differential conversions. In

single-ended mode, input signal voltages are referred to AGND. In differential mode,

the voltage difference between two channels is measured. Select unipolar operation

if single-ended mode is used. See Tables 1 and 2.

1

PD1

Selects clock and power-down modes.

0(LSB)

PD0

PD1

PD0

Mode

0

0

0

1

1

0

Internal clock mode

1

1

External clock mode

Table 3. Control-Byte Format

Table 2. Channel Selection in Differential Mode (SGL/DIF = 0)

SEL2

SEL1

SEL0

CH0

CH1

CH2

CH3

CH4

CH5

CH6

CH7

0

0

0

+

–

0

0

1

+

–

0

1

0

+

–

0

1

1

+

–

1

0

0

–

+

1

0

1

–

+

1

1

0

–

+

1

1

1

–

+