Multirange, +5V, 8-Channel,

Serial 12-Bit ADCs

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Table 1. Control-Byte Format

BIT 7

(MSB)

BIT 6

BIT 5

BIT 4

BIT 3

BIT 2

BIT 1

BIT 0

(LSB)

START

SEL2

SEL1

SEL0

RNG

BIP

PD1

PD0

BIT

NAME

DESCRIPTION

7 (MSB)

START

First logic 1 after CS goes low defines the beginning of the control byte.

6, 5, 4

SEL2, SEL1,

SEL0

These 3 bits select the desired “on” channel (Table 2).

3

RNG

Selects the full-scale input voltage range (Table 3).

2

BIP

Selects the unipolar or bipolar conversion mode (Table 3).

1, 0 (LSB)

PD1, PD0

Select clock and power-down modes (Table 4).

Table 2. Channel Selection

SEL2

SEL1

SEL0

CHANNEL

000

CH0

001

CH1

010

CH2

011

CH3

100

CH4

101

CH5

110

CH6

111

CH7

Table 4. Power-Down and Clock Selection

PD1

PD0

MODE

00

Normal operation (always on), internal clock

mode.

01

Normal operation (always on), external clock

mode.

10

Standby power-down mode (STBYPD), clock

mode unaffected.

11

Full power-down mode (FULLPD), clock mode

unaffected.

Table 3. Range and Polarity Selection for MAX1270/MAX1271

RANGE AND POLARITY SELECTION FOR THE MAX1270

INPUT RANGE

RNG

BIP

Negative

FULL SCALE

ZERO

SCALE (V)

FULL SCALE

0 to +5V

0

0

—

0

0 to +10V

1

0

—

0

±5V

0

1

0

±10V

1

1

0

RANGE AND POLARITY SELECTION FOR THE MAX1271

INPUT RANGE

RNG

BIP

Negative

FULL SCALE

ZERO

SCALE (V)

FULL SCALE

0

0

—

0

10

—

0

0

1

0

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