AD7631/AD7634

Preliminary Technical Data

Rev. PrC | Page 12 of 14

Pin

No.

Mnemonic

Type1

Description

38

REFGND

AI

Reference Input Analog Ground.

39

IN−

AI

Differential Negative Analog Input; referenced to IN+.

40

P

High Voltage Positive Supply.

41

P

High Voltage Negative Supply.

43

IN+

AI

Differential Positive Analog Input; referenced to IN-.

45

TEMP

AO

Temperature Sensor Analog Output.

46

REFBUFIN

AI/O

Reference Buffer Input.

When using an external reference with the internal buffer (PDBUF = low, PDREF = high), applying 2.5V

on this pin produces 5V on the REF pin.

When using the internal reference (PDBUF = PDREF = low), this pin should not be connected.

47

PDREF

DI

Internal Reference Power-Down Input.

When low, the internal reference is enabled (PDBUF also needs to be low).

When high, the internal reference is powered down and an external reference must been used.

48

PDBUF

DI

Internal Reference Buffer Power-Down Input.

When low, the buffer is enabled (PDREF also needs to be low).

When high, the buffer is powered-down and an external reference must be used.

Table 7. Data Bus Interface Definition

MODE

MODE1

MODE0

D0/OB/2C

D1/A0

D2/A1

D[3]

D[4:9]

D[10:11]

D[12:15]

D[16:17]

Description

0

0

0

R[0]

R[1]

R[2]

R[3]

R[4:9]

R[10:11]

R[12:15]

R[16:17]

18-Bit Parallel

1

0

1

OB/2C

A0 = 0

R[2]

R[3]

R[4:9]

R[10:11]

R[12:15]

R[16:17]

16-Bit High Word

1

0

1

OB/2C

A0 = 1

R[0]

R[1]

All Zeros

16-Bit Low Word

2

1

0

OB/2C

A0 = 0

A1 = 0

All Hi-Z

R[10:11]

R[12:15]

R[16:17]

8-Bit High Byte

2

1

0

OB/2C

A0 = 0

A1 = 1

All Hi-Z

R[2:3]

R[4:7]

R[8:9]

8-Bit Mid Byte

2

1

0

OB/2C

A0 = 1

A1 = 0

All Hi-Z

R[0:1]

All Zeros

8-Bit Low Byte

2

1

0

OB/2C

A0 = 1

A1 = 1

All Hi-Z

All Zeros

R[0:1]

8-Bit Low Byte

3

1

1

OB/2C

All Hi-Z

Serial Interface

Serial Interface

Table 8. Input Range Selection. Parallel Mode and Serial Hardware Mode

Range

BIP

TEN

HW/SW (serial

mode)

0 - 5V

Low

Low

High

0 - 10V

Low

High

High

±5V

High

Low

High

±10V

High

High

High

All Ranges1

X

X

Low