Data Sheet

AD7951

Rev. A | Page 11 of 32

Pin No.

Mnemonic

Type1

Description

37

REF

AI/O

Reference Input/Output. When PDREF/PDBUF = low, the internal reference and buffer are enabled,

producing 5 V on this pin. When PDREF/PDBUF = high, the internal reference and buffer are disabled,

allowing an externally supplied voltage reference up to AVDD volts. Decoupling with at least a 22 μF is

required with or without the internal reference and buffer. See the Reference Decoupling section.

38

REFGND

AI

Reference Input Analog Ground. Connected to analog ground plane.

39

IN−

AI

Analog Input Ground Sense. Should be connected to the analog ground plane or to a remote sense ground.

40

VCC

P

High Voltage Positive Supply. Normally +7 V to +15 V.

41

VEE

P

High Voltage Negative Supply. Normally 0 V to −15 V (0 V in unipolar ranges).

43

IN+

AI

Analog Input. Referenced to IN−.

45

TEMP

AO

Temperature Sensor Analog Output. Enabled when the internal reference is turned on

(PDREF = PDBUF = low). See the Temperature Sensor section.

46

REFBUFIN

AI

Reference Buffer Input. When using an external reference with the internal reference buffer

(PDBUF = low, PDREF = high), applying 2.5 V on this pin produces 5 V on the REF pin.

See the Voltage Reference Input section.

47

PDREF

DI

Internal Reference Power-Down Input.

When low, the internal reference is enabled.

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

48

PDBUF

DI

Internal Reference Buffer Power-Down Input.

When low, the buffer is enabled (must be low when using internal reference).

When high, the buffer is powered-down.

49

NC

Exposed Pad. The exposed pad is not connected internally. It is recommended that the pad be

soldered to VEE.

Hardware Configuration section and Software Configuration section.