REV. A

AD7751

–6–

Pin No.

Mnemonic

Description

20

REVP

This logic output will go logic high when negative power is detected, i.e., when the phase angle

between the voltage and current signals is greater that 90

°. This output is not latched and will be

reset when positive power is once again detected. The output will go high or low at the same time as

a pulse is issued on CF.

21

DGND

This provides the ground reference for the digital circuitry in the AD7751, i.e., multiplier, filters

and digital-to-frequency converter. This pin should be tied to the analog ground plane of the PCB.

The digital ground plane is the ground reference for all digital circuitry, e.g., counters (mechanical

and digital), MCUs and indicator LEDs. For good noise suppression the analog ground plane

should only be connected to the digital ground plane at one point, e.g., a star ground.

22

CF

Calibration Frequency Logic Output. The CF logic output gives instantaneous real power informa-

tion. This output is intended to be used for calibration purposes. Also see SCF pin description.

23, 24

F2, F1

Low Frequency Logic Outputs. F1 and F2 supply average real power information. The logic outputs

can be used to directly drive electromechanical counters and two-phase stepper motors. See Transfer

Function section.

PIN CONFIGURATION

DIP and SSOP Packages

TOP VIEW

(Not to Scale)

24

23

22

21

20

19

18

17

16

15

14

13

1

2

3

4

5

6

7

8

9

10

11

12

AD7751

SCF

AGND

RESET

V2P

AC/

DC

V1A

V2N

V1N

V1B

S1

S0

G1

G0

CLKIN

F1

F2

CF

DGND

CLKOUT

FAULT

REVP