ADE7760

Rev. 0 | Page 11 of 24

OPERATION

POWER SUPPLY MONITOR

The ADE7760 contains an on-chip power supply monitor. The

If the supply is less than 4 V ± 5%, the ADE7760 goes into an

inactive state, that is, no energy is accumulated and the CF, F1,

and F2 outputs is disabled. This is useful to ensure correct

device operation at power-up and during power-down. The

power supply monitor has built-in hysteresis and filtering. This

gives a high degree of immunity to false triggering due to noisy

supplies.

The power supply and decoupling for the part should be such

normal operation.

ADE7760

REVP - FAULT - CF -

F1 - F2 OUTPUTS

INACTIVE

ACTIVE

TIME

INACTIVE

5V

4V

0V

Figure 8. On-Chip Power Supply Monitoring

ANALOG INPUTS

Channel V1 (Current Channel)

The voltage outputs from the current transducers are connected

However, at any one time, only one is selected to perform the

power calculation (see the Fault Detection section).

be referenced to a common mode such as AGND.

DIFFERENTIAL INPUT B

±660mV MAX PEAK

V1

V1

COMMON MODE

±100mV MAX

DIFFERENTIAL INPUT A

±660mV MAX PEAK

AGND

Figure 9. Maximum Signal Levels, Channel 1

Channel V2 (Voltage Channel)

The output of the line voltage transducer is connected to the

ADE7760 at this analog input. Channel V2 is a single-ended

voltage input. The maximum peak differential signal on

maximum signal levels that can be connected to Channel 2.

COMMON MODE

±100mV MAX

V2

DIFFERENTIAL INPUT

±660mV MAX PEAK

V2

Figure 10. Maximum Signal Levels, Channel 2

common mode (usually AGND). The analog inputs of the

ADE7760 can be driven with common-mode voltages of up to

100 mV with respect to AGND. However, the best results are

achieved using a common mode equal to AGND.

Typical Connection Diagrams

Figure 11 shows a typical connection diagram for Channel V1.

The analog inputs are being used to monitor both the phase and

neutral currents. Because of the large potential difference

between the phase and neutral, two current transformers (CTs)

must be used to provide the isolation. Note that both CTs are

referenced to AGND (analog ground); the common-mode

voltage is, therefore, 0 V. The CT turns ratio and burden resistor

(RB) are selected to give a peak differential voltage of ±660 mV.

AGND

CT

CT

RB

RB

IN

IP

Figure 11. Typical Connection for Channel 1

Figure 12 shows two typical connections for Channel V2. The

first option uses a potential transformer (PT) to provide

complete isolation from the main voltage. In the second option,

the ADE7760 is biased around the neutral wire, and a resistor

divider is used to provide a voltage signal that is proportional to

the line voltage. Adjusting the ratio of RA and RB + VR is a

convenient way of carrying out a gain calibration on the meter.