ADE7761B

Rev. 0 | Page 22 of 24

Frequency Outputs

Figure 2 is a timing diagram for the various frequency outputs.

The high frequency CF output is intended for communication

and calibration purposes. CF produces a 90 ms wide, active high

to half the period. For example, if the CF frequency is 20 Hz,

the CF pulse width is 25 ms.

No-Load Threshold

The ADE7761B includes a no-load threshold and start-up current

feature that eliminate creep effects in the meter. The ADE7761B

is designed to issue a minimum output frequency. Any load

generating a frequency lower than this minimum frequency

does not cause a pulse to be issued on F1, F2, or CF. The minimum

output frequency is given as 0.0045% of the full-scale output

frequency (see Table 8 for maximum output frequencies for

ac signals).

For example, with an energy meter with a meter constant of

100 impulses per kWh on F1, F2 using SCF = 1, S1 = 0, and

S0 = 1, the maximum output frequency at F1 or F2 is 0.68 Hz

and 43.52 Hz on CF. The minimum output frequency at F1

In this example, the no-load threshold is equivalent to 1.1 W of

load or a startup current of 4.6 mA at 240 V. Compare this value

to the IEC 62053-21 specification, which states that the meter must

Note that the no-load threshold is not enabled when using the

high CF frequency mode: SCF = 0, S1 = S0 = 1.

NEGATIVE POWER INFORMATION

The ADE7761B detects when the current and voltage channels

have a phase shift greater than 90°. This mechanism can detect

a wrong connection of the meter or the generation of negative

power. The REVP pin output goes active high when negative

power is detected and active low when positive power is detected.

The REVP pin output changes state as a pulse is issued on CF.