ADE7752/ADE7752A

Rev. C | Page 21 of 24

Table 6 shows a complete listing of all maximum output

frequencies when using all three channel inputs.

As the voltage and current inputs respect Equations 5 and 6, the

total real power (P) is

() (

) () (

)

()

()

⎟

⎠

⎞

⎜

⎝

⎛

+

×

×

×

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

⎟

⎠

⎞

⎜

⎝

⎛

+

×

×

−

⎟

⎠

⎞

⎜

⎝

⎛

+

×

×

+

×

×

×

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

⎟

⎠

⎞

⎜

⎝

⎛

+

×

×

−

×

×

=

−

×

−

+

−

−

=

3

2

cos

2

3

4

cos

2

3

2

cos

2

cos

2

3

4

cos

2

cos

2

π

ω

π

ω

π

ω

ω

π

ω

ω

t

I

t

V

v

t

V

t

I

t

V

t

V

P

I

I

V

V

I

I

V

V

P

l

B

l

C

l

B

l

A

l

C

l

A

BN

BP

C

B

AN

AP

C

A

Table 6. Maximum Output Frequency on F1 and F2

B

C

= 0 and

B

()

()

⎟

⎠

⎞

⎜

⎝

⎛

+

×

+

×

⎟

⎠

⎞

⎜

⎝

⎛

×

×

×

+

×

⎟

⎠

⎞

⎜

⎝

⎛

+

×

⎟

⎠

⎞

⎜

⎝

⎛

×

×

×

=

3

2

cos

sin

3

sin

2

cos

3

2

sin

3

2

sin

2

π

t

ω

π

t

ω

π

I

V

t

ω

π

t

ω

π

I

V

P

l

l

B

l

l

A

(9)

P then becomes:

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

⎟

⎠

⎞

⎜

⎝

⎛

+

+

⎟

⎠

⎞

⎜

⎝

⎛

×

×

+

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

⎟

⎠

⎞

⎜

⎝

⎛

+

+

⎟

⎠

⎞

⎜

⎝

⎛

×

×

=

3

2

sin

3

sin

3

2

2

sin

3

2

sin

π

ω

π

π

ω

π

t

I

V

t

I

V

P

l

B

BN

l

A

AN

(10)

As the LPF on each channel eliminates the 2ωl component of

the equation, the real power measured by the ADE7752 is

2

3

2

3

×

×

+

×

×

=

B

BN

A

AN

I

V

I

V

P

If full-scale ac voltage of ±500 mV peak is applied to the voltage

channels and current channels, the expected output frequency

is calculated as follows:

value

reference

nominal

V

4

.

2

0

2

5

.

0

500

1

1

0

,

60

.

0

7

1

=

=

=

=

=

=

=

=

=

=

=

=

=

−

REF

C

CN

C

B

A

BN

AN

V

I

V

rms

ac

peak

I

I

I

V

V

S

S

SCF

F

V

V

m

Hz

Note that if the on-chip reference is used, actual output fre-

quencies may vary from device to device due to reference

tolerance of ±8%.

Hz

139

.

0

2

3

4

.

2

2

2

60

.

0

5

.

0

5

.

0

181

.

6

2

2

=

×

×

×

×

×

×

×

=

Freq

SCF

S1

S0

Max Frequency for

AC Inputs (Hz)

Max Frequency for

DC Inputs (Hz)

1.02

0

0

0

0.51

1

0

0

0.48

0.96

0

0

1

2.04

4.09

1

0

1

1.91

3.84

0

1

0

7.67

15.35

1

1

0

7.67

15.35

0

1

1

30.70

61.4

0.48

1

1

1

0.24

FREQUENCY OUTPUT CF

The pulse output calibration frequency (CF) is intended for use

during calibration. The output pulse rate on CF can be up to

frequency selected, the higher the CF scaling. Table 7 shows

how the two frequencies are related, depending on the states of

the logic inputs S0, S1, and SCF. Because of its relatively high

pulse rate, the frequency at this logic output is proportional to

the instantaneous real power. As with F1 and F2, the frequency

is derived from the output of the low-pass filter after multiplica-

tion. However, because the output frequency is high, this real

power information is accumulated over a much shorter time.

Thus, less averaging is carried out in the digital-to-frequency

conversion. With much less averaging of the real power signal,

the CF output is much more responsive to power fluctuations.

See Figure 15.

Table 7. Maximum Output Frequency on CF

SCF

S1

S0

CF Max for AC Signals (Hz)

0

0

0

1.27

160 × F1, F2 = 81.87

1

0

0

1.19

8 × F1, F2 = 3.83

0

0

1

5.09

160 × F1, F2 = 327.46

1

0

1

4.77

16 × F1, F2 = 30.70

0

1

0

19.07

16 × F1, F2 = 122.81

1

1

0

19.07

8 × F1, F2 = 61.40

0

1

1

76.29

8 × F1, F2 = 245.61

1

1

1

0.60

16 × F1, F2 = 3.84