CS5466

12

DS659F1

5.3.3

Selecting Frequency of FOUT

The pulse output FOUT is designed to assist with meter

calibration. Using the FREQ[2:0] pins, FOUT can be set

to frequencies higher than that of E1 and E2. The FOUT

frequency is directly proportional to the E1 and E2 fre-

quencies. Table 2 defines the maximum frequencies for

FOUT and the dependency of FOUT on E1 and E2.

5.3.4

Absolute Max Frequency on E1

and E2

The CS5466 supports input signals on the voltage and

current channels that may not be a sine wave. A typical

situation of achieving the absolute maximum frequency

on E1 and E2 would be if a 250 mV dc signal is applied

to the VIN and IIN input pins. The digital high-pass filter

should be disengaged by selecting HPF = 1.

The absolute maximum pulse rate observed on E1 and

E2, determined by the FREQ[2:0] selection is defined

below in Table 3.

Frequency Select

Maximum Frequency for a Sine Wave (Notes 1, 2 and 3)

FREQ2

FREQ1

FREQ0

E1 or E2

E1+E2

FOUT

0

0

0

0.125 Hz

0.25 Hz

64x(E1+E2)16 Hz

0

0

1

0.25 Hz

0.5 Hz

32x(E1+E2)16 Hz

0

1

0

0.5Hz

1.0 Hz

16x(E1+E2)16 Hz

0

1

1

1.0 Hz

2.0 Hz

2048x(E1+E2)

4,096 Hz

1

0

0

0.125 Hz

0.25 Hz

128x(E1+E2)32 Hz

1

0

1

0.25 Hz

0.5 Hz

64x(E1+E2)32 Hz

1

1

0

0.5 Hz

1.0 Hz

32x(E1+E2)32 Hz

1

1

1

1.0 Hz

2.0 Hz

16x(E1+E2)32 Hz

Notes:

1 A pure sinusoidal input with zero phase shift is applied to the voltage and current channel.

2 MCLK = 4.096 MHz

3 See Figure 1 on page 8 for E1 and E2 timing diagram.

Table 2. Maximum Frequency for E1, E2, and FOUT

Frequency Select

Absolute Max Frequency

FREQ2 FREQ1 FREQ0

E1 or E2

E1+E2

x

0

0

0.25 Hz

0.5 Hz

x

0

1

0.5 Hz

1.0 Hz

x

1

0

1.0 Hz

2.0 Hz

x

1

1

2.0 Hz

4.0 Hz

Table 3. Absolute Max Frequency on E1 and E2