BL6502A

BL6502A

BL6502A

BL6502A

http://www.belling.com.cn

- 9 -

3/15/2007

Total 14 Pages

Single Phase Energy Meter IC

Single Phase Energy Meter IC

Single Phase Energy Meter IC

Single Phase Energy Meter IC

with Integrated Oscillator

with Integrated Oscillator

with Integrated Oscillator

with Integrated Oscillator

such, the meter designed for the 50Hz input signal can be used on the transmission-line system of

electric power whose frequency is 60Hz.

VOLTAGE CHANNEL INPUT

The output of the line voltage transducer is connected to the BL6502A at this analog input. As

Figure4 shows that channel V2 is a fully differential voltage input. The maximum peak differential

signal on Channel 2 is ±660mV. Figure4 illustrates the maximum signal levels that can be

connected to the BL6502A Voltage Channel.

V1

V2

+660mV

-660mV

V1

V2

AGND

V1A

V1N

+

-

V1B

+

-

V1

GAIN

GAIN

Maximun input differential voltage

±660mV

Maximun input common-mode voltage

±100mV

Figure 4.

Voltage Channels

Voltage Channel must be driven from a common-mode voltage, i.e., the differential voltage signal

on the input must be referenced to a common mode (usually GND). The analog inputs of the

BL6502A can be driven with common-mode voltages of up to 100 mV with respect to GND.

However, best results are achieved using a common mode equal to GND.

Figure5 shows two typical connections for Channel V2. The first option uses a PT (potential

transformer) to provide complete isolation from the mains voltage. In the second option, the

BL6502A 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 is also a convenient

way of carrying out a gain calibration on the meter.

AGND

VAP

VN

+

-

CF

AGND

CF

RF

RF

CT

±660mV

AGND

AGND

VAP

VN

+

-

CF

AGND

CF

Ra

RF

±660mV

AGND

AGND

Rb

Rv

AGND

Ra >> RF

Rb+Rv=RF

Phase Neutral

Phase Neutral

Figure 5.

Typical Connections for Voltage Channels