SA9602E(2017) Просмотр технического описания (PDF) - South African Micro Electronic Systems

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SA9602E
(Rev.:2017)

Single Phase Unidirectional Power/Energy Metering IC with Instantaneous Pulse Output

South African Micro Electronic Systems 

SA9602E

TYPICAL APPLICATION

In Figure 6 the components required for a stand-alone power

metering application are shown. The application uses a shunt

resistor for the mains current sensing. The meter is designed

for 220V/80A IMAX operation. The most important external

components for the SA9602E integrated circuit are the

current sense resistors, the voltage sense resistors as well as

the bias setting resistor.

Bias Resistor

R12 defines all on-chip and reference currents. Optimum

conditions are set by using R12=24k. Device calibration is

done on the voltage input of the device.

Shunt Resistor

The voltage drop across the shunt resistor at rated current

should be at least 20mV. A shunt resistor with a value of

250μis chosen. The voltage drop across the shunt resistor

is therefore 25mV at rated conditions (IMAX). The maximum

power dissipation in the current sensor is:

�� = (80��)2 × 250��Ω = 1.6��

Current Sense Resistors

The resistors R6 and R7 define the current level into the

current sense inputs of the device. The resistor values are

selected for an input current of 16μARMS on the current inputs

of the SA9602E at rated conditions. According to the equation

described in the Current Sense Inputs section:

��6

=

��7

=

����

16����

×

������

2

=

80��

16����

×

250��Ω

2

≈

620Ω

Voltage Divider

The voltage divider is calculated for a voltage drop of 14V.

Equations for the voltage divider in Figure 6 are:

���� = ��1 + ��2 + ��3

���� = ��11 || (��10 + ��1)

Combining the two equations gives:

(���� + ����) ����

220�� = 14

A 5k trimpot will be used on the voltage channel for meter

calibration. The center position on the pot is used in the

calculations. Therefore P1=2.5k and values for resistors

R10=22kand R11=1M are chosen.

Substituting the values will result in RB=23.91k and

RA=352k. Therefore R1, R2 and R3 are chosen to be

120k.

SPEC-3117 (REV. 5)

6/10

29-09-2017

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