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SA9602M

SINGLE PHASE POWER/ENERGY METERING IC WITH SELECTABLE PULSE RATE FOR MECHANICAL DISPLAY APPLICATIONS

South African Micro Electronic Systems 

SA9602M

FUNCTIONAL DESCRIPTION

The SA9602M is a CMOS mixed signal Analog/Digital integrated circuit, which performs

power/energy calculations across a power range of 1000:1, to an overall accurancy of

better than Class 1.

The integrated circuit includes all the required functions for 1-phase power and energy

measurement such as two oversampling A/D converters for the voltage and current

sense inputs, power calculation and energy integration. Internal offsets are eliminated

through the use of cancellation procedures. The SA9602M generates pulses, the

frequency of which is proportional to the power consumption. Two frequency outputs

(MOTOR and LED) are available. The pulse rate follows the instantaneous power

consumption measured.

The motor drive pin can be configured as a unipolar or bipolar output using input MD. This

choice allows the manufacturer to use either an impulse counter (unipolar) or stepper

motor (bipolar).

1. Power Calculation

In the Application Circuit (Figure 1), the voltage drop across the shunt will be

between 0 and 16mVRMS (0 to 80A through a shunt resistor of 200µΩ). This voltage

is converted to a current of between 0 and 16µARMS, by means of resistors R1 and

R.

2

The current sense input saturates at an input current of ±25µA peak.

For the voltage sensor input, the mains voltage (230VAC) is divided down through

a divider to 14V . The current into the A/D converter input is set at 14µA at

RMS

RMS

nominal mains voltage, via resistor R4 (1MΩ).

Different pulse rates are available at the motor drive pin. The device may be

programmed for a 1 pulse/kWh, 10 pulses/kWh or 100 pulses/kWh output,

depending on the status of the motor pulse rate select pins MPD and MP1.

The LED pulse rate is fixed at 1000 pulses/kWh. The frequency of the motor drive

and LED pin is dependant on the settings of R0 and R1 which allow selection of

different rated conditions. Rated conditions such as 230V/40A, 230V/60A, 230V/

80A and 230V/100A may be chosen. This facility allows meter manufacturers to

cater for a wide range of metering applications with minimal design changes.

2. Analog Input Configuration

The input circuitry of the current and voltage sensor inputs are illustrated below.

These inputs are protected against electrostatic discharge through clamping

diodes.

The feedback loops from the outputs of the amplifiers AI and AV generate virtual

shorts on the signal inputs. Exact duplications of the input currents are generated

for the analog signal processing circuitry.

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