SA9602E
FUNCTIONAL DESCRIPTION
The SA9602E 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 SA9602E in both DIP-20 and SOIC-20 package options is a direct replacement for
the SA9102E with the advantage of no external loop capacitors.
The integrated circuit includes all the required functions for 1-phase power and energy
measurementsuchastwooversamplingA/Dconvertersforthevoltageandcurrentsense
inputs, power calculation and energy integration. Internal offsets are eliminated through
the use of cancellation procedures. The SA9602E generates pulses, the frequency of
which is proportional to the power consumption. Two frequency outputs (FOUT1 and
FOUT2) are available, with a third frequency option available on request. The pulse rate
follows the instataneous power consumption measured.
1. Power Calculation
IntheApplicationCircuit(Figure1),thevoltagedropacrosstheshuntwillbebetween
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 R2.
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
adividerto14V. ThecurrentintotheA/Dconverterinputissetat14µARMSatnominal
mains voltage, via resistor R4 (1MΩ).
In this configuration, with a mains voltage of 230V and a current of 80A, the output
frequency of the SA9602E power meter chip at FOUT1 (Pin 12) is 1.16kHz. In this
case 1 pulse will correspond to an energy consumption of 18.4kW/1160Hz =
15.9Ws.
The output frequency at FOUT2 is FOUT1 /290 (i.e. The frequency ouput at FOUT1
divided by 290).
2. Analog Input Configuration
The input circuitry of the current and voltage sensor inputs are illustrated below.
Theseinputsareprotectedagainstelectrostaticdischargethroughclampingdiodes.
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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