SA9602H
FUNCTIONAL DESCRIPTION
The SA9602H 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
measurementsuchastwooversamplingA/Dconvertersforthevoltageandcurrentsense
inputs, power calculation and energy integration. Internal offsets are eliminated through
the use of cancellation procedures. The SA9602H generates pulses, the frequency of
which is proportional to the power consumption. The pulse rate follows the instataneous
power consumption measured. Direction information is also provided.
A voltage zero crossover signal, relevant to the positive going half cycle, is available on
pin FMO. This signal can be used to sychronise circuit breaker switching.
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/Dconverterinputissetat14µARMS atnominal
mains voltage, via resistor R4 (1MΩ).
In this configuration, with a mains voltage of 230V and a current of 80A, the output
frequencyoftheSA9602HpowermeterchipatFOUTis1.16kHz. Inthiscase1pulse
will correspond to an energy consumption of 18.4kW/1160Hz = 15.9Ws.
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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