ADE7759 Analog Devices, ADE7759 Datasheet
ADE7759
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ADE7759 Summary of contents
Page 1
... The ADE7759 contains a sampled Waveform register and an Active Energy register capable of holding at least 11.53 seconds of accumu- lated power at full ac load. Data is read from the ADE7759 via the serial interface. The ADE7759 also provides a pulse output (CF) with frequency that is proportional to the active power. ...
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... CURRENT SENSOR AND DIGITAL INTEGRATOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 ZERO CROSSING DETECTION . . . . . . . . . . . . . . . . . . . 13 LINE VOLTAGE SAG DETECTION . . . . . . . . . . . . . . . . 14 Sag Level Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 POWER SUPPLY MONITOR . . . . . . . . . . . . . . . . . . . . . . 14 INTERRUPTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Using the ADE7759 Interrupts with an MCU . . . . . . . . . 15 Interrupt Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 TEMPERATURE MEASUREMENT . . . . . . . . . . . . . . . . 16 ANALOG-TO-DIGITAL CONVERSION . . . . . . . . . . . . . 16 Antialias Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 ADC Transfer Function . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Reference Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 CHANNEL 1 ADC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Channel 1 ADC Gain Adjust ...
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... Gain = 1 Sampling CLKIN/128, 3.579545 MHz/128 = 27.9 kSPS See Channel 1 Sampling 62 dB typ 150 mV rms/60 Hz, Range = 0.5 V, Gain = 2 14 kHz CLKIN = 3.579545 MHz See Channel 2 Sampling 52 dB typ 150 mV rms/60 Hz, Gain = 2 156 Hz CLKIN = 3.579545 MHz ADE7759 = 175 mV rms/120 ± 250 ...
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... ADE7759–SPECIFICATIONS Parameter REFERENCE INPUT REF Input Voltage Range IN/OUT Input Capacitance ON-CHIP REFERENCE Reference Error Current Source Output Impedance Temperature Coefficient CLKIN Input Clock Frequency LOGIC INPUTS RESET, DIN, SCLK, CLKIN, and CS Input High Voltage, V INH Input Low Voltage, V INL ...
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... DB7 COMMAND BYTE MOST SIGNIFICANT BYTE DB7 COMMAND BYTE MOST SIGNIFICANT BYTE ADE7759 2. DB0 DB7 DB0 LEAST SIGNIFICANT BYTE DB0 DB7 DB0 LEAST SIGNIFICANT BYTE ...
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... ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although the ADE7759 features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high-energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality ...
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... Mnemonic Description RESET 1 Reset Pin for the ADE7759. A logic low on this pin will hold the ADCs and digital circuitry (including the serial interface reset condition Digital Power Supply. This pin provides the supply voltage for the digital circuitry in the ADE7759. ...
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... ADE7759. The CLKOUT pin can drive one CMOS load when either an external clock is supplied at CLKIN or a crystal is being used Chip Select. Part of the 4-wire SPI Serial Interface. This active low logic input allows the ADE7759 to share the serial bus with several other devices. See Serial Interface section. 18 SCLK Serial Clock Input for the Synchronous serial interface. All serial data transfers are synchronized to this clock— ...
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... 0.5 0.3 0.2 + 0.1 0.0 –0.1 –0.2 –0.3 –0.4 + 0.5 –0.5 100 0.01 0.1 ADE7759 + 0.5 – 0.5 + 0.5 + 100 CURRENT – A – 0.5 + 0 100 CURRENT – A – 0.5 FULL SCALE = 0.5V GAIN = 4 INTEGRATOR OFF INTERNAL REFERENCE ...
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... ADE7759 0.5 0.4 0.3 – 0.2 0.1 0.0 –0.1 –0.2 FULL SCALE = 0.5V –0.3 GAIN = 4 INTEGRATOR OFF –0.4 EXTERNAL REFERENCE –0.5 0.01 0.1 1 CURRENT – A 0.5 0.4 0.3 – 0.2 0.1 0.0 –0.1 + –0.2 FULL SCALE = 0.5V –0.3 GAIN = 4 INTEGRATOR ON –0.4 INTERNAL REFERENCE –0.5 0.01 0.1 1 CURRENT – A 0.5 FULL SCALE = 0.5V 0.4 GAIN = 4 INTEGRATOR ON 0.3 EXTERNAL REFERENCE – ...
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... ANALOG INPUTS The ADE7759 has two fully differential voltage input channels. The maximum differential input voltage for input pairs V1P/V1N and V2P/V2N are ± 0 addition, the maximum signal level on analog inputs for V1P/V1N and V2P/V2N are ± 0.5 V with respect to AGND. ...
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... The ADE7759 has a built-in digital integrator to recover the current signal from the di/dt sensor. The digital integrator on Channel 1 is switched on by default when the ADE7759 is powered up. Setting the MSB of the CH1OS register to 0 will turn off the integrator. Figures show the magnitude and phase response of the digital integrator ...
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... A more effective antialiasing filter is needed to avoid noise due to aliasing—see Antialias Filter section. When the digital integrator is switched off, the ADE7759 can be used directly with a conventional current sensor such as current transformer (CT low resistance current shunt. ...
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... The ADE7759 also contains an on-chip power supply monitor. The Analog Supply (AVDD) is continuously monitored by the ADE7759. If the supply is less than 4 V ± 5%, the ADE7759 will go into an inactive state, i.e., no energy will be accumulated when the supply voltage is below 4 V. This is useful to ensure correct device operation at power-up and during power-down ...
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... Using the ADE7759 Interrupts with an MCU Figure 17 shows a timing diagram with a suggested implementa- tion of ADE7759 interrupt management using an MCU. At time t the IRQ line will go active low, indicating that one or more interrupt events have occurred in the ADE7759. The IRQ logic output should be tied to a negative edge-triggered external inter- rupt on the MCU ...
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... For example, the sampling rate in the ADE7759 is CLKIN/4 (894 kHz) and the band of interest kHz. Oversampling has the effect of spreading the quantization noise (noise due to sampling) over a wider bandwidth. ...
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... Phase Compensation section. ADC Transfer Function Below is an expression which relates the output of the LPF in the sigma-delta ADC to the analog input signal level. Both ADCs in the ADE7759 are designed to produce the same out- put code for the same input signal level × ...
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... WHEN DIGITAL INTEGRATOR IS ENABLED, FULL-SCALE OUTPUT DATA VARIES DEPENDING ON THE SIGNAL FREQUENCY BECAUSE OF –20dB/DECADE FREQUENCY RESPONSE. waveform samples are transferred from the ADE7759 one byte (eight-bits time, with the most significant byte shifted out first. The 20-bit data word is right justified and sign extended to 24 bits (three bytes)— ...
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... The ADE7759 provides a means of digitally calibrating these small phase errors. The ADE7759 allows a small time delay or time advance to be introduced into the signal processing chain in order to compensate for small phase errors. Because the compensation is in time, this technique should only be used for small phase errors in the range of 0.1° ...
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... Real Power. Note that the active power is equal to the dc com- ponent of the instantaneous power signal p(t) in Equation 3, i.e., VI. This is the relationship used to calculate active power in the ADE7759. The instantaneous power signal p(t) is generated by multiplying the current and voltage signals. The dc component of the instantaneous power signal is then extracted by LPF2 (Low-Pass Filter) to obtain the active power information ...
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... Where n is the discrete time sample number and T is the sample period. The discrete time sample period (T) for the accumulation regis- ter in the ADE7759 is 1.1 µs (4/CLKIN). As well as calculating ACTIVE POWER SIGNAL – P the Energy, this integration removes any sinusodial components CCCDh which may be in the Active Power signal ...
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... Figure 37. Conversely, if the power is negative, the energy register would underflow to full-scale positive (7F, FFFF, FFFFh) and continue decreasing in value. By using the Interrupt Enable register, the ADE7759 can be configured to issue an interrupt (IRQ) when the Active Energy register is half-full (positive or negative) or when an over/underflow occurs ...
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... Figure 38 illustrates the Energy-to-Frequency conversion in the ADE7759. The Energy-to-Frequency conversion is accomplished by accumu- lating the Active power signal in a 24-bit register. An output pulse is generated when there is a zero to one transition on the MSB (most significant bit) of the register. Under steady load conditions the output frequency is proportional to the Active Power ...
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... LINE CYCLE ENERGY ACCUMULATION MODE In Line Cycle Energy Accumulation mode, the energy accumu- lation of the ADE7759 can be synchronized to the Channel 2 zero crossing so that active energy can be accumulated over an integral number of half line cycles. The advantage of summing the active energy over an integer number of half-line cycles is that the sinusoidal component in the active energy is reduced to zero ...
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... Hz with the CLKIN frequency equal to 3.579545 MHz. However, the ADE7759 is designed to have the same accuracy at any CLKIN frequency within the specified range. If the CLKIN frequency is not 3.579545 MHz, various timing and filter charac- teristics will need to be redefined with the new CLKIN frequency. ...
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... The CS logic input may be tied low if the ADE7759 is the only device on the serial bus. However with CS tied low, all initiated data transfer operations must be fully com- pleted, i ...
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... The MSB of this byte transfer indicating that the next data transfer operation is a read. The LSBs of this byte contain the address of the register that read. The ADE7759 starts shifting out of the register data on the next rising edge of SCLK— ...
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... The Mode Register. This is a 16-bit register through which most of the ADE7759 functionality is accessed. Signal sample rates, filter enabling and calibration modes are selected by writing to this register. The contents may be read at any time—see Mode Register section. ...
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... Communications Register The Communications register is an 8-bit, write-only register that controls the serial data transfer between the ADE7759 and the host processor. All data transfer operations must begin with a write to the Communications register. The data written to the Communica- tions register determines whether the next operation is a read or a write and which register is being accessed ...
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... CLKIN pin. 5 TEMPSEL The temperature conversion starts when this bit is set to 1. This bit is automatically reset to 0 when the temperature conversion is finished. Software Chip Reset. A data transfer should not take place to the ADE7759 for at least 18 µs after 6 SWRST a software reset. 7 CYCMODE Setting this bit to Logic 1, places the chip in Line Cycle Energy Accumulation mode ...
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... The Status register is used by the MCU to determine the source of an interrupt request (IRQ). When an interrupt event occurs in the ADE7759, the corresponding flag in the Interrupt Status register is set logic high. If the enable bit for this flag is Logic 1 in the Inter- rupt Enable register, the IRQ logic output goes active low. When the MCU services the interrupt, it must first carry out a read from the Interrupt Status register to determine the source of the interrupt ...
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... ADE7759 (ACTIVE ENERGY REGISTER OVERFLOW) (TEMPERATURE REGISTER READY) (ZERO CROSSING DETECTED) CH1OS Register (08H) The CH1OS register is an 8-bit, read/write enabled register. The MSB of this register is used to switch on/off the digital integrator in Channel 1, and Bits indicate the amount of the offset correction in Channel 1. Table VIII summarizes the function of this register. ...