SA4120A SAMES | Alldatasheet
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Single Channel Single Phase Bidirectional Energy Metering IC with Instantaneous Frequency Output SPEC-3094 (REV. 2) 1/14 29-09-2017 SA4120A
FEATURES
Meets the IEC62053, CBIP -88 and IS137799 -1999 specification requirements for Class 1 AC static watt - hour meters for active energy Pulse output supplies instantaneous active power information Bidirectional power and energy measurement Adaptable to different types of current sensors Precision on-chip oscillator (70ppm/°C drift) Precision on-chip voltage reference (10ppm/°C drift) Integrated anti-creep function Low power consumption (<20mW typical) Measures AC inputs only Functionally compatible with SA2002H
DESCRIPTION
The SA4120A is an accurate single phase power/energy metering integrated circuit providing a single chip solution for single phase energy metering. Very few external components are required and the SA4120A does not require an external crystal or voltage reference. A precision oscillator and a precision voltage reference to supply the circuitry with a stable frequency and stable reference currents are integrated on the chip. The SA4120A metering integrated circuit generates a pulse output, the frequency of which is proportional to the instantaneous active power consumption. The pulse output is intended to interface with a micro controller or similar pulse counting circuitry. The SA4120A includes an anti -creep feature preventing any creep effects in the meter under no - load conditions. The SA4120A integrated circuit is available in 8 pin dual inline (PDIP8) as well as 20 pin and 16 pin small outline (SOIC20, SOIC16) RoHS compliant package options. Figure 1: Block diagram *FMO and DIR not available in PDIP8 package type VREF VSS OSCILLATOR AND TIMING VOLTAGE REFERENCE AND CURRENT BIASING VOLTAGE CHANNEL ADC CURRENT CHANNEL ADC AGND IVP IIN IIP POWER ON RESET DIGITAL OUTPUT DIGITAL OUTPUT Instantaneous power SIGNAL PROCESSING FOUTPULSE GENERATION DIR FM VDD
SPEC-3094 (REV. 2) 2/14 29-09-2017 SA4120A
ELECTRICAL CHARACTERISTICS
(VDD - VSS = 5V ± 10%, over the temperature range -40°C to +85°C, unless otherwise specified. Refer to Figure 2 “Test circuit for electrical characteristics”.) Parameter Symbol Min Typ Max Unit Condition General Supply Voltage: Positive VDD 2.25 2.5 2.75 V With respect to AGND Supply Voltage: Negative VSS -2.75 -2.5 -2.25 V With respect to AGND Supply Current: Positive IDD 3.5 4.5 mA Supply Current: Negative ISS -3.5 -4.5 mA Analog Inputs Current Sensor Inputs (Differential) Input Current Range IRIIP, IRIIN -25 25 μA Peak value Offset Voltage VOIIP, VOIIN -4 4 mV With R = 4.7k connected to AGND Voltage Sensor Inputs (Asymmetrical) Input Current Range IRIVP -25 25 μA Peak value Offset Voltage VOIVP -4 4 mV With R = 4.7k connected to AGND Digital Outputs FOUT Output Frequency FMAX 1.04 1.16 1.25 kHz At rated input conditions: 14µARMS on voltage channel, 16μARMS on current channel FOUT, DIR, FMO Output High Voltage Output Low Voltage VOH VOL VDD-1 VSS+1 V V ISOURCE = 5mA ISINK = 5mA On-chip Voltage Reference Reference Voltage VR 1.15 1.20 1.25 V Reference Current -IR 24.4 25.5 26.6 μA With R = 47k connected to VSS Temperature Coefficient TCR 10 70 ppm/ºC On-chip Oscillator Oscillator Frequency fOSC 3.15 3.57 4.00 MHz Temperature Coefficient TCOSC 70 200 ppm/ºC During manufacturing, testing and shipment we take great care to protect our products against potential external environmental damage such as Electrostatic Discharge (ESD). Although our products have ESD protection circuitry, permanent damage may occur on products subjected to high -energy electrostatic discharges accumulated on the human body and/or test equipment that can discharge without detection. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality during product handling. ATTENTION: Electrostatic sensitive device. Requires special handling.
SPEC-3094 (REV. 2) 3/14 29-09-2017 SA4120A ABSOLUTE MAXIMUM RATINGS* Parameter Symbol Min Max Unit Supply Voltage VDD - VSS 6 V Current on any Pin IPIN -150 150 mA Storage Temperature TSTG -60 +125 ºC Specified Operating Temperature Range TO -40 +85 ºC Limit Range of Operating Temperature Tlimit -40 +85 ºC *Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating only. Functional operation of the device at these or any other condition above those indicated in the operational sections of this specification, is not implied. Exposure to Absolute Maximum Ratings for extended periods may affect device reliability. Figure 2: Test circuit for electrical characteristics SA4120A R10.1A to 100A 50Hz AC 220V 50Hz AC IIN IIP VREF VSS VSS FMO DIR FOUT VDD VDD R11 R10 GND GND VDD VSS GND R1: 1.2 R2: 1.2 R3: 1.5k R4: 1.5k R5: 1.5k R6: 1.5k R7: 250k R8: 1k R9: 100k R10: 47k R11: 1k CT1: TZ76V (2500:1) P1: 1k C1: 22nF C2: 22nF C3: 5.6nF C4: 220nF C5: 220nF C6: 1µF CT1 2.5V DC 2.5V DC VDD VSS Phase angle between voltage and current -60 to 60 GND IVP N N Single Phase Source AGND R9C3 GND GND
SPEC-3094 (REV. 2) 5/14 29-09-2017 SA4120A TERMINOLOGY Anti-Creep Threshold The anti-creep threshold is defined as the minimum energy threshold below which no energy is registered and therefore no pulses are generated on the pulse output. Positive Energy Positive energy is defined when the phase difference between the input signals IIP and IVP is less than 90 degrees (-90..90 degrees). Negative Energy Negative energy is defined when the phase difference between the input signals IIP and IVP is greater than 90 degrees (90..270 degrees). Percentage Error* Percentage error is given by the following formula: %𝐸𝑟𝑟𝑜𝑟 = 𝐸𝑛𝑒𝑟𝑔𝑦 𝑟𝑒𝑔𝑖𝑠𝑡𝑒𝑟𝑒𝑑 − 𝑇𝑟𝑢𝑒 𝐸𝑛𝑒𝑟𝑔𝑦 𝑇𝑟𝑢𝑒 𝐸𝑛𝑒𝑟𝑔𝑦 × 100 NOTE: Since the true value cannot be determined, it is approximated by a value with a stated uncertainty that can be traced to standards agreed upon between manufacturer and user or to national standards. Rated Operating Conditions* Set of specified measuring ranges for performance characteristics and specified operating ranges for influence quantities, within which the variations or operating errors of a meter are specified and determined. Specified Measuring Range* Set of values of a measured quantity for which the error of a meter is intended to lie within specified limits. Specified Operating Range* A range of values of a single influence quantity, which forms a part of the rated operating conditions. Limit Range of Operation* Extreme conditions which an operating meter can withstand without damage and without degradation of its metrological characteristics when it is subsequ ently operated under its rated operating conditions. Maximum Rated Mains Current (IMAX) Maximum rated mains current is the specified maximum current flowing through the energy meter at rated operating conditions. Constant* Value expressing the relation b etween the active energy registered by the meter and the corresponding value of the test output. If this value is a number of pulses, the constant should be either pulses per kilowatt -hour (imp/kWh) or watt - hours per pulse (Wh/imp). Nominal Mains Voltage (VNOM) Nominal mains voltage (VNOM) is the voltage specified for the energy meter at rated operating conditions. Maximum Output Frequency (FMAX) The maximum output frequency (F MAX) is the output frequency when 14μA RMS and 16μARMS input current with zero phase shift are applied to the voltage and current inputs respectively. Both the voltage and current inputs saturate at an input current magnitude of 25μA, or at 17.68μA RMS when using sine waves. The maximum input current on any channel is therefore defined to be 16μA RMS, which leaves about 10% headroom to the saturation point. An additional headroom of 15% is reserved on the voltage channel to account for mains voltage fluctuations. The nominal output frequency of 1160Hz is achieved under such conditions. * IEC 62052-11, 2003. Electricity Metering Equipment (AC) – General Requirements, Test and Test Conditions – Part 11: Metering Equipment
SPEC-3094 (REV. 2) 6/14 29-09-2017 SA4120A PERFORMANCE GRAPHS Figure 6: Test circuit for performance graphs Graph 1: Freq = 50Hz, VMains = VNOM, Temp = 25°C, VDD-VSS = 5.0V Graph 3: PF = 1, VMains = VNOM, Temp = 25°C, VDD-VSS = 5.0V Graph 2: PF = 1, Freq = 50Hz, Temp = 25°C, VDD-VSS = 5.0V Graph 4: PF = 1, Freq = 50Hz, VMains = VNOM, Temp = 25°C SA4120A R10.1A to 100A 50Hz AC 220V 50Hz AC IIN IIP VREF VSS VSS FMO DIR FOUT VDD VDD R11 R10 GND GND VDD VSS GND R1: 1.2 R2: 1.2 R3: 1.5k R4: 1.5k R5: 1.5k R6: 1.5k R7: 250k R8: 1k R9: 100k R10: 47k R11: 1k CT1: TZ76V (2500:1) P1: 1k C1: 22nF C2: 22nF C3: 5.6nF C4: 220nF C5: 220nF C6: 1µF CT1 2.5V DC 2.5V DC VDD VSS Phase angle between voltage and current -60 to 60 GND IVP N N Single Phase Source AGND R9C3 GND GND -0.5 -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.1 1 10 100 %Error %IMAX PF = 1 PF = 0.5 LAG PF = 0.5 LEAD PF = -1 -0.5 -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.1 1 10 100 %Error %IMAX Freq = 50Hz Freq = 45Hz Freq = 65Hz -0.5 -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.1 1 10 100 %Error %IMAX VMains = 100%VNOM VMains = 50% VNOM VMains = 115% VNOM -0.5 -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.1 1 10 100 %Error %IMAX VDD-VSS = 5.0V VDD-VSS = 4.5V VDD-VSS = 5.5V
SPEC-3094 (REV. 2) 7/14 29-09-2017 SA4120A FUNCTIONAL DESCRIPTION Theory of Operation The SA4120A includes all the required functions for single channel single phase power and energy measurement. Two AD converters sample the voltage and cur rent input signals. The two digital signals, accurately representing the voltage and current inputs, are multiplied using digital multiplication. The output o f the multiplier represents the instantaneous power. The pulse generation circuit creates a pulse output where the instantaneous frequency is proportional to the instantaneous power measured. For given voltage and current signals the instantaneous power is calculated by: 𝑝(𝑡) = 𝑣(𝑡) × 𝑖(𝑡) 𝑝(𝑡) = 𝑉𝑀 cos(𝜔𝑡 + 𝜃) × 𝐼𝑀 cos(𝜔𝑡 + 𝜓) Let 𝜙 = 𝜃 − 𝜓, and 𝑉𝑅𝑀𝑆 = 𝑉𝑀 √2 and 𝐼𝑅𝑀𝑆 = 𝐼𝑀 √2 then 𝑝(𝑡) = 𝑉𝑀 cos(𝜔𝑡 + 𝜃) × 𝐼𝑀 cos(𝜔𝑡 + 𝜃 − 𝜙) 𝑝(𝑡) = 𝑉𝑅𝑀𝑆𝐼𝑅𝑀𝑆(cos 𝜙 + cos(2(𝜔𝑡 + 𝜃) − 𝜙)) where p(t) is the instantaneous power, v(t) is the instantaneous voltage signal, i(t) is the instantaneous current signal, VM is the amplitude of the voltage signal, IM is the amplitude of the current signal, is the phase angle of the voltage signal and is the phase angle of the current signal. The instantaneous power output is integrated over time to obtain the output energy by simply counting the output pulses. This removes the double mains frequency component cos(2(t+)-) and the average pulse output rate is therefore equivalent to 𝑃 = 1 𝑇 ∫ 𝑝(𝑡)𝑑𝑡 𝑇 𝑃 = 𝑉𝑅𝑀𝑆𝐼𝑅𝑀𝑆 cos 𝜙 where P is the average power and cos is the power factor. Linearity The SA4120A is a CMOS integrated circuit, which performs power/energy calculations across a dynamic range of 500:1 to an accuracy that exceeds the IEC62053 specification. Analog Inputs The input circuitry of the current and voltage sensor inputs is illustrated in Figure 7. These inputs are protected against electrostatic discharge through clamping diodes. The feedback loops from the outputs of the am plifiers AI and AV generate virtual short circuits between IIP and IIN as well as IVP and AGND. The current sense inputs (IIP and IIN) are identical and balanced. The AD converters convert the signals on the voltage and current sense inputs to a digital format for further p rocessing. All internal offsets are eliminated through the use of various cancellation techniques. Figure 7: Analog input configuration Digital Outputs The calculations required for power and energy are performed and the result is converted to pulses on the FOUT pulse output. The instantaneous output frequency on the pulse output is proportional to the instantaneous active power consumption measured. The pulse output is intended for interfacing the SA4120A to a microcontroller or similar pulse processing circuit. Anti-Creep Threshold An integrated anti-creep function prevents any output pulses from appearing on the pulse output if the energy measured is less than 0.02% of FMAX, where FMAX is the energy registered when the input currents for voltage and current are 14μA RMS and 16μARMS with zero phase shift respectively. AI IIN IIP VDD VSS VDD VSS AV IVP VDD VSS AGND VOLTAGE SENSOR INPUT CURRENT SENSOR INPUT CURRENT CHANNEL ADC VOLTAGE CHANNEL ADC
SPEC-3094 (REV. 2) 10/14 29-09-2017 SA4120A 𝐶1 = 𝐶2 = 1 𝜋𝑓𝐶𝐼 𝑅𝐶 = 1 𝜋 × 15𝑘𝐻𝑧 × 200Ω ≈ 100𝑛𝐹 = 𝐶𝐶 where fCI is the cut-off frequency of the anti -alias filter of the current input network. Voltage Input Network The voltage sense input requires an input current of 14μARMS at VNOM (220V). The mains voltage is divided by means of a voltage divide r to a lower voltage that is converted to the required input current by means of the input resistor. Once again an anti -alias filter is required to remove any high frequency signals that could affect the performance of the SA4120A. A shunt typically has very little phase shift so phase compensation is not required. The input resistor R8 sets the current input into the device. This resistor should not be too large else the capacitor for the anti-alias filter will be quite small which could cause inaccurate phase shift due to parasitic capacitances. Therefore R8 = 100k is chosen and the voltage at the centre of the trimpot should be 1.4V (14μA x 100k). The calibration range of the voltage input network should be about ±15% to ensure that all component tolerances can be catered for, so the total tuning range can be set to ±0. 22V. Therefore the voltage across the trimpot and R9 is 1. 62V. Choosing a 1k trimpot results in: 𝑅9 = 1𝑘Ω The effect of R8 can be ignored in the above equation, given the fact that R8 is significantly larger than P1 and R9. Now let RA = R5 + R6 + R7 and 1.62𝑉 − 1) ≈ 499𝑘Ω so choose R5 = R6 = 200kand R7 = 100k. The cut-off frequency of the anti-alias filter is adjusted so that it is identical to that of the current input network anti -alias filters. This ensures that the phase shift caused by the anti - alias filters is identical on the current and voltage input networks. Therefore 𝜋𝐶𝐶 × 𝑅𝐶 = 1 2𝜋(𝑃1 + 𝑅9) × 𝐶3 and so C3 = 2.7nF. Figure 11: Typical application circuit VDD VSS VREF IIP IIN SA4120A FMO DIR FOUT IVP AGND R3 R4 R1 R2 200 200 200 200 C1 100nF 100nF R10 47k-2.5V +2.5V 200k 200k 100k 100k P1 1k R9 2.7k LIVE IN NEUTRAL LIVE OUT 2.7nF 220nF 220nF 1µF +2.5V -2.5V RSH 320µ 0V +2.5V Pulse Processing Circuit e.g. Microcontroller
SPEC-3094 (REV. 2) 11/14 29-09-2017 SA4120A Table 1: Component list for typical application Symbol Description U1 Energy metering device, SA4120ASAR-20 RSH Shunt Resistor, 40A, 320μ R1, R21, R3, R41 Resistor, 200, 1%, metal film R5, R6 Resistor, 200k, 1%, metal film R7, R81 Resistor, 100k, 1%, metal film Symbol Description R9 Resistor, 2.7k, 1%, metal film R101 Resistor, 47k, 1%, metal film P1 Trim-pot, 25 turns, 1k C1, C2 Capacitor, 100nF, ceramic C3 Capacitor, 2.7nF, ceramic C42, C52 Capacitor, 220nF, ceramic C62 Capacitor, 1μF, ceramic Note 1: Resistors R2, R4, R8 and R10 must be positioned as close as possible to the respective device pins Note 2: Capacitors C4, C5 and C6 must be positioned as close as possible to the VDD and VSS power supply pins
SPEC-3094 (REV. 2) 12/14 29-09-2017 SA4120A PACKAGE DIMENSIONS SOIC16 and SOIC20 Packages Dimensions are shown in inches
SPEC-3094 (REV. 2) 13/14 29-09-2017 SA4120A NOTES
SPEC-3094 (REV. 2) 14/14 29-09-2017 SA4120A DISCLAIMER The information contained in this document is confidential and proprietary to Integrated Circuit Design Centre (Pty) Ltd ("ICDC"), a division of South African Micro-Electronic Systems (Pty) Ltd ("SAMES"), and may not be copied or disclosed to a third party, in whole or in part, without the express written consent of ICDC. The information contained herein is current as of the date of publication; however, delivery of this document shall not under any circumstances create any impl ication that the information contained herein is correct as of any time subsequent to such date. ICDC does not undertake to inform any recipient of this document of any changes in the information contained herein, and ICDC expressly reserves the right to m ake changes in such information, without notification, even if such changes would render information contained herein inaccurate or incomplete. ICDC makes no representation or warranty that any circuit designed by reference to the information contained her ein, will function without errors and as intended by the designer. Any sales or technical questions may be sent to our support e-mail address: support@sames.co.za For the latest updates on datasheets, please visit our web site: http://www.sames.co.za. INTEGRATED CIRCUIT DESIGN CENTRE (PTY) LTD a division of SOUTH AFRICAN MICRO-ELECTRONIC SYSTEMS (PTY) LTD Tel: 012 333 6021 Tel Int: 00 27 12 333 6021 Fax: 012 333 6393 Fax Int: 00 27 12 333 6393 PO BOX 15888 LYNN EAST 0039 REPUBLIC OF SOUTH AFRICA UNIT 4, PERSEQUOR CLOSE
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