AS8002 AMSCO | Alldatasheet
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Technical content
Datasheet sections
- 1 General Description
- 2 Key Features
- 3 Applications
- 4 Pin Assignments
- 4.1 Pin Descriptions
- 5 Absolute Maximum Ratings
- 6 Electrical Characteristics
- 6.1 Operating Conditions
- 6.2 Block Electrical Characteristics
- 7 Detailed Description
- 7.1 Operating Modes
- 7.2 SPI Interface
- 7.3 SPI Interface Data Transfer Protocol
- 7.4 SPI Hardware Connection
- 7.5 SPI Timing
- 7.6 Measurement Example
- 7.7 Measurement Control and Calibration
- 7.8 Interrupts
- 7.9 Register Map Table
- 7.10 Register Description
- 8 Application Information
- 8.1 Application Hints
- 9 Package Drawings and Markings
- 10 Ordering Information
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8141 Unterpremstaetten, Austria
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Solar Photovoltaic Inverter Measure ment IC with Fast Over Current Detection www.austriamicrosystems.com/AS8002 Revision 1.1 1 - 24 Data Sheet
1 General Description
Power inverters in solar photovoltaic systems are often connected directly to the electricity grid in order to inject the created energy into the mains and act as an electricity supplier. This energy must comply with certain regulations that set the standard in terms of quality and safety which requires of accurate measurements. The AS8002 is a highly accurate measurement IC that allows monitoring the generated energy with low cost shunt resistors or other sensors for the current and resistor dividers for the voltage. This approach allows avoiding more expensive sensing devices while achieving the required accuracy for DC and AC measurements of current and voltage, as well as stability over the operating temperature range of the inverter. The 12-bit ADC samples the voltage and current and provides their instantaneous values through an SPI interface. The 12-bit ADC is preceded by low noise programmable gain amplifiers in order to accommodate different sensors. The ADC has three multiplexed inputs, offering one secondary channel in addition to the main voltage and current. The on-chip temperature sensor provides the inverter designer the option of temperature compensation for any of the measured parameters or functional blocks provided, over the full operating temperature range of the device. The on-chip voltage reference is connected to the ADC and to REF. An external crystal oscillator is not required as a high accuracy internal oscillator clock is available. The independent over current interrupt detects a high current on the grid and allows the processor to open the switches without waiting for the ADC conversion.
2 Key Features
12-Bit 100 kSPS ADCs for accurate voltage and current measurement Programmable gain amplifiers to accommodate for different sensors Three multiplexed inputs to the 12-Bit ADC for secondary measurements that require high accuracy and fast sampling rates On chip temperature sensor connected to one of the inputs of the multiplexer On-chip voltage reference with small temperature coefficient (10ppm/K typ). This reference is available at the pin REF. Low power on chip oscillator SPI compatible interface Internal registers for easy offset and gain compensation Interrupt alerts (including Under Voltage Lock-Out and Over Temperature) Independent programmable over current interrupt
3 Applications
The AS8002 is suitable for PV inverter grid monitoring, Wind inverter grid monitoring, Isolated voltage sensing, Uninterruptible Power supplies and Power conditioners. ams AG Technical content still valid
Figure 1. AS8002 Block Diagram
4 Pin Assignments
Figure 2. Pin Assignments (T op View)
4.1 Pin Descriptions
Note: Pin number assignment is likely to change. Table 1. Pin Descriptions IOP_VOP 1 Analog pin Analog Input Channel 0. Positive input of the differential analog input. IOM_VOM 2 Analog pin Analog Input Channel 0. Negative input of the differential analog input. V1P 3 Analog pin Analog Input Channel 1. Positive input of the differential analog input. V1M 4 Analog pin Analog Input Channel 1. Negative input of the differential analog input. V2P 5 Analog pin Analog Input Channel 2. Positive input of the differential analog input. V2M 6 Analog pin Analog Input Channel 2. Negative input of the differential analog input. REF 7 Analog pin Reference Positive Input Voltage. AVSS 8 Supply pin Ground reference for the analog circuitry. DVSS 9 Supply pin Ground reference for the digital circuitry. AVSS PAD Supply pin Ground reference for the analog circuitry.
5 Absolute Maximum Ratings
absolute maximum rating conditions for extended periods may affect device reliability. Table 2. Absolute Maximum Ratings
6 Electrical Characteristics
6.1 Operating Conditions
6.2 Block Electrical Characteristics
Table 3. Operating Conditions Table 4. Block Electrical Characteristics
7 Detailed Description
such a solar inverter or microinverter. case of the voltage, a resistor divider is enough to scale down the voltage. In the case of the current, a low ohmic shunt resistor should be used. The value of this shunt resistor should be calculated in order not to saturate the inputs of the AS8002 but to provide a good signal to noise ratio. It is also important to minimize the value of the shunt resistor to lower the losses and increase the overall efficiency. resistor as the sensing device. The isolation is achieved by means of a digital isolator which should be able to handle a data rate of up to 2Mbps. measurements and allowed bandwidth. All these lead to an accurate control of the DC-AC converter with low DC injection currents. Figure 3. Typical Application Circuit
7.1 Operating Modes
go immediately back to Off mode by setting chip_en to 0.
7.2 SPI Interface
Mode 3 (SCLK initial state = high, data latched with rising edge of SCLK). order to reset the interface for the next read/write cycle. The address is split into an upper 7 bit address (addr[0…6]) and a lower 8 th bit (R/W) containing the read/write information. address specified in the first 8 bits.
7.3 SPI Interface Data Transfer Protocol
Figure 4. Write Mode Table 5. Characteristics
Figure 5. Read Mode read register to be addressed and read in the same 16-bit transfer.
7.4 SPI Hardwa re Connection
Figure 6. AS8002 and the Controller
7.5 SPI Timing
Figure 7. Timing Diagram Table 6. Timing Characteristics
7.6 Measurement Example
- Select the Current channel input (IOM, IOP) : 0610h
- Select the Voltage channel input (V1M, V1P) : 0611h
- Change the input multiplexer back to Current channel input (IOM, IOP) : 0610h
- The 16-bit current input data from the second to last invoked command (1 above) can be read on SDO.
Note: In sequence 2, the 16-bit voltage input data from the second to last command can be read on SDO. Figure 8. Measurement Diagram upper 4 bits (see Register Map Table on page 15).
7.7 Measurement Control and Calibration
Figure 9. ADC Burst Mode
7.8 Interrupts
When an over current, an under voltage or an over temperature occurs the bit warning_detected is set to 1. The interrupt state is present on interrupt_detected and on the pin XINT. under_voltage_int_i, over_temp_int_i. Values of the register Interrupt Status are kept until this register is read. Table 7. Current and Voltage Measurements
7.9 Register Map Table
Note: Highlighted registers are Read only registers (bits). Table 8. Register Map
7.10 Register Description
Table 9. 01h Note: This bit must be set to allow ADC measurements. Table 10. 02h Table 11. 03h
Table 12. 04h Table 13. 05h Table 14. 06h Table 15. 10h
Table 16. 11h Table 17. 12h Table 18. 13h Table 19. 14h
Table 20. 15h Table 21. 16h Table 22. 17h Table 23. 18h Table 24. 19h
Table 25. 1Ah Table 26. 1Bh Table 27. 3Ah Table 28. 3Bh Table 29. 3Ch
8 Application Information
Table 30 provides examples of Gain selection of Channel 1 for different shunt resistors and maximum RMS currents.
8.1 Application Hints
use of ground planes that can be easily separated. possible to the ground pins on the AS8002. paths and reduce the effects of glitches on the power supply line. Likewise, the positive supply pins AVDD and DVDD should be connected only at one common star point close the output of the power supply. For best performance of the analog blocks of the AS8002, it is important to have a clean, noise-free supply voltage at AVDD. frequencies to handle transient currents due to internal logic switching. Table 30. Gain Selection
9 Package Drawings and Markings
The device is available in a 16-pin QFN (4x4x0.9mm) package. Figure 10. 16-pin QFN (4x4x0.9mm) Package
- Dimensioning and tolerancing conform to ASME Y14.5M-1994.
- All dimensions are in millimeters, angles are in degrees.
- Dimension b applies to metallized terminal and is measured between 0.25 and 0.30mm from terminal tip. Dimension L1 represents
terminal full back from package edge up to 0.1mm is acceptable.
- Coplanarity applies to the exposed heat slug as well as the terminal.
- Radius on terminal is optional.
www.austriamicrosystems.com/AS8002 Revision 1.1 23 - 24 AS8002 Data Sheet - Revision History
Revision History
Note: Typos may not be explicitly mentioned under revision history. Revision Date Owner Description 1.0 14 May, 2010 jja Initial revision 1.1 25 Aug, 2010 spo Updated the following in Register Map (page 15): 1) Register bit b4 at address 01 (previously under_voltage_en) is now adc_ref_en 2) ASIC ID 2 register value is now 5Xh ams AG Technical content still valid
The devices are available as the standard products shown in Table 31. Note: All products are RoHS compliant and Pb-free. Copyright © 1997-2010, austriamicrosystems AG, Tobelbaderstrasse 30, 8141 Unterpremstaetten, Austria-Europe. Trademarks Registered ®. All products and companies mentioned are trademarks or registered trademarks of their respective companies. Devices sold by austriamicrosystems AG are covered by the warranty and patent indemnification provisions appearing in its Term of Sale. parts the manufacturing flow might show deviations from the standard production flow, such as test flow or test location. austriamicrosystems AG rendering of technical or other services. Table 31. Ordering Information