AD7151 Analog Devices, AD7151 Datasheet
AD7151
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AD7151 Summary of contents
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... The AD7151 operates with a 2 3.6 V power supply specified over the temperature range of −40°C to +85°C. FUNCTIONAL BLOCK DIAGRAM ...
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... Configuration Register .............................................................. 19 Power-Down Timer Register .................................................... 20 CAPDAC Register...................................................................... 20 Serial Number Register.............................................................. 20 Chip ID Register......................................................................... 20 Serial Interface ................................................................................ 21 Read Operation........................................................................... 21 Write Operation.......................................................................... 21 AD7151 Reset ............................................................................. 22 General Call ................................................................................ 22 Hardware Design Considerations ................................................ 23 Overview ..................................................................................... 23 Parasitic Capacitance to Ground.............................................. 23 Parasitic Resistance to Ground................................................. 23 Parasitic Parallel Resistance ...................................................... 23 Parasitic Serial Resistance ......................................................... 24 Input Overvoltage Protection ................................................... 24 Input EMC Protection ...
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... MΩ kΩ CIN and EXC pins disconnected fF CIN and EXC pins disconnected % fF LSB % of C Range IN V kHz pF MΩ −4 mA SINK SOURCE V V μ − 6.0 mA SINK μ OUT DD V AD7151 ...
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... AD7151 Parameter POWER REQUIREMENTS V -to-GND Voltage Current Current Power-Down Mode DD 1 Capacitance units: one picofarad (1 pF × The CAPDAC can be used to shift (offset) the input range. The total capacitance of the sensor can, therefore the sum of the CAPDAC value and the conversion input range ...
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... Exposure to absolute –0 0 maximum rating conditions for extended periods may affect 4 kV device reliability. ESD CAUTION 1 kV –40°C to +85°C –65°C to +150°C 150°C 206°C/W 44°C/W 260(+0/−5)°C 10 sec to 40 sec Rev Page AD7151 ...
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... Serial Interface Clock Input. Connects to the master clock line. Requires a pull-up resistor if not provided elsewhere in the system. 10 SDA Serial Interface Bidirectional Data. Connects to the master data line. Requires a pull-up resistor if not provided elsewhere in the system. GND SDA 1 10 VDD SCL 2 9 AD7151 TOP VIEW (Not to Scale) CIN OUT EXC 5 ...
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... CAPACITANCE EXC TO GND (pF 3.3 V, CIN to EXC = 200 100 100 RESISTANCE CIN TO GND (MΩ 3.3 V, EXC Pin Open Circuit –5 – 100 RESISTANCE CIN TO GND (MΩ 3.3 V, CIN to EXC = AD7151 250 300 1000 1000 ...
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... AD7151 –5 – RESISTANCE EXC TO GND (MΩ) Figure 10. Capacitance Input Offset Error vs. Resistance EXC to GND 3.3 V, CIN Pin Open Circuit DD 0.50 0.25 0 –0.25 –0. RESISTANCE EXC TO GND (MΩ) Figure 11. Capacitance Input Gain Error vs. Resistance EXC to GND 3.3 V, CIN to EXC = 2 pF ...
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... V (V) DD Figure 17. EXC Frequency Error vs –20 –40 –60 –80 75 100 0 Figure 18. Capacitance to Digital Converter Frequency Response 0.50 0.25 0 –0.25 –0.50 3.6 0 Figure 19. CAPDAC Differential Nonlinearity (DNL), Rev Page AD7151 0.5 1.0 1.5 2 INPUT SIGNAL FREQUENCY (kHz CAPDAC CODE ...
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... GND Figure 20. AD7151 Block Diagram C 0pF TO 4pF CAPDAC The AD7151 CDC core maximum full-scale input range is 4 pF. However, the part can accept a higher capacitance on the input, and the offset (nonchanging component) capacitance can be balanced by a programmable on-chip CAPDAC. . The ...
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... The AD7151 logic output (active high) indicates either a positive or a negative change in the input capacitance, in both adaptive and fixed threshold modes (see Figure 23 and Figure 24). ...
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... AD7151 SENSITIVITY In adaptive threshold mode, the output comparator threshold is set as a defined distance (sensitivity) above the data average, below the data average, or both, depending on the selected threshold mode of operation (see Figure 29). The sensitivity value is programmable in the range 0 to 255 LSBs of the 12-bit CDC converter (see the Register Descriptions section) ...
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... CDC capacitive input range. See the Setup Register section. POWER-DOWN TIMER In power sensitive applications, the AD7151 can be set to automatically enter power-down mode after a programmed period of time in which the output has not been activated. The AD7151 can be then returned to a normal operational mode either via the serial interface or by the power supply off/on sequence ...
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... AD7151 REGISTER DESCRIPTIONS Table 5. Register Summary Pointer Register (Dec) (Hex) R/W Status 0 0x00 R Data High 1 0x01 R Data Low 2 0x02 R – 3 0x03 R – 4 0x04 R Average High 5 0x05 R Average Low 6 0x06 R – 7 0x07 R – 8 0x08 R Sensitivity 9 0x09 R/W Threshold High Timeout 10 0x0A R/W Threshold Low Setup ...
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... RDY = 0 indicates a finished CDC conversion. The bit is reset back to 1 when the data register is read via the serial interface or after the part reset or power-up. Bit 6 Bit 5 Bit 4 – – DacStep Rev Page AD7151 Bit 3 Bit 2 Bit 1 OUT – – below the power supply DD ...
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... BIT 1 BIT 0 BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 12-BIT CDC RESULT Figure 34. CDC Data Register The nominal AD7151 CDC transfer function (an ideal transfer function excluding offset and/or gain error) maps the input capacitance between zero scale and full scale to output data codes between 0x3000 and 0xCFF0 only (see Table 8) ...
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... Figure 37. Threshold Timeout Approaching After a Large Change in CDC Data Toward Threshold DATA AVERAGE + SENSITIVITY DATA AVERAGE THRESHOLD After a Large Change in CDC Data Away from Threshold Rev Page AD7151 LARGE CHANGE IN DATA TOWARDS THRESHOLD TIME TIMEOUT APPROACHING TIMEOUT RECEDING TIME LARGE CHANGE IN DATA AWAY FROM THE THRESHOLD Figure 38 ...
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... AD7151 SETUP REGISTER Address Pointer 0x0B 8 Bits, Read/Write, Factory Preset 0x0B Table 10. Setup Register Bit Map Bit Bit 7 Mnemonic RngH Default 0 Table 11. Setup Register Bit Descriptions Bit Mnemonic Description 7 RngH Range bits set the CDC input range and determine the step for the AutoDAC function. ...
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... Part performs a single conversion, provided the EnConv bit is set. After finishing the conversion(s), the part goes to the idle mode. 1 Power-Down Powers down the on-chip circuits, except the digital interface. X Reserved Do not use these modes. Rev Page AD7151 Bit 3 Bit 2 Bit 1 – MD2 MD1 Output Active When Fixed Threshold Mode Data < ...
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... AD7151 POWER-DOWN TIMER REGISTER Address Pointer 0x10 8 Bits, Read/Write, Factory Preset 0x00 Table 14. Power-Down Timer Register Bit Map Bit Bit 7 Mnemonic – Default 0 Table 15. Power-Down Timer Register Bit Descriptions Bit Mnemonic Description [7:6] - These bits must be 0 for proper operation [5:0] Power-Down Defines the period duration of the power-down timeout. ...
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... In this case, the AD7151 becomes a slave transmitter. In all instances, the AD7151 acts as a standard slave device on the serial bus. The start byte address for the AD7151 is 0x90 for a write and 0x91 for a read. READ OPERATION When a read is selected in the start byte, the register that is currently addressed by the address pointer is transmitted to the SDA line by the AD7151 ...
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... AD7151 RESET To reset the AD7151 without having to reset the entire serial bus, an explicit reset command is provided. This uses a particular address pointer word as a command word to reset the part and upload all default settings. The AD7151 does not respond to the serial bus commands (do not acknowledge) during the default values upload for approximately 2 ms ...
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... GND for CIN and information about excitation). See Figure 4, Figure 5, Figure 6, and Figure 7. PARASITIC RESISTANCE TO GROUND R GND1 R The AD7151 CDC result is affected by a leakage current from C to ground; therefore The equivalent resistance between C maximized (see Figure 43). See Figure 8, Figure 9, Figure 10, and Figure 11. ...
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... PARASITIC SERIAL RESISTANCE R S1 CIN EXC Figure 45. Parasitic Serial Resistance The AD7151 CDC result is affected by a resistance in series with the measured capacitance. The total serial resistance ( Figure 45) should be on the order of hundreds of Ω. S2 See Figure 12. INPUT OVERVOLTAGE PROTECTION R S1 CIN ...
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... C SENS C SENS 39kΩ 82kΩ 68pF 22pF C SENS 10kΩ 47pF Figure 51. AD7151 Standalone Operation with EMC Protection and Optional Serial Interface 0.1µF 10kΩ VDD AD7151 CIN SDA SCL EXC OUT GND Figure 49. AD7151 Standalone Operation Application Diagram 0.1µF 1kΩ ...
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... AD7151 OUTLINE DIMENSIONS ORDERING GUIDE Model Temperature Range 1 AD7151BRMZ −40°C to +85°C AD7151BRMZ-REEL 1 −40°C to +85° RoHS Compliant Part. 3.10 3.00 2. 5.15 3.10 4.90 3.00 4.65 2. PIN 1 0.50 BSC 0.95 0.85 1.10 MAX 0.75 0.15 0.33 SEATING 0.23 0.05 PLANE 0.17 0.08 COPLANARITY 0.10 COMPLIANT TO JEDEC STANDARDS MO-187-BA Figure 52. 10-Lead Mini Small Outline Package [MSOP] ...
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... NOTES Rev Page AD7151 ...
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... AD7151 NOTES Purchase of licensed components of Analog Devices or one of its sublicensed Associated Companies conveys a license for the purchaser under the Philips I 2 Rights to use these components system, provided that the system conforms to the I ©2007 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners ...