AD7715AR-3 Analog Devices Inc, AD7715AR-3 Datasheet
AD7715AR-3
Specifications of AD7715AR-3
Available stocks
Related parts for AD7715AR-3
AD7715AR-3 Summary of contents
Page 1
FEATURES Charge-balancing ADC 16-bits no missing codes 0.0015% nonlinearity Programmable gain front end Gains and 128 Differential input capability Three-wire serial interface SPI-, QSPI™-, MICROWIRE™-, and DSP-compatible Ability to buffer the analog input 3 V (AD7715-3) ...
Page 2
AD7715 TABLE OF CONTENTS Features .............................................................................................. 1 Functional Block Diagram .............................................................. 1 General Description ......................................................................... 1 Product Highlights ........................................................................... 1 Revision History ............................................................................... 2 Specifications..................................................................................... 3 AD7715-5 ...................................................................................... 3 AD7715-3 ...................................................................................... 5 Timing Characteristics ................................................................ 8 Absolute Maximum Ratings............................................................ 9 ...
Page 3
SPECIFICATIONS AD7715 REF IN(+) = 2.5 V; REF IN(−) = AGND unless otherwise noted. MIN MAX Table 1. 1 Parameter Min STATIC ...
Page 4
AD7715 1 Parameter Min LOGIC OUTPUTS (Including MCLK OUT Output Low Voltage Output Low Voltage Output High Voltage 4 Output High Voltage DV OH Floating State Leakage Current 13 ...
Page 5
AD7715 REF IN (+) = 1.25 V; REF IN(−) = AGND unless otherwise noted. MAX Table 2. 1 Parameter Min STATIC PERFORMANCE No Missing Codes 16 ...
Page 6
AD7715 1 Parameter Min LOGIC OUTPUTS (Including MCLK OUT Output Low Voltage Output High Voltage Floating State Leakage Current 13 Floating State Output Capacitance Data Output Coding 1 Temperature range as follows: ...
Page 7
REF IN(+) = 1.25 V (AD7715-3) or 2.5 V (AD7715-5); REF IN(−) = AGND; MCLK MHz 2.4576 MHz, unless otherwise ...
Page 8
AD7715 TIMING CHARACTERISTICS 5. 5.25 V; AGND = DGND = otherwise noted. Table 4. Limit MIN MAX (A Version) 1, ...
Page 9
ABSOLUTE MAXIMUM RATINGS T = 25°C, unless otherwise noted. A Table 5. Parameter AV to AGND DGND AGND DGND DD DGND to AGND Analog Input Voltage ...
Page 10
AD7715 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS Table 6. Pin Function Descriptions Pin No. Mnemonic Description 1 SCLK Serial Clock. Logic input. An external serial clock is applied to this input to access serial data from the AD7715. This serial clock ...
Page 11
TERMINOLOGY Integral Nonlinearity This is the maximum deviation of any code from a straight line passing through the endpoints of the transfer function. The endpoints of the transfer function are zero-scale (not to be confused with bipolar zero), a point ...
Page 12
AD7715 ON-CHIP REGISTERS The AD7715 contains four on-chip registers, which can be accessed by via the serial port on the part. The first of these is a communications register that decides whether the next operation is a read or write ...
Page 13
COMMUNICATIONS REGISTER (RS1, RS0 = 0, 0) The communications register is an eight-bit register from which data can either be read or to which data can be written. All communica- tions to the part must start with a write operation ...
Page 14
AD7715 SETUP REGISTER (RS1, RS0 = 0, 1); POWER ON/RESET STATUS: 28 HEX The setup register is an eight-bit register from which data can either be read or to which data can be written. This register controls the setup that ...
Page 15
Table 13. MD1 MD0 Operating Mode 0 0 Normal mode. This operating mode is the default mode of operation of the device whereby the device is performing normal conversions. The AD7705 is placed in this mode after power-on or reset. ...
Page 16
AD7715 OUTPUT NOISE AD7715-5 Table 15 shows the AD7715-5 output rms noise for the selecta- ble notch and −3 dB frequencies for the part, as selected by FS1 and FS0 of the setup register. The numbers given are for the ...
Page 17
AD7715-3 Table 19 shows the AD7715-3 output rms noise for the selecta- ble notch and −3 dB frequencies for the part, as selected by FS1 and FS0 of the setup register. The numbers given are for the bipolar input ranges ...
Page 18
AD7715 CALIBRATION SEQUENCES The AD7715 contains a number of calibration options as outlined in Table 13. Table 23 summarizes the calibration types, the operations involved and the duration of the operations. There are two methods of determining the end of ...
Page 19
CIRCUIT DESCRIPTION The AD7715 is a Σ-Δ ADC with on-chip digital filtering, intended for the measurement of wide dynamic range, low frequency signals such as those in industrial control or process control applications. It contains a Σ-Δ (or charge-balancing) ADC, ...
Page 20
AD7715 In unbuffered mode, the analog inputs look directly into the input sampling capacitor The dc input leakage current in SAMP this unbuffered mode maximum result, the analog inputs see a dynamic load ...
Page 21
REFERENCE INPUT The reference inputs of the AD7715, REF IN(+) and REF IN(−), provide a differential reference input capability. The common- mode range for these differential inputs is from AGND to AV The nominal reference voltage, V (REF IN(+) − ...
Page 22
AD7715 Filter Characteristics The AD7715’s digital filter is a low-pass filter with a (sinx/x) 3 response (also called sinc ). The transfer function for this filter is described in the z-domain by 3 ⎡ − ⎤ − ...
Page 23
ANALOG FILTERING The digital filter does not provide any rejection at integer mul- tiples of the modulator sample frequency, as outlined earlier. However, due to the high oversampling ratio of AD7715, these bands occupy only a small fraction of the ...
Page 24
AD7715 System Calibration System calibration allows the AD7715 to compensate for system gain and offset errors as well as its own internal errors. System calibration performs the same slope factor calculations as self calibration but uses voltage values presented by ...
Page 25
If the part is used in unipolar mode with a required span of 0.8 × V /GAIN, then the offset range which the system REF calibration can handle is from −1.05 × /GAIN. If the part is used ...
Page 26
AD7715 USING THE AD7715 CLOCKING AND OSCILLATOR CIRCUIT The AD7715 requires a master clock input, which may be an external CMOS compatible clock signal applied to the MCLK IN pin with the MCLK OUT pin left unconnected. Alternatively, a crystal ...
Page 27
Because the FSYNC bit resets the digital filter, the full settling time of 3 × 1/output rate must elapse before there is a new word loaded to the output register on the part. If the DRDY signal is low when ...
Page 28
AD7715 POWER SUPPLIES There is no specific power sequence required for the AD7715; either the AV or the DV supply can come up first. While DD DD the latch-up performance of the AD7715 is good important that power ...
Page 29
Evaluating the AD7715 Performance The recommended layout for the AD7715 is outlined in the evaluation board for the AD7715. The evaluation board package includes a fully assembled and tested evaluation board, documentation, software for controlling the board over the USB ...
Page 30
AD7715 Figure 8 and Figure 9 show timing diagrams for interfacing to the AD7715 with CS used to decode the part. read operation from the AD7715’s output shift register, while Figure 9 shows a write operation to the input shift ...
Page 31
CONFIGURING THE AD7715 The AD7715 contains three on-chip registers which the user accesses via the serial interface. Communication with any of these registers is initiated by writing to the communications register first. Figure 10 outlines a flow chart of the ...
Page 32
AD7715 MICROCONTROLLER/MICROPROCESSOR INTERFACING The flexible serial interface of the AD7715 allows for easy interface to most microcontrollers and microprocessors. The flow chart of Figure 10 outlines the sequence which should be followed when interfacing a microcontroller or microprocessor to the ...
Page 33
AD7715 TO 8XC51 INTERFACE An interface circuit between the AD7715 and the 8XC51 microcontroller is shown in Figure 12. The diagram shows the minimum number of interface connections with CS on the AD7715 hardwired low. In the case of the ...
Page 34
AD7715 CODE FOR SETTING UP THE AD7715 The C Code for Interfacing AD7715 to 68HC11 section gives a set of read and write routines in C code for interfacing the 68HC11 microcontroller to the AD7715. The sample program sets up ...
Page 35
PORTC &= 0xfb; /* /CS is low */ SPDR = byteword; /* put the byte into data register */ while(!(SPSR & 0x80)); /* wait for /DRDY to go low */ PORTC |= 0x4; /* /CS high */ } Read(int amount, ...
Page 36
AD7715 APPLICATIONS INFORMATION The AD7715 provides a low cost, high resolution analog-to- digital function. Because the analog-to-digital function is provided by a Σ-Δ architecture, it makes the part more immune to noisy environments thus making the part ideal for use ...
Page 37
TEMPERATURE MEASUREMENT Another application area for the AD7715 is in temperature measurement. Figure 15 outlines a connection from a thermo- couple to the AD7715. In this application, the AD7715 is operated in its buffered mode to allow large decoupling capacitors ...
Page 38
AD7715 SMART TRANSMITTERS Another area where the low power, single supply, three-wire interface capabilities is of benefit is in smart transmitters. Here, the entire smart transmitter must operate from the loop. Tolerances in the loop ...
Page 39
OUTLINE DIMENSIONS 0.210 (5.33) MAX 0.150 (3.81) 0.130 (3.30) 0.115 (2.92) 0.022 (0.56) 0.018 (0.46) 0.014 (0.36) CONTROLLING DIMENSIONS ARE IN INCHES; MILLIMETER DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF INCH EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN ...
Page 40
... V 1 AD7715ARZ AD7715ARZ-5REEL 5 V AD7715ARU AD7715ARU-5REEL 5 V AD7715ARU-5REEL7 AD7715ARUZ AD7715ARUZ-5REEL7 5 V AD7715ACHIPS AD7715AN AD7715ANZ AD7715AR AD7715AR-3REEL AD7715ARZ AD7715ARZ-3REEL 3 V AD7715ARU AD7715ARU-3REEL 3 V AD7715ARU-3REEL7 AD7715ARUZ AD7715ARUZ-3REEL7 3 V AD7715ACHIPS EVAL-AD7715-3EBZ RoHS Compliant Part. ©2009 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. ...