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| Full Accurate 16 Bit Vout nanoDacTM, 2.7V- 5.5V, in a Sot 23 Preliminary Technical Data FEATURES Single 16-Bit DAC, 1Lsb inl. 1.8 Volt Digital Interface Capability Power-On-Reset to Zero Volts/Mid Scale Three Power-Down Functions Low Power Serial Interface with SchmittTriggered Inputs 8-Lead Sot23, 10-Lead MSOP Package Low Power Fast Settling 3us. 2.7-5.5 V Power Supply Low Glitch on Powerup. Unbuffered Voltage Capable of driving 60k Ohm load. APPLICATIONS Process Control Data Acquisition Systems Portable Battery Powered Instruments Digital Gain and Offset Adjustment Programmable Voltage and Current Sources Programmable Attenuators AD5062/AD5063 AD5062 8 Ld Sot23. The AD5062/AD5063, a member of the nanoDACTM family, are single 16-bit unbuffered voltage out DACs that operate from a single 2.7-5V supply. The AD5062 version is available in a 8 ld Sot23. The AD5063 version is available with on board resistors in a 10 ld uSOIC, making it easy to generate bipolar signals on the output. The parts utilize a versatile three-wire serial interface that operates at clock rates up to 30 MHz and is compatible with standard SPITM, QSPITM, MICROWIRETM and DSP interface standards. The reference for AD5062/AD5063 is supplied from an external REF pin. A reference buffer is also provided on chip. The part incorporates a power-on-reset circuit that ensures that the DAC output powers up to zero volts/ mid scale and remains there until a valid write takes place to the device. The part contains a power-down feature that reduces the current consumption of the device to 50nA at 5 V and provides software selectable output loads while in power-down mode. The part is put into power-down mode over the serial interface. Total unadjusted error for the part is <1mV. These parts also provide a very low glitch on power-up. Part Number AD5061 GENERAL DESCRIPTION AD5063. 10 Ld MSOP. Description 2.7 V to 5.5 V, 16 Bit nanoDACTM D/A, 4 LSBs INL, Sot 23 2.7 V to 5.5 V, 14/16 Bit nanoDACTM D/A, 1 LSBs INL, Sot23. AD5040/60 PRODUCT HIGHLIGHTS 1. Available in 8-lead SOT23, 10-lead MSOP. 2. 16 Bit Accurate, 1 LSB INL. 3. Low Glitch on Power-up. 4. High speed serial interface with clock speeds up to 30 MHz. 5. Three power down modes available to the user. Rev. PrB Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.326.8703 (c) 2004 Analog Devices, Inc. All rights reserved. Rev. Pr B | Page 1 of 17 AD5062/AD5063 AD5062/AD5063--SPECIFICATIONS1 (VDD = 2.7-5.5 V, Vref =4.096V @ VDD = 5.0V . TMIN to TMAX unless otherwise noted) Preliminary Technical Data Parameter STATIC PERFORMANCE AD5062/AD5063 Resolution Relative Accuracy TUE Differential Nonlinearity Offset Zero Code Error Gain Error Offset Drift Gain Temperature Coefficient AD5063 Bipolar Resistor Matching Bipolar Zero Offset Error Bipolar Zero Temperature Co-ef. OUTPUT CHARACTERISTICS Output Voltage Range Output Voltage Settling Time Slew Rate Output Noise Spectral Density B Version1 Min Typ Max Unit Test Conditions/Comments 16 1 0.5 1 0.65 100 200 6 2.5 +/-0.025 1 2 0 3 1 50 50 5 0.5 12 Vref -100mV Bits LSB mV LSB mV uV uV V/C ppm of FSR/C % Ratio Error mV uV/oC V s V/s nV/Hz nV/Hz nV-s nV-s Guaranteed Monotonic by Design. CODE TBD DAC code=TBD , 1kHz DAC code=TBD , 10kHz 1 LSB Change Around Major Carry. Digital-to-Analog Glitch Impulse Digital Feedthrough DC Output Impedance REFERENCE INPUT/OUPUT Vref Input Range Input Current DC Input Impedance LOGIC INPUTS Input Current VINL, Input Low Voltage VINH, Input High Voltage Pin Capacitance POWER REQUIREMENTS VDD IDD (Normal Mode) VDD = +2.7 V to +5.5 V IDD (All Power-Down Modes) VDD = +2.7 V to +5.5 V POWER EFFICIENCY IOUT/IDD 2 1 1 VDD-100mV uA M 1 0.8 1.8 3 2.7 5.5 600 A V V pF V A VDD = +5 V VDD = +5 V All Digital Inputs at Zero or VDD DAC Active and Excluding Load Current VIH = VDD and VIL = GND 50 nA VIH = VDD and VIL = GND TBD % Rev. Pr B | Page 2 of 17 ILOAD = 2 mA. VDD = +5 V Preliminary Technical Data Parameter PSSR B Version1 Min Typ Max 0.5 Unit LSB VDD +/- 10% AD5062/AD5603 Test Conditions/Comments NOTES 1Temperature ranges are as follows: B Version: -40C to +125C, typical at 25C. 2Guaranteed by design and characterization, not production tested. Specifications subject to change without notice. Rev. Pr B | Page 3 of 17 AD5062/AD5063 TIMING CHARACTERISTICS (VDD = 2.7-5.5 V; all specifications TMIN to TMAX unless otherwise noted) Preliminary Technical Data Parameter t13 t2 t3 t4 t5 t6 t7 t8 t9 Limit1 33 13 12 13 5 4.5 0 33 13 Unit ns min ns min ns min ns min ns min ns min ns min ns min ns min Test Conditions/Comments SCLK Cycle Time SCLK High Time SCLK Low Time SYNC to SCLK Falling Edge Setup Time Data Setup Time Data Hold Time SCLK Falling Edge to SYNC Rising Edge Minimum SYNC High Time SYNC Rising Edge to next SCLK Fall Ignore . NOTES 1All input signals are specified with tr = tf = 1 ns/V (10% to 90% of VDD) and timed from a voltage level of (VIL + VIH)/2. 2See Figure 1. 3Maximum SCLK frequency is 30 MHz. Specifications subject to change without notice. Figure 1. Timing Diagram Rev. Pr B | Page 4 of 17 Preliminary Technical Data ABSOLUTE MAXIMUM RATINGS Table 1. Absolute Maximum Ratings (TA = 25C unless otherwise noted) AD5062/AD5603 Parameter VDD to GND Digital Input Voltage to GND VOUT to GND1 Operating Temperature Range Industrial (B Version) Storage Temperature Range Maximum Junction Temperature SOT23 Package Power Dissipation JA Thermal Impedance Lead Temperature, Soldering Vapour Phase (60 Sec) Infrared (15 Sec) Rating -0.3 V to + 7.0 V -0.3 V to VDD + 0.3 V -0.3 V to VDD + 0.3 V -40C to +125C -65C to +150C 150C (Tj Max-Ta)/ JA 240C/W 215C 220C uSOIC Package JA Thermal Impedance Jc Thermal Impedance Lead Temperature, Soldering Vapour Phase (60 Sec) Infrared (15 Sec) 206C/W 44C/W 215C 220C 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 conditions above those listed in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. This device is a high performance RF integrated circuit with an ESD rating of <2 kV, and it is ESD sensitive. Proper precautions should be taken for handling and assembly. Model AD5062BRJ-1 AD5062BRJ-2 AD5062BRJ-3 AD5063BRM-1 Temperature Range -40OC to 125 OC -40OC to 125 OC -40OC to 125 OC -40OC to 125 OC INL 1 LSB 1 LSB 2 LSB 1 LSB Description 2.7-5.5V, Reset to Zero 2.7-5.5V, Reset to Mid 2.7-5.5V, Reset to Zero 2.7-5.5V, Reset to Zero Package Options RT8 RT8 RT8 RM-10 Rev. Pr B | Page 5 of 17 AD5062/AD5063 PIN CONFIGURATION AND FUNCTION DESCRIPTION Preliminary Technical Data Figure 2. AD5062 8ld Sot23 Figure 3. AD5063 10 ld uSOIC. Table 2. Pin Function Descriptions Mnemonic VDD REF DacGND VOUT SYNC Function Power Supply Input. These parts can be operated from +2.5 V to +5.5 V and VDD should be decoupled to GND. Reference Voltage Input. Ground input to the DAC. Analog output voltage from DAC. Level triggered control input (active low). This is the frame synchronization signal for the input data. When SYNC goes low, it enables the input shift register and data is transferred in on the falling edges of the following clocks. The DAC is updated following the 16th clock cycle unless SYNC is taken high before this edge in which case the rising edge of SYNC acts as an interrupt and the write sequence is ignored by the DAC. Serial Clock Input. Data is clocked into the input shift register on the falling edge of the serial clock input. Data can be transferred at rates up to 30 MHz. Serial Data Input. This device has a 24 bit shift register. Data is clocked into the register on the falling edge of the serial clock input. Ground reference point for Analog circuitry on the part. Feedback Resistor. In bipolar mode connect this pin to external op amp circuit. Connected to the internal Scaling resistors of the DAC. Connect INV pin to external op-amps inverting input in bipolar mode. SCLK DIN AGND RFB INV Rev. Pr B | Page 6 of 17 Preliminary Technical Data Gain Error TERMINOLOGY Relative Accuracy For the DAC, relative accuracy or Integral Nonlinearity (INL) is a measure of the maximum deviation, in LSBs, from a straight line passing through the endpoints of the DAC transfer function. A typical INL vs. code plot can be seen in Figure 2. AD5062/AD5063 This is a measure of the span error of the DAC. It is the deviation in slope of the DAC transfer characteristic from ideal expressed as a percent of the full-scale range. Total Unadjusted Error Total Unadjusted Error (TUE) is a measure of the output error taking all the various errors into account. A typical TUE vs. code plot can be seen in Figure 4. Differential Nonlinearity Differential Nonlinearity (DNL) is the difference between the measured change and the ideal 1 LSB change between any two adjacent codes. A specified differential nonlinearity of 1 LSB maximum ensures monotonicity. This DAC is guaranteed monotonic by design. A typical DNL vs. code plot can be seen in Figure 3. Zero-Code Error Drift This is a measure of the change in zero-code error with a change in temperature. It is expressed in V/C. Gain Error Drift This is a measure of the change in gain error with changes in temperature. It is expressed in (ppm of full-scale range)/C. Zero-Code Error Zero-code error is a measure of the output error when zero code (0000Hex) is loaded to the DAC register. Ideally the output should be 0 V. The zero-code error is always positive in the AD5062/AD5063 because the output of the DAC cannot go below 0 V. It is due to a combination of the offset errors in the DAC and output amplifier. Zero-code error is expressed in mV. A plot of zero-code error vs. temperature can be seen in Figure 6. Digital-to-Analog Glitch Impulse Digital-to-analog glitch impulse is the impulse injected into the analog output when the input code in the DAC register changes state. It is normally specified as the area of the glitch in nV secs and is measured when the digital input code is changed by 1 LSB at the major carry transition (7FFF Hex to 8000 Hex). See Figure 19. Full-Scale Error Full-scale error is a measure of the output error when full-scale code (FFFF Hex) is loaded to the DAC register. Ideally the output should be VDD - 1 LSB. Full-scale error is expressed in percent of full-scale range. A plot of full-scale error vs. temperature can be seen in Figure 6. Digital Feedthrough Digital feedthrough is a measure of the impulse injected into the analog output of the DAC from the digital inputs of the DAC but is measured when the DAC output is not updated. It is specified in nV secs and measured with a full-scale code change on the data bus, i.e., from all 0s to all 1s and vice versa. Rev. Pr B | Page 7 of 17 AD5062/AD5063 INL Linearity Plot Preliminary Technical Data DNL Linearity Plot 1 1 0.6 LSB 0.2 -0.2 -0.6 -1 DAC Code Figure 4. Typical INL Plot 0.6 LSB 0.2 -0.2 -0.6 -1 DAC Code Figure 6. Typical DNL PloT. Figure 7. INL & DNLvs Supply Figure 5. Zero Scale Error and Full Scale Error vs. Temperature Figure 8. Idd Histogram @ Vdd=3/5 Volts. Rev. Pr B | Page 8 of 17 Preliminary Technical Data AD5062/AD5063 Figure 9. Supply Current vs. Temperature Figure 12. Supply Current vs SupplyoVoltage Figure 13. Half Scale Settling Time Figure 10. Full Scale Settling Time Figure 14. Power on Reset to 0 Volts. Figure 11. Supply Current vs Code. Rev. Pr B | Page 9 of 17 AD5062/AD5063 Preliminary Technical Data Figure 15. Digital to Analog Glitch Impulse Figure 18. Harmonic Distortion on digitally Generated Waveform. Figure 16. Output Spectral Density 100k Bandwidth Figure 19. 0.1 Hz to 10 Hz Noise Plot Figure 17. Exiting Power-Down Figure 20. PowerUp Transient Rev. Pr B | Page 10 of 17 Preliminary Technical Data AD5062/AD5063 Figure 21. Glitch Energy Figure 22. Offset Error Distribution Figure 23. Gain Error Distribution Rev. Pr B | Page 11 of 17 AD5062/AD5063 GENERAL DESCRIPTION The AD5062/AD5063 are single 16-bit, serial input, voltage output DACs. It operates from supply voltages of 2.7-5.5 V. Data is written to the AD5062/63 in a 24-bit word format, via a 3wire serial interface The AD5062/AD5063 incorporates a power-on reset circuit, which ensures that the DAC output powers up to 0 V or midscale. The device also has a software power-down mode pin, which reduces the typical current consumption to XX. Preliminary Technical Data buffered reference for the DAC core SERIAL INTERFACE The AD5062/AD5063 have a three-wire serial interface (SYNC, SCLK and DIN), which is compatible with SPI, QSPI and MICROWIRE interface standards as well as most DSPs. See Figure 1 for a timing diagram of a typical write sequence. The write sequence begins by bringing the SYNC line low. Data from the DIN line is clocked into the 24-bit shift register on the falling edge of SCLK. The serial clock frequency can be as high as 30 MHz, making these parts compatible with high speed DSPs. On the 24th falling clock edge, the last data bit is clocked in and the programmed function is executed (i.e., a change in DAC register contents and/or a change in the mode of operation). At this stage, the SYNC line may be kept low or be brought high. In either case, it must be brought high for a minimum of 33 ns before the next write sequence so that a falling edge of SYNC can initiate the next write sequence. Since the SYNC buffer draws more current when VIN = 1.8 V than it does when VIN = 0.8 V, SYNC should be idled low between write sequences for even lower power operation of the part. As is mentioned above, however, it must be brought high again just before the next write sequence. DAC Architecture The DAC architecture of the AD5062/AD5063 consists of two matched DAC sections. A simplifed circuit diagram is shown in Figure X The four MSBs of the 16-bit data word are decoded to drive 15 switches, E1 to E15. Each of these switches connects one of 15 matched resistors to either AGND or VREF. The remaining 12 bits of thedata word drive switches S0 to S11 of a 12-bit voltage modeR-2R ladder network. Input Shift Register The input shift register is 24 bits wide (see Figure 22). Bit D22 is the Reset Reg bit. When this is enabled the data will be loaded into the Reset Register. This will remain the reset code until the part powers down. D21, D20 are control bits that control which mode of operation the part is in (normal mode or any one of three power-down modes). There is a more complete description of the various modes in the Power-Down Modes section. The next twenty bits are the data bits. These are transferred to the DAC register on the 24th falling edge of SCLK. Figure X. DAC Ladder Structure Reference Buffer The AD5062/AD5063 operates with an external reference. The reference input (REFIN) has an input range of up to 4.096 V. This input voltage is then used to provide a Figure 22. Input Register Contents Rev. Pr B | Page 12 of 17 Preliminary Technical Data SYNC Interrupt In a normal write sequence, the SYNC line is kept low for at least 24 falling edges of SCLK and the DAC is updated on the 24th falling edge. However, if SYNC is brought high before the 24th falling edge this acts as an interrupt to the write sequence. The shift register is reset and the write sequence is seen as invalid. Neither an update of the DAC register contents or a change in the operating mode occurs--see Figure 23. AD5062/AD5063 the amplifier to a resistor network of known values. This has the advantage that the output impedance of the part is known while the part is in power-down mode. There are three different options. The output is connected internally to GND through a 1k resistor, a 100 k resistor or it is left open-circuited (Three-State). The output stage is illustrated in Figure 24. Power-On-Reset The AD5062/AD5063 contains a power-on-reset circuit that controls the output voltage during power-up. The DAC register is filled with zeros and the output voltage is 0 V. It remains there until a valid write sequence is made to the DAC. This is useful in applications where it is important to know the state of the output of the DAC while it is in the process of powering up. Figure 24. Output Stage During Power-Down The bias generator, the output amplifier, the resistor string and other associated linear circuitry are all shut down when the power-down mode is activated. However, the contents of the DAC register are unaffected when in powerdown. The time to exit power-down is typically 2.5 s for VDD = 5 V and 5 s for VDD = 3 V. See Figure 18 for a plot. Software Reset. The AD5062/AD5063 can be put into software reset by setting all in the Dac register to one. For the AD5060 this includes writing ones to bits D23-D16, which in not the normal mode of operation. Note: The SYNC Interrupt command cannot be performed if a software reset command is started. Power-Down Modes The AD5062/AD5063 contains four separate modes of operation. These modes are software-programmable by setting two bits (DB17 and DB16) in the control register. Table I shows how the state of the bits corresponds to the mode of operation of the device. MICROPROCESSOR INTERFACING AD5062/AD5063 to ADSP-2101/ADSP-2103 Interface Figure 25 shows a serial interface between the AD5062/AD5063 and the ADSP-2101/ADSP-2103. The ADSP-2101/ADSP-2103 should be set up to operate in the SPORT Transmit Alternate Framing Mode. The ADSP-2101/ADSP-2103 SPORT is programmed through the SPORT control register and should be configured as follows: Internal Clock Operation, Active Low Framing, 16-Bit Word Length. Transmission is initiated by writing a word to the Tx register after the SPORT has been enabled. Table I. Modes of Operation for the AD5062/AD5063 DB15 0 0 1 1 DB14 0 1 0 1 Operating Mode Normal Operation Power-Down Mode TRI-STATE 100 k to GND 1 k to GND When both bits are set to 0, the part works normally with its normal power consumption. However, for the three powerdown modes, the supply current falls to 200 nA at 5 V (50 nA at 3 V). Not only does the supply current fall but the output stage is also internally switched from the output of Figure 25. AD5062/AD5063 to ADSP-2101/ADSP-2103 Interface Rev. Pr B | Page 13 of 17 AD5062/AD5063 SCLK Preliminary Technical Data SYNC DIN DB23 DB0 DB23 DB0 INVALID WRITE SEQUENCE: SYNC HIGH BEFORE 24TH FALLING EDGE VALID WRITE SEQUENCE, OUTPUT UPDATES ON THE 24TH FALLING EDGE Figure 23. SYNC Interrupt Facility AD5062/AD5063 to 68HC11/68L11 Interface Figure 26 shows a serial interface between the AD5060 and the 68HC11/68L11 microcontroller. SCK of the 68HC11/68L11 drives the SCLK of the AD5060, while the MOSI output drives the serial data line of the DAC. The SYNC signal is derived from a port line (PC7). The setup conditions for correct operation of this interface are as follows: the 68HC11/68L11 should be configured so that its CPOL bit is a 0 and its CPHA bit is a 1. When data is being transmitted to the DAC, the SYNC line is taken low (PC7). When the 68HC11/68L11 is configured as above, data appearing on the MOSI output is valid on the falling edge of SCK. Serial data from the 68HC11/68L11 is transmitted in 8-bit bytes with only eight falling clock edges occurring in the transmit cycle. Data is transmitted MSB first. In order to load data to the AD5062/AD5063, PC7 is left low after the first eight bits are transferred, and a second serial write operation is performed to the DAC and PC7 is taken high at the end of this procedure. AD5062/AD5063 to 80C51/80L51 Interface Figure 27 shows a serial interface between the AD5062/AD5063 and the 80C51/80L51 microcontroller. The setup for the interface is as follows: TXD of the 80C51/80L51 drives SCLK of the AD5062/AD5063, while RXD drives the serial data line of the part. The SYNC signal is again derived from a bit programmable pin on the port. In this case port line P3.3 is used. When data is to be transmitted to the AD5062/AD5063, P3.3 is taken low. The 80C51/80L51 transmits data only in 8-bit bytes; thus only eight falling clock edges occur in the transmit cycle. To load data to the DAC, P3.3 is left low after the first eight bits are transmitted, and a second write cycle is initiated to transmit the second byte of data. P3.3 is taken high following the completion of this cycle. The 80C51/80L51 outputs the serial data in a format which has the LSB first. The AD5062/AD5063 requires its data with the MSB as the first bit received. The 80C51/80L51 transmit routine should take this into account. Figure 26. AD5062/AD5063 to 68HC11/68L11 Interface AD5062/AD5063 to Blackfin ADSP-BF53X Interface Figure 2X shows a serial interface between the AD5641 and the Blackfin ADSP-53X microprocessor. The ADSP-BF53X processor family incorporates two dual-channel synchronous serial ports, SPORT1 and SPORT0 for serial and multiprocessor communications. Using SPORT0 to connect to the AD5062/63, the setup for the interface is as follows. DT0PRI drives the SDIN pin of the AD5062/63, while TSCLK0 drives the SCLK of the part. The SYNC is driven from TFS0. Figure 27. AD5062/AD5063 to 80C51/80L51 Interface AD5062/AD5063 to Microwire Interface Figure 28 shows an interface between the AD5062/AD5063 and any microwire compatible device. Serial data is shifted out on the falling edge of the serial clock and is clocked into the AD5062/AD5063 on the rising edge of the SK. Figure 28. AD5062/AD5063 to MICROWIRE Interface APPLICATIONS Choosing a Reference for the AD5062/AD5063. Figure 2X. AD5062/AD5063 to Blackfin ADSP-BF53X Interface To achieve the optimum performance from the AD5060, thought should be given to the choice of a precision voltage Rev. Pr B | Page 14 of 17 Preliminary Technical Data reference. The AD5062/AD5063 have just one reference input, REFIN. The voltage on the reference input is used to supply the positive input to the Dac . Therefore any error in the reference will be reflected in the Dac. There are 4 possible sources of error when choosing a voltage reference for high accuracy applications; initial accuracy, ppm drift, long term drift and output voltage noise. Initial accuracy on the output voltage of the Dac will lead to a full scale error in the Dac. To minimize these errors, a reference with high initial accuracy is preferred. Also, choosing a reference with an output trim adjustment, such as the ADR425 allow a system designer to trim system errors out by setting a reference voltage to a voltage other than the nominal. The trim adjustment can also be used at temperature to trim out any error. AD5062/AD5063 Bipolar Operation Using the AD5062/AD5063 The AD5062/AD5063 has been designed for single-supply operation but a bipolar output range is also possible using the circuit in Figure 30. The circuit below will give an output voltage range of 4.096 V. Rail-to-rail operation at the amplifier output is achievable using an AD820 or an OP295 as the output amplifier. The output voltage for any input code can be calculated as follows: D R1 + R2 x V O = V DD x 65536 R1 R2 V DD x R1 5V ADR392 4.096V where D represents the input code in decimal (0-16384). With VREF = 5 V, R1 = R2 = 10 kW: VOUT = 0V TO 4.096V THREE-WIRE SERIAL INTERFACE SYNC SCLK DIN AD5062/3 10 x D VO = 65536 5V Figure 29. ADR392 as Reference to AD5062/AD5063 Long term drift is a measure of how much the reference drifts over time. A reference with a tight long term drift specification ensures that the overall solution remains relatively stable during its entire lifetime. The temperature co-efficient of a references output voltage affect INL,DNL TUE. A reference with a tight temperature coefficient specification should be chosen to reduce temperatue dependence of the Dac output voltage on ambient conditions. In high accuracy applications, which have a relatively low noise budget, reference output voltage noise needs to be considered. Choosing a reference with as low an output noise voltage as practical for the system noise resolution required is important. Precision voltage references such as the ADR435 produce low output noise in the 0.1-10Hz region. Examples of some recommended precision references for use as supply to the AD5060 are shown in the figure below.. This is an output voltage range of 5 V with 0000Hex corresponding to a -5 V output and 3FFF Hex corresponding to a +5 V output. +4.096V +5V 0.1u F 10u F 0.1u F RFB SERIAL INTERFACE +5V INV OUT -5V EXTERNAL OP AMP BIPOLAR OUTPUT VDD SYNC DIN SCLK REF RINV RFB AD5063 AGND DacGND Figure 30. Bipolar Operation with the AD5063 Using AD5062/AD5063 with an Opto-Isolated Interface Chip. In process-control applications in industrial environments it is often necessary to use an opto-isolated interface to protect and isolate the controlling circuitry from any hazardous commonmode voltages that may occur in the area where the DAC is functioning. Because the AD5062/AD5063 uses a three-wire serial logic interface, the ADuM130Xifamily s an ideal way to provide digital isolation for the DAC interface. The ADuM130x isolators provide three independent isolation channels in a variety of channel configurations and data rates. They operate across the full range from 2.7V to 5.5V, providing compatibility with lower voltage systems as well as enabling a voltage translation functionality across the isolation barrier. Part list of precision references for use with AD5062/AD5063. Part No. ADR435 ADR425 ADR02 ADR395 Initial Accuracy (mV max) +/-6 +/-6 +/-5 +/-6 Temp Drift o (ppm C max) 0.1-10Hz Noise (uV p-p typ) 3 3 3 25 3.4 3.4 15 5 Rev. Pr B | Page 15 of 17 AD5062/AD5063 Figure 31. The power supply to the part also needs to be isolated. This is done by using a transformer. On the DAC side of the transformer, a +5 V regulator provides the +5 V supply required for the AD5062/AD5063. +5V REGULATOR POWER Preliminary Technical Data AGND to DGND connection, the connection should be made at one point only. This ground point should be as close as possible to the AD5062/AD5063. The power supply to the AD5062/AD5063 should be bypassed with 10 F and 0.1 F capacitors. The capacitors should be physically as close as possible to the device with the 0.1 F capacitor ideally right up against the device. The 10 F capacitors are the tantalum bead type. It is important that the 0.1 F capacitor has low Effective Series Resistance (ESR) and Effective Series Inductance (ESI), e.g., common ceramic types of capacitors. This 0.1 F capacitor provides a low impedance path to ground for high frequencies caused by transient currents due to internal logic switching. The power supply line itself should have as large a trace as possible to provide a low impedance path and reduce glitch effects on the supply line. Clocks and other fast switching digital signals should be shielded from other parts of the board by digital ground. Avoid crossover of digital and analog signals if possible. When traces cross on opposite sides of the board, ensure that they run at right angles to each other to reduce feedthrough effects through the board. The best board layout technique is the microstrip technique where the component side of the board is dedicated to the ground plane only and the signal traces are placed on the solder side. However, this is not always possible with a two-layer board. 10. F 0.1. F SCLK V1A VOA SCLK VDD ADMu103x SDI V1B DAC VOB SDI VOUT DATA V1C VOC DIN GND Figure 31. AD5062/AD5063 with An Opto-Isolated Interface Power Supply Bypassing and Grounding When accuracy is important in a circuit it is helpful to carefully consider the power supply and ground return layout on the board. The printed circuit board containing the AD5062/AD5063 should have separate analog and digital sections, each having its own area of the board. If the AD5062/AD5063 is in a system where other devices require an Rev. Pr B | Page 16 of 17 Preliminary Technical Data Outline Dimensions Dimensions shown in inches and mms AD5062/AD5063 8 ld SOT23 10 ld uSOIC (c) 2004 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owner. PR04766-0-9/04(PrB). Rev. Pr A | Page 17 of 17 |
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