16-Bit DACPORT AD766 PRODUCT DESCRIPTION AD766 16-bit DACPOR
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FEATURES Zero-Chip Interface Digital Signal Processors Complete DACPORT® On-Chip Voltage Reference Voltage Current Outputs Serial, Twos-Complement Input Output Sample Rates kSPS Minimum Signal-to-Noise Ratio Maximum Total Harmonic Distortion 15-Bit Monotonicity Operation 16-Pin Plastic Ceramic Packages Available Commercial, Industrial, Military Temperature Ranges APPLICATIONS Digital Signal Processing Noise Cancellation Radar Jamming Automatic Test Equipment Precision Industrial Equipment Waveform Generation
16-Bit DACPORT AD766
PRODUCT DESCRIPTION
AD766 16-bit DACPORT provides direct, threewire interface serial ports popular processors, including ADSP-2101, TMS320CXX, DSP56001. additional "glue logic" required. AD766 also complete, offering on-chip serial-to-parallel input format conversion, 16-bit current-steering DAC, voltage reference, voltage output amp. AD766 fabricated Analog Devices' BiMOS mixed-signal process which provides bipolar transistors, transistors, thin-film resistors precision analog circuits addition CMOS devices logic. design layout AD766 have been optimized performance responsible guaranteed tested signal-to-noise ratio kHz. Laser-trimming AD766's silicon chromium thinfilm resistors reduces total harmonic distortion below kHz), specification also production tested. optional linearity trim allows elimination midscale differential linearity error even lower with small signals. AD766's output amplifier provides signal with high slew rate, small glitch, fast settling. output amplifier short circuit protected withstand indefinite shorts ground.
DACPORT registered trademark Analog Devices, Inc.
serial interface consists clock, data, latch enable inputs. twos-complement data word clocked first falling clock edges into serial-to-parallel converter, consistent with serial protocols popular processors. input clock support data transfers 12.5 MHz. falling edge latch enable updates internal input register sample rate with sixteen bits most recently clocked into serial input register. AD766 operates over power supply range. digital supplies, -VL, separated from analog signal supplies, -VS, reduced digital crosstalk. Separate analog digital ground pins also provided. internal bandgap reference provides precision voltage source output that stable over temperature time. Power dissipation typically with supplies with AD766 available commercial (0°C +70°C), industrial (-40°C +85°C), military (-55°C +125°C) grades. Commercial industrial grade parts available 16-pin plastic DIP; military parts processed MIL-STD-883B packaged 16-pin ceramic DIP. Analog Devices' Military Products Databook current military data sheet specifications military version.
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Information furnished Analog Devices believed accurate reliable. However, responsibility assumed Analog Devices use, infringements patents other rights third parties which result from use. license granted implication otherwise under patent patent rights Analog Devices.
Technology Way, P.O. 9106, Norwood, 02062-9106, U.S.A. Tel: 617/329-4700 Fax: 617/326-8703
AD766-SPECIFICATIONS trimming used.)
Parameter RESOLUTION DIGITAL INPUTS IIH, IIL, SERIAL PORT TIMING Serial Clock Period (tCLK) Serial Clock (tHI) Serial Clock (tLO) Data Valid (tDATA) Data Setup (tS) Data Hold (tH) Clock-to-Latch-Enable (tCTLE) Latch-Enable-to-Clock (tLETC) Latch Enable (tLEHI) Latch Enable (tLELO) ACCURACY1 Gain Error Gain Drift Midscale Output Voltage Error Bipolar Zero Drift Differential Linearity Error Monotonicity TOTAL HARMONIC DISTORTION 1037 FOUT 49.07 kHz2 SIGNAL-TO-NOISE RATIO3 (FOUT 1037 Hz)1 (FOUT 49.07 kHz)2 SETTLING TIME 0.0015% FSR) Voltage Output1 Step Step Slew Rate Current Output Step Load Load OUTPUT Voltage Output Configuration1 Bipolar Range Output Current Output Impedance Short Circuit Duration Current Output Configuration Bipolar Range Output Impedance 30%) POWER SUPPLY Voltage: Voltage: Current Case Current Case Current Case Current Case Current Case Current Case Power Dissipation: Power Dissipation: Power Dissipation: Power Dissipation: AD766J
(TMIN TMAX,
supplies, kSPS unless otherwise noted. deglitchers
AD766A
Units Bits
0.001
0.001
FSR/°C FSR/°C Bits
V/µs
2.88
3.12 Indefinite Common
2.88
3.12 Indefinite Common
4.75 -13.2 12.0 -12.0 10.5
13.2 -4.75 15.0 -15.0
4.75 -13.2 12.0 -12.0 10.5
13.2 -4.75 15.0 -15.0
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AD766
Parameter TEMPERATURE RANGE Specified Storage AD766J +100 AD766A +100 Units
NOTES grade only, voltage outputs guaranteed only Specified using external amp, Figure more details.
Tested full-scale input. grade only, power supplies must symmetric, i.e., |-VS| |-VL|. Each supply must independently meet this equality within
specifications guaranteed. Specifications boldface tested production units final electrical test. Results from those tests used calculate outgoing quality levels.
Specifications subject change without notice.
ABSOLUTE MAXIMUM RATINGS*
DGND 13.2 AGND 13.2 DGND -13.2 AGND -13.2 Digital Inputs DGND -0.3 AGND DGND Short Circuit Protection Indefinite Short Ground Soldering +300°C,
*Stresses greater than those listed under "Absolute Maximum Ratings" cause permanent damage device. This stress rating only functional operation device these other conditions above those indicated operational section this specification implied. Exposure absolute maximum rating conditions extended periods affect device reliability.
ORDERING GUIDE
Model
Temperature Range
Package Option* N-16 N-16 D-16
AD766JN +70°C AD766AN -40°C +85°C AD766SD/883B -55°C +125°C
Plastic DIP; Ceramic DIP.
CONNECTION DIAGRAM
DESIGNATIONS
Function DGND DATA VOUT AGND IOUT TRIM
Description Analog Negative Power Supply Digital Ground Logic Positive Power Supply Connection Clock Input Latch Enable Input Serial Data Input Logic Negative Power Supply Voltage Output Feedback Resistor Summing Junction Analog Ground Current Output Adjustment Terminal Trimming Potentiometer Terminal Analog Positive Power Supply
SENSITIVITY
AD766 features input protection circuitry consisting large "distributed" diodes polysilicon series resistors dissipate both high energy discharges (Human Body Model) fast, energy pulses (Charged Device Model). Method 3015.2 MIL-STD-883C, AD766 been classified Category Device. Proper precautions strongly recommended avoid functional damage performance degradation. Charges high 4000 volts readily accumulate human body test equipment, discharge without detection. Unused devices must stored conductive foam shunts, foam discharged destination socket before devices removed. further information precaution, refer Analog Devices' Prevention Manual. REV.
WARNING!
SENSITIVE DEVICE
AD766-Definition Specifications
TOTAL HARMONIC DISTORTION FUNCTIONAL DESCRIPTION
Total Harmonic Distortion (THD) defined ratio square root squares values harmonics value fundamental input frequency. expressed percent decibels (dB). measure magnitude distribution integral linearity error differential linearity error. distribution these errors different, depending amplitude output signal. Therefore, most useful, should specified both large small signal amplitudes.
SETTLING TIME
Serial input data clocked into AD766's shift register falling edge CLK. Data presumed twos complement format with (i.e., sign bit) clocked first. shift register converts most recently clocked-in bits parallel word. falling edge latch enable (LE) signal causes most recent parallel word transferred internal input latch. Figure detailed serial port timing requirements. contents input latch cause 16-bit generate corresponding current. This current available directly IOUT pin. internal amp, connect IOUT (Pin directly summing junction pin, (Pin connect feedback resistor pin, (Pin VOUT (Pin Note that internal inverting configuration. Using internal feedback resistor, this will produce outputs. advantage external pins each feedback resistor that allows user implement single pole active low-pass filter simply adding capacitor across these pins (Pins 13). circuit best understood redrawn shown Figure
Settling Time time required output reach remain within specified error band about final value, measured from digital input transition. primary measure dynamic performance.
BIPOLAR ZERO ERROR
Bipolar Zero Error midscale error deviation actual analog output from ideal output when complement input code representing half scale (all loaded input register.
DIFFERENTIAL LINEARITY ERROR
Differential Linearity Error measure variation analog value, normalized full scale, associated with change digital input. Monotonic behavior requires that differential linearity error exceed negative direction.
MONOTONICITY
converter monotonic output either increases remains constant digital input increases.
SIGNAL-TO-NOISE RATIO
Figure Low-Pass Filter Using External Capacitor
frequency response from this filter will
IOUT
defined ratio fundamental square root squares values nonfundamental, nonharmonic signals specified bandwidth. tested full-scale input. AD766 specifies bandwidths.
where 20%).
Figure AD766 Serial Input Timing
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Analog Circuit Considerations-AD766
applications requiring broader bandwidths and/or even lower noise than that afforded AD766's internal amp, external easily used place. IOUT (Pin drives negative (inverting) input terminal external amp, external voltage output connected feedback resistor pin, (Pin 10). insure that AD766's unused internal remains closed-loop configuration, VOUT (Pin should tied summing junction pin, (Pin 11). example, Figure shows AD766 using AD744 external current-to-voltage converter. this inverting configuration, AD744 will provide same output internal would have. Other recommended amplifiers include AD845 AD846. Note that single pole low-pass filtering could also attained with this circuit simply adding capacitor parallel with feedback resistor just shown Figure
Figure Recommended Circuit Schematic
digital ground returns ground current from digital logic portions AD766 circuitry. This should connected digital common point system. illustrated Figure analog digital grounds should connected together point system.
AD766 four power supply input pins. provide supply voltages operate linear portions including voltage reference, output amplifier control amplifier. supplies designed operate from supplies operate digital portions chip, including input shift register input latching circuitry. supplies also designed operate from assure freedom from latch-up, should never more negative than -VS. Special restrictions power supplies apply extended temperature range versions AD766 that apply commercial AD766J. First, supplies must symmetric. That Each supply must independently meet this equality within Since require that guarantee latch-up immunity, this symmetry principle implies that positive analog supply must greater than equal positive digital supply, i.e., extended-temperature range parts. other words, digital supply range must inside analog supply range. Second, internal amp's performance generating voltage outputs only guaranteed (and symmetry principle). These constraints apply AD766J. Decoupling capacitors should used power supply pins. Furthermore, good engineering practice suggests that these capacitors placed close possible package pins well common points. logic supplies, should decoupled digital common; analog supplies, should decoupled analog common. four separate power supplies will reduce feedthrough from digital portion system linear portions system, thus contributing performance tested. However, four separate voltage supplies necessary good circuit performance. example, Figure illustrates
POWER SUPPLIES DECOUPLING
Figure External Connections
Residual differential linearity error around midscale externally trimmed out, improving beyond AD766's guaranteed tested specifications. This error most significant with low-amplitude signals because ratio midscale linearity error signal amplitude greatest this case, thereby increasing THD. adjust circuitry shown Figure used improving with low-level signals. Otherwise, AD766 will operate specifications with (Pin TRIM (Pin unconnected.
Figure Optional Adjustment Circuit
ANALOG CIRCUIT CONSIDERATIONS
GROUNDING RECOMMENDATIONS
AD766 ground pins, designated AGND (analog ground) DGND (digital ground). analog ground "high-quality" ground reference point device. analog ground should connected analog common point system. output load should also connected that same point.
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AD766
system where only single positive single negative supply available. this case, positive logic positive analog supplies both connected single positive supply. negative logic negative analog supplies both connected single negative supply. Performance would benefit from measure isolation between supplies introduced using simple low-pass filters individual power supply leads. signal processing applications, tested output frequencies three signal levels over full operating temperature ranges. block diagram test setup shown Figure this test setup, digital data stream, representing sine wave sent device under test. frequencies used 1037 49.07 kHz. Input data latched into AD766 kSPS. AD766 under test produces analog output signal using on-board external kHz. automatic test equipment digitizes output test waveform, then performed results test. Based first harmonics fundamental 1037 first harmonics 49.07 output waves, total harmonic distortion device calculated. Neither deglitcher trim used during test. circuit design, layout manufacturing techniques employed production AD766 result excellent performance. Figure shows typical unadjusted performance AD766 various amplitudes sine waves. seen, AD766 offers excellent performance even amplitudes Figure illustrates typical versus frequency performance from internal amplifier filtered AD766 output. frequencies greater than approximately kHz, depending lowpass filter used, improvement over performance shown figure achieved. Figure illustrates consistent performance AD766 over temperature.
Figure Alternate Recommended Schematic
Figure Power Dissipation Clock Frequency
with most linear circuits, changes power supplies will affect output DAC. Analog Devices recommends that well regulated power supplies with less than ripple incorporated into design system using these device.
MEASUREMENT TOTAL HARMONIC DISTORTION
specification represents amount undesirable signal produced during reconstruction digital waveform. account variety operating conditions
Figure Typical Unadjusted
Figure Distortion Test Circuit
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Applications-AD766
AD766 TMS320C25
Figure shows zero-chip interface TMS320C25. interface other TMS320C2X processors similar. Note that should continuous mode. C25's frame synch signal (FSX) will asserted beginning each 16-bit word will actually latch previous word.
Figure Typical Frequency Figure AD766 ADSP-2101/ADSP-2102/ ADSP-2105/ ADSP-2111
Figure AD766 TMS320C25
Figure Temperature
INTERFACING AD766 DIGITAL SIGNAL PROCESSORS
CLKS, outputs TMS320C25 connected CLK, DATA inputs AD766, respectively. Data (DX) valid falling edge CLKX. maximum serial clock rate TMS320C25 MHz.
AD766 DSP56000/56001
AD766 specifically designed easily interface several popular digital signal processors (DSP) without additional logic. Such interface reduces possibility interface problems improves system reliability minimizing component count.
AD766 ADSP-2101
Figure shows zero-chip interface DSP56000/ 56001. 56000/56001 allows serial clock rates fosc/4. SCK, directly connected CLK, DATA inputs AD766. control register 56000 allows internally generated software configurable various divisions master clock frequency. data (STD) valid falling edge SCK.
ADSP-2101 incorporates complete serial ports which directly interfaced AD766 shown Figure SCLK, outputs ADSP-2101 connected directly CLK, DATA inputs AD766, respectively. SCLK internally generated programmed operate from 6.25 MHz. Data (DT) valid falling edge SCLK. After bits have been transmitted, falling edge updates AD766's data latch. Using both serial ports ADSP-2101, AD766's directly interfaced with additional hardware.
Figure AD766 DSP56000/DSP56001
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AD766
OUTLINE DIMENSIONS
Dimensions shown inches (mm).
16-Pin Plastic (N-16)
D-16 16-Lead Side Brazed Ceramic
REV.
PRINTED U.S.A.
C1385a-16-3/91
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