AD7675PIN CONFIGURATION48-Lead LQFP(ST-48)NCNCNCNCNCIN+NCNCNCIN–REFGNDREF48 47 46 45 44 43 42 41 40 39 38 37AGND 136 AGNDPIN 1AVDD 2IDENTIFIER35 CNVSTNC 334 PDBYTESWAP 433 RESET5OB/2C32 CSNC 6AD767531 RDTOP VIEWNC 730(Not to Scale)DGND8SER/PAR29 BUSYD0 928 D15D1 1027 D1411D2/DIVSCLK[0]26 D13D3/DIVSCLK[1] 1225 D1213 14 15 16 17 18 19 20 21 22 23 24NC = NO CONNECTDDINTDDOROGNDOVDVDGNDD9/SCLKD10/SYNCD4/EXT/D8/SDOUTD5/INVSYNCD6/INVSCLKD7/RDC/SDIND11/RDERRDEFINITION OF SPECIFICATIONSEFFECTIVE NUMBER OF BITS (ENOB)INTEGRAL NONLINEARITY ERROR (INL) ENOB is a measurement of the resolution with a sine wave Integral Nonlinearity is the maximum deviation of a straight line input. It is related to S/(N+D) by the following formula: drawn through the transfer function of the actual ADC. The deviation is measured from the middle of each code. ENOB = S / N ( [ +D] – .17 )6/ .602 dB DIFFERENTIAL NONLINEARITY ERROR (DNL) and is expressed in bits. In an ideal ADC, code transitions are 1 LSB apart. Differential nonlinearity is the maximum deviation from this ideal value. It TOTAL HARMONIC DISTORTION (THD) is often specified in terms of resolution for which no missing THD is the ratio of the rms sum of the first five harmonic codes are guaranteed. components to the rms value of a full-scale input signal and is expressed in decibels. +FULL-SCALE ERROR The last transition (from 011 . 10 to 011 . 11 in two’s SIGNAL-TO-NOISE RATIO (SNR) complement coding) should occur for an analog voltage 1 1/2 LSB SNR is the ratio of the rms value of the actual input signal to the below the nominal +full scale (+2.499886 V for the ±2.5 V range). rms sum of all other spectral components below the Nyquist The +full-scale error is the deviation of the actual level of the frequency, excluding harmonics and dc. The value for SNR is last transition from the ideal level. expressed in decibels. –FULL-SCALE ERRORSIGNAL-TO-(NOISE + DISTORTION) RATIO (S/[N+D]) The first transition (from 100 . 00 to 100 . 01 in two’s S/(N+D) is the ratio of the rms value of the actual input signal complement coding) should occur for an analog voltage 1/2 LSB to the rms sum of all other spectral components below the above the nominal –full scale (–2.499962 V for the ±2.5 V range). Nyquist frequency, including harmonics but excluding dc. The The –full-scale error is the deviation of the actual level of the value for S/(N+D) is expressed in decibels. last transition from the ideal level. APERTURE DELAYBIPOLAR ZERO ERROR Aperture delay is a measure of the acquisition performance and The bipolar zero error is the difference between the ideal midscale is measured from the falling edge of the CNVST input to when input voltage (0 V) and the actual voltage producing the midscale the input signal is held for a conversion. output code. TRANSIENT RESPONSESPURIOUS FREE DYNAMIC RANGE (SFDR) The time required for the AD7675 to achieve its rated accuracy The difference, in decibels (dB), between the rms amplitude of after a full-scale step function is applied to its input. the input signal and the peak spurious signal. REV. A –7– Document Outline FEATURES APPLICATIONS FUNCTIONAL BLOCK DIAGRAM PulSAR Selection GENERAL DESCRIPTION PRODUCT HIGHLIGHTS SPECIFICATIONS Table I. Serial Clock Timings in Master Read after Convert ABSOLUTE MAXIMUM RATINGS ORDERING GUIDE PIN FUNCTION DESCRIPTIONS PIN CONFIGURATION DEFINITION OF SPECIFICATIONS INTEGRAL NONLINEARITY ERROR (INL) DIFFERENTIAL NONLINEARITY ERROR (DNL) +FULL-SCALE ERROR –FULL-SCALE ERROR BIPOLAR ZERO ERROR SPURIOUS FREE DYNAMIC RANGE (SFDR) EFFECTIVE NUMBER OF BITS (ENOB) TOTAL HARMONIC DISTORTION (THD) SIGNAL-TO-NOISE RATIO (SNR) SIGNAL-TO-(NOISE + DISTORTION) RATIO (S/[N+D]) APERTURE DELAY TRANSIENT RESPONSE Typical Performance Characteristics CIRCUIT INFORMATION CONVERTER OPERATION Transfer Functions TYPICAL CONNECTION DIAGRAM Analog Inputs Single to Differential Driver Driver Amplifier Choice Voltage Reference Input Power Supply POWER DISSIPATION CONVERSION CONTROL DIGITAL INTERFACE PARALLEL INTERFACE SERIAL INTERFACE MASTER SERIAL INTERFACE Internal Clock SLAVE SERIAL INTERFACE External Clock External Discontinuous Clock Data Read after Conversion External Clock Data Read During Conversion MICROPROCESSOR INTERFACING SPI Interface (MC68HC11) ADSP-21065L in Master Serial Interface APPLICATION HINTS Layout Evaluating the AD7675 Performance OUTLINE DIMENSIONS Revision History