Datasheet AD7675 (Analog Devices) - 7

AD7675 PIN FUNCTION DESCRIPTIONS (continued) Pin No. Mnemonic Type Description
21 DATA[8] DO When SER/PAR is LOW, this output is used as the Bit 8 of the Parallel Port Data Output Bus. or SDOUT When SER/PAR is HIGH, this output, part of the serial port, is used as a serial data output synchronized to SCLK. Conversion results are stored in an on-chip register. The AD7675 provides the conversion result, MSB first, from its internal shift register. The DATA format is determined by the logic level of OB/2C. In serial mode, when EXT/INT is LOW, SDOUT is valid on both edges of SCLK. In serial mode, when EXT/INT is HIGH: If INVSCLK is LOW, SDOUT is updated on SCLK rising edge and valid on the next falling edge. If INVSCLK is HIGH, SDOUT is updated on SCLK falling edge and valid on the next rising edge. 22 DATA[9] DI/O When SER/PAR is LOW, this output is used as the Bit 9 of the Parallel Port Data Output Bus. or SCLK When SER/PAR is HIGH, this pin, part of the serial port, is used as a serial data clock input or output, dependent upon the logic state of the EXT/INT Pin. The active edge where the data SDOUT is updated depends upon the logic state of the INVSCLK Pin. 23 DATA[10] DO When SER/PAR is LOW, this output is used as the Bit 10 of the Parallel Port Data Output Bus. or SYNC When SER/PAR is HIGH, this output, part of the serial port, is used as a digital output frame synchronization for use with the internal data clock (EXT/INT = Logic LOW). When a read sequence is initiated and INVSYNC is LOW, SYNC is driven HIGH and remains HIGH while SDOUT output is valid. When a read sequence is initiated and INVSYNC is HIGH, SYNC is driven LOW and remains LOW while SDOUT output is valid. 24 DATA[11] DO When SER/PAR is LOW, this output is used as the Bit 11 of the Parallel Port Data Output Bus. or RDERROR When SER/PAR is HIGH and EXT/INT is HIGH, this output, part of the serial port, is used as an incomplete read error flag. In slave mode, when a data read is started and not complete when the following conversion is complete, the current data is lost and RDERROR is pulsed high. 25–28 DATA[12:15] DO Bit 12 to Bit 15 of the Parallel Port Data output bus. These pins are always outputs regardless of the state of SER/PAR. 29 BUSY DO Busy Output. Transitions HIGH when a conversion is started, and remains HIGH until the conversion is complete and the data is latched into the on-chip shift register. The falling edge of BUSY could be used as a data ready clock signal. 30 DGND P Must Be Tied to Digital Ground 31 RD DI Read Data. When CS and RD are both LOW, the interface parallel or serial output bus is enabled. 32 CS DI Chip Select. When CS and RD are both LOW, the interface parallel or serial output bus is enabled. CS is also used to gate the external serial clock. 33 RESET DI Reset Input. When set to a logic HIGH, reset the AD7675. Current conversion if any is aborted. 34 PD DI Power-Down Input. When set to a logic HIGH, power consumption is reduced and conver- sions are inhibited after the current one is completed. 35 CNVST DI Start Conversion. If CNVST is HIGH when the acquisition phase (t8) is complete, the next falling edge on CNVST puts the internal sample/hold into the hold state and initiates a conversion. This mode is the most appropriate if low sampling jitter is desired. If CNVST is LOW when the acquisition phase (t8) is complete, the internal sample/hold is put into the hold state and a conversion is immediately started. 36 AGND P Must Be Tied to Analog Ground 37 REF AI Reference Input Voltage 38 REFGND AI Reference Input Analog Ground 39 IN– AI Differential Negative Analog Input 43 IN+ AI Differential Positive Analog Input NOTES AI = Analog Input DI = Digital Input DI/O = Bidirectional Digital DO = Digital Output P = Power –6– REV. A 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