CS5531/32/33/34 - Eshop-Rychle.cz

CS5531/32/33/342.2.4. Serial Port InterfaceThe CS5531/32/33/34’s serial interface consists offour control lines: CS, SDI,SDO,SCLK.Figure7details the command and data word timing.CS, Chip Select, is the control line which enablesaccess to the serial port. If the CS pin is tied low,the port can function as a three wire interface.SDI, Serial Data In, is the data signal used to transferdata to the converters.SDO, Serial Data Out, is the data signal used totransfer output data from the converters. The SDOoutput will be held at high impedance any time CSis at logic 1.SCLK, Serial Clock, is the serial bit-clock whichcontrols the shifting of data to or from the ADC’sserial port. The CS pin must be held low (logic 0)before SCLK transitions can be recognized by theport logic. To accommodate optoisolators SCLK isdesigned with a Schmitt-trigger input to allow anoptoisolator with slower rise and fall times to directlydrive the pin. Additionally, SDO is capableof sinking or sourcing up to 5 mA to directly drivean optoisolator LED. SDO will have less than a 400mV loss in the drive voltage when sinking or sourcing5 mA.CSSCLKSDICommand Time8SCLKsMSBWrite Cycle000000000000000000000000000000000000000000000000000000Data Time 32 SCLKsLSBCSSCLKSDICommand Time8SCLKs000000SDO MSB000000LSB000000Read Cycle000000000000000000000000000000000000000000000000000000000000Data Time 32 SCLKsCSSCLKSDISDOCommand Time8SCLKs00000000000000000000000000000000000000000000000000t * d8 SCLKs Clear SDO FlagMSB00000000000000000000000000000000000000000000000000MCLK /OWRClock CyclesLSB00000000000000000000000000000000000000000000000000Data Conversion CycleData Time 32 SCLKs*tdisthetimeittakestheADCtoperformaconversion.SeetheSingleConversion and Continuous Conversion sections of the data sheet for moredetails about conversion timing.Figure 7. Command and Data Word Timing24 DS289PP5