AL Tech 8CH Manual de usuario

1LTC2424/LTC24284-/8-Channel 20-Bit µPowerNo Latency ∆ΣTM ADCsThe LTC®2424/LTC2428 are 4-/8-channel 2.7V to 5.5Vmicropower 20-bit A/D converters with

10LTC2424/LTC2428PIN FUNCTIONSUUUCSADC (Pin 23): ADC Chip Select Input. A low on this pinenables the SDO digital output and following each conver-sion

11LTC2424/LTC2428APPLICATIONS INFORMATIONWUUUConverter Operation CycleThe LTC2424/LTC2428 are low power, 4-/8-channel delta-sigma analog-to-digital co

12LTC2424/LTC2428Ease of UseThe LTC2424/LTC2428 data output has no latency, filtersettling or redundant data associated with the conversioncycle. Ther

13LTC2424/LTC2428APPLICATIONS INFORMATIONWUUUThe LTC2424/LTC2428 can be interchanged with theLTC2404/LTC2408. The two devices are designed to allowthe

14LTC2424/LTC2428As long as the voltage on the VIN pin is maintained withinthe –0.3V to (VCC + 0.3V) absolute maximum operatingrange, a conversion res

15LTC2424/LTC2428APPLICATIONS INFORMATIONWUUUFigure 5. LTC2424/LTC2428 Normal Mode Rejection WhenUsing an External Oscillator of Frequency fEOSCLOW. T

16LTC2424/LTC2428As shown in Figure 6, an external clock of 2.051MHzapplied to the FO pin results in a notch frequency of 800Hzwith a data output rate

17LTC2424/LTC2428APPLICATIONS INFORMATIONWUUUFor output data rates up to 50 samples/second, the totalunadjusted error (TUE) is better than 16 bits, an

18LTC2424/LTC2428APPLICATIONS INFORMATIONWUUUFigure 12. Using the LTC2424/LTC2428’s High Accuracy Wide Dynamic Rangeto Digitize a 300mVP-P 15Hz Wavefo

19LTC2424/LTC2428APPLICATIONS INFORMATIONWUUUIn the Internal SCK mode of operation, the SCK pin is anoutput and the LTC2424/LTC2428 creates its own se

2LTC2424/LTC2428ORDERPART NUMBER(Notes 1, 2)Supply Voltage (VCC) to GND...–0.3V to 7VAnalog Input Voltage to GND ... –0.3V to

20LTC2424/LTC2428APPLICATIONS INFORMATIONWUUUExternal Serial Clock (SPI/MICROWIRE Compatible)This timing mode uses an external serial clock (SCK) tosh

21LTC2424/LTC2428APPLICATIONS INFORMATIONWUUUthe 24th rising edge of SCK. On the 24th falling edge ofSCK, the device begins a new conversion. SDO goes

22LTC2424/LTC2428APPLICATIONS INFORMATIONWUUUFigure 16. Internal Serial Clock Timing DiagramSCKCLKSDODINCSADCCSMUXtEOCtestMSBLSBEXRSIGBIT0BIT4 BIT3 BI

23LTC2424/LTC2428APPLICATIONS INFORMATIONWUUUIn order to select the internal serial clock timing mode, theserial clock pin (SCK) must be floating (Hi-

24LTC2424/LTC2428APPLICATIONS INFORMATIONWUUUA similar situation may occur during the sleep state whenCSADC is pulsed HIGH-LOW-HIGH in order to test t

25LTC2424/LTC2428APPLICATIONS INFORMATIONWUUUWhile a digital input signal is in the 0.5V to (VCC␣ –␣ 0.5V)range, the CMOS input receiver draws additio

26LTC2424/LTC2428APPLICATIONS INFORMATIONWUUUInput Current (VIN)If complete settling occurs on the input, conversion re-sults will be unaffected by th

27LTC2424/LTC2428nonlinearity of the multiplexer switch is seen in theoverall transfer characteristic.In addition to the input current spikes, the inp

28LTC2424/LTC2428APPLICATIONS INFORMATIONWUUUFigure 29. Sync4 Filter RejectionINPUT FREQUENCY0–60–400fS = 15,360Hz24248 F29–80–100fS/2 fS–120–140–20RE

29LTC2424/LTC2428than 60% full scale, and only marginally increases noiseapproaching full scale. Even lower power references canbe used if only the lo

3LTC2424/LTC2428SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITSVINInput Voltage Range (Note 14) ● –0.125 • VREF1.125 • VREFVVREFReference Voltage Range

30LTC2424/LTC2428The LTC2428’s Resolution and Accuracy Allows Youto Measure Points in a Ladder of SensorsIn many industrial processes, for example, cr

31LTC2424/LTC2428APPLICATIONS INFORMATIONWUUUFigure 34. Using the Multiplexer to Produce Programmable Gains of 1 to 12824248 F34CH0CH1CH2CH3CH4CH5CH6C

32LTC2424/LTC2428APPLICATIONS INFORMATIONWUUUchannel resistance of the multiplexer does not contributemuch to the error budget, as only input op amp c

33LTC2424/LTC2428An 8-Channel DC-to-Daylight DigitizerThe circuit in Figure 36 shows an example of the LTC2428’sflexibility in digitizing a number of

34LTC2424/LTC2428could be used to measure the case temperature of theRTD-based thermal power measurement scheme describedpreviously. In general, therm

35LTC2424/LTC2428Dimensions in millimeters (inches) unless otherwise noted.PACKAGE DESCRIPTIOUG Package28-Lead Plastic SSOP (0.209)(LTC DWG # 05-08-16

36LTC2424/LTC2428RELATED PARTSPART NUMBER DESCRIPTION COMMENTSLTC2400 24-Bit µPower, No Latency ∆Σ ADC in SO-8 4ppm INL, 10ppm TUE, 200µA, Pin Compati

4LTC2424/LTC2428SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITSVIHHigh Level Input Voltage 2.7V ≤ VCC ≤ 5.5V ● 2.5 VCS, FO2.7V ≤ VCC ≤ 3.3V 2.0 VVILLow

5LTC2424/LTC2428The ● denotes specifications which apply over the full operating temperature range,otherwise specifications are at TA = 25°C. (Note 3)

6LTC2424/LTC2428TYPICAL PERFOR A CE CHARACTERISTICS UWTotal Unadjusted Error (3V Supply)Negative Input Extended TotalUnadjusted Error (3V Supply)I

7LTC2424/LTC2428TYPICAL PERFOR A CE CHARACTERISTICS UWRMS Noise vs Reference Voltage Offset Error vs VCCRMS Noise vs VCCNoise HistogramRMS Noise v

8LTC2424/LTC2428TYPICAL PERFOR A CE CHARACTERISTICS UWSleep Current vs Temperature Rejection vs Frequency at VCCRejection vs Frequency at VCCRejec

9LTC2424/LTC2428TYPICAL PERFOR A CE CHARACTERISTICS UWINL vs Output Rate INL vs Output RateResolution vs Output RateOUTPUT RATE (Hz)0TUE RESOLUTIO