DS1722 Digital Thermometer with SPI/3-Wire Interface ASSIGNMENT

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DS1722 Digital Thermometer with SPI/3-Wire Interface ASSIGNMENT

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DS1722 Digital Thermometer with SPI/3-Wire Interface
ASSIGNMENT
VDDD SCLK VDDA SERMODE VDDD SCLK VDDA SERMODE
FEATURES
Temperature measurements require external components Measures temperatures from -55°C +120°C. Fahrenheit equivalent -67°F +248°F Thermometer accuracy ±2.0°C Thermometer resolution configurable from bits (1.0°C 0.0625°C resolution) Data read from/written Motorola Serial Peripheral Interface (SPI) standard 3-wire serial interface Wide analog power supply range (2.65V 5.5V) Separate digital supply allows 1.8V logic Available 8-pin SOIC (150 mil), 8-pin uSOP, flip chip package
DS1722S 8-Pin SOIC (150-mil)
DS1722U 8-PIN µ-SOP
DESCRIPTION
SERMODE SCLK VDDA VDDD Serial Interface Mode Chip Enable Serial Clock Ground Analog Supply Voltage Serial Data Serial Data Digital Supply Voltage
DESCRIPTION
DS1722 Digital Thermometer Thermostat with SPI/3-Wire Interface provides temperature readings which indicate temperature device. additional components required; device truly temperature-to-digital converter. Temperature readings communicated from DS1722 over Motorola interface standard 3-wire serial interface. choice interface standard selectable user. applications that require greater temperature resolution, user adjust readout resolution from bits. This particularly useful applications where thermal runaway conditions must detected quickly. application flexibility, DS1722 features wide analog supply rail 2.65V 5.5V. separate digital supply allows range 1.8V 5.5V. DS1722 available 8-pin SOIC (150-mil), 8-pin uSOP, flip chip package. Applications DS1722 include personal computers/servers/workstations, cellular telephones, office equipment, thermally-sensitive system.
080602
DS1722
DETAILED DESCRIPTION Table
SOIC SYMBOL VDDD SCLK DESCRIPTION Digital Supply Voltage 1.8V-5.5V. Defines rails digital inputs outputs. Chip Enable Must asserted high communication take place either 3-wire interface. Serial Clock Input Used synchronize data movement serial interface either 3-wire interface. Ground pin. Serial Data Output When communication selected, serial data output bus. When 3-wire communication selected, this must tied (the pins function single when tied together.) Serial Data Input When communication selected, serial data input bus. When 3-wire communication selected, this must tied (the pins function single when tied together.) Serial Interface Mode Input This selects which interface standard will used: when connected standard 3-wire when connected GND. Analog Supply Voltage 2.65V 5.5V input power pin.
SERMODE VDDA
OVERVIEW
block diagram DS1722 shown Figure DS1722 consists four major components: Precision temperature sensor Analog-to-digital converter SPI/3-wire interface electronics Data registers factory-calibrated temperature sensor requires external components. DS1722 powerconserving shutdown state upon power-up. After power-up, user alter configuration register place device continuous temperature conversion mode one-shot conversion mode. continuous conversion mode, DS1722 continuously converts temperature stores result temperature register. conversions performed background, reading temperature register does affect conversion progress. one-shot temperature conversion mode, DS1722 will perform temperature conversion, store result temperature register, then return shutdown state. This conversion mode ideal power sensitive applications. More information configuration register contained "OPERATION-Programming" section. temperature conversion results will have default resolution bits. applications where small incremental temperature changes critical, user change conversion resolution from bits This accomplished programming configuration register. Each additional resolution approximately doubles conversion time.
DS1722
DS1722 communicate using either Motorola Serial Peripheral Interface (SPI) standard 3wire interface. user select either communication standard through SERMODE pin, tying VDDD ground 3-wire. device contains both analog supply voltage digital supply voltage (VDDA VDDD, respectively). analog supply powers device operation while digital supply provides rails digital inputs outputs. DS1722 designed 1.8V Logic-Ready.
DS1722 FUNCTIONAL BLOCK DIAGRAM Figure
OPERATION-Measuring Temperature
core DS1722 functionality direct-to-digital temperature sensor. DS1722 measures temperature through on-chip temperature measurement technique with operating range from -55° +120°C. device powers power-conserving shutdown mode. After power-up, DS1722 placed continuous conversion mode one-shot conversion mode. continuous conversion mode, device continuously computes temperature stores most recent result temperature register addresses (LSB) (MSB). one-shot conversion mode, DS1722 performs temperature conversion then returns shutdown mode, storing temperature temperature register. Details change setting after powerup contained "OPERATION-Programming" section.
DS1722
resolution temperature conversion configurable bits), with 9-bit readings default state. This equates temperature resolution 1.0°C, 0.5°C, 0.25°C, 0.125°C, 0.0625°C. Following each conversion, thermal data stored thermometer register two's complement format; information retrieved over 3-wire interface with address temperature register, (LSB) then (MSB). Table describes exact relationship output data measured temperature. table assumes DS1722 configured 12-bit resolution; device configured lower resolution mode, those bits will contain data transmitted serially over digital interface, first communication first 3-wire communication. temperature register contains "sign" bit, denoting whether temperature positive negative. Fahrenheit usage, lookup table conversion routine must used.
Temperature/Data Relationships Table
Address Location (unit
TEMPERATURE +120°C +25.0625°C +10.125°C +0.5°C -0.5°C -10.125°C -25.0625°C -55°C
DIGITAL OUTPUT (BINARY) 0111 1000 0000 0000 0001 1001 0001 0000 0000 1010 0010 0000 0000 0000 1000 0000 0000 0000 0000 0000 1111 1111 1000 0000 1111 0101 1110 0000 1110 0110 1111 0000 1100 1001 0000 0000
DIGITAL OUTPUT (HEX) 7800h 1910h 0A20h 0080h 0000h FF80h F5E0h E6F0h C900h
OPERATION-Programming
area interest programming DS1722 Configuration register. programming done 3-wire communication interface selecting appropriate address desired register location. Table illustrates addresses registers (configuration temperature) DS1722.
Register Address Structure Table
Read Address Write Address access access
Active Register Configuration Temperature Temperature
DS1722
CONFIGURATION REGISTER PROGRAMMING
configuration register accessed DS1722 with address reads address writes. Data read from written configuration register first communication first 3-wire communication. format register illustrated Figure effect each DS1722 functionality described below along with power-up state bit. entire register volatile, thus will power-up default state.
CONFIGURATION/STATUS REGISTER Figure
1SHOT
1SHOT One-shot temperature conversion bit. "1", (continuous temperature conversions taking place), written 1SHOT will cause DS1722 perform temperature conversion store results temperature register addresses (LSB) (MSB). will clear itself upon completion temperature conversion. user read/write access 1SHOT bit, although writes this will ignored "0", (continuous conversion mode). power-up default one-shot "0". Thermometer resolution bits. Table below defines resolution digital thermometer, based settings these bits. There direct tradeoff between resolution conversion time, depicted Electrical Characteristics. user read/write access bits power-up default state R2="0", R1="0", R0="1" (9-bit conversions).
THERMOMETER RESOLUTION CONFIGURATION Table
x=Don't care. Thermometer Resolution 8-bit 9-bit 10-bit 11-bit 12-bit Conversion Time 0.075s 0.15s 0.3s 0.6s 1.2s
Shutdown bit. "0", DS1722 will continuously perform temperature conversions store last completed result temperature register. changed "1", conversion progress will completed stored then device will revert low-power shutdown mode. communication port remains active. user read/write access power-up default (shutdown mode).
SERIAL INTERFACE
DS1722 offers flexibility choose between serial interface modes. DS1722 communicate with interface with standard 3-wire interface. interface method used determined SERMODE pin. When this connected VDDD communication selected. When this connected ground, standard 3-wire communication selected.
SERIAL PERIPHERAL INTERFACE (SPI)
serial peripheral interface (SPI) synchronous address data transfer. mode serial communication selected tying SERMODE VDDD. Four pins used SPI. four pins (Serial Data Out), (Serial Data In), (Chip Enable), SCLK (Serial Clock). DS1722 slave device application, with microcontroller being master.
DS1722
pins serial data input output pins DS1722, respectively. input used initiate terminate data transfer. SCLK used synchronize data movement between master (microcontroller) slave (DS1722) devices. shift clock (SCLK), which generated microcontroller, active only when high during address data transfer device bus. inactive clock polarity programmable some microcontrollers. DS1722 offers important feature that level inactive clock determined sampling SCLK when becomes active. Therefore, either SCLK polarity accommodated. Input data (SDI) latched internal strobe edge output data (SDO) shifted shift edge (See Table Figure There clock each transferred. Address data bits transferred groups eight, first.
FUNCTION TABLE Table
MODE Disable Reset Write Read SCLK Input Disabled CPOL=1* CPOL=0 CPOL=1 Input Disabled Data Latch High High Next data shift**
CPOL=0 *CPOL "Clock Polarity" that control register microcontroller. remains High until eight bits data ready shifted during read.
NOTE:
CPHA polarity must "1".
SERIAL CLOCK FUNCTION MICROCONTROLLER CLOCK POLARITY (CPOL) Figure
CPOL=1
SCLK SHIFT INTERNAL STROBE
CPOL=0
SHIFT
INTERNAL STROBE
SCLK
NOTE:
CPOL that microcontroller's Control Register.
DS1722
ADDRESS DATA BYTES
Address data bytes shifted first into serial data input (SDI) serial data output (SDO). transfer requires address byte specify write read, followed more bytes data. Data transferred read operation into write operation.
SINGLE BYTE WRITE Figure
SINGLE-BYTE READ Figure
address byte always first byte entered after driven high. most significant (A7) this byte determines read write will take place. "0", more read cycles will occur. "1", more write cycles will occur. Data transfers occur byte time multiple-byte burst mode. After driven high address written DS1722. After address, more data bytes written read. singlebyte transfer, byte read written then driven (see Figures multiplebyte transfer, however, multiple bytes read written DS1722 after address been written (see Figure single-byte burst read/write will sequentially point through memory will loop from 02h/82h 00h/80h.
DS1722
MULTIPLE BYTE BURST TRANSFER Figure
3-WIRE SERIAL DATA
3-wire communication mode operates similar mode. However, 3-wire mode, there bi-directional instead separate data data signals. 3-wire consists (SDI pins tied together), SCLK pins. 3-wire mode, each byte shifted first unlike mode where each byte shifted first. case with mode, address byte written device followed single data byte multiple data bytes. Figure illustrates read write cycle. Figure illustrates multiple byte burst transfer. 3-wire mode, data input rising edge SCLK output falling edge SCLK.
3-WIRE SINGLE BYTE TRANSFER Figure
3-WIRE MULTIPLE BYTE BURST TRANSFER Figure
DS1722
ABSOLUTE MAXIMUM RATINGS*
Voltage Relative Ground Voltage other pin, Relative Ground Operating Temperature Storage Temperature Soldering Temperature -0.3V +6.0V -0.3V +6.0V -55°C +125°C -55°C +125°C 260°C seconds
This stress rating only functional operation device these other conditions above those indicated operation sections this specification implied. Exposure absolute maximum rating conditions extended periods time affect reliability. Dallas Semiconductor DS1722 built highest quality standards manufactured long term reliability. Dallas Semiconductor devices made using same quality materials manufacturing methods. However, DS1722 exposed environmental stresses, such burn-in, that some industrial applications require. specific reliability information this product, please contact factory Dallas (972) 371-4448.
RECOMMENDED OPERATING CONDITIONS (-55°C +120°C, 2.65V VDDA
PARAMETER Analog Supply Voltage Digital Supply Voltage SYMBOL VDDA VDDD CONDITION 2.65 UNITS NOTES
ELECTRICAL CHARACTERISTICS (-55°C +120°C, 2.65V VDDA 5.5V)
PARAMETER Input Logic High Input Logic Logic Output Logic Output Input Resistance Active Current Shutdown Current SYMBOL SDI, SDO, SCLK VDDD VDDA 3.3V VDDD CONDITION VDDD UNITS NOTES VDDD VDDD
DS1722
ELECTRICAL CHARACTERISTICS: DIGITAL THERMOMETER (-55°C +120°C, 2.65V VDDA 5.5V)
PARAMETER Thermometer Error Resolution Conversion Time SYMBOL TERR CONDITION -40°C +85°C -55°C +120°C
tCONVT 8-bit conversions 9-bit conversions 10-bit conversions 11-bit conversions 12-bit conversions 67.5 1000
UNITS NOTES ±2.0 ±3.0 bits 1200
ELECTRICAL CHARACTERISTICS: 3-WIRE INTERFACE (-55°C +120°C, 2.65V 5.5V)
PARAMETER Data SCLK Setup SCLK Data Hold SCLK Data Valid SCLK Time SCLK High Time SCLK Frequency SCLK Rise Fall SCLK Setup SCLK Hold Inactive Time Output High SCLK Output High SYMBOL tCDH tCDD tCLK tCCH tCWH tCDZ tCCZ CONDITION UNITS NOTES
TIMING DIAGRAM: 3-WIRE READ DATA TRANSFER Figure
DS1722
TIMING DIAGRAM: 3-WIRE WRITE DATA TRANSFER Figure
*I/O tied together.
ELECTRICAL CHARACTERISTICS: Interface (-55°C +120°C, 2.65V 5.5V)
PARAMETER Data SCLK Setup SCLK Data Hold SCLK Data Valid SCLK Time SCLK High Time SCLK Frequency SCLK Rise Fall SCLK Setup SCLK Hold Inactive Time Output High SYMBOL tCDH tCDD tCLK tCCH tCWH tCDZ CONDITION UNITS
NOTES
TIMING DIAGRAM: READ DATA TRANSFER Figure
DS1722
TIMING DIAGRAM: WRITE DATA TRANSFER Figure
*SCLK either polarity, timing shown CPOL
NOTES:
voltages referenced ground. Logic voltages specified sink current Logic voltages specified source current specified with SCLK=VDDD CE=GND. Typical ICC1 0.25 25°C VDDD 2.65V. Measured =0.7 VDDD VIL=0.2 VDDD maximum rise fall time. Measured with load Measured =0.7 VDDD =0.2 VDDD. Measured from point SCLK minimum SDO. Figure shows mean thermometer error pre-characterization sample. Data covering larger sample over full temperature range pending.
DS1722
TYPICAL DS1722 THERMOMETER ERROR

DS1722 Digital Thermometer with SPI/3-Wire Interface ASSIGNMENT

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