User Manual

ManualsBrandsRainbow Electronics ManualsSensorsDS1722

1 of 13 021500

FEATURES

 Temperature measurements require no

external components

 Measures temperatures from -55°C to

+120°C. Fahrenheit equivalent is -67°F to

+248°F

 Thermometer accuracy is ±2.0°C

 Thermometer resolution is configurable from

8 to 12 bits (1.0°C to 0.0625°C resolution)

 Data is read from/written to via a Motorola

Serial Peripheral Interface (SPI) or standard

3-wire serial interface

 Wide analog power supply range (2.65V -

5.5V)

 Separate digital supply allows for 1.8V logic

 Available in an 8-pin SOIC (150 mil), 8-pin

uSOP, and flip chip package

PIN ASSIGNMENT

PIN DESCRIPTION

SERMODE - Serial Interface Mode

CE - Chip Enable

SCLK - Serial Clock

GND - Ground

DDA

- Analog Supply Voltage

SDO - Serial Data Out

SDI - Serial Data In

DDD

- Digital Supply Voltage

DESCRIPTION

The DS1722 Digital Thermometer and Thermostat with SPI/3-Wire Interface provides temperature

readings which indicate the temperature of the device. No additional components are required; the device

is truly a temperature-to-digital converter. Temperature readings are communicated from the DS1722

over a Motorola SPI interface or a standard 3-wire serial interface. The choice of interface standard is

selectable by the user.

For applications that require greater temperature resolution, the user can adjust the readout resolution

from 8 to 12 bits. This is particularly useful in applications where thermal runaway conditions must be

detected quickly.

For application flexibility, the DS1722 features a wide analog supply rail of 2.65V - 5.5V. A separate

digital supply allows a range of 1.8V to 5.5V.

The DS1722 is available in an 8-pin SOIC (150-mil), 8-pin uSOP, and flip chip package.

Applications for the DS1722 include personal computers/servers/workstations, cellular telephones, office

equipment, or any thermally-sensitive system.

DS1722

Digital Thermometer with

SPI/3-Wire Interface

PRELIMINARY

www.dalsemi.com

DDD

SCLK

GND

DDA

DS1722S

8-Pin SOIC (150-mil)

SERMODE

SDI

SDO

1 8

2 7

3 6

4 5

DS1722U

8-PIN

-SOP

DDA

SERMODE

SDI

SDO

DDD

SCLK

GND

PRELIMINARY

Summary of content (13 pages)

PAGE 1
PRELIMINARY PRELIMINARY DS1722 Digital Thermometer with SPI/3-Wire Interface www.dalsemi.com FEATURES Temperature measurements require no external components Measures temperatures from -55°C to +120°C. Fahrenheit equivalent is -67°F to +248°F Thermometer accuracy is ±2.0°C Thermometer resolution is configurable from 8 to 12 bits (1.0°C to 0.
PAGE 2
DS1722 DETAILED PIN DESCRIPTION Table 1 SOIC SYMBOL PIN 1 VDDD PIN 2 CE PIN 3 SCLK PIN 4 GND PIN 5 SDO PIN 6 SDI PIN 7 SERMODE PIN 8 VDDA DESCRIPTION Digital Supply Voltage 1.8V-5.5V. Defines the top rails for the digital inputs and outputs. Chip Enable Must be asserted high for communication to take place for either the SPI or 3-wire interface. Serial Clock Input Used to synchronize data movement on the serial interface for either the SPI or 3-wire interface. Ground pin.
PAGE 3
DS1722 The DS1722 can communicate using either a Motorola Serial Peripheral Interface (SPI) or standard 3wire interface. The user can select either communication standard through the SERMODE pin, tying it to VDDD for SPI and to ground for 3-wire. The device contains both an analog supply voltage and a digital supply voltage (VDDA and VDDD, respectively). The analog supply powers the device for operation while the digital supply provides the top rails for the digital inputs and outputs.
PAGE 4
DS1722 The resolution of the temperature conversion is configurable (8, 9, 10, 11, or 12 bits), with 9-bit readings the default state. This equates to a temperature resolution of 1.0°C, 0.5°C, 0.25°C, 0.125°C, or 0.0625°C. Following each conversion, thermal data is stored in the thermometer register in two’s complement format; the information can be retrieved over the SPI or 3-wire interface with the address set to the temperature register, 01h (LSB) and then 02h (MSB).
PAGE 5
DS1722 CONFIGURATION REGISTER PROGRAMMING The configuration register is accessed in the DS1722 with the 00h address for reads and the 80h address for writes. Data is read from or written to the configuration register MSb first for SPI communication and LSb first for 3-wire communication. The format of the register is illustrated in Figure 2. The effect each bit has on DS1722 functionality is described below along with the power-up state of the bit.
PAGE 6
DS1722 The SDI and SDO pins are the serial data input and output pins for the DS1722, respectively. The CE input is used to initiate and terminate a data transfer. The SCLK pin is used to synchronize data movement between the master (microcontroller) and the slave (DS1722) devices. The shift clock (SCLK), which is generated by the microcontroller, is active only when CE is high and during address and data transfer to any device on the SPI bus.
PAGE 7
DS1722 ADDRESS AND DATA BYTES Address and data bytes are shifted MSB first into the serial data input (SDI) and out of the serial data output (SDO). Any transfer requires the address of the byte to specify a write or a read, followed by one or more bytes of data. Data is transferred out of the SDO for a read operation and into the SDI for a write operation. SPI SINGLE BYTE WRITE Figure 4 SPI SINGLE-BYTE READ Figure 5 The address byte is always the first byte entered after CE is driven high.
PAGE 8
DS1722 SPI MULTIPLE BYTE BURST TRANSFER Figure 6 3-WIRE SERIAL DATA BUS The 3-wire communication mode operates similar to the SPI mode. However, in 3-wire mode, there is one bi-directional I/O instead of separate data in and data out signals. The 3-wire consists of the I/O (SDI and SDO pins tied together), CE, and SCLK pins. In 3-wire mode, each byte is shifted in LSB first unlike SPI mode where each byte is shifted in MSB first.
PAGE 9
DS1722 ABSOLUTE MAXIMUM RATINGS* Voltage on V DD , Relative to Ground Voltage on any other pin, Relative to Ground Operating Temperature Storage Temperature Soldering Temperature -0.3V to +6.0V -0.3V to +6.0V -55°C to +125°C -55°C to +125°C 260°C for 10 seconds * This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operation sections of this specification is not implied.
PAGE 10
DS1722 ELECTRICAL CHARACTERISTICS: DIGITAL THERMOMETER (-55°°C to +120°°C, 2.65V ≤=VDDA ≤=5.5V) PARAMETER Thermometer Error Resolution Conversion Time SYMBOL TERR CONDITION -40°C to +85°C -55°C to +120°C MIN TYP 8 tCONVT 8-bit conversions 9-bit conversions 10-bit conversions 11-bit conversions 12-bit conversions 67.5 125 250 500 1000 MAX UNITS NOTES 8, 9 ±2.0 °C ±3.0 12 bits ms 75 150 300 600 1200 AC ELECTRICAL CHARACTERISTICS: 3-WIRE INTERFACE (-55°C to +120°C, 2.65V ≤=VDD ≤=5.
PAGE 11
DS1722 TIMING DIAGRAM: 3-WIRE WRITE DATA TRANSFER Figure 10 *I/O is SDI and SDO tied together. AC ELECTRICAL CHARACTERISTICS: SPI Interface (-55°°C to +120°°C, 2.65V ≤=VDD ≤=5.5V) PARAMETER Data to SCLK Setup SCLK to Data Hold SCLK to Data Valid SCLK Low Time SCLK High Time SCLK Frequency SCLK Rise and Fall CE to SCLK Setup SCLK to CE Hold CE Inactive Time CE to Output High Z SYMBOL tDC tCDH tCDD tCL tCH tCLK tR , tF tCC tCCH tCWH tCDZ CONDITION MIN 35 35 TYP MAX 80 100 100 DC 5.
PAGE 12
DS1722 TIMING DIAGRAM: SPI WRITE DATA TRANSFER Figure 12 *SCLK can be either polarity, timing shown for CPOL = 1. NOTES: 1. All voltages are referenced to ground. 2. Logic 0 voltages are specified at a sink current of 4 mA. 3. Logic 1 voltages are specified at a source current of 1 mA. 4. ICC specified with SCLK=VDDD and CE=GND. Typical ICC1 is 0.25 µA and ICC is 0.3 mA at 25°C and VDDD = 2.65V. 5. Measured at VIH =0.7 VDDD or VIL=0.2 VDDD and 10 ms maximum rise and fall time. 6.
PAGE 13
DS1722 TYPICAL DS1722 THERMOMETER ERROR 13 of 13