AD7814ART-500RL7

AD7814 AD | Alldatasheet

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REV. E a AD7814 Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. Tel: 781/329-4700 www.analog.com Fax: 781/326-8703 © 2004 Analog Devices, Inc. All rights reserved. 10-Bit Digital Temperature Sensor in 6-Lead SOT-23 FUNCTIONAL BLOCK DIAGRAM SERIAL BUS INTERFACE AD7814 VDD CS SCLK DIN DOUT GND TEMPERATURE VALUE REGISTER 10-BIT ANALOG/DIGITAL CONVERTER BAND GAP TEMPERATURE SENSOR

FEATURES

10-Bit Temperature-to-Digital Converter –55/H11543C to +125 /H11543C Operating Temperature Range /H115502/H11543C Accuracy SPI- and DSP-Compatible Serial Interface Shutdown Mode Space-Saving SOT-23 Package

APPLICATIONS

The AD7814 is a complete temperature monitoring system in a SOT-23 package or 8-lead MSOP package. It contains a band gap temperature sensor and 10-bit ADC to monitor and digitize the temperature reading to a resolution of 0.25 °C. The AD7814 has a flexible serial interface that allows easy inter- facing to most microcontrollers. The interface is compatible with SPI ® , QSPI™, and MICROWIRE™ protocol, and is also compatible with DSPs. The part features a standby mode that is controlled via the serial interface. The AD7814’s wide supply voltage range, low supply current, and SPI-compatible interface make it ideal for a variety of applications, including personal computers, office equipment, and domestic appliances. Purchase of licensed I 2C components of Analog Devices or one of its sublicensed Associated Companies conveys a license for the purchaser under the Philips I 2C Patent Rights to use these components in an I 2C system, provided that the system conforms to the I 2C Standard Specification as defined by Philips. PRODUCT HIGHLIGHTS 1. The AD7814 has an on-chip temperature sensor that allows an accurate measurement of the ambient temperature. The measurable temperature range is –55 °C to +125°C, with a ±2°C temperature accuracy. 2. Supply voltage of 2.7 V to 5.5 V 3. Space-saving 6-lead SOT-23 package and 8-lead MSOP package 4. 10-bit temperature reading to 0.25 °C resolution 5. Standby mode that reduces the current consumption to 1 µA

REV. E–2– AD7814–SPECIFICATIONS1 Parameter Min Typ Max Unit Test Conditions/Comments TEMPERATURE SENSOR AND ADC Accuracy ±2.0 °CT A = 0°C to 85°C. VDD = 3 V to 5.5 V2 ±2.5 °CT A = –40°C to 0°C. VDD = 3 V to 5.5 V2 ±2.0 ±3.5 °CT A = –55°C to +125°C. VDD = 3 V to 5.5 V Resolution 10 Bits Update Rate, tR 400 µs Temperature Conversion Time 25 µs SUPPLIES Supply Voltage 2.7 5.5 V For Specified Performance Supply Current Normal Mode 250 400 µA Shutdown Mode (VDD = 5 V) 1.23 3 µA Shutdown Mode (VDD = 3 V) 0.43 1 µA Power Dissipation 80 µWV DD = 3 V. Using Normal Mode Power Dissipation V DD = 3 V. Using Shutdown Mode 1 sps 3.7 µW 10 sps 3.9 µW 100 sps 5.8 µW DIGITAL INPUT3 Input High Voltage, V IH 2.4 V Input Low Voltage, V IL 0.8 V Input Current, IIN ± 1 µAV IN = 0 V to VDD Input Capacitance, CIN 10 pF All Digital Inputs DIGITAL OUTPUT3 Output High Voltage, V OH VDD – 0.3 V I SOURCE = ISINK = 200 µA Output Low Voltage, V OL 0.4 V I OL = 200 µA Output Capacitance, C OUT 50 pF NOTES 1All specifications apply for –55 °C to +125 °C unless otherwise stated. 2For VDD = 2.7 V to 3 V and T A = –40°C to +85°C, the typical temperature error is ±2°C. 3Guaranteed by design and characterization, not production tested. Specifications subject to change without notice. TIMING CHARACTERISTICS1, 2, 3 Parameter Limit Unit Comments t1 0 ns min CS to SCLK Setup Time t2 50 ns min SCLK High Pulse Width t3 50 ns min SCLK Low Pulse Width 4 35 ns max Data Access Time After SCLK Falling Edge t5 20 ns min Data Setup Time Prior to SCLK Rising Edge t6 0 ns min Data Hold Time After SCLK Rising Edge t7 0 ns min CS to SCLK Hold Time 4 40 ns max CS to DOUT High Impedance NOTES 1Guaranteed by design and characterization, not production tested. 2All input signals are specified with tr = tf = 5 ns (10% to 90% of V DD) and timed from a voltage level of 1.6 V. 3See Figure 2. 4Measured with the load circuit of Figure 1. Specifications subject to change without notice. (TA = TMIN to TMAX, VDD = 2.7 V to 5.5 V, unless otherwise noted.) (TA = TMIN to TMAX, VDD = 2.7 V to 5.5 V, unless otherwise noted.)

1Temperature error is over 0 °C to 85°C temperature range. conditions for extended periods may affect device reliability. accumulate on the human body and test equipment and can discharge without detection. precautions are recommended to avoid performance degradation or loss of functionality. Figure 1. Load Circuit for Data Access Time and Bus

REV. E AD7814 –4– PIN FUNCTION DESCRIPTIONS Pin SOT-23 MSOP Mnemonic Pin No. Pin No. Description GND 1 7 Analog and Digital Ground DIN 2 6 Serial Data Input. Serial data to be loaded to the part’s control register is provided on this input. Data is clocked into the control register on the rising edge of SCLK. VDD 35 Positive Supply Voltage, 2.7 V to 5.5 V SCLK 4 4 Serial Clock Input. This is the clock input for the serial port. The serial clock is used to clock data out of the temperature value register of the AD7814 and to clock data into the control register on the part. CS 53 Chip Select Input. Logic input. The device is selected when this input is low. The SCLK input is disabled when this pin is high. DOUT 6 2 Serial Data Output. Logic output. Data is clocked out of the temperature value register at this pin. Data is clocked out on the falling edge of SCLK. NC 1, 8 No Connect PIN CONFIGURATIONS SOT-23 GND TOP VIEW (Not to Scale) AD7814 DIN VDD DOUT CS SCLK MSOP TOP VIEW (Not to Scale) NC = NO CONNECT NC DOUT CS SCLK NC GND DIN VDD AD7814

REV. E –5– AD7814 CIRCUIT INFORMATION The AD7814 is a 10-bit digital temperature sensor. The part houses an on-chip temperature sensor, a 10-bit A/D converter, a reference, and serial interface logic functions in a SOT-23 package. The A/D converter section consists of a conventional successive-approximation co nverter based around a capacitor DAC. The parts are capable of running on a 2.7 V to 5.5 V power supply. The on-chip temperature sensor allows an accurate measurement of the ambient device tem perature to be made. The working measurement range of the AD7814 is –55 °C to +125°C. CONVERTER DETAILS The conversion clock for the part is internally generated so no external clock is required except when reading from and writing to the serial port. In normal mode, an internal clock oscillator runs the automatic conversion sequence. A conversion is initi- ated approximately every 350 µs. At this time, the part wakes up and performs a temperature conversion. This temperature con- version typically takes 25 µs, at which time the part automati- cally shuts down. The result of the most recent temperature conversion is available in the serial output register at any time. Once the conversion is finished, an internal oscillator starts counting and is designed to time out every 350 µs. The AD7814 then powers up and does a conversion. Please note that if the CS is brought low every 350 µs (±30%), then the same tempera- ture value will be output onto the DOUT line every time with- out changing. It is recommended that the CS line is not brought low every 350 µs (±30%). The ± 30% covers process variation. The CS should become active (high to low) outside this range. The device is designed to autoconvert every 350 µs. If the AD7814 is accessed during the conversion process, an internal signal is generated to prevent any update of the temperature value register during the conversion. Otherwise the user could read back spurious data. The design of this feature results in this internal lockout signal being reset only at the start of the next autoconversion. Therefore, if the CS line goes active before the internal lockout signal has been reset to its inactive mode, the internal lockout signal will not be reset. To ensure that no lock- out signal is set, bring the CS low at a greater or less time than 350 µs (±30%). This will mean that the AD7814 is not inter- rupted during a conversion process. The AD7814 can be placed in a shutdown mode, via the control register, in which case the on-chip oscillator is shut down and no further conversions are initiated until the AD7814 is taken out of shutdown mode. The conversion result from the last conversion prior to shutdown can still be read from the AD7814 even when it is in shutdown mode. In the automatic conversion mode, every time a read or write operation takes place, the internal clock oscillator is restarted at the end of the read or write operation. The result of the con- version is typically available 25 µs later. Similarly, when the part is taken out of shutdown mode, the internal clock oscil- lator is restarted and the conversion result is typically available 25 µs later. Reading from the device before conversion is com- plete will provide the same set of data. TEMPERATURE VALUE REGISTER The temperature value register is a read-only register that stores the temperature reading from the ADC in 10-bit twos comple- ment format. The temperature data format is shown in Table I. This shows the full theoretical range of the ADC from –128°C to +127°C, but in practice the temperature measurement range is limited to the operating temperature range of the device (–55°C to +125 °C). A typical performance curve is shown in Figure 7. Table I. Temperature Data Format Digital Output Temperature DB9 . . . DB0 –128°C 10 0000 0000 –125°C 10 0000 1100 –100°C 10 0111 0000 –75°C 10 1101 0100 –50°C 11 0011 1000 –25°C 11 1001 1100 –0.25°C 11 1111 1111 0°C 00 0000 0000 +0.25°C 00 0000 0001 +10°C 00 0010 1000 +25°C 00 0110 0100 +50°C 00 1100 1000 +75°C 01 0010 1100 +100°C 01 1001 0000 +125°C 01 1111 0100 +127°C 01 1111 1100 SERIAL INTERFACE The serial interface on the AD7814 consists of four wires CS, SCLK, DIN, and DOUT. The interface can be operated in 3-wire mode with DIN tied to Ground, in which case the inter- face has read-only capability, with data being read from the data register via the DOUT line. The DIN line is used to write the part into standby mode, if required. The CS line is used to select the device when more than one device is connected to the serial clock and data lines. The part operates in a slave mode and requires an externally applied serial clock to the SCLK input to access data from the data register. The serial interface on the AD7814 is designed to allow the part to be interfaced to systems that provide a serial clock that is synchronized to the serial data, such as the 80C51, 87C51, 68HC11, 68HC05, and PIC16Cxx microcontrollers, as well as DSP processors. A read operation from the AD7814 accesses data from the temperature value register, while a write op eration to the part writes data to the control register.

REV. E AD7814 –8– C01041–0–8/04(E) OUTLINE DIMENSIONS 6-Lead Small Outline Transistor Package [SOT-23] (RT-6) Dimensions shown in millimeters 1 3 4 5

2.90 BSC

1.60 BSC 2.80 BSC 1.90 BSC

0.95 BSC

0.22 0.08 10/H11543 4/H11543 0/H11543 0.50 0.30

0.15 MAX

1.30 1.15

0.90 SEATING

1.45 MAX

0.60 0.45 0.30 PIN 1 INDICATOR COMPLIANT TO JEDEC STANDARDS MO-178AB 8-Lead Mini Small Outline Package [MSOP] (RM-8) Dimensions shown in millimeters 0.80 0.60 0.40 8/H11543 0/H11543 4.90 BSC PIN 1

0.65 BSC

3.00 BSC SEATING PLANE 0.15 0.00 0.38 0.22

1.10 MAX

3.00 BSC COPLANARITY 0.10 0.23 0.08 COMPLIANT TO JEDEC STANDARDS MO-187AA

Revision History

8/04—Data Sheet Changed from REV. D to REV. E. 5/02—Data Sheet Changed from REV. C to REV. D.