ADT7301BRT-500RL7 - Analog Devices, Inc.

13-Bit, ±0.5°C Accurate, MicroPower Digital

Temperature Sensor in 6-Lead SOT-23

Preliminary Technical Data

ADT7301

Rev. PrI

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FEATURES

13-bit temperature-to-digital converter

−40°C to +150°C operating temperature range

±0.5°C accuracy

0.03125°C temperature resolution

Shutdown current of 1 µA

Power dissipation of 0.631 mW at VDD = 3.3 V

SPI- and DSP-compatible serial interface

Shutdown mode

Space-saving SOT-23 and MSOP packages

APPLICATIONS

Medical equipment

Automotive:

Environmental controls

Oil temperature

Hydraulic systems

Cell phones

Hard disk drives

Personal computers

Electronic test equipment

Office equipment

Domestic appliances

Process control

FUNCTIONAL BLOCK DIAGRAM

SERIAL

BUS

INTERFACE

02884-0-001

ADT7301

SCLK

DIN

DOUT

GND

13-BIT

ANALOG/DIGITAL

CONVERTER

TEMPERATURE

VALUE

BAND GAP

TEMPERATURE

SENSOR

Figure 1. Functional Block Diagram

GENERAL DESCRIPTION

The ADT7301 is a complete temperature monitoring system

available in SOT-23 and MSOP packages. It contains a band gap

temperature sensor and a 13-bit ADC to monitor and digitize

the temperature reading to a resolution of 0.03125°C.

The ADT7301 has a flexible serial interface that allows easy

interfacing to most microcontrollers. The interface is compat-

ible with SPI®, QSPI™, and MICROWIRE™ protocols as well as

DSPs. The part features a standby mode that is controlled via

the serial interface.

The ADT7301’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,

automotive, and domestic appliances.

PRODUCT HIGHLIGHTS

1. The ADT7301 has an on-chip temperature sensor that

allows an accurate measurement of the ambient tempera-

ture. The measurable temperature range is −40°C to

+150°C.

2. Supply voltage of 2.7 V to 5.5 V.

3. Space-saving 6-lead SOT-23 and 8-lead MSOP packages.

4. Temperature accuracy of ±0.5°C.

5. 13-bit temperature reading to 0.03125°C resolution.

6. The ADT7301 features a shutdown mode that reduces the

power consumption to 4.88 µW with VDD = 3.3 V @ 1 SPS.

ADT7301 Preliminary Technical Data

Rev. PrI | Page 2 of 15

TABLE OF CONTENTS

Specifications.....................................................................................3

Timing Characteristics.................................................................5

Absolute Maximum Ratings............................................................ 6

ESD Caution..................................................................................6

Pin Configurations and Function Descriptions............................7

Typical Performance Characteristics..............................................8

Circuit Information ..........................................................................9

Converter Details..........................................................................9

Temperature Value Register........................................................ 9

Serial Interface ............................................................................ 10

Microprocessor Interfacing....................................................... 11

Mounting The ADT7301........................................................... 13

Supply Decoupling ..................................................................... 13

OUTLINE DIMENSIONS............................................................. 14

Ordering Guide............................................................................... 15

REVISION HISTORY

Revision PrI: Preliminary Version

Preliminary Technical Data ADT7301

Rev. PrI | Page 3 of 15

SPECIFICATIONS

TA = TMIN to TMAX, VDD = 2.7 V to 5.5 V, unless otherwise noted. All specifications apply for –40°C to +150°C, unless otherwise stated

Table 1. A Grade Specifications

Parameter Min Typ Max Unit Test Conditions/Comments

TEMPERATURE SENSOR AND ADC VDD = +3.3 V (±10%) and 5 V (±10%)

Accuracy TBD ±1 °C TA = 0°C to 70°C.

TBD ±2 °C TA = −20°C to +85°C.

TBD ±3 °C TA = −40°C to +125°C.

TBD ±41 °C TA = −40°C to +150°C.

Temperature Resolution 0.03125 °C

Auto Conversion Update Rate, tR 1 sec Temperature measurement every 1 second

Temperature Conversion Time 2 ms

Thermal Time Constant2 2 sec

SUPPLIES

Supply Voltage 2.7 5.5 V For Specified Performance

Supply Current

Normal Mode 1.6 2.2 mA VDD = 3.3 V. Powered up and converting

190 300 µA VDD = 3.3 V. Powered up and not converting

1.6 2.2 mA VDD = 5 V. Powered up and converting

280 400 µA VDD = 5 V. Powered up and not converting

Shutdown Mode 0.2 1 µA VDD = 3.3 V.

0.2 1 µA VDD = 5 V.

Power Dissipation

Normal Mode (Average) 631 µW VDD = 3.3 V. Auto conversion update, tR.

1.41 mW VDD = +5 V. Auto conversion update, tR.

Shutdown Mode (Average)3

1 sps 4.88 µW VDD = 3.3 V

7.4 µW VDD = 5 V

10 sps 42.9 µW VDD = 3.3 V

65 µW VDD = 5 V

100 sps 423 µW VDD = 3.3 V

641 µW VDD = 5 V

DIGITAL INPUT4

Input High Voltage, VIH 2.5 V

Input Low Voltage, VIL 0.8 V

Input Current, IIN ±1 µA VIN = 0 V to VDD

Input Capacitance, CIN 10 pF All digital inputs

DIGITAL OUTPUT5

Output High Voltage, VOH V

DD − 0.3 V ISOURCE = ISINK = 200 µA

Output Low Voltage, VOL 0.4 V IOL = 200 µA

Output Capacitance, COUT 50 pF

1 It is not recommended to operate the device at temperatures above +125°C for greater than a total of 5% of the lifetime of the device. Any exposure beyond this limit

will affect device reliability.

2 Thermal Time Constant is the time it takes for a starting temperature difference to change to 36.8% of it’s starting value. For example if the ADT7301 experienced a

thermal shock from 0°C to 100°C, it would take typically 2 secs for the ADT7301 to reach 63.2°C.

3 The ADT7301 is taken out of shutdown mode and a temperature conversion is immediately performed after this write operation. Once the temperature conversion is

complete the ADT7301 is put back into shutdown mode.

4 Guaranteed by design and characterization, not production tested.

5 Guaranteed by design and characterization, not production tested.

Specifications subject to change without notice

ADT7301 Preliminary Technical Data

Rev. PrI | Page 4 of 15

TA = TMIN to TMAX, VDD = 2.7 V to 5.5 V, unless otherwise noted. All specifications apply for –40°C to +150°C, unless otherwise stated.

Table 2. B Grade Specifications

Parameter Min Typ Max Unit Test Conditions/Comments

TEMPERATURE SENSOR AND ADC VDD = 3.3 V (± 10%) and 5 V (± 10%)

Accuracy TBD ±0.5 °C TA = 0°C to 70°C.

TBD ±1 °C TA = −20°C to +85°C.

TBD ±2 °C TA = −40°C to +125°C.

TBD ±31 °C TA = −40°C to +150°C.

Temperature Resolution 0.03125 °C

Autoconversion Update Rate, tR 1 sec Temperature measurement every 1 second

Temperature Conversion Time 2 ms

Thermal Time Constant2 2 sec

SUPPLIES

Supply Voltage 2.7 5.5 V For specified performance

Supply Current

Normal Mode 1.6 2.2 mA VDD = 3.3 V. Powered up and converting.

190 300 µA VDD = 3.3 V. Powered up and not converting.

1.6 2.2 mA VDD = 5 V. Powered up and converting.

280 400 µA VDD = 5 V. Powered up and not converting.

Shutdown Mode 0.2 1 µA VDD = 3.3 V.

0.2 1 µA VDD = 5 V.

Power Dissipation

Normal Mode (Average) 631 µW VDD = 3.3 V. Auto conversion update, tR

1.41 mW VDD = 5 V. Auto conversion update, tR

Shutdown Mode (Average)3

1 sps 4.88 µW VDD = 3.3 V

7.4 µW VDD = 5 V

10 sps 42.9 µW VDD = 3.3 V

65 µW VDD = 5 V

100 sps 423 µW VDD = 3.3 V

641 µW VDD = 5 V

DIGITAL INPUT4

Input High Voltage, VIH 2.5 V

Input Low Voltage, VIL 0.8 V

Input Current, IIN ±1 µA VIN = 0 V to VDD

Input Capacitance, CIN 10 pF All digital inputs

DIGITAL OUTPUT5

Output High Voltage, VOH V

DD −0.3 V ISOURCE = ISINK = 200 µA

Output Low Voltage, VOL 0.4 V IOL = 200 µA

Output Capacitance, COUT 50 pF

1 It is not recommended to operate the device at temperatures above +125 °C for greater than a total of 5% of the lifetime of the device. Any exposure beyond this limit

will affect device reliability.

2 Thermal Time Constant is the time it takes for a starting temperature difference to change to 36.8% of it’s starting value. For example if the ADT7301 experienced a

thermal shock from 0°C to 100°C, it would take typically 2 secs for the ADT7301 to reach 63.2°C.

3 The ADT7301 is taken out of shutdown mode and a temperature conversion is immediately performed after this write operation. Once the temperature conversion is

complete the ADT7301 is put back into shutdown mode

4 Guaranteed by design and characterization, not production tested

5 Guaranteed by design and characterization, not production tested

Specifications subject to change without notice

Preliminary Technical Data ADT7301

Rev. PrI | Page 5 of 15

TIMING CHARACTERISTICS

Guaranteed by design and characterization, not production tested. All input signals are specified with tr = tf = 5 ns (10% to 90% of VDD)

and timed from a voltage level of 1.6 V. See Figure 3.

TA = TMIN to TMAX, VDD = 2.7 V to 5.5 V, unless otherwise noted.

Table 3.

Parameter Limit Unit Comments

t1 5 ns min

CS to SCLK Setup Time

t2 25 ns min SCLK High Pulse Width

t3 25 ns min SCLK Low Pulse Width

t4 1 35 ns max Data Access Time after SCLK Falling Edge

t5 20 ns min Data Setup Time prior to SCLK Rising Edge

t6 5 ns min Data Hold Time after SCLK Rising Edge

t7 5 ns min

CS to SCLK Hold Time

t81 40 ns max

CS to DOUT High Impedance

1 Measured with the load circuit of Figure 2

1.6V

200µA

200µAI

02884-0-002

OUTPUT

PIN C

50pF

Figure 2. Load Circuit for Data Access Time and Bus Relinquish Time

ADT7301 Preliminary Technical Data

Rev. PrI | Page 6 of 15

ABSOLUTE MAXIMUM RATINGS

Table 4. ADT7301 Stress Ratings

Parameter Rating

VDD to GND −0.3 V to +7 V

Digital Input Voltage to GND −0.3 V to VDD + 0.3 V

Digital Output Voltage to GND −0.3 V to VDD + 0.3 V

Operating Temperature Range1 −40°C to +150°C

Storage Temperature Range −65°C to +150°C

Junction Temperature +150°C

6-Lead SOT-23 (RJ-6)

Power Dissipation2 W

MAX = (TJMAX - TA3)/θJA

Thermal Impedance

θJA, Junction-to-Ambient (still air) 190.4°C/W

8-Lead MSOP (RM-8)

Power Dissipation2 W

MAX = (TJMAX - TA3)/θJA

Thermal Impedance4

θJA, Junction-to-Ambient (still air) 205.9°C/W

θJC, Junction-to-Case 43.74°C/W

IR Reflow Soldering

Peak Temperature +220°C (−0/+5°C)

Time at Peak Temperature 10 s to 20 s

Ramp-up Rate 2°C/s to 3°C/s

Ramp-down Rate −6°C/sec

1It is not recommended to operate the ADT7301 at temperatures above 125°C

for greater than a total of 5% of the lifetime of the device. Any exposure

beyond this limit will affect device reliability.

2Values relate to package being used on a standard 2-layer PCB. Reference

Figure 3 for a plot of maximum power dissipation versus ambient

temperature (TA).

3TA = ambient temperature

4Junction-to-case resistance is applicable to components featuring a

preferential flow direction, e.g., components mounted on a heat sink.

Junction-to-ambient resistance is more useful for air-cooled, PCB mounted

components.

Stresses above those listed under Absolute Maximum Ratings

may cause permanent damage to the device. This is a stress

rating only; functional operation of the device at these or any

other conditions above those indicated in the operational

section of this specification is not implied. Exposure to absolute

maximum rating conditions for extended periods may affect

device reliability

0.2

0.6

0.4

0.8

1.0

1.2

MAXIMUM POWER DISSIPATION (W)

150

140

130

120

110

100

–10

–20

–30

–40

TEMPERATURE (°C)

02884-0-003

SOT-23

MSOP

Figure 3. Plot of Maximum Power Dissipation vs. Temperature

ESD CAUTION

ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the

human body and test equipment and can discharge without detection. Although this product features

proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy

electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance

degradation or loss of functionality.

Preliminary Technical Data ADT7301

Rev. PrI | Page 7 of 15

PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS

GND

TOP VIEW

(Not to Scale)

02884-0-004

ADT7301

DIN

DOUT

SCLK

Figure 4. SOT-23

TOP VIEW

(Not to Scale)

ADT7301

DOUT

GND

SCLK V

DIN

02884-0-005

Figure 5. MSOP

Table 5. Pin Function Description

Mnemonic

SOT-23

Pin No. Description

GND 1 Analog and Digital Ground.

DIN 2 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 3 Positive Supply Voltage, 2.7 V to 5.5 V.

SCLK 4 Serial Clock Input. This is the clock input for the serial port. The serial clock is used to clock data out of the

ADT7301’s temperature value register and to clock data into the ADT7301’s control register.

CS 5 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 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.

ADT7301 Preliminary Technical Data

Rev. PrI | Page 8 of 15

TYPICAL PERFORMANCE CHARACTERISTICS

TBD

–000

–000 –000 –000 –000 –000

ALL CAPS (Initial caps)

Figure 6. Temperature Accuracy @ 3.3 V and 5 V

TBD

–000

–000 –000 –000 –000 –000

ALL CAPS (Initial caps)

Figure 7. Operating Supply Current vs. Temperature

TBD

–000

–000 –000 –000 –000 –000

ALL CAPS (Initial caps)

Figure 8. Operating Supply Current vs. Supply Voltage

TBD

–000

–000 –000 –000 –000 –000

ALL CAPS (Initial caps)

Figure 9. Power-Down Current vs. Supply Voltage

TBD

–000

–000 –000 –000 –000 –000

ALL CAPS (Initial caps)

Figure 10. Temperature Accuracy vs. Supply Ripple Frequency

TBD

–000

–000 –000 –000 –000 –000

ALL CAPS (Initial caps)

Figure 11. Response to Thermal Shock

Preliminary Technical Data ADT7301

Rev. PrI | Page 9 of 15

CIRCUIT INFORMATION

The ADT7301 is a 13-bit digital temperature sensor with a 14th

bit that acts as a sign bit. The part houses an on-chip tempera-

ture sensor, a 13-bit A/D converter, a reference circuit, and

serial interface logic functions in SOT-23 and MSOP packages.

The A/D converter section consists of a conventional

successive-approximation converter 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 measure-

ment of the ambient device temperature to be made. The

specified measurement range of the ADT7301 is −40°C to

+150°C. At +150°C, the ADT7301 is limited to 5% of its +55°C

operational lifetime. The structural integrity of the device starts

to deteriorate when operated at voltage and temperature

maximum specifications.

CONVERTER DETAILS

The conversion clock for the part is internally generated; no

external clock is required except when reading from and

writing to the serial port. In normal mode, an internal clock

oscillator runs an automatic conversion sequence. During this

automatic conversion sequence, a conversion is initiated every 1

second. At this time, the part powers up its analog circuitry and

performs a temperature conversion. This temperature

conversion typically takes 800 µs, after which time the analog

circuitry of the part automatically shuts down. The analog

circuitry powers up again when the 1 second timer times out

and the next conversion begins. The result of the most recent

temperature conversion is always available in the serial output

The ADT7301 can be placed in a shutdown mode via the con-

trol register, in which case the on-chip oscillator is shut down

and no further conversions are initiated until the ADT7301 is

taken out of shutdown mode. The ADT7301 can be taken out of

shutdown mode by writing all zeros into the control register.

The conversion result from the last conversion prior to shut-

down can still be read from the ADT7301 even when it is in

shutdown mode.

In normal conversion mode, the internal clock oscillator is reset

after every read or write operation. This causes the device to

start a temperature conversion, the result of which is typically

available 800 µs later. Similarly, when the part is taken out of

shutdown mode, the internal clock oscillator is started and a

conversion is initiated. The conversion result is available 800 µs

later, typically. Reading from the device before a conversion is

complete causes the ADT7301 to stop converting; the part starts

again when serial communication is finished. This read

operation provides the previous result.

TEMPERATURE VALUE REGISTER

The temperature value register is a 14-bit read-only register that

stores the temperature reading from the ADC in 13-bit twos

complement format plus a sign bit. The MSB (DB13) is the sign

bit. The ADC can theoretically measure a 255°C temperature

span. The internal temperature sensor is guaranteed to a low

value limit of –40°C and a high limit of +150°C. The

temperature data format is shown in Table 6, which shows the

temperature measurement range of the device (–40°C to

+150°C). A typical performance curve is shown in Figure 6.

Table 6. Temperature Data Format

Temperature Digital Output DB13…DB0

−40°C 11, 1011 0000 0000

−30°C 11, 1100 0100 0000

−25°C 11, 1100 1110 0000

−10°C 11, 1110 1100 0000

−0.03125°C 11, 1111 1111 1111

0°C 00, 0000 0000 0000

+0.03125°C 00, 0000 0000 0001

+10°C 00, 0001 0100 0000

+25°C 00, 0011 0010 0000

+50°C 00, 0110 0100 0000

+75°C 00, 1001 0110 0000

+100°C 00, 1100 1000 0000

+125°C 00, 1111 1010 0000

+150°C 01, 0010 1100 0000

Temperature Conversion Formula

1. Positive Temperature = ADC Code(d)/32

2. Negative Temperature = (ADC Code*(d) – 16384)/32

*Using all 14 bits of the data byte, includes the sign bit.

Negative Temperature = (ADC Code(d)* – 8192)/32

*DB13 (sign bit) is removed from the ADC code

DIGITAL OUTPUT

–40°C –0.03125°C

–30°C

11, 1111, 1111, 1111

11, 1100, 0100, 0000

11, 1011, 0000, 0000

TEMPERATURE (°C)

75°C

02884-0-006

150°C

01, 0010, 1100, 0000

00, 1001, 0110, 0000

00, 0000, 0000, 0001

Figure 12. Temperature to Digital Transfer Function

ADT7301 Preliminary Technical Data

Rev. PrI | Page 10 of 15

SCLK

DOUT

DIN POWER-

DOWN

LEADING ZEROS DB13 DB0

1234 15 16

DB12 DB1 DB0

02884-0-007

Figure 13. Serial Interface Timing Diagram

SERIAL INTERFACE

The serial interface on the ADT7301 consists of four wires: CS,

SCLK, DIN, and DOUT. The interface can be operated in 2-

wire mode with CS and DIN tied to ground, in which case the

interface has read-only capability, with data being read from the

data register via the DOUT line. It is advisable to utilize CS,

which improves synchronization between the ADT7301 and the

master device. 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

ADT7301 allows the part to be interfaced to systems that

provide a serial clock 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 ADT7301 accesses data from the

temperature value register while a write operation to the part

writes data to the control register.

Read Operation

Figure 13 shows the timing diagram for a serial read from the

ADT7301. The CS line enables the SCLK input. Thirteen bits of

data plus a sign bit are transferred during a read operation.

Read operations occur during streams of 16 clock pulses. The

first two bits out are leading zeros and the next 14 bits contain

the temperature data. If CS remains low and 16 more SCLK

cycles are applied, the ADT7301 loops around and outputs the

two leading zeros plus the 14 bits of data that are in the temper-

ature value register. When CS returns high, the DOUT line goes

into three-state. Data is clocked out onto the DOUT line on the

falling edge of SCLK.

Write Operation

Figure 13 also shows the timing diagram for a serial write to the

ADT7301. The write operation takes place at the same time as

the read operation. Only the third bit in the data stream

provides a user-controlled function. This third bit is the power-

down bit, which, when set to a 1, puts the ADT7301 into

shutdown mode. Besides the power-down bit, all bits in the

input data stream should be zero to ensure correct operation of

the ADT7301. Data is loaded into the control register on the

16th rising SCLK edge; the data takes effect at this time, i.e., if

the part is programmed to go into shutdown, it does so at this

point. If CS is brought high before this 16th SCLK edge, the

control register is not loaded and the power-down status of the

part does not change. Data is clocked into the ADT7301 on the

rising edge of SCLK.

Preliminary Technical Data ADT7301

Rev. PrI | Page 11 of 15

MICROPROCESSOR INTERFACING

The ADT7301’s serial interface allows for easy interface to most

microcomputers and microprocessors. Figure 14 through

Figure 17 show some typical interface circuits. The serial

interface on the ADT7301 consists of four wires: CS, DIN,

DOUT and SCLK. All interface circuits shown utilize all four

interface lines. However, it is possible to operate the interface

with three wires. If the application does not require the power-

down facility offered by the ADT7301, the DIN line can be tied

permanently low. Thus, the interface can be operated from just

three wires: SCLK, CS, and DOUT.

The serial data transfer to and from the ADT7301 requires a 16-

bit read operation. Many 8-bit microcontrollers have 8-bit serial

ports, and this 16-bit data transfer is handled as two 8-bit trans-

fers. Other microcontrollers and DSP processors transfer 16 bits

of data in a serial data operation.

ADT7301 to MC68HC11 Interface

Figure 14 shows an interface between the ADT7301 and the

MC68HC11 microcontroller. The MC68HC11 is configured in

master mode with its CPOL and CPHA bits set to a Logic 1.

When the MC68HC11 is configured like this, its SCLK line

idles high between data transfers. Data is transferred to and

from the ADT7301 in two 8-bit serial data operations. The

diagram shows the full (4-wire) interface. PC1 of the

MC68HC11 is configured as an output and is used to drive the

CS input.

ADT7301*

SCLK

DOUT

DIN

MC68HC11*

SCLK

MISO

MOSI

PC1

02884-0-008

*ADDITIONAL PINS OMITTED FOR CLARITY

Figure 14. ADT7301 to MC68HC11 Interface

ADT7301 to 8051 Interface

An interface circuit between the ADT7301 and the microcon-

troller is shown in Figure 15. The 8051 is configured in its Mode

0 serial interface mode. The serial clock line of the 8051 (on

P3.1) idles high between data transfers. Data is transferred to

and from the ADT7301 in two 8-bit serial data operations. The

ADT7301 outputs the MSB of its data stream as the first valid

bit while the 8051 expects the LSB first. Thus, the data read into

the serial buffer needs to be rearranged before the correct data-

word from the ADT7301 is available in the accumulator.

In the example shown, the ADT7301 is connected to the serial

port of the 8051. Because the serial interface of the 8051

contains only one data line, the DIN line of the ADT7301 is tied

low in the interface example given in Figure 15.

For applications that require the ADT7301’s power-down

feature, the serial interface should be implemented using data

port lines on the 8051. This allows a full-duplex serial interface

to be implemented. The method involves “bit-banging” a port

line to generate a serial clock while using two other port lines to

shift data in and out with the fourth port line connecting to CS.

Port lines 1.0 through 1.3 (with P1.1 configured as an input)

can be used to connect to SCLK, DOUT, DIN, and CS,

respectively, to implement this scheme.

ADT7301*

02884-0-009

SCLK

DOUT

DIN

8051*

P3.1

P3.0

P1.2

P1.3

*ADDITIONAL PINS OMITTED FOR CLARITY

Figure 15. ADT7301 to 8051 Interface

ADT7301 to PIC16C6x/7x Interface

Figure 16 shows an interface circuit between the ADT7301 and

the PIC16C6x/7x microcontroller. The PIC16C6x/7x

synchronous serial port (SSP) is configured as an SPI master

with the clock polarity bit set to a Logic 1. In this mode, the

serial clock line of the PIC16C6x/7x idles high between data

transfers. Data is transferred to and from the ADT7301 in two

8-bit serial data operations. In the example shown, port line

RA1 is being used to generate the CS for the ADT7301.

ADT7301*

SCLK

DOUT

DIN

PIC16C6x/7x*

SCK

SDO

SDI

RA1

02884-0-010

*ADDITIONAL PINS OMITTED FOR CLARITY

Figure 16. ADT7301 to PIC16C6x/7x Interface

The following software program shows how to program an

PIC16F873 to communicate with the ADT7301. The

PIC16F873 is configured as an SPI master with the PortA.1 pin

used as CS. Any Microchip microcontroller can use this

program by simply exchanging the include file for the device

that’s being used.

ADT7301 Preliminary Technical Data

Rev. PrI | Page 12 of 15

#include <16F873.h>

#device adc=8

#use delay(clock=4000000)

#fuses NOWDT,XT, PUT, NOPROTECT, BROWNOUT, LVP

#BIT CKP = 0x14.4

#define CS PIN_A1

void main(){

int MSByte,LSByte;

long int ADC_Temp_Code;

float TempVal,ADC_Temp_Code_dec;

setup_spi(spi_master); //Pic is set up as Master device.

CKP = 1; //Idle state of clock is high.

do{

delay_ms(10); //Allow time for conversions.

Output_low(CS); //Pull CS low.

delay_us(10); //CS to SCLK setup time.

MSByte = SPI_Read(0); //The first byte is clocked in.

LSByte = SPI_Read(0); //The second byte is clocked in.

delay_us(10); //SCLK to CS setup time.

Output_High(CS); //Bring CS high.

MSByte = 0x03;

LSByte = 0x20;

ADC_Temp_Code = make16(MSByte,LSByte); //16bit ADC code is stored ADC_Temp_Code.

ADC_Temp_Code_dec = (float)ADC_Temp_Code; //Covert to float for division.

if ((0x2000 & ADC_Temp_Code) == 0x2000) //Check sign bit for negative value.

{

TempVal = (ADC_Temp_Code_dec - 16384)/32; //Conversion formula if negative temperature.

}

else

{

TempVal = (ADC_Temp_Code_dec/32); //Conversion formula if positive temperature.

}

}while(True);

//Temperature value stored in TempVal.

}

Preliminary Technical Data ADT7301

Rev. PrI | Page 13 of 15

ADT7301 to ADSP-21xx Interface

Figure 17 shows an interface between the ADT7301 and the

ADSP-21xx DSP processor. To ensure correct operation of the

interface, the SPORT control register should be set up as

follows:

TFSW = RFSW = 1, alternate framing

INVRFS = INVTFS = 1, active low framing signal

DTYPE = 00, right justify data

SLEN = 1111, 16-bit data-words

ISCLK = 1, internal serial clock

TFSR = RFS = 1, frame every word

IRFS = 0, RFS configured as input

ITFS = 1, TFS configured as output

The interface requires an inverter between the SCLK line of the

ADSP-21xx and the SCLK input of the ADT7301. The ADSP-

21xx has the TFS and RFS of the SPORT tied together, with TFS

set as an output and RFS set as an input. The DSP operates in

alternate framing mode, and the SPORT control register is set

up as described previously.

ADT7301*

SCLK

DOUT

DIN

ADSP-21xx*

SCK

RFS

02884-0-011

*ADDITIONAL PINS OMITTED FOR CLARITY

TFS

Figure 17. ADT7301 to ADSP-21 Interface

MOUNTING THE ADT7301

The ADT7301 can be used for surface- or air-temperature

sensing applications. If the device is cemented to a surface with

thermally conductive adhesive, the die temperature will be

within about 0.1°C of the surface temperature, thanks to the

ADT7301’s low power consumption. Care should be taken to

insulate the back and leads of the device from the air if the

ambient air temperature is different from the surface tempera-

ture being measured.

The ground pin provides the best thermal path to the die, so the

temperature of the die will be close to that of the printed circuit

ground track. Care should be taken to ensure that this is in

good thermal contact with the surface being measured.

As with any IC, the ADT7301 and its associated wiring and

circuits must be kept free from moisture to prevent leakage and

corrosion, particularly in cold conditions where condensation is

more likely to occur. Water-resistant varnishes and conformal

coatings can be used for protection. The small size of the

ADT7301 allows it to be mounted inside sealed metal probes,

which provide a safe environment for the device.

SUPPLY DECOUPLING

The ADT7301 should be decoupled with a 0.1 µF ceramic

capacitor between VDD and GND. This is particularly important

if the ADT7301 is mounted remote from the power supply.

ADT7301 Preliminary Technical Data

Rev. PrI | Page 14 of 15

OUTLINE DIMENSIONS

4 5

2.90 BSC

PIN 1

1.60 BSC 2.80 BSC

1.90

BSC

0.95 BSC

0.22

0.08 0.60

0.45

0.30

10°

4°

0°

0.50

0.30

.15 MAX

1.30

1.15

0.90

SEATING

PLANE

1.45 MAX

COMPLIANT TO JEDEC STANDARDS MO-178AB

Figure 18. 6-Lead Small Outline Transistor Package [SOT-23]

(RJ-6)

Dimensions shown in millimeters

0.80

0.60

0.40

8°

0°

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

Figure 19. 8-Lead Mini Small Outline Package [MSOP]

(RM-8)

Dimensions shown in millimeters

Preliminary Technical Data ADT7301

Rev. PrI | Page 15 of 15

ORDERING GUIDE

Model Temperature Range

Temperature

Accuracy1

Package

Description

Samples Branding

Information

Package

Option

ADT7301ART-500RL7 −40°C to +150°C ±1°C 6-Lead SOT-23 TCS RJ-6

ADT7301ART-REEL7 −40°C to +150°C ±1°C 6-Lead SOT-23 TCS RJ-6

ADT7301ART-REEL −40°C to +150°C ±1°C 6-Lead SOT-23 TCS RJ-6

ADT7301ARM −40°C to +150°C ±1°C 8-Lead MSOP TCS RM-8

ADT7301ARM-REEL7 −40°C to +150°C ±1°C 8-Lead MSOP TCS RM-8

ADT7301ARM-REEL −40°C to +150°C ±1°C 8-Lead MSOP TCS RM-8

ADT7301BRT-500RL7 −40°C to +150°C ±0.5°C 6-Lead SOT-23 TCC RJ-6

ADT7301BRT-REEL7 −40°C to +150°C ±0.5°C 6-Lead SOT-23 TCC RJ-6

ADT7301BRT-REEL −40°C to +150°C ±0.5°C 6-Lead SOT-23 TCC RJ-6

ADT7301BRM −40°C to +150°C ±0.5°C 8-Lead MSOP TCC RM-8

ADT7301BRM-REEL7 −40°C to +150°C ±0.5°C 8-Lead MSOP TCC RM-8

ADT7301BRM-REEL −40°C to +150°C ±0.5°C 8-Lead MSOP TCC RM-8

ADT7301BRTZ-500RL72 −40°C to +150°C ±0.5°C 6-Lead SOT-23 RJ-6

ADT7301BRTZ-REEL72 −40°C to +150°C ±0.5°C 6-Lead SOT-23 RJ-6

ADT7301BRTZ-REEL2 −40°C to +150°C ±0.5°C 6-Lead SOT-23 RJ-6

1 Temperature accuracy is over 0°C to 70°C temperature range.

2 Pb-free models.

registered trademarks are the property of their respective owners.

PR02884-0-4/04(PrI)