±1°C Accurate, 13-Bit,
FEATURES
13-bit temperature-to-digital converter
−40°C to +150°C operating temperature range
±0.5°C typical accuracy
0.03125°C temperature resolution
Shutdown current of 1 μA
Power dissipation of 0.631 mW at V
SPI- and DSP-compatible serial interface
Shutdown mode
Space-saving SOT-23 and MSOP packages
Compatible with AD7814
APPLICATIONS
Medical equipment
Automotive
Environmental controls
Oil temperature
Hydraulic systems
Cellular phones
Hard disk drives
Personal computers
Electronic test equipment
Office equipment
Domestic appliances
Process control
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 compati-
ble with SPI
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. The
ADT7301 is rated for operation over the −40°C to +150°C
temperature range. It is not recommended to operate the device
at temperatures above +125°C for greater than a total of 5%
(5,000 hours) of the lifetime of the device. Exposure beyond this
limit affects device reliability.
®, QSPI™, and MICROWIRE™ protocols as well as
= 3.3 V
DD
Digital Temperature Sensor
ADT7301
FUNCTIONAL BLOCK DIAGRAM
BAND GAP
TEMPERATURE
SENSOR
GND
ADT7301
INTERFACE
PRODUCT HIGHLIGHTS
1. On-chip temperature sensor that allows an accurate
measurement of the ambient temperature. The measurable
temperature range is −40°C to +150°C.
2. Supply voltage of 2.7 V to 5.25 V.
3. Space-saving 6-lead SOT-23 and 8-lead MSOP packages.
4. Typical temperature accuracy of ±0.5°C.
5. 13-bit temperature reading to 0.03125°C resolution.
6. Shutdown mode that reduces the power consumption to
4.88 μW with V
7. Compatible with AD7814.
= 3.3 V @ 1 SPS.
DD
13-BIT
ANALOG/DIGITAL
CONVERTER
TEMPERATURE
VALUE
REGISTER
SERIAL
BUS
Figure 1.
V
DD
CS
SCLK
DIN
DOUT
02884-0-001
Rev. 0
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.
Specifications subject to change without notice. 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.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700 www.analog.com
Fax: 781.461.3113 © 2005 Analog Devices, Inc. All rights reserved.
ADT7301
TABLE OF CONTENTS
Specifications..................................................................................... 3
Temperature Value Register...................................................... 10
Timing Characteristics ................................................................ 4
Absolute Maximum Ratings............................................................ 5
ESD Caution.................................................................................. 5
Pin Configurations and Function Descriptions ........................... 6
Typical Performance Characteristics ............................................. 7
Theory of Operation ........................................................................ 9
Converter Details.......................................................................... 9
REVISION HISTORY
10/05—Revision 0: Initial Version
Serial Interface............................................................................ 11
Applications..................................................................................... 12
Microprocessor Interfacing....................................................... 12
Mounting the ADT7301............................................................ 14
Supply Decoupling..................................................................... 14
Outline Dimensions....................................................................... 15
Ordering Guide .......................................................................... 15
Rev. 0 | Page 2 of 16
ADT7301
SPECIFICATIONS
TA = T
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 (±5%)
±2 °C T
±3 °C T
±42°C TA = −40°C to +150°C
SUPPLIES
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
0.4 2 μA VDD = 5 V, TA = 0°C to 70°C
20 μA VDD = 2.7 V to 5.25 V, TA = –40°C to +150°C
7.4 μW VDD = 5 V
65 μW VDD = 5 V
641 μW VDD = 5 V
DIGITAL INPUT
DIGITAL OUTPUT
1
The accuracy specifications for 0°C to 70°C are specified to 3.5-Σ performance.
2
It is not recommended to operate the device at temperatures above 125°C for greater than a total of 5% (5,000 hours) of the lifetime of the device. Any exposure
beyond this limit affects device reliability.
3
The thermal time constant is the time it takes for a temperature delta to change to 63.2% of its final value. For example, if the ADT7301 experiences a thermal shock
from 0°C to 100°C, it would take typically two seconds for the ADT7301 to reach 63.2°C.
4
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.
5
Guaranteed by design and characterization, not production tested.
MIN
Accuracy
to T
, VDD = 2.7 V to 5.25 V, unless otherwise noted. All specifications for –40°C to +150°C, unless otherwise noted.
MAX
1
±0.5 ±1 °C TA = 0°C to 70°C
= −20°C to +85°C
A
= −40°C to +125°C
A
Temperature Resolution 0.03125 °C
Auto Conversion Update Rate, tR 1 sec Temperature measurement every 1 second
Temperature Conversion Time 800 μs
Thermal Time Constant
3
2 sec
Supply Voltage 2.7 5.25 V For specified performance
Supply Current
Normal Mode 1.6 2.2 mA VDD = 3.3 V, powered up and converting
Shutdown Mode 0.2 1 μA VDD = 3.3 V, TA = 0°C to 70°C
Power Dissipation
Normal Mode (Average) 631 μW VDD = 3.3 V, autoconversion update, tR
1.41 mW VDD = 5 V, autoconversion update, tR
Shutdown Mode (Average)
4
1 SPS 4.88 μW VDD = 3.3 V
10 SPS 42.9 μW VDD = 3.3 V
100 SPS 423 μW VDD = 3.3 V
5
Input High Voltage, VIH 2.5 V
Input Low Voltage, VIL 0.8 V
Input Current, IIN ±1 μA V
= 0 V to VDD
IN
Input Capacitance, CIN 10 pF All digital inputs
5
Output High Voltage, VOH V
− 0.3 V I
DD
SOURCE
= I
SINK
= 200 μA
Output Low Voltage, VOL 0.4 V IOL = 200 μA
Output Capacitance, C
50 pF
OUT
Rev. 0 | Page 3 of 16
ADT7301
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. T
Table 2.
Parameter
1
Limit Unit Comments
t1 5 ns min
t2 25 ns min SCLK high pulse width
t3 25 ns min SCLK low pulse width
2
t4
t
5
35 ns max Data access time after SCLK falling edge
20 ns min Data set-up time prior to SCLK rising edge
t6 5 ns min Data hold time after SCLK rising edge
t7 5 ns min
2
t
8
1
See Figure 14 for the SPI timing diagram.
2
Measured with the load circuit of Figure 2.
40 ns max
= T
A
MIN
to T
, VDD = 2.7 V to 5.25 V, unless otherwise noted.
MAX
CS
to SCLK set-up time
CS
to SCLK hold time
CS
to DOUT high Impedance
I
OL
1.6V
OH
02884-0-002
TO
OUTPUT
PIN
50pF
C
L
200μA
200μAI
Figure 2. Load Circuit for Data Access Time and Bus Relinquish Time
Rev. 0 | Page 4 of 16
ADT7301
ABSOLUTE MAXIMUM RATINGS
Table 3.
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 Range
1
−40°C to +150°C
Storage Temperature Range −65°C to +150°C
Junction Temperature 150°C
6-Lead SOT-23 (RT-6)
Power Dissipation
2
W
= (TJ max − T
MAX
A
3
)/θJA
Thermal Impedance
θJA, Junction-to-Ambient
190.4°C/W
(Still Air)
8-Lead MSOP (RM-8)
Power Dissipation
Thermal Impedance
2
4
θJA, Junction-to-Ambient
W
= (TJ max − T
MAX
205.9°C/W
A
3
)/θJA
(Still Air)
θJC, Junction-to-Case 43.74°C/W
IR Reflow Soldering
Peak Temperature 220°C (0°C /5°C)
Time at Peak Temperature 10 sec to 20 sec
Ramp-Up Rate 3°C/s max
Ramp-Down Rate −6°C/s max
Time 25°C to Peak Temperature 6 minutes max
IR Reflow Soldering—Pb-Free Package
Peak Temperature 260°C (0°C)
Time at Peak Temperature 20 sec to 40 sec
Ramp-Up Rate 3°C/s max
Ramp-Down Rate −6°C/s max
Time 25°C to Peak Temperature 8 minutes max
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
1.2
1.0
0.8
0.6
0.4
0.2
MAXIMUM POWER DISSIPATION (W)
0
–40
0
–10
–20
–30
Figure 3. Plot of Maximum Power Dissipation vs. Temperature
1
It is not recommended to operate the ADT7301 at temperatures above
125°C for greater than a total of 5% (5,000 hours) of the lifetime of the
device. Any exposure beyond this limit affects device reliability.
2
Values relate to the package being used on a standard 2-layer PCB. Refer
to Figure 3 for a plot of maximum power dissipation vs. ambient
temperature (TA).
3
TA = ambient temperature.
4
Junction-to-case resistance is applicable to components featuring a
preferential flow direction, for example, components mounted on a heat
sink. Junction-to-ambient resistance is more useful for air-cooled,
PCB-mounted components.
SOT-23
MSOP
50
40
30
20
10
TEMPERATURE (°C)
90
80
70
60
100
110
120
130
140
150
02884-003
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.
Rev. 0 | Page 5 of 16
ADT7301
PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS
GND
DIN
V
DD
1
ADT7301
2
TOP VIEW
(Not to Scale)
3
6
5
4
DOUT
CS
SCLK
02884-0-004
Figure 4. SOT-23 Pin Configuration
Table 4. Pin Function Descriptions
SOT-23
Pin No.
MSOP
Pin No.
Mnemonic Description
1 7 GND Analog and Digital Ground.
2 6 DIN
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.
3 5 VDD Positive Supply Voltage. 2.7 V to 5.25 V.
4 4 SCLK
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.
5 3
CS Chip Select Input. Logic Input. The device is selected when this input is low. The SCLK input is
disabled when this pin is high.
6 2 DOUT
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.
1, 8 NC No Connect.
NC
DOUT
CS
SCLK
1
ADT7301
2
TOP VIEW
(Not to Scale)
3
4
8
NC
7
GND
6
DIN
5
V
DD
02884-0-005
Figure 5. MSOP Pin Configuration
Rev. 0 | Page 6 of 16
ADT7301
TYPICAL PERFORMANCE CHARACTERISTICS
215
210
205
200
195
190
CURRENT (μA)
185
180
175
170
–45 5 55 105 155
5.5V
3.3V
TEMPERATURE (°C)
Figure 6. Average Operating Supply Current vs. Temperature
02884-018
20
250mV p-p RIPPLE @ VDD = 5V
15
10
5
0
TEMPERATURE ERROR (°C)
–5
–10
10k 100k 1M 10M 100M
FREQUENCY (Hz)
Figure 9. Temperature Accuracy vs. Supply Ripple Frequency
02884-021
205
200
195
190
CURRENT (μA)
185
180
175
2.5 3.0 3.5 5.04.0 4.5 5.5 6.0
SUPPLY VOLTAGE (V)
02884-019
Figure 7. Average Operating Supply Current vs. Supply Voltage @ 30°C
500
450
400
350
300
250
200
150
SHUTDOWN CURRENT (nA)
100
50
0
2.5 3.0 3.5 5.04.0 4.5 5.5 6.0
SUPPLY VOLTAGE (V)
02884-020
140
120
100
80
60
TEMPERATURE (°C)
40
20
0
0105152520 403530 45 50
TIME (SEC)
02884-022
Figure 10. Response to Thermal Shock
Figure 8. Shutdown Current vs. Supply Voltage @ 30°C
Rev. 0 | Page 7 of 16
ADT7301
5
4
3
C)
°
2
1
0
–1
–2
TEMPERATURE ERROR (
–3
–4
–5
–40
Figure 11. Temperature Accuracy of 40 ADT7301s @ 3.3 V
UPPER TEMPERATURE
0
–30
–20
–10
ERROR LIMIT
LOWER TEMPERATURE
ERROR LIMIT
102030405060708090
TEMPERATURE (°C)
100
110
120
130
140
02884-006
150
5
C)
°
TEMPERATURE ERROR (
4
3
2
1
0
–1
–2
–3
–4
–5
–40
–30
UPPER TEMPERATURE
ERROR LIMIT
LOWER TEMPERATURE
ERROR LIMIT
0
102030405060708090
–20
–10
TEMPERATURE (°C)
Figure 12. Temperature Accuracy of 40 ADT7301s @ 5 V
100
110
120
130
140
02884-023
150
Rev. 0 | Page 8 of 16
ADT7301
THEORY OF OPERATION
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 temperature
sensor, a 13-bit A/D converter, a reference circuit, and serial
interface logic functions in SOT-23 and MSOP packages. The
ADC section consists of a conventional successive approximation
converter based around a capacitor DAC. The parts run on a
2.7 V to 5.25 V power supply.
The on-chip temperature sensor allows an accurate measurement of the ambient device temperature to be made. The
specified measurement range of the ADT7301 is −40°C to
+150°C. Greater than 125°C, the ADT7301 is limited to 5%
of its 55°C operational lifetime. The structural integrity of the
device may start to deteriorate when continuously operated at
absolute maximum voltage and temperature 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 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.
Since the serial interface circuitry never shuts down, the result
of the most recent temperature conversion is always available in
the serial output register.
The ADT7301 can be placed into shutdown mode via the control
register. This means that 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 0s 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. Every
result is stored in a buffer register and is loaded into the
temperature value register only at the first falling SCLK edge of
every serial port activity. Serial port activity does not interfere
with conversion processes, and every conversion is completed,
even during a read operation. A conversion has to be completed
before a read occurs, otherwise its result is not loaded into the
temperature value register and instead is loaded into the buffer
register. A new conversion is triggered at the end of each serial
port activity, except when a conversion is already in progress.
Rev. 0 | Page 9 of 16
ADT7301
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 5, which shows the temperature
measurement range of the device (–40°C to +150°C). The
typical performance curve is shown in
Table 5. 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
Figure 11.
Temperature Conversion Equations
Positive Temperature = ADC Code(d)/32
Negative Temperature = (ADC Code(d)
Negative Temperature = (ADC Code(d)
01, 0010, 1100, 0000
00, 1001, 0110, 0000
00, 0000, 0000, 0001
–0.03125°C
–40°C
–30°C
1
ADC code uses all 14 bits of the data byte, including the sign bit.
2
DB13 (the sign bit) is removed from the ADC code.
Figure 13. Temperature-to-Digital Transfer Function
DIGITAL OUTPUT
11, 1111, 1111, 1111
11, 1100, 0100, 0000
11, 1011, 0000, 0000
1
− 16384)/32
2
− 8192)/32
75°C
TEMPERATURE (°C)
150°C
02884-0-006
Rev. 0 | Page 10 of 16
ADT7301
CS
t
SCLK
DOUT
DIN
1
1
LEADING ZEROS
t
2
234
t
3
t
4
DB13 DB0
t
5
POWER-
DOWN
Figure 14. Serial Interface Timing Diagram
DB12
t
6
SERIAL INTERFACE
The serial interface on the ADT7301 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
interface has read only capability, with data being read from the
data register via the DOUT line. It is advisable to always use
to create a communications window, as shown in
Figure 14; this
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.
CS
15
DB1
Read Operation
Figure 14 shows the timing diagram for a serial read from the
ADT7301. The
CS
data plus a sign bit are transferred during a read operation.
Read operations occur during streams of 16 clock pulses. The
first 2 bits out are leading zeros and the next 14 bits contain the
temperature data. If
are applied, the ADT7301 loops around and outputs the two
leading zeros plus the 14 bits of data that are in the temperature value register. When
goes into three-state. Data is clocked out onto the DOUT line
on the falling edge of SCLK.
Write Operation
Figure 14 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 1, puts the ADT7301 into shutdown mode.
In addition to the power-down bit, all bits in the input data
stream should be 0 to ensure correct operation of the ADT7301.
Data is loaded into the control register on the 16
edge; the data takes effect at this time. Therefore, if the part is
programmed to go into shutdown, it does so at this point. If
is brought high before this 16
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.
t
7
16
t
8
DB0
02884-0-007
line enables the SCLK input. Thirteen bits of
CS
remains low and 16 more SCLK cycles
CS
returns high, the DOUT line
th
rising SCLK
CS
th
SCLK edge, the control register
Rev. 0 | Page 11 of 16
ADT7301
APPLICATIONS
MICROPROCESSOR INTERFACING
The ADT7301 serial interface allows easy interface to most
microcomputers and microprocessors.
show some typical interface circuits. The serial interface on the
ADT7301 consists of four wires:
All interface circuits shown use 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 low permanently.
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
transfers. Other microcontrollers and DSP processors transfer
16 bits of data in a serial data operation.
ADT7301-to-MC68HC11 Interface
Figure 15 shows an interface circuit 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.
shows the full (4-wire) interface. PC1 of the MC68HC11 is
configured as an output and is used to drive the
ADT7301*
SCLK
DOUT
DIN
CS
*ADDITIONAL PINS OMITTED FOR CLARITY
Figure 15. ADT7301 to MC68HC11 Interface
ADT7301-to-8051 Interface
Figure 16 shows an interface circuit between the ADT7301 and
the microcontroller. 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.
Figure 15 to Figure 18
CS
, DIN, DOUT, and SCLK.
CS
input.
MC68HC11*
SCLK
MISO
MOSI
PC1
02884-0-008
Figure 15
In the example shown in
Figure 16, 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
Figure 16.
For applications that require the ADT7301 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 generating a serial clock on
one port line while using two other port lines to shift data
in and out with the fourth port line connecting to
CS
. Port
lines 1.0 to 1.3 (with P1.1 configured as an input) can be used
CS
to connect to SCLK, DOUT, DIN, and
, respectively, to
implement this scheme.
ADT7301*
SCLK
DOUT
DIN
CS
*ADDITIONAL PINS OMITTED FOR CLARITY
Figure 16. ADT7301 to 8051 Interface
8051*
P3.1
P3.0
P1.2
P1.3
02884-0-009
ADT7301-to-PIC16C6x/7x Interface
Figure 17 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 in
being used to generate the
ADT7301*
DOUT
*ADDITIONAL PINS OMITTED FOR CLARITY
Figure 17. ADT7301-to-PIC16C6x/7x Interface
CS
SCLK
DIN
CS
Figure 17, port line RA1 is
for the ADT7301.
PIC16C6x/7x*
SCK
SDO
SDI
RA1
02884-0-010
Rev. 0 | Page 12 of 16
ADT7301
The following software program shows how to program a
PIC16F873 to communicate with the ADT7301. The
PIC16F873 is configured as an SPI master with the Port A.1 pin
CS
used as
. Any microchip microcontroller can use this
program by simply exchanging the include file for the device
that is being used.
#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 set-up 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 set-up time.
Output_High(CS); //Bring CS high.
ADC_Temp_Code = make16(MSByte,LSByte); //16 bit 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.
}
Rev. 0 | Page 13 of 16
ADT7301
ADT7301-to-ADSP-21xx Interface
Figure 18 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. On the
ADSP-21xx interface, the TFS and RFS of the SPORT are tied
together; TFS is set as an output, and RFS is set as an input. The
DSP operates in alternate framing mode and the SPORT control
register is set up as described in this section.
ADT7301*
SCLK
DOUT
DIN
CS
*ADDITIONAL PINS OMITTED FOR CLARITY
Figure 18. ADT7301-to-ADSP-21 Interface
ADSP-21xx*
SCK
DR
DT
RFS
TFS
02884-0-011
MOUNTING THE ADT7301
The ADT7301 can be used for surface or air temperature
sensing applications. If the device is cemented to a surface with
a thermally conductive adhesive, the die temperature will be
within about 0.1°C of the surface temperature because of the
ADT7301’s low power consumption. Care should be taken to
insulate the back and leads of the device if the ambient air
temperature is different from the surface temperature being
measured.
The ground pin provides the best thermal path to the die;
therefore the temperature of the die is close to that of the
printed circuit ground track. Care should be taken to ensure
that this is in good thermal contact with the measured surface.
As in 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 V
if the ADT7301 mount is remote from the power supply.
and GND. This is particularly important
DD
Rev. 0 | Page 14 of 16
ADT7301
0
OUTLINE DIMENSIONS
2.90 BSC
1.90
BSC
0.50
0.30
4 5
2.80 BSC
2
0.95 BSC
1.45 MAX
SEATING
PLANE
0.22
0.08
1.60 BSC
1.30
1.15
0.90
.15 MAX
6
13
PIN 1
COMPLIANT TO JEDEC STANDARDS MO-178AB
Figure 19. 6-Lead Small Outline Transistor Package [SOT-23]
(RT-6)
Dimensions shown in millimeters
10°
3.00
BSC
85
3.00
BSC
PIN 1
0.15
0.00
0.60
4°
0.45
0°
0.30
COPLANARITY
0.10
4
0.65 BSC
0.38
0.22
COMPLIANT TO JEDEC STANDARDS MO-187AA
SEATING
PLANE
Figure 20. 8-Lead Mini Small Outline Package [MSOP]
Dimensions shown in millimeters
4.90
BSC
1.10 MAX
0.23
0.08
(RM-8)
8°
0°
0.80
0.60
0.40
ORDERING GUIDE
Model Temperature Range Temperature Accuracy1Package Description Package Option Branding
ADT7301ART-500RL7 −40°C to +150°C ±1°C 6-Lead SOT-23 RT-6 TCA
ADT7301ARTZ-500RL72−40°C to +150°C ±1°C 6-Lead SOT-23 RT-6 T1H
ADT7301ARTZ-REEL7
ADT7301ARMZ
ADT7301ARMZ-REEL7
1
Temperature accuracy is over a 0°C to 70°C temperature range.
2
Z = Pb-free part.
2
2
−40°C to +150°C ±1°C 6-Lead SOT-23 RT-6 T1H
−40°C to +150°C ±1°C 8-Lead MSOP RM-8 T1H
2
−40°C to +150°C ±1°C 8-Lead MSOP RM-8 T1H
Rev. 0 | Page 15 of 16
ADT7301
NOTES
© 2005 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D02884–0–10/05(0)
Rev. 0 | Page 16 of 16
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