TC72
Digital Temperature Sensor with SPI Interface
Features
General Description
•
•
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•
•
•
•
TC72 is a digital temperature sensor capable of
reading temperatures from -55°C to +125°C. This
sensor features a serial interface that allows
communication with a host controller or other
peripherals. The TC72 interface is compatible with the
SPI protocol, and does not require any additional
external components. However, it is recommended that
a decoupling capacitor of 0.01 µF to 0.1 µF be provided
between the VDD and GND pins.
Temperature-to-Digital Converter
SPI Compatible Interface
10-Bit Resolution (0.25°C/Bit)
±2°C (maximum) Accuracy from -40°C to +85°C
±3°C (maximum) Accuracy from -55°C to +125°C
2.65V to 5.5V Operating Range
Low Power Consumption:
- 250 µA (typical) Continuous Temperature
Conversion Mode
- 1 µA (maximum) Shutdown Mode
• Power Saving One-Shot Temperature
Measurement
• Industry Standard 8-Pin MSOP Package
• Space Saving 8-Pin DFN (3x3 mm) Package
Typical Applications
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•
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Personal Computers and Servers
Hard Disk Drives and Other PC Peripherals
Entertainment Systems
Office Equipment
Datacom Equipment
Mobile Phones
General Purpose Temperature Monitoring
TC72 can be used either in a Continuous Temperature
Conversion mode or a One-Shot Conversion mode.
The Continuous Conversion mode measures the
temperature approximately every 150 ms and stores
the data in the temperature registers. In contrast, the
One-Shot mode performs a single temperature
measurement and returns to the power saving
shutdown mode.
TC72 features high temperature accuracy, ease-of-use
and is the ideal solution for implementing thermal
management in a variety of systems. The device is
available in both 8-pin MSOP and 8-pin DFN spacesaving packages. TC72 also features a Shutdown
mode for low power operation.
Block Diagram
VDD
Package Types
Internal
Diode
Temperature
Sensor
TC72
MSOP
NC 1
8 VDD
CE 2
7 NC
SCK 3
6 SDI
GND 4
5 SDO
10-Bit
Sigma Delta
A/D Converter
TC72
3x3 DFN*
NC 1
SCK 2
CE 3
8 VDD
EP
9
GND 4
Temperature
Register
7 NC
6 SDO
5 SDI
TC72
Manufacturer
ID Register
Serial
Port
Interface
CE
SCK
SDO
SDI
GND
Control
Register
* Includes Exposed Thermal Pad (EP); see Table 3-1.
© 2011 Microchip Technology Inc.
DS21743B-page 1
TC72
NOTES:
DS21743B-page 2
© 2011 Microchip Technology Inc.
TC72
1.0
ELECTRICAL
CHARACTERISTICS
1.1
Maximum Ratings†
† Notice: Stresses above those listed under "Maximum
Ratings" may cause permanent damage to the device. This is
a stress rating only and functional operation of the device at
those or any other conditions above those indicated in the
operation listings of this specification is not implied. Exposure
to maximum rating conditions for extended periods may affect
device reliability.
VDD........................................................................ 6.0V
All inputs and outputs w.r.t. GND ...-0.3V to VDD +0.3V
Storage temperature .......................... -65°C to +150°C
Ambient temp. with power applied ..... -55°C to +125°C
Junction Temperature ........................................ 150°C
ESD protection on all pins:
Human Body Model (HBM)............................. > 4 kV
Man Machine Model (MM)............................. > 400V
Latch-Up Current at each pin ........................ ±200 mA
Maximum Power Dissipation........................... 250 mW
DC CHARACTERISTICS
Electrical Specifications: Unless otherwise noted, all parameters apply at VDD = 2.65V to 5.5V,
TA = -55°C to +125°C.
Parameters
Sym
Min
Typ
Max
Units
Conditions
VDD
2.65
—
5.5
V
Note 1
IDD-CON
—
250
400
µA
Continuous Temperature Conversion
mode (Shutdown Bit = ‘0’)
ISHD
—
0.1
1.0
µA
Shutdown mode (Shutdown Bit = ‘1’)
°C
-40°C < TA < +85°C
Power Supply
Operating Voltage Range
Operating Current:
Normal Mode, ADC Active
Shut-Down Supply Current
Temperature Sensor and Analog-to-Digital Converter
Temperature Accuracy
(Note 1)
TACY
Resolution
ADC Conversion Time
-2.0
—
+2.0
-3.0
—
+3.0
-55°C < TA < +125°C
—
10
—
Bits
tCONV
—
150
200
ms
VIH
0.7 VDD
—
—
V
Note 4
Digital Input / Output
High Level Input Voltage
Low Level Input Voltage
VIL
—
—
0.2 VDD
V
High Level Output Voltage
VOH
0.7 VDD
—
—
V
IOH = 1 mA
Low Level Output Voltage
VOL
—
—
0.2 VDD
V
IOL = 4 mA
Input Resistance
RIN
1.0
—
—
MΩ
CIN
—
15
—
pF
COUT
—
50
—
Pin Capacitance
Note 1:
2:
3:
4:
The TC72-2.8MXX, TC72-3.3MXX and TC72-5.0MXX will operate from a supply voltage of 2.65V to 5.5V.
However, the TC72-2.8MXX, TC72-3.3MXX and TC72-5.0MXX are tested and specified at the nominal
operating voltages of 2.8V, 3.3V and 5.0V respectively. As VDD varies from the nominal operating value,
the accuracy may be degraded. Refer to Figure 2-5 and Figure 2-6.
Measured with a load of CL = 50 pF on the SDO output pin of the TC72.
All time measurements are measured with respect to the 50% point of the signal, except for the SCK rise
and fall times. The rise and fall times are defined as the 10% to 90% transition time.
Resolution = Temperature Range/No. of Bits = (+127°C – -128°C) / (210) = 256/1024 = 0.25°C/Bit
© 2011 Microchip Technology Inc.
DS21743B-page 3
TC72
DC CHARACTERISTICS (CONTINUED)
Electrical Specifications: Unless otherwise noted, all parameters apply at VDD = 2.65V to 5.5V,
TA = -55°C to +125°C.
Parameters
Sym
Min
Typ
Max
Units
Conditions
Serial Port AC Timing (Note 2, 3)
Clock Frequency
fCLK
DC
—
7.5
MHz
SCK Low Time
tCL
65
—
—
ns
SCK High Time
tCH
65
—
—
ns
CE to SCK Setup
tCC
400
—
—
ns
SCK to Data Out Valid
tCDD
—
—
55
ns
CE to Output Tri-state
tCDZ
—
—
40
ns
SCK to Data Hold Time
tCDH
35
—
—
ns
Data to SCK Set-up Time
tDC
35
—
—
ns
SCK to CE Hold Time
tCCH
100
—
—
ns
tR
—
—
200
ns
SCK Rise Time
SCK Fall Time
CE Inactive Time
Note 1:
2:
3:
4:
tF
—
—
200
ns
tCWH
400
—
—
ns
The TC72-2.8MXX, TC72-3.3MXX and TC72-5.0MXX will operate from a supply voltage of 2.65V to 5.5V.
However, the TC72-2.8MXX, TC72-3.3MXX and TC72-5.0MXX are tested and specified at the nominal
operating voltages of 2.8V, 3.3V and 5.0V respectively. As VDD varies from the nominal operating value,
the accuracy may be degraded. Refer to Figure 2-5 and Figure 2-6.
Measured with a load of CL = 50 pF on the SDO output pin of the TC72.
All time measurements are measured with respect to the 50% point of the signal, except for the SCK rise
and fall times. The rise and fall times are defined as the 10% to 90% transition time.
Resolution = Temperature Range/No. of Bits = (+127°C – -128°C) / (210) = 256/1024 = 0.25°C/Bit
TEMPERATURE SPECIFICATION
Electrical Specifications: Unless otherwise noted, all parameters apply at VDD = 2.65V to 5.5V,
TA = -55°C to +125°C.
Parameters
Sym
Min
Typ
Max
Units
Specified Temperature Range
TA
-55
—
+125
°C
Operating Temperature Range
TA
-55
—
+125
°C
Storage Temperature Range
TA
-65
—
+150
°C
Thermal Resistance 8-L 3x3 DFN
θJA
—
56.7
—
°C/W
Thermal Resistance 8-L MSOP
θJA
—
211
—
°C/W
Conditions
Temperature Ranges
Thermal Package Resistances
DS21743B-page 4
© 2011 Microchip Technology Inc.
TC72
SPI READ DATA TRANSFER
(CP = 0, data shifted on rising edge of SCK, data clocked on falling edge of SCK, A7 = 0)
tCWH
CE
tCCH
1/fCLK
tCC
SCK
SDI
tDC
tCDH
A7
MSb
tF
tR
tCH
A0
tCL
LSb
tCDD
SDO
HIGH Z
tCDZ
HIGH Z
MSb
D7
D0
LSb
SPI WRITE DATA TRANSFER
(CP = 0, data shifted on rising edge of SCK, data clocked on falling edge of SCK, A7 = 1)
tCWH
CE
1/fCLK
tCC
tCCH
SCK
tF
SDI
A7 = 1 MSb
Note:
FIGURE 1-1:
tCH
tR
A0 LSb
tDC
tCDH
D7
MSb
tCL
D0
LSb
The timing diagram is drawn with CP = 0. The TC72 also functions with CP = 1;
however, the edges of SCK are reversed as defined in Table 4-3 and Figure 4-2.
Serial Port Timing Diagrams.
© 2011 Microchip Technology Inc.
DS21743B-page 5
TC72
NOTES:
DS21743B-page 6
© 2011 Microchip Technology Inc.
TC72
2.0
TYPICAL PERFORMANCE CURVES
Note:
The graphs and tables provided following this note are a statistical summary based on a limited number of
samples and are provided for informational purposes only. The performance characteristics listed herein
are not tested or guaranteed. In some graphs or tables, the data presented may be outside the specified
operating range (e.g., outside specified power supply range) and therefore outside the warranted range.
3.5
3
2.5
2
1.5
1
0.5
0
-0.5
-1
-1.5
-2
-2.5
-3
-3.5
0.20
Upper Specification Limit
Mean
Mean + 3V
Mean - 3V
Lower Specification Limit
Shutdown Current (µA)
Temperature Error (°C)
Note: Unless otherwise indicated, all parameters apply at VDD = 2.65V to 5.5V, TA = -55°C to +125°C.
0.15
TC72-3.3MXX
TC72-5.0MXX
VDD = 3.3V
VDD = 5.0V
TC72-5.0MXX
VDD = 2.8V
0.10
0.05
0.00
-55
-25
5
35
65
95
125
-55
-25
5
Reference Temperature (°C)
FIGURE 2-1:
(TC72-X.XMXX).
Accuracy vs. Temperature
95
125
FIGURE 2-4:
Temperature.
Shutdown Current vs.
0.4
Temperature Change (°C)
TC72-X.XMXX
Supply Current (µA)
65
Temperature (°C)
260
250
TA = +25°C
240
230
220
TA = -55°C
210
TA = +125°C
200
2.5
3.0
3.5
0.3
TC72-2.8MXX
0.2
TA = +85°C
0.1
0.0
-0.1
FIGURE 2-2:
Voltage.
TA = +25°C
-0.3
-0.4
4.0
4.5
5.0
2.6
5.5
2.7
Supply Current vs. Supply
300
250
200
TC72-2.8MXX
VDD = 2.8V
150
100
50
0
-55
-25
5
35
65
95
Temperature (°C)
FIGURE 2-3:
Temperature.
Supply Current vs.
© 2011 Microchip Technology Inc.
2.9
3.0
FIGURE 2-5:
Temperature Accuracy vs.
Supply Voltage (TC72-2.8MXX).
Temperature Change (°C)
TC72-3.3MXX
VDD = 3.3V
TC72-5.0MXX
VDD = 5.0V
2.8
Supply Voltage (V)
400
350
TA = -25°C
-0.2
Supply Voltage (V)
Supply Current (uA)
35
125
1.0
0.8
0.6
0.4
0.2
0.0
-0.2
-0.4
-0.6
-0.8
-1.0
TC72-5.0MXX
TA = +85°C
TA = -25°C
TA = +25°C
4.5 4.6 4.7 4.8 4.9 5.0 5.1 5.2 5.3 5.4 5.5
Supply Voltage (V)
FIGURE 2-6:
Temperature Accuracy vs.
Supply Voltage (TC72-5.0MXX).
DS21743B-page 7
TC72
TC72-X.XMXX
Sample Size = 166
TA = +65°C
50
40
30
20
10
Temperature Error (°C)
TC72-X.XMXX
Sample Size = 166
TA = -40°C
40
30
20
10
0
1.5
2
-2
-1.5
1.50
1.25
0.75
0.50
0.25
0.00
1.00
1.5
2
Temperature Error (°C)
FIGURE 2-9:
Histogram of Temperature
Accuracy at +25 Degrees C.
25
20
15
10
5
3
2.5
0
2
1.50
1.25
1.00
0.75
0.50
0.25
0.00
-0.25
-0.50
-0.75
0
30
-2
10
-1.00
1
TC72-X.XMXX
Sample Size = 166
TA = +125°C
35
-3
20
-1.25
0.5
40
-2.5
30
DS21743B-page 8
0
FIGURE 2-11:
Histogram of Temperature
Accuracy at +85 Degrees C.
Percentage of Occurances (%)
TC72-X.XMXX
Sample Size = 166
TA = +25°C
-1.50
Percentage of Occurances (%)
60
40
-0.5
Temperature Error (°C)
FIGURE 2-8:
Histogram of Temperature
Accuracy at -40 Degrees C.
50
-1
1
1
1.5
0.5
0.5
0
0
-0.5
Temperature Error (°C)
-0.5
-1
TC72-X.XMXX
Sample Size = 166
TA = +85°C
-1
-1.5
50
45
40
35
30
25
20
15
10
5
0
-1.5
-2
-0.25
FIGURE 2-10:
Histogram of Temperature
Accuracy at +65 Degrees C.
Percentage of Occurances (%)
Percentage of Occurances (%)
50
-0.50
Temperature Error (°C)
FIGURE 2-7:
Histogram of Temperature
Accuracy at -55 Degrees C.
60
-0.75
-1.00
-1.25
0
-1.50
Percentage of Occurances (%)
60
3
2
2.5
1
0
0.5
-1
-0.5
-2
-1.5
-3
1.5
TC72-X.XMXX
Sample Size = 166
TA = -55°C
50
45
40
35
30
25
20
15
10
5
0
-2.5
Percentage of Occurances (%)
Note: Unless otherwise indicated, all parameters apply at VDD = 2.65V to 5.5V, TA = -55°C to +125°C.
Temperature Error (°C)
FIGURE 2-12:
Histogram of Temperature
Accuracy at +125 Degrees C.
© 2011 Microchip Technology Inc.
TC72
3.0
PIN DESCRIPTION
Pin functionalities are described in Table 3-1.
TABLE 3-1:
PIN FUNCTION TABLE
TC72
Symbol
3x3 DFN
MSOP
1
1
NC
2
3
SCK
3
2
CE
4
4
GND
3.1
Function
No internal connection
Serial Clock input
Chip Enable input, the device is selected when this input is high
Ground
5
6
SDI
Serial Data input
6
5
SDO
Serial Data output
7
7
NC
No internal connection
8
8
VDD
Power supply
9
—
EP
Exposed pad (Ground)
No Connection (NC)
This pin is not internally connected to the die.
3.2
Serial Clock Input (SCK)
The SCK pin is an Input pin. All communication and
timing is relative to the signal on this pin. The clock is
generated by the host controller on the SPI bus (see
Section 4.3 “Serial Bus Interface”).
3.3
Chip Enable Input (CE)
3.7
Power Supply (VDD)
VDD is the Power pin. The operating voltage range, as
specified in the DC electrical specification table, is
applied on this pin.
3.8
Exposed Pad (EP)
There is an internal electrical connection between the
Exposed Thermal Pad (EP) and the GND pin; they can
be connected to the same potential on the Printed
Circuit Board (PCB). This provides better thermal
conduction from the PCB to the die.
The CE is a Chip Enable pin. This is an active high
input, therefore the device is enabled when CE is
toggled to VDD. Once the device is enabled, all serial
communication begins (see Section 4.3 “Serial Bus
Interface”).
3.4
Ground (GND)
The GND is the system Ground pin.
3.5
Serial Data Input (SDI)
The SDI is a Data Input pin, used to transmit data from
the host to the device (see Section 4.3 “Serial Bus
Interface”).
3.6
Serial Data Output (SDO)
The SDO is a Data Output pin, used to transmit data
from the device to the host (see Section 4.3 “Serial
Bus Interface”).
© 2011 Microchip Technology Inc.
DS21743B-page 9
TC72
NOTES:
DS21743B-page 10
© 2011 Microchip Technology Inc.
TC72
4.0
FUNCTIONAL DESCRIPTION
The Continuous Conversion mode measures the
temperature approximately every 150 ms and stores
the data in the temperature registers. TC72 has an
internal clock generator that controls the automatic
temperature conversion sequence. The automatic
temperature sampling operation is repeated indefinitely
until TC72 is placed in Shutdown mode by a write
operation to the Control register. TC72 will remain in
Shutdown mode until the shutdown bit in the Control
register is reset.
TC72 consists of a band-gap type temperature sensor,
a 10-bit Sigma Delta Analog-to-Digital Converter
(ADC), an internal conversion oscillator and a double
buffer digital output port. The 10-bit ADC is scaled from
-128°C to +127°C; therefore, the resolution is 0.25°C
per bit. The ambient temperature operating range of
the TC72 is specified from -55°C to +125°C.
This device features a four-wire serial interface that is
fully compatible with the SPI specification and, therefore, allows simple communications with common
microcontrollers and processors. TC72 can be used
either in a Continuous Temperature Conversion mode
or a One-Shot Conversion mode. TC72 temperature
measurements are performed in the background and,
therefore, reading the temperature via the serial I/O
lines does not affect the measurement in progress.
MSB
LSB
0111 1101 / 0000 0000
In contrast, the One-Shot mode performs a single
temperature measurement and returns to the powersaving shut down mode. This mode is especially useful
for low power applications.
Output
Code
+25°C
+0.25°C
MSB
LSB
0001 1001 / 0000 0000
MSB
LSB
0000 0000 / 0100 0000
MSB
LSB
0°C
0000 0000 / 0000 0000
Temp
-55°C
MSB
LSB
1111 1111 / 1100 0000
Temp
+125°C
MSB
LSB
1110 0111 / 0000 0000
-0.125°C
-25°C
MSB
LSB
1100 1001 / 0000 0000
Note:
FIGURE 4-1:
The ADC converter is scaled from -128°C to +127°C, but the operating range of the
TC72 is specified from -55°C to +125°C.
Temperature-To-Digital Transfer Function (Non-Linear Scale).
© 2011 Microchip Technology Inc.
DS21743B-page 11
TC72
4.1
Temperature Data Format
4.3
Temperature data is represented by a 10-bit two’s complement word with a resolution of 0.25°C per bit. The
temperature data is stored in the Temperature registers
in a two’s complement format. The ADC converter is
scaled from -128°C to +127°C, but the operating range
of TC72 is specified from -55°C to +125°C.
EXAMPLE 4-1:
Temperature
= +41.5°C
MSB Temperature Register
= 00101001b
= 25 + 23 + 20
= 32 + 8 + 1 = 41
= 10000000b = 2-1 = 0.5
LSB Temperature Register
TABLE 4-1:
TC72 TEMPERATURE
OUTPUT DATA
Temperature
Binary
MSB / LSB
Hex
+125°C
0111 1101/0000 0000
7D00
+25°C
0001 1001/0000 0000
1900
+0.5°C
0000 0000/1000 0000
0080
+0.25°C
0000 0000/0100 0000
0040
0°C
0000 0000/0000 0000
0000
-0.25°C
1111 1111/1100 0000
FFC0
-25°C
1110 0111/0000 0000
E700
-55°C
1100 1001/0000 0000
C900
TABLE 4-2:
TEMPERATURE REGISTER
D7
D6
D5
D4
D3
D2
D1
D0
Address/
Register
Sign
26
25
24
23
23
21
20
02H
Temp. MSB
2-1
2-2
0
0
0
0
0
0
01H
Temp. LSB
4.2
Power-Up And Power-Down
TC72 is in low-power consumption Shutdown mode at
power-up. The Continuous Temperature Conversion
mode is selected by performing a Write operation to the
Control register, as described in Section 5.0 “Internal
Register Structure”.
Serial Bus Interface
The serial interface consists of the Chip Enable (CE),
Serial Clock (SCK), Serial Data Input (SDI) and Serial
Data Output (SDO) signals. TC72 operates as a slave
and is compatible with the SPI bus specifications. The
serial interface is designed to be compatible with the
Microchip PIC® family of microcontrollers.
The CE input is used to select TC72 when multiple
devices are connected to the serial clock and data
lines. The CE is active-high, and data is written to or
read from the device, when CE is equal to a logic high
voltage. The SCK input is disabled when CE is low. The
rising edge of the CE line initiates a read or write
operation, while the falling edge of CE completes a
read or write operation.
The SCK input is provided by the external
microcontroller and is used to synchronize the data on
the SDI and SDO lines. The SDI input writes data into
TC72’s Control register, while the SDO outputs the
temperature data from the Temperature register and
the status of Shutdown bit of the Control register.
TC72 has the capability to function with either an
active-high or low SCK input. The SCK inactive state is
detected when the CE signal goes high, while the
polarity of the clock input (CP) determines whether the
data is clocked and shifted on either the rising or falling
edge of the system clock, as shown in Figure 4-2.
Table 4-3 gives the appropriate clock edge used to
transfer data into and out of the registers. Each data bit
is transferred at each clock pulse, and the data bits are
clocked in groups of eight bits, as shown in Figure 4-3.
The address byte is transferred first, followed by the
data. A7, the MSb of the address, determines whether
a read or write operation will occur. If A7 = ‘0’, one or
more read cycles will occur; otherwise, if A7 = ‘1’, one
or more write cycles will occur.
Data can be transferred either in a single byte or a
multi-byte packet, as shown in Figure 4-3. In the 3-byte
packet, the data sequence consists of the MSb
temperature data, LSb temperature data, followed by
the Control register data. The multi-byte read feature is
initiated by writing the highest address of the desired
packet to registers. TC72 will automatically send the
register addressed and all of the lower address
registers, as long as the Chip Enable pin is held active.
A supply voltage lower than 1.6V (typical) is considered
a power-down state for TC72. If the supply voltage
drops below the 1.6V threshold, the internal registers
are reset to the power-up default state.
DS21743B-page 12
© 2011 Microchip Technology Inc.
TC72
TABLE 4-3:
OPERATIONAL MODES
Mode
CE
SCK (Note 1)
SDI
SDO
Disable
L
Input Disabled
Input Disabled
High Z
Data Bit Latch
High Z
X
Next data bit shift,
Note 2
Write (A7 = 1)
H
CP=1, Data Shifted on Falling Edge,
Data Clocked on Rising Edge
CP=0, Data Shifted on Rising Edge,
Data Clocked on Falling Edge
Read (A7 = 0)
H
CP=1, Data Shifted on Falling Edge,
Data Clocked on Rising Edge
CP=0, Data Shifted on Rising Edge,
Data Clocked on Falling Edge
Note 1:
2:
4.4
CP is the Clock Polarity of the microcontroller system clock. If the inactive state of SCK is logic level high,
CP is equal to ‘1’; otherwise, if the inactive state of SCK is low, CP is equal to ‘0’.
During a Read operation, SDO remains at a high impedance (High Z) level until the eight bits of data begin
to be shifted out of the Temperature register.
Read Operation
The TC72 uses the CE, SCK and SDO lines to output
the Temperature and Control register data. Figure 4-3
shows a timing diagram of the read operation.
Communication is initiated by the chip enable (CE)
going high. The SDO line remains at the voltage level
of the LSb bit that is output and goes to the tri-state
level when the CE line goes to a logic low level.
4.5
CP = 0
CE
SCK
SHIFT
EDGE
Write Operation
Data is clocked into the Control register in order to
enable TC72’s power saving shutdown mode. The
write operation is shown in Figure 4-3 and is
accomplished using the CE, SCK and SDI lines.
CLOCK
EDGE
CP = 1
CE
SCK
SHIFT
EDGE
FIGURE 4-2:
Operation.
© 2011 Microchip Technology Inc.
CLOCK
EDGE
Serial Clock Polarity (CP)
DS21743B-page 13
TC72
Single Byte Write Operation
(CP=0, data shifted on rising edge of SCK, data clocked on falling edge of SCK, A7=1)
CE
SCK
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
A7=1
A
7
SDI
A
6
A
5
A
4
A
3
A
2
A
1
A
0
D
7
D
6
D
5
D
4
D
3
D
2
D
1
MSb
SDO
D
0
LSb
High Z
Single Byte Read Operation
(CP=0, data shifted on rising edge of SCK, data clocked on falling edge of SCK, A7=0)
CE
SCK
2
1
3
4
5
6
7
8
9
10
11
12
13
14
15
16
A7=0
A
7
SDI
A
6
A
5
A
4
A
3
SDO
A
2
A
1
A
0
High Z
D
7
D
0
MSb
LSb
High Z
SPI Multiple Byte Transfer
CE
SCK
Write Operation
(CP=0, data shifted on rising edge of SCK, data clocked on falling edge of SCK, A7=1)
SDI
Address Byte = 80hex
A7
A0
Control Byte
D7
D0
High Z
SDO
Read Operation
(CP=0, data shifted on rising edge of SCK, data clocked on falling edge of SCK, A7=0)
SDI
Address Byte = 02hex
A0
A7
SDO
High Z
FIGURE 4-3:
DS21743B-page 14
MSB Temp. Byte
D7
Control Byte
LSB Temp. Byte
D0
D7
D0
D7
D0
High Z
Serial Interface Timing Diagrams (CP=0).
© 2011 Microchip Technology Inc.
TC72
5.0
INTERNAL REGISTER
STRUCTURE
TC72 registers are listed below.
TABLE 5-1:
REGISTERS FOR TC72
Read
Address
Write
Address
Bit
7
Bit
6
Bit
5
Bit
4
Control
00hex
80hex
0
0
0
One-Shot
(OS)
0
1
LSB Temperature
01hex
N/A
T1
T0
0
0
0
0
MSB Temperature
02hex
N/A
T9
T8
T7
T6
Manufacturer ID
03hex
N/A
0
1
0
1
Register
5.1
Control Register
The Control register is both a read and a write register
that is used to select either the Shutdown, Continuous
or One-Shot Conversion operating mode. The Temperature Conversion mode selection logic is shown in
Table 5-2. The Shutdown (SHDN) bit is stored in bit 0
of the Control register. If SHDN is equal to ‘1’, TC72 will
go into power-saving Shutdown mode. If SHDN is
equal to ‘0’, TC72 will perform a temperature
conversion approximately every 150 ms.
At power-up, the SHDN bit is set to ‘1’. Thus, TC72 is
in Shutdown operating mode at startup. Continuous
Temperature Conversion mode is selected by writing a
‘0’ to the SHDN bit of the Control register.
Shutdown mode can be used to minimize the power
consumption of TC72 when active temperature
monitoring is not required. The Shutdown mode
disables the temperature conversion circuitry;
however, the serial I/O communication port remains
active. A temperature conversion will be initialized by a
Write operation to the Control register to select either
the Continuous Temperature Conversion or the OneShot operating mode. The temperature data will be
available in the MSB and LSB Temperature registers
approximately 150 ms after the Control register Write
operation.
Bit Bit Bit
3 2 1
Bit
0
Value on
POR/BOR
0
Shutdown
(SHDN)
05hex
0
0
00hex
T5 T4 T3
T2
00hex
0
0
54hex
1
0
One-Shot mode is selected by writing a ‘1’ into bit 4 of
the Control register. The One-Shot mode performs a
single temperature measurement and returns to the
power-saving Shutdown mode. After completion of the
temperature conversion, the One-Shot bit (OS) is reset
to ‘0’ (i.e. “OFF”). The user must set the One-Shot bit
to ‘1’ to initiate another temperature conversion.
Bits 1, 3, 5, 6 and 7 of the Control register are not used
by TC72. Bit 2 is set to a logic ‘1’. Any write operation
to these bit locations will have no affect on the
operation of TC72.
5.2
Temperature Register
The Temperature register is a read-only register and
contains a 10-bit two’s complement representation of
the temperature measurement. Bit 0 through Bit 5 of
the LSB Temperature register are always set to a logic
‘0’.
At Power-On Reset (POR) or a Brown-Out Reset
(BOR) low voltage occurrence, the temperature register is reset to all zeroes, which corresponds to a temperature value of 0°C. A VDD power supply less than
1.6V is considered a reset event and will reset the
Temperature register to the power-up state.
5.3
Manufacturer ID Register
The Manufacturer Identification (ID) register is a readonly register used to identify the temperature sensor as
a Microchip component.
TABLE 5-2:
CONTROL REGISTER TEMPERATURE CONVERSION MODE SELECTION
Operational Mode
One-Shot (OS) Bit 4
Shutdown (SHDN) Bit 0
Continuous Temperature Conversion
0
0
Shutdown
0
1
Continuous Temperature Conversion
(One-Shot Command is ignored if SHDN = ‘0’)
1
0
One-Shot
1
1
© 2011 Microchip Technology Inc.
DS21743B-page 15
TC72
NOTES:
DS21743B-page 16
© 2011 Microchip Technology Inc.
TC72
6.0
APPLICATIONS INFORMATION
The TC72 does not require any additional components
in order to measure temperature; however, it is
recommended that a decoupling capacitor of 0.1mF to
1mF be provided between the VDD and GND pins.
Although the current consumption of the TC72 is
modest (250 mA, typical), the TC72 contains an on
chip data acquisition with internal digital switching
circuitry. Thus, it is considered good design practice to
use an external decoupling capacitor with the sensor. A
high frequency ceramic capacitor should be used and
be located as close as possible to the IC power pins in
order to provide effective noise protection to the TC72.
The TC72 measures temperature by monitoring the
voltage of a diode located on the IC die. The IC pins of
the TC72 provide a low impedance thermal path
between the die and the PCB, allowing the TC72 to
effectively monitor the temperature of the PCB board.
The thermal path between the ambient air is not as
efficient because the plastic IC housing package
functions as a thermal insulator. Thus, the ambient air
temperature (assuming that a large temperature
gradient exists between the air and PCB) has only a
small effect on the temperature measured by the TC72.
VDD
0.1µF
VDD
TC72
CE
PICmicro®
MCU
I/O
SCK
SCK
SDO
SDI
SDI
SDO
GND
FIGURE 6-1:
Typical Application.
Note that the exposed metal center pad on the bottom
of the DFN package is connected to the silicon
substrate. The center pad should be connected to
either the PCB ground plane or treated as a “No
Connect” pin. The mechanical dimensions of the center
pad are given in Section 7.0 “Packaging
Information” of this data sheet.
A potential for self-heating errors can exist if the TC72
SPI communication lines are heavily loaded. Typically,
the self-heating error is negligible because of the
relatively small current consumption of the TC72. A
temperature accuracy error of approximately +0.5°C
will result from self-heating if the SPI communication
pins sink/source the maximum current specified for the
TC72. Thus, to maximize temperature accuracy, the
output loading of the SPI signals should be minimized.
© 2011 Microchip Technology Inc.
DS21743B-page 17
TC72
7.0
PACKAGING INFORMATION
7.1
Package Marking Information
8-Lead MSOP
XXXXXX
YWWNNN
8-Lead DFN
XXXXXXXX
MYWW
NNN
Legend: XX...X
Y
YY
WW
NNN
e3
*
Note:
DS21743B-page 18
Example:
TC722M
109256
Example:
7228
M109
256
Customer-specific information
Year code (last digit of calendar year)
Year code (last 2 digits of calendar year)
Week code (week of January 1 is week ‘01’)
Alphanumeric traceability code
Pb-free JEDEC designator for Matte Tin (Sn)
This package is Pb-free. The Pb-free JEDEC designator ( e3 )
can be found on the outer packaging for this package.
In the event the full Microchip part number cannot be marked on one line, it will
be carried over to the next line, thus limiting the number of available
characters for customer-specific information.
© 2011 Microchip Technology Inc.
TC72
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