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TMP75C
SBOS707B – APRIL 2014 – REVISED AUGUST 2014
TMP75C 1.8-V Digital Temperature Sensor with Two-Wire Interface and Alert
1 Features
3 Description
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•
•
•
The TMP75C is an integrated digital temperature
sensor with a 12-bit analog-to-digital converter (ADC)
that can operate at a 1.8-V supply, and is pin and
register compatible with the NCT75 and ADT75. This
device is available in SOIC-8 and VSSOP-8
packages and requires no external components to
sense the temperature. The TMP75C is capable of
reading temperatures with a resolution of 0.0625°C
and is specified over a temperature range of –55°C to
+125°C.
1
•
•
•
•
•
•
•
•
Low-Voltage Alternative to NCT75 and ADT75
Digital Output with Two-Wire Serial Interface
Up to 8 Pin-Programmable Bus Addresses
Overtemperature ALERT Pin with Programmable
Trip Values
Shutdown Mode for Battery Power Saving
One-Shot Conversion Mode
Operating Temperature Range: –55°C to +125°C
Operating Supply Range: 1.4 V to 3.6 V
Quiescent Current:
– 15 μA Active (typ)
– 0.3 μA Shutdown (typ)
Accuracy:
– ±0.25°C (typ) from 0°C to +70°C
– ±0.5°C (typ) from –20°C to +85°C
– ±1°C (typ) from –55°C to +125°C
Resolution: 12 Bits (0.0625°C)
Packages: SOIC-8 and VSSOP-8
2 Applications
•
•
•
•
•
•
•
•
•
The TMP75C features SMBus and two-wire interface
compatibility, and allows up to eight devices on the
same bus with the SMBus overtemperature alert
function. The programmable temperature limits and
the ALERT pin allow the sensor to operate as a
stand-alone thermostat, or an overtemperature alarm
for power throttling or system shutdown.
The factory-calibrated temperature accuracy and the
noise-immune digital interface make the TMP75C the
preferred solution for temperature compensation of
other sensors and electronic components, without the
need for additional system-level calibration or
elaborate board layout for distributed temperature
sensing.
The TMP75C is ideal for thermal management and
protection of a variety of consumer, computer,
communication,
industrial,
and
environmental
applications.
Server and Computer Thermal Management
Telecommunication Equipment
Office Machines
Video Game Consoles
Set-Top Boxes
Power Supply and Battery Thermal Protection
Thermostat Control
Environmental Monitoring and HVAC
Electrical Motor Driver Thermal Protection
Device Information(1)
DEVICE NAME
TMP75C
PACKAGE
BODY SIZE (NOM)
SOIC (8)
4.90 mm × 3.90 mm
VSSOP (8)
3.00 mm × 3.00 mm
(1) For all available packages, see the package option addendum
at the end of the datasheet.
Temperature Accuracy (Error) vs Ambient
Temperature
Simplified Schematic
1.4 V to 3.6 V
3
TMP75C
1
2
Two-Wire
Host Controller
3
SDA
VS
SCL
A0
ALERT
A1
8
7
6
Temperature Error (C)
2
0.01 PF
1
0
±1
Mean
Mean - 61
Mean + 61
±2
4
GND
A2
5
±3
±75
±50
±25
0
25
50
75
Temperature (C)
100
125
150
C005
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
TMP75C
SBOS707B – APRIL 2014 – REVISED AUGUST 2014
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Table of Contents
1
2
3
4
5
6
7
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Pin Configuration and Functions .........................
Specifications.........................................................
1
1
1
2
3
4
6.1
6.2
6.3
6.4
6.5
6.6
4
4
4
4
5
6
Absolute Maximum Ratings ......................................
Handling Ratings.......................................................
Recommended Operating Conditions.......................
Thermal Information ..................................................
Electrical Characteristics...........................................
Typical Characteristics ..............................................
Detailed Description .............................................. 7
7.1 Overview ................................................................... 7
7.2 Functional Block Diagram ......................................... 7
7.3 Feature Description................................................... 8
7.4 Device Functional Modes........................................ 15
7.5 Programming........................................................... 16
7.6 Register Map........................................................... 16
8
Application and Implementation ........................ 19
8.1 Application Information............................................ 19
8.2 Typical Application ................................................. 19
9 Power Supply Recommendations...................... 20
10 Layout................................................................... 21
10.1 Layout Guidelines ................................................. 21
10.2 Layout Example .................................................... 21
11 Device and Documentation Support ................. 22
11.1
11.2
11.3
11.4
Documentation Support .......................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
22
22
22
22
12 Mechanical, Packaging, and Orderable
Information ........................................................... 22
4 Revision History
Changes from Revision A (April 2014) to Revision B
•
Added DGK (VSSOP-8) package to data sheet .................................................................................................................... 1
Changes from Original (April 2014) to Revision A
•
2
Page
Page
Changed from product preview to production data ................................................................................................................ 1
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5 Pin Configuration and Functions
D and DGK Packages
SOIC-8 and VSSOP-8
(Top View)
SDA
1
8
VS
SCL
2
7
A0
ALERT
3
6
A1
GND
4
5
A2
Pin Functions
PIN
NAME
NO.
I/O
DESCRIPTION
A0
7
I
Address select. Connect to GND or VS.
A1
6
I
Address select. Connect to GND or VS.
A2
5
I
Address select. Connect to GND or VS.
ALERT
3
O
Overtemperature alert. Open-drain output; requires a pull-up resistor.
GND
4
—
Ground.
SCL
2
I
SDA
1
I/O
VS
8
I
Serial clock.
Serial data. Open-drain output; requires a pull-up resistor.
Supply voltage, 1.4 V to 3.6 V.
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6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted)
(1)
MIN
MAX
UNIT
4
V
V
Supply voltage, VS
Input voltage
Sink current
SDA, SCL, ALERT, A2, A1
-0.3
4
A0
-0.3
(VS) + 0.3
V
10
mA
150
°C
SDA, ALERT
Operating junction temperature
(1)
-55
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended
Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
6.2 Handling Ratings
MIN
Tstg
Storage temperature range
V(ESD)
(1)
Electrostatic Human body model (HBM), per ANSI/ESDA/JEDEC JS-001, all pins
discharge
Charged device model (CDM), per JEDEC specification JESD22-C101, all pins (2)
(1)
(2)
MAX
UNIT
°C
-60
150
–2000
2000
–1000
1000
V
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
6.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)
MIN
NOM
Supply voltage
1.4
1.8
Operating free-air temperature, TA
-55
MAX
UNIT
3.6
V
125
°C
6.4 Thermal Information
TMP75C
THERMAL METRIC (1)
D (SOIC)
DGK (VSSOP)
8 PINS
8 PINS
188.1
RθJA
Junction-to-ambient thermal resistance
125.4
RθJC(top)
Junction-to-case (top) thermal resistance
71.5
79.1
RθJB
Junction-to-board thermal resistance
65.8
109.6
ψJT
Junction-to-top characterization parameter
21.1
15.3
ψJB
Junction-to-board characterization parameter
65.3
108
RθJC(bot)
Junction-to-case (bottom) thermal resistance
N/A
N/A
(1)
4
UNIT
°C/W
For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953.
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6.5 Electrical Characteristics
At TA = –55°C to +125°C and VS = +1.4 V to +3.6 V, unless otherwise noted. Typical values at TA = 25°C and VS = +1.8 V.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
+125
°C
TEMPERATURE INPUT
Temperature range
–55
Temperature resolution
0.0625
0°C to +70°C
Temperature accuracy
(error)
–20°C to +85°C
–55°C to +125°C
°C
±0.25
±1
°C
±0.5
±2
°C
±1
±3
°C
V
DIGITAL INPUT/OUTPUT
VIH
High-level input voltage
0.7(VS)
VS
VIL
Low-level input voltage
-0.3
0.3(VS)
V
IIN
Input current
0 V < VIN < (VS) + 0.3 V
1
μA
VOL
Low-level output
voltage
VS ≥ 2 V, IOUT = 3 mA
0.4
V
VS < 2 V, IOUT = 3 mA
0.2(VS)
ADC resolution
Conversion time
12
One-shot mode
20
Update Rate
27
35
80
Bus timeout time
16
22
V
Bit
ms
ms
29
ms
POWER SUPPLY
Operating supply range
IQ
ISD
Quiescent current
Shutdown current
1.4
Serial bus inactive
15
Serial bus active, SCL frequency = 400 kHz
25
3.6
V
37
μA
μA
μA
Serial bus active, SCL frequency = 3.4 MHz
95
Serial bus inactive
0.3
Serial bus active, SCL frequency = 400 kHz
10
μA
Serial bus active, SCL frequency = 3.4 MHz
80
μA
8
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6.6 Typical Characteristics
At TA = 25°C and VS = +1.8 V (unless otherwise noted).
50
Vs = 1.8V
8
Vs = 3.6V
35
Vs = 1.4V
9
Vs = 1.8V
40
Vs = 3.6V
7
30
ISD ( A)
IQ ( A)
10
Vs = 1.4V
45
25
20
6
5
4
15
3
10
2
5
1
0
0
±75
±50
±25
0
25
50
75
100
125
±75
150
Temperature (C)
±25
0
25
50
75
100
125
150
Temperature (C)
Figure 1. Quiescent Current vs Temperature
C002
Figure 2. Shutdown Current vs Temperature
30
200
29
175
28
Ta = -Û&
7D Û&
7D Û&
150
27
125
26
IQ ( A)
Conversion Time (ms)
±50
C001
25
24
100
75
23
22
21
Vs = 1.4V
50
Vs = 1.8V
25
Vs = 3.6V
20
±75
±50
±25
0
25
50
75
100
125
0
150
Temperature (C)
10
Figure 3. Conversion Time vs Temperature
100
1000
10000
Bus Frequency (kHz)
C003
C004
Figure 4. Quiescent Current vs Bus Frequency
3
Population
1
0
±1
Mean
Mean - 61
Mean + 61
±2
±3
±75
±50
±25
0
25
50
75
100
125
Temperature (C)
150
-1
-0.9
-0.8
-0.7
-0.6
-0.5
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Temperature Error (C)
2
C005
Temperature Error (C)
C006
Figure 5. Temperature Error vs Temperature
6
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Figure 6. Temperature Error at 25°C
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7 Detailed Description
7.1 Overview
The TMP75C is a digital temperature sensor optimal for thermal management and thermal protection
applications. The TMP75C is two-wire and SMBus interface compatible, and is specified over a temperature
range of –55°C to +125°C.
The temperature sensing device for the TMP75C is the chip itself. A bipolar junction transistor (BJT) inside the
chip is used in a band-gap configuration to produce a voltage proportional to the chip temperature. The voltage is
digitized and converted to a 12-bit temperature result in degrees Celsius, with resolution of 0.0625°C. The
package leads provide the primary thermal path because of the lower thermal resistance of the metal. Thus, the
temperature result is equivalent to the local temperature of the printed circuit board (PCB) where the sensor is
mounted.
7.2 Functional Block Diagram
VS
Device
Voltage Regulator
Register Bank
Oscillator
SDA
Serial Interface
Control Logic
SCL
A0
NxI
I
ALERT
A1
A2
ADC
Thermal
BJT
GND
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7.3 Feature Description
7.3.1 Digital Temperature Output
The 12-bit digital output from each temperature measurement conversion is stored in the read-only temperature
register. Two bytes must be read to obtain the data, as shown in Figure 14. Note that byte 1 is the most
significant byte, followed by byte 2, the least significant byte. The temperature result is left-justified with the 12
most significant bits used to indicate the temperature. There is no need to read the second byte if resolution
below 1°C is not required. Table 1 summarizes the temperature data format. One LSB equals 0.0625°C.
Negative numbers are represented in binary twos complement format.
Table 1. Temperature Data Format (1)
DIGITAL OUTPUT
(1)
TEMPERATURE (°C)
BINARY
HEX
128
0111 1111 1111
7FF
127.9375
0111 1111 1111
7FF
100
0110 0100 0000
640
80
0101 0000 0000
500
75
0100 1011 0000
4B0
50
0011 0010 0000
320
25
0001 1001 0000
190
0.25
0000 0000 0100
004
0
0000 0000 0000
000
–0.25
1111 1111 1100
FFC
–25
1110 0111 0000
E70
–55
1100 1001 0000
C90
The temperature sensor resolution is 0.0625°C/LSB.
Table 1 does not supply a full list of all temperatures. Use the following rules to obtain the digital data format for
a given temperature, and vice versa.
To convert positive temperatures to a digital data format:
Divide the temperature by the resolution. Then, convert the result to binary code with a 12-bit, left-justified
format, and MSB = 0 to denote a positive sign.
Example: (+50°C) / (0.0625°C / LSB) = 800 = 320h = 0011 0010 0000
To convert a positive digital data format to temperature:
Convert the 12-bit, left-justified binary temperature result, with the MSB = 0 to denote a positive sign, to a
decimal number. Then, multiply the decimal number by the resolution to obtain the positive temperature.
Example: 0011 0010 0000 = 320h = 800 × (0.0625°C / LSB) = +50°C
To convert negative temperatures to a digital data format:
Divide the absolute value of the temperature by the resolution, and convert the result to binary code with a
12-bit, left-justified format. Then, generate the twos complement of the result by complementing the binary
number and adding one. Denote a negative number with MSB = 1.
Example: (|–25°C|) / (0.0625°C / LSB) = 400 = 190h = 0001 1001 0000
Two's complement format: 1110 0110 1111 + 1 = 1110 0111 0000
To convert a negative digital data format to temperature:
Generate the twos compliment of the 12-bit, left-justified binary number of the temperature result (with MSB
= 1, denoting negative temperature result) by complementing the binary number and adding one. Convert to
decimal number and multiply by the resolution to get the absolute temperature, then multiply by –1 for the
negative sign.
Example: 1110 0111 0000 has twos complement of 0001 1001 0000 = 0001 1000 1111 + 1
Convert to temperature: 0001 1001 0000 = 190h = 400; 400 × (0.0625°C / LSB) = 25°C = (|–25°C|);
(|–25°C|) × (–1) = –25°C
8
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7.3.2 Temperature Limits and Alert
The temperature limits are stored in the TLOW and THIGH registers (Table 7 and Table 8) in the same format as
the temperature result, and their values are compared to the temperature result on every conversion. The
outcome of the comparison drives the behavior of the ALERT pin, which can operate as a comparator output or
an interrupt, and is set by the TM bit in the Configuration register (Table 6).
In comparator mode (TM = 0, default), the ALERT pin becomes active when the temperature is equal to or
exceeds the value in THIGH (fault conditions) for a consecutive number of conversions as set by the FQ bits of the
configuration register. ALERT clears when the temperature falls below TLOW for the same consecutive number of
conversions. The difference between the two limits acts as a hysteresis on the comparator output, and a fault
counter prevents false alerts as a result of environmental noise.
In interrupt mode (TM = 1), the ALERT pin becomes active when the temperature equals or exceeds the value in
THIGH for a consecutive number of fault conditions. The ALERT pin remains active until a read operation of any
register occurs. After the ALERT pin is cleared, this pin becomes active again only when temperature falls below
TLOW for a consecutive number of fault conditions, and remains active until cleared by a read operation of any
register. The cycle repeats with the ALERT pin becoming active when the temperature equals or exceeds THIGH,
and so on. The ALERT pin is cleared also when the device is placed in shutdown mode (see Shutdown Mode for
shutdown mode description). This action also clears the fault counter memory.
The active state of the ALERT pin is set by the POL bit in the configuration register. When POL = 0 (default), the
ALERT pin is active low. When POL = 1, the ALERT pin is active high. The operation of the ALERT pin in the
various modes is illustrated in Figure 7.
THIGH
Measured
Temperature
TLOW
Device ALERT PIN
(Comparator Mode)
POL = 0
Device ALERT PIN
(Interrupt Mode)
POL = 0
Device ALERT PIN
(Comparator Mode)
POL = 1
Device ALERT PIN
(Interrupt Mode)
POL = 1
Read
Read
Read
Time
Figure 7. ALERT Pin Modes of Operation
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7.3.3 Serial Interface
The TMP75C operates as a slave device only on the two-wire bus and SMBus. Connections to the bus are made
using the open-drain I/O lines, SDA and SCL. The SDA and SCL pins feature integrated spike-suppression filters
and Schmitt triggers to minimize the effects of input spikes and bus noise. The TMP75C supports the
transmission protocol for both fast (1 kHz to 400 kHz) and high-speed (1 kHz to 3 MHz) modes. All data bytes
are transmitted MSB first.
7.3.3.1 Bus Overview
The device that initiates the transfer is called a master, and the devices controlled by the master are slaves. The
bus must be controlled by a master device that generates the serial clock (SCL), controls the bus access, and
generates the start and stop conditions.
To address a specific device, initiate a start condition by pulling the data line (SDA) from a high to a low logic
level while SCL is high. All slaves on the bus shift in the slave address byte; the last bit indicates whether a read
or write operation follows. During the ninth clock pulse, the slave being addressed responds to the master by
generating an acknowledge bit and pulling SDA low.
Data transfer is then initiated and sent over eight clock pulses followed by an acknowledge bit. During data
transfer, SDA must remain stable while SCL is high because any change in SDA while SCL is high is interpreted
as a start or stop signal.
After all data have been transferred, the master generates a stop condition indicated by pulling SDA from low to
high, while SCL is high.
7.3.3.2 Serial Bus Address
To communicate with the TMP75C, the master must first communicate with slave devices using a slave address
byte. The slave address byte consists of seven address bits, and a direction bit indicating the intent of executing
either a read or write operation. The TMP75C features three address pins that allow up to eight devices to be
addressed on a single bus. The TMP75C latches the status of the address pins at the start of a communication.
Table 2 describes the pin logic levels and the corresponding address values.
Table 2. Address Pin Connections and Slave Addresses
DEVICE TWO-WIRE ADDRESS
A2
A1
A0
1001000
GND
GND
GND
1001001
GND
GND
VS
1001010
GND
VS
GND
1001011
GND
VS
VS
1001100
VS
GND
GND
1001101
VS
GND
VS
1001110
VS
VS
GND
1001111
VS
VS
VS
7.3.3.3 Writing and Reading Operation
Accessing a particular register on the TMP75C is accomplished by writing the appropriate value to the pointer
register. The value for the pointer register is the first byte transferred after the slave address byte with the R/W
bit low. Every write operation to the TMP75C requires a value for the pointer register (see Figure 9).
When reading from the TMP75C, the last value stored in the pointer register by a write operation is used to
determine which register is read by a read operation. To change the register pointer for a read operation, a new
value must be written to the pointer register. This action is accomplished by issuing a slave address byte with the
R/W bit low, followed by the pointer register byte. No additional data are required. The master can then generate
a start condition and send the slave address byte with the R/W bit high to initiate the read command. See
Figure 10 for details of this sequence. If repeated reads from the same register are desired, there is no need to
continually send the pointer register bytes because the TMP75C stores the pointer register value until it is
changed by the next write operation.
Note that register bytes are sent with the most significant byte first, followed by the least significant byte.
10
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7.3.3.4 Slave Mode Operations
The TMP75C can operate as a slave receiver or slave transmitter.
7.3.3.4.1 Slave Receiver Mode:
The first byte transmitted by the master is the slave address, with the R/W bit low. The TMP75C then
acknowledges reception of a valid address. The next byte transmitted by the master is the pointer register. The
TMP75C then acknowledges reception of the pointer register byte. The next byte or bytes are written to the
register addressed by the pointer register. The TMP75C acknowledges reception of each data byte. The master
can terminate data transfer by generating a start or stop condition.
7.3.3.4.2 Slave Transmitter Mode:
The first byte transmitted by the master is the slave address, with the R/W bit high. The slave acknowledges
reception of a valid slave address. The next byte is transmitted by the slave and is the most significant byte of
the register indicated by the pointer register. The master acknowledges reception of the data byte. The next byte
transmitted by the slave is the least significant byte. The master acknowledges reception of the data byte. The
master can terminate data transfer by generating a not-acknowledge bit on reception of any data byte, or by
generating a start or stop condition.
7.3.3.5 High-Speed (Hs) Mode
In order for the two-wire bus to operate at frequencies above 400 kHz, the master device must issue an SMBus
Hs-mode master code (00001xxx) as the first byte after a start condition to switch the bus to high-speed
operation. The TMP75C does not acknowledge this byte, but does switch its input filters on SDA and SCL and its
output filters on SDA to operate in Hs-mode, allowing transfers at up to 3 MHz. After the Hs-mode master code
has been issued, the master transmits a two-wire slave address to initiate a data-transfer operation. The bus
continues to operate in Hs-mode until a stop condition occurs on the bus. Upon receiving the stop condition, the
TMP75C switches the input and output filters back to fast-mode operation.
7.3.3.6 Timeout Function
The TMP75C resets the serial interface if SCL or SDA are held low for 22 ms (typ) between a start and stop
condition. If the TMP75C is pulled low, it releases the bus and then waits for a start condition. To avoid activating
the timeout function, it is necessary to maintain a communication speed of at least 1 kHz for the SCL operating
frequency.
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7.3.3.7 Two-Wire Timing
The TMP75C is two-wire and SMBus compatible. Figure 8 to Figure 10 describe the various operations on the
TMP75C. Parameters for Figure 8 are defined in Table 3. Bus definitions are:
Bus Idle
Both SDA and SCL lines remain high.
Start Data Transfer A change in the state of the SDA line, from high to low, while the SCL line is high defines a
start condition. Each data transfer is initiated with a start condition.
Stop Data Transfer A change in the state of the SDA line from low to high while the SCL line is high defines a
stop condition. Each data transfer is terminated with a repeated start or stop condition.
Data Transfer The number of data bytes transferred between a start and a stop condition is not limited, and is
determined by the master device.
The receiver acknowledges the transfer of data. It is also possible to use the TMP75B for
single-byte updates. To update only the MS byte, terminate communication by issuing a start
or stop condition on the bus.
Acknowledge Each receiving device, when addressed, must generate an acknowledge bit.
A device that acknowledges must pull down the SDA line during the acknowledge clock
pulse so that the SDA line is stable low during the high period of the acknowledge clock
pulse. Setup and hold times must be taken into account. When a master receives data, the
termination of the data transfer can be signaled by the master generating a not-acknowledge
(1) on the last byte transmitted by the slave.
Table 3. Timing Diagram Requirements
FAST MODE
SYMBOL
f(SCL)
PARAMETER
SCL operating frequency
HIGH-SPEED MODE
MIN
MAX
MIN
MAX
UNIT
VS ≥ 1.8 V
0.001
0.4
VS < 1.8 V
0.001
0.4
0.001
3
MHz
0.001
2.5
VS ≥ 1.8 V
1300
160
MHz
ns
VS < 1.8 V
1300
260
ns
t(BUF)
Bus free time between
stop and start conditions
t(HDSTA)
Hold time after repeated start condition.
After this period, the first clock is generated.
600
160
ns
t(SUSTA)
Repeated start condition setup time
600
160
ns
t(SUSTO)
Stop condition setup time
600
t(HDDAT)
Data hold time
t(SUDAT)
Data setup time
160
ns
VS ≥ 1.8 V
0
900
0
100
ns
VS < 1.8 V
0
900
0
140
ns
VS ≥ 1.8 V
100
10
ns
VS < 1.8 V
100
20
ns
VS ≥ 1.8 V
1300
190
ns
VS < 1.8 V
1300
240
ns
t(LOW)
SCL clock low period
t(HIGH)
SCL clock high period
tR(SDA), tF(SDA)
Data rise and fall time
300
80
ns
tR(SCL), tF(SCL)
Clock rise and fall time
300
40
ns
tR
Clock and data rise time for SCLK ≤ 100 kHz
12
600
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60
1000
ns
ns
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7.3.3.8 Two-Wire Timing Diagrams
t(LOW)
tF
tR
t(HDSTA)
SCL
t(HDSTA)
t(HIGH)
t(SUSTO)
t(SUSTA)
t(HDDAT)
t(SUDAT)
SDA
t(BUF)
P
S
S
P
Figure 8. Two-Wire Timing Diagram
1
9
1
9
SCL
¼
1
SDA
0
0
1
A2(1)
A1(1)
A0(1)
R/W
Start By
Master
0
0
0
0
0
P2
P1
ACK By
Device
P0
¼
ACK By
Device
Frame 2 Pointer Register Byte
Frame 1 Two-Wire Slave Address Byte
9
1
1
9
SCL
(Continued)
SDA
(Continued)
D7
D6
D5
D4
D3
D2
D1
D0
D7
D6
D5
D4
D3
D2
ACK By
Device
D0
ACK By
Device
Stop By
Master
Frame 4 Data Byte 2
Frame 3 Data Byte 1
(1)
D1
The value of A0, A1, and A2 are determined by the connections of the corresponding pins.
Figure 9. Two-Wire Timing Diagram for Write Word Format
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1
9
1
9
SCL
¼
SDA
1
0
0
1
A2
(1)
A1
(1)
A0
(1)
R/W
Start By
Master
0
0
0
0
0
P2
P1
P0
ACK By
Device
ACK By
Device
Frame 1 Two-Wire Slave Address Byte
Stop By
Master
Frame 2 Pointer Register Byte
1
9
1
9
SCL
(Continued)
¼
SDA
(Continued)
1
0
0
1
A2
(1)
A1
(1)
A0
(1)
D7
R/W
Start By
Master
D6
D5
D4
D3
1
D1
D0
From
Device
ACK By
Device
Frame 3 Two-Wire Slave Address Byte
D2
¼
ACK By
Master
(2)
Frame 4 Data Byte 1 Read Register
9
SCL
(Continued)
SDA
(Continued)
D7
D6
D5
D4
D3
D2
D1
D0
From
Device
ACK By
Master
(3)
Stop By
Master
Frame 5 Data Byte 2 Read Register
(1)
The value of A0, A1, and A2 are determined by the connections of the corresponding pins.
(2)
Master should leave SDA high to terminate a single-byte read operation.
(3)
Master should leave SDA high to terminate a two-byte read operation.
Figure 10. Two-Wire Timing Diagram for Read Word Format
14
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7.4 Device Functional Modes
7.4.1 Continuous-Conversion Mode
The default mode of the TMP75C is continuous conversion, where the ADC performs continuous temperature
conversions and stores each result to the Temperature register, overwriting the result from the previous
conversion. The typical conversion rate of TMP75C is 12 Hz, with 80 ms between the start of each consecutive
conversion. The TMP75C has a typical conversion time of 27 ms. To achieve its conversion rates, the TMP75C
makes a conversion, and then powers down and waits for a delay 53 ms.
After power-up, the TMP75C immediately starts a conversion, as shown in Figure 11. The first result is available
after 27 ms (typical). The active quiescent current during conversion is 45 μA (typical at +25°C). The quiescent
current during delay is 1 μA (typical at +25°C).
Delay
(1)
Delay
(1)
27 ms
27 ms
27 ms
Startup
(1)
Start of
Conversion
Start of
Conversion
Delay is set to 53 ms (typ).
Figure 11. Conversion Start
7.4.2 Shutdown Mode
The shutdown mode saves maximum power by shutting down all device circuitry other than the serial interface,
and reduces current consumption to typically less than 0.3 μA. Shutdown mode is enabled when the SD bit in the
configuration register is set to 1; the device shuts down and terminates a conversion if it is ongoing. When SD is
equal to 0, the device operates in continuous-conversion mode. When shutdown mode is enabled, the ALERT
pin and fault counter clear in both comparator and interrupt modes. The ALERT pin and the fault counter remain
clear until the SD bit is set.
7.4.3 One-Shot Mode
The TMP75C features a one-shot temperature measurement mode. When the device is in continuous conversion
(SD = 0), writing a 1 to the OS bit enables shutdown mode, where any write to the one-shot register triggers a
single temperature conversion. The device returns to the shutdown state at the completion of the single
conversion, and a subsequent write to the one-shot register triggers another single conversion followed by a
return to shutdown state. This mode reduces power consumption in the TMP75C when continuous temperature
monitoring is not required.
When the device is in complete shutdown (SD = 1), the one-shot mode is not active regardless of the state of the
OS bit, and a write to the one-shot register has no effect.
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7.5 Programming
Figure 12 shows the internal register structure of the TMP75C. Use the 8-bit pointer register to address a given
data register. The pointer register uses the three LSBs to identify which of the data registers respond to a read or
write command. Figure 13 identifies the bits of the pointer register byte.
Pointer
Register
Temperature
Register
Configuration
Register
SCL
I/O
Control
Interface
TLOW
Register
SDA
THIGH
Register
One-Shot
Register
Figure 12. Internal Register Structure
7.6 Register Map
Table 4 describes the registers available in the TMP75C with their pointer addresses, followed by the description
of the bits in each register.
Table 4. Register Map and Pointer Addresses
P2
P1
P0
REGISTER
0
0
0
Temperature register (read only, default)
0
0
1
Configuration register (read/write)
0
1
0
TLOW register (read/write)
0
1
1
THIGH register (read/write)
1
0
0
One-Shot register (write only; write any value to start a
conversion)
Figure 13. Pointer Register (pointer = N/A) [reset = 00h]
7
6
5
Reserved
W-0h
4
3
2
P2
W-0h
1
P1
W-0h
0
P0
W-0h
LEGEND: R/W = Read/Write; R = Read only; W = Write only; -n = value after reset
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Figure 14. Temperature Register (pointer = 0h) [reset = 0000h]
15
T11
14
T10
13
T9
12
T8
7
T3
6
T2
5
T1
4
T0
11
T7
10
T6
3
2
9
T5
8
T4
1
0
R-00h
Reserved
R-0h
R-0h
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 5. Temperature Register Description
Name
Description
T11 to T4
The 8 MSBs of the temperature result (resolution of 1°C)
T3 to T0
The 4 LSBs of the temperature result (resolution of 0.0625°C)
Figure 15. Configuration Register (pointer = 1h) [reset = 0000h]
15
14
Reserved
R/W-0h
7
13
OS
R/W-0h
12
5
4
6
11
10
POL
R/W-0h
9
TM
R/W-0h
8
SD
R/W-0h
3
2
1
0
FQ
R/W-0h
Reserved
R-00h
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 6. Configuration Register Description
Name
Reserved
Description
Reserved bits
Write 0 to these bits on configuration register update.
OS
One-shot control
SD = 0 and OS = 0: Continuous conversion mode (default)
SD = 0 and OS = 1: One-shot mode; the device is in shutdown mode but writing any value to the one-shot register
initiates a conversion. The device returns to shutdown mode at the end of the conversion.
SD = 1 and OS = x: The device is in shutdown mode and the status of the OS bit has no effect. Writing to the oneshot register does not start a conversion.
FQ
Fault queue to trigger the ALERT pin
FQ = 0h: 1 fault (default)
FQ = 1h: 2 faults
FQ = 2h: 4 faults
FQ = 3h: 6 faults
POL
ALERT polarity control
POL = 0: ALERT is active low (default)
POL = 1: ALERT is active high
TM
ALERT thermostat mode control
TM = 0: ALERT is in comparator mode (default)
TM = 1: ALERT is in interrupt mode
SD
Shutdown control bit
SD = 0: Device is in continuous conversion mode (default)
SD = 1: Device is in shutdown mode
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Figure 16. TLOW - Temperature Low Limit Register (pointer = 2h) [reset = 4B00h] (1)
15
L11
14
L10
13
L9
12
L8
11
L7
10
L6
3
2
9
L5
8
L4
1
0
R/W-4Bh
7
L3
6
L2
5
L1
4
L0
Reserved
R-0h
R/W-0h
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
(1)
4B00h = 75°C.
Table 7. TLOW Register Description
Name
Description
L11 to L4
The 8 MSBs of the temperature low limit (resolution of 1°C)
L3 to L0
The 4 LSBs of the temperature low limit (resolution of 0.0625°C)
Figure 17. THIGH - Temperature High Limit Register (pointer = 3h) [reset = 5000h] (1)
15
H11
14
H10
13
H9
12
H8
11
H7
10
H6
3
2
9
H5
8
H4
1
0
R/W-50h
7
H3
6
H2
5
H1
4
H0
Reserved
R-0h
R/W-0h
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
(1)
5000h = 80°C.
Table 8. THIGH Register Description
Name
Description
H11 to H4
The 8 MSBs of the temperature high limit (resolution of 1°C)
H3 to H0
The 4 LSBs of the temperature high limit (resolution of 0.0625°C)
18
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8 Application and Implementation
8.1 Application Information
The TMP75C is used to measure the PCB temperature of the location it is mounted. The programmable address
options allow up to eight locations on the board to be monitored on a single serial bus. Connecting the ALERT
pins together and programming the temperature limit registers to desired values allows for a temperature
watchdog operation of all devices, interrupting the host controller only if the temperature exceeds the limits.
8.2 Typical Application
1.4 V to 3.6 V
0.01 PF
TMP75C
1
2
Two-Wire
Host Controller
3
4
SDA
VS
SCL
A0
ALERT
A1
GND
A2
8
7
6
Connect to VS or
GND for up to 8
Address
Combinations
5
1.4 V to 3.6 V
TMP75C
1
2
3
4
0.01 PF
SDA
VS
SCL
A0
ALERT
A1
GND
A2
8
7
6
Connect to VS or
GND for up to 8
Address
Combinations
5
Additional
Sensor
Locations
Figure 18. Temperature Monitoring of Multiple Locations on a PCB
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Typical Application (continued)
8.2.1 Design Requirements
The TMP75C only requires pull-up resistors on SDA and ALERT, although a pull-up resistor is typically present
on the SCL as well. A 0.01-μF bypass capacitor on the supply is recommended, as shown in Figure 18. The
SCL, SDA, and ALERT lines can be pulled up to a supply that is equal to or higher than VS through the pull-up
resistors. To configure one of eight different addresses on the bus, connect A0, A1, and A2 to either VS or GND.
8.2.2 Detailed Design Procedure
The TMP75C should be placed in close proximity to the heat source to be monitored, with a proper layout for
good thermal coupling. This ensures that temperature changes are captured within the shortest possible time
interval.
8.2.3 Application Curves
Temperature (C)
Figure 19 shows the step response of the TMP75C to a submersion in an oil bath of 100°C from room
temperature (27°C). The time-constant, or the time for the output to reach 63% of the input step, is 1.5 seconds.
100
95
90
85
80
75
70
65
60
55
50
45
40
35
30
25
±1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (s)
C007
Figure 19. Temperature Step Response
9 Power Supply Recommendations
The TMP75C operates with a power supply in the range of 1.4 V to 3.6 V. It is optimized for operation at 1.8-V
supply but can measure temperature accurately in the full supply range.
A power-supply bypass capacitor is required for stability; place this capacitor as close as possible to the supply
and ground pins of the device. A typical value for this supply bypass capacitor is 0.01 μF. Applications with noisy
or high-impedance power supplies may require additional decoupling capacitors to reject power-supply noise.
20
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10 Layout
10.1 Layout Guidelines
Place the power-supply bypass capacitor as close as possible to the supply and ground pins. The recommended
value of this bypass capacitor is 0.01 μF. Additional decoupling capacitance can be added to compensate for
noisy or high-impedance power supplies.
Pull up the open-drain output pins (SDA and ALERT) to a supply voltage rail (VS or higher but up to 3.6 V)
through 10-kΩ pull-up resistors.
10.2 Layout Example
Via to Power or Ground Plane
Via to Internal Layer
Pull-Up Resistors
Supply Bypass
Capacitor
Supply Voltage
SDA
VS
SCL
A0
ALERT
A1
GND
A2
Ground Plane for
Thermal Coupling
to Heat Source
Serial Bus Traces
Heat Source
Figure 20. Layout Example
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11 Device and Documentation Support
11.1 Documentation Support
11.1.1 Related Documentation
SBOU141 — TMP75xEVM User's Guide
11.2 Trademarks
All trademarks are the property of their respective owners.
11.3 Electrostatic Discharge Caution
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
11.4 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
12 Mechanical, Packaging, and Orderable Information
The following pages include mechanical, packaging, and orderable information. This information is the most
current data available for the designated devices. This data is subject to change without notice and revision of
this document. For browser-based versions of this data sheet, refer to the left-hand navigation.
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PACKAGE OPTION ADDENDUM
www.ti.com
10-Dec-2020
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
(4/5)
(6)
TMP75CID
ACTIVE
SOIC
D
8
75
RoHS & Green
NIPDAU-DCC
Level-1-260C-UNLIM
-55 to 125
TMP75C
TMP75CIDGKR
ACTIVE
VSSOP
DGK
8
2500
RoHS & Green
NIPDAUAG
Level-2-260C-1 YEAR
-55 to 125
T75C
TMP75CIDGKT
ACTIVE
VSSOP
DGK
8
250
RoHS & Green
NIPDAUAG
Level-2-260C-1 YEAR
-55 to 125
T75C
TMP75CIDR
ACTIVE
SOIC
D
8
2500
RoHS & Green
NIPDAU-DCC
Level-1-260C-UNLIM
-55 to 125
TMP75C
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
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