TMP441
TMP442
www.ti.com .............................................................................................................................................. SBOS425A – DECEMBER 2008 – REVISED MARCH 2009
±1°C TEMPERATURE SENSOR
with Automatic Beta Compensation,
Series-R, and η-Factor in a SOT23-8
FEATURES
DESCRIPTION
1
•
•
•
•
•
•
•
•
•
•
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234
SOT23-8 PACKAGE
±1°C REMOTE DIODE SENSOR (MAX)
±1°C LOCAL TEMPERATURE SENSOR (MAX)
AUTOMATIC BETA COMPENSATION
SERIES RESISTANCE CANCELLATION
η-FACTOR CORRECTION
TWO-WIRE/SMBus™ SERIAL INTERFACE
MULTIPLE INTERFACE ADDRESSES
DIODE FAULT DETECTION
RoHS-COMPLIANT AND NO Sb/Br
TRANSISTOR AND DIODE MODEL
OPERATION
The TMP441 and TMP442 are remote temperature
monitors with a built-in local temperature sensor.
Remote
temperature
sensor
diode-connected
transistors are typically low-cost, NPN- or PNP-type
transistors or diodes that are an integral part of
microcontrollers,
microprocessors,
or
field-programmable gate arrays (FPGAs).
Remote accuracy is ±1°C for multiple IC
manufacturers, with no calibration needed. The
Two-Wire serial interface accepts SMBus write byte,
read byte, send byte, and receive byte commands to
configure the device.
The TMP441 has a single remote temperature
monitor with address pins. The TMP442 has dual
remote temperature monitors, and is available with
two different interface addresses. All versions include
automatic beta compensation (correction), series
resistance cancellation, programmable non-ideality
factor
(η-factor),
wide
remote
temperature
measurement range (up to +150°C), and diode fault
detection.
APPLICATIONS
•
•
•
•
•
PROCESSOR/FPGA TEMPERATURE
MONITORING
LCD/DLP®/LCOS PROJECTORS
SERVERS
CENTRAL OFFICE TELECOM EQUIPMENT
STORAGE AREA NETWORKS (SAN)
The TMP441 and TMP442 are both available in an
8-lead, SOT23 package.
+5V
TMP441
TMP442
1
8
V+
1
DXP
2
SCL
DXP1
2
DXN
SDA
DXN1
7
6
SMBus
Controller
3
3
DXP2
A1
4
4
A0
DXN2
GND
5
1 Channel Local
1 Channel Remote
1 Channel Local
2 Channels Remote
1
2
3
4
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas
Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
DLP is a registered trademark of Texas Instruments.
SMBus is a trademark of Intel Corporation.
All other trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2008–2009, Texas Instruments Incorporated
TMP441
TMP442
SBOS425A – DECEMBER 2008 – REVISED MARCH 2009 .............................................................................................................................................. www.ti.com
This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling and installation procedures can cause damage.
ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more
susceptible to damage because very small parametric changes could cause the device not to meet its published specifications.
PACKAGE INFORMATION (1)
PRODUCT
DESCRIPTION
TMP441
Single-Channel
Remote Junction
Temperature Sensor
TMP442A
Dual-Channel
Remote Junction
Temperature Sensor
TMP442B
(1)
TWO-WIRE
ADDRESS
PACKAGE-LEAD
PACKAGE
DESIGNATOR
PACKAGE
MARKING
100 11xx
SOT23-8
DCN
DIGI
100 1100
SOT23-8
DCN
DIHI
100 1101
SOT23-8
DCN
DIJI
For the most current package and ordering information see the Package Option Addendum at the end of this document, or see the TI
web site at www.ti.com.
ABSOLUTE MAXIMUM RATINGS (1)
Over operating free-air temperature range, unless otherwise noted.
PARAMETER
Power Supply
Input Voltage
VS
Pins 1, 2, 3, and 4 only
Pins 6 and 7 only
Input Current
Operating Temperature Range
Storage Temperature Range
2
V
–0.5 to VS + 0.5
V
–0.5 to 7
V
10
mA
–55 to +127
°C
–60 to +130
°C
+150
°C
Human Body Model
HBM
3000
V
Charged Device Model
CDM
1000
V
MM
200
V
Machine Model
(1)
UNIT
+7
TJ max
Junction Temperature
ESD Rating
TMP441, TMP442
Stresses above these ratings may cause permanent damage. Exposure to absolute maximum conditions for extended periods may
degrade device reliability. These are stress ratings only, and functional operation of the device at these or any other conditions beyond
those specified is not implied.
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ELECTRICAL CHARACTERISTICS
At TA = –40°C to +125°C and VS = 2.7V to 5.5V, unless otherwise noted.
TMP441, TMP442
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNIT
TEMPERATURE ERROR
Local Temperature Sensor
Remote Temperature Sensor (1)
TELOCAL
TEREMOTE
TA = –40°C to +125°C
±1.25
±2.5
°C
TA = 0°C to +100°C, VS = 3.3V
±0.25
±1
°C
TA = 0°C to +100°C, TDIODE = –40°C to +150°C, VS = 3.3V
±0.25
±1
°C
TA = –40°C to +100°C, TDIODE = –40°C to +150°C, VS = 3.3V
±0.5
±1.5
°C
TA = –40°C to +125°C, TDIODE = –40°C to +150°C
±3
±5
°C
VS = 2.7V to 5.5V
0.2
±0.5
°C/V
12
15
17
ms
RC = 1
97
126
137
ms
RC = 0
36
47
52
ms
RC = 1
72
93
100
ms
RC = 0
33
44
47
ms
vs Supply (Local/Remote)
TEMPERATURE MEASUREMENT
Conversion Time (per channel)
Local Channel
Remote Channel
Beta Correction Enabled (2)
M
Beta Correction Disabled (3)
M
Resolution
Local Temperature Sensor
12
Bits
Remote Temperature Sensor
12
Bits
Remote Sensor Source Currents
120
µA
Medium High
60
µA
Medium Low
12
µA
Low
6
µA
Series resistance (beta correction) (4)
High
Remote Transistor Ideality Factor
η
1.000 (2)
TMP441/TMP442 optimized ideality factor
1.008 (3)
β
0.1
Logic Input High Voltage (SCL, SDA)
VIH
2.1
Logic Input Low Voltage (SCL, SDA)
VIL
Beta Correction Range
27
SMBus INTERFACE
Hysteresis
500
SMBus Output Low Sink Current
SDA Output Low Voltage
V
0.8
6
VOL
IOUT = 6mA
0 ≤ VIN ≤ 6V
Logic Input Current
mA
0.15
–1
SMBus Input Capacitance (SCL, SDA)
0.4
V
+1
µA
3.4
MHz
35
ms
1
µs
3
SMBus Clock Frequency
SMBus Timeout
25
V
mV
32
SCL Falling Edge to SDA Valid Time
pF
DIGITAL INPUTS
Input Capacitance
3
pF
Input Logic Levels
(1)
(2)
(3)
(4)
Input High Voltage
VIH
0.7(V+)
(V+)+0.5
Input Low Voltage
VIL
–0.5
0.3(V+)
V
Leakage Input Current
IIN
1
µA
0V ≤ VIN ≤ VS
V
Tested with less than 5Ω effective series resistance, 100pF differential input capacitance, and an ideal diode with η-factor = 1.008. TA is
the ambient temperature of the TMP441/42. TDIODE is the temperature at the remote diode sensor.
Beta correction configuration set to '1000' and sensor is GND collector-connected (PNP collector to ground).
Beta correction configuration set to '0111' or sensor is diode-connected (base shorted to collector).
If beta correction is disabled ('0111'), then up to 1kΩ of series line resistance is cancelled; if beta correction is enabled ('1xxx'), up to
300Ω is cancelled.
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TMP442
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ELECTRICAL CHARACTERISTICS (continued)
At TA = –40°C to +125°C and VS = 2.7V to 5.5V, unless otherwise noted.
TMP441, TMP442
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNIT
POWER SUPPLY
Specified Voltage Range
VS
Quiescent Current
IQ
Undervoltage Lockout
Power-On Reset Threshold
2.7
5.5
V
45
µA
0.7
1
mA
3
10
µA
0.0625 conversions per second
35
Eight conversions per second (5)
Serial Bus inactive, Shutdown Mode
Serial Bus active, fS = 400kHz, Shutdown Mode
90
Serial Bus active, fS = 3.4MHz, Shutdown Mode
350
UVLO
2.3
POR
µA
µA
2.4
2.6
V
1.6
2.3
V
°C
TEMPERATURE RANGE
Specified Range
–40
+125
Storage Range
–60
+130
Thermal Resistance, SOT23-8
(5)
4
θJA
170
°C
°C/W
Beta correction disabled.
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TMP441 PIN CONFIGURATION
DCN PACKAGE
SOT23-8
(TOP VIEW)
DXP
1
DXN
2
8
V+
7
SCL
TMP441
A1
3
6
SDA
A0
4
5
GND
TMP441 PIN ASSIGNMENTS
TMP441
NO.
NAME
1
DXP
DESCRIPTION
Positive connection to remote temperature sensor
2
DXN
Negative connection to remote temperature sensor
3
A1
Address pin
4
A0
Address pin
5
GND
Ground
6
SDA
Serial data line for SMBus, open-drain; requires pull-up resistor to V+.
7
SCL
Serial clock line for SMBus, open-drain; requires pull-up resistor to V+.
8
V+
Positive supply voltage (2.7V to 5.5V)
TMP442 PIN CONFIGURATION
DCN PACKAGE
SOT23-8
(TOP VIEW)
DXP1
1
DXN1
2
8
V+
7
SCL
TMP442
DXP2
3
6
SDA
DXN2
4
5
GND
TMP442 PIN ASSIGNMENTS
TMP442
NO.
NAME
DESCRIPTION
1
DXP1
Channel 1 positive connection to remote temperature sensor
2
DXN1
Channel 1 negative connection to remote temperature sensor
3
DXP2
Channel 2 positive connection to remote temperature sensor
4
DXN2
Channel 2 negative connection to remote temperature sensor
5
GND
Ground
6
SDA
Serial data line for SMBus, open-drain; requires pull-up resistor to V+.
7
SCL
Serial clock line for SMBus, open-drain; requires pull-up resistor to V+.
8
V+
Positive supply voltage (2.7V to 5.5V)
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TYPICAL CHARACTERISTICS
At TA = +25°C and VS = +3.3V, unless otherwise noted.
REMOTE TEMPERATURE ERROR
vs TEMPERATURE
LOCAL TEMPERATURE ERROR
vs TEMPERATURE
3
2
Local Temperature Error (°C)
Remote Temperature Error (°C)
3
1
0
-1
-2
Beta Compensation Disabled.
GND Collector-Connected Transistor with n-Factor = 1.008.
-3
2
1
0
-1
-2
-3
-50
75
0
25
50
Ambient Temperature, TA (°C)
-25
100
125
-50
-25
75
0
25
50
Ambient Temperature, TA (°C)
Figure 1.
Figure 2.
REMOTE TEMPERATURE ERROR
vs LEAKAGE RESISTANCE
QUIESCENT CURRENT
vs CONVERSION RATE
150
700
100
600
100
125
RGND (Low Beta)
50
500
RGND
IQ (mA)
Remote Temperature Error (°C)
VS = 5.5V
0
-50
400
TMP442
300
200
RVs
-100
TMP441
100
RVs (Low Beta)
0
0.0625 0.125
-150
0
5
10
15
20
25
30
1
4
2
Figure 4.
SHUTDOWN QUIESCENT CURRENT
vs SCL CLOCK FREQUENCY
SHUTDOWN QUIESCENT CURRENT
vs SUPPLY VOLTAGE
500
4.0
450
3.5
8
3.0
350
VS = 5.5V
300
2.5
IQ (mA)
IQ (mA)
0.5
Figure 3.
400
250
200
2.0
1.5
150
1.0
100
50
0.5
VS = 3.3V
0
0
1k
6
0.25
Conversion Rate (conversions/s)
Leakage Resistance (MW)
10k
100k
1M
10M
2.5
3.0
3.5
4.0
SCL Clock Frequency (Hz)
VS (V)
Figure 5.
Figure 6.
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4.5
5.0
5.5
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TYPICAL CHARACTERISTICS (continued)
At TA = +25°C and VS = +3.3V, unless otherwise noted.
REMOTE TEMPERATURE ERROR vs SERIES RESISTANCE
(Low-Beta Transistor)
REMOTE TEMPERATURE ERROR vs SERIES RESISTANCE
2.5
GND Collector-Connected Transistor, 2N3906 (PNP)
(1)(2)
Remote Temperature Error (°C)
Remote Temperature Error (°C)
3
2
1
0
Diode-Connected Transistor, 2N3906 (PNP)
(2)
-1
NOTES (1): Temperature offset is the result of
h-factor being automatically set to 1.000.
Approximate h-factor of 2N3906 is 1.008.
(2) See Figure 10 for schematic configuration.
-2
2.0
1.5
1.0
0.5
0
-0.5
-1.0
-1.5
-2.0
-2.5
-3
0
100 200 300 400 500 600 700 800 900
0
1k
100
200
300
RS (W)
RS (W)
Figure 7.
Figure 8.
400
500
REMOTE TEMPERATURE ERROR
vs DIFFERENTIAL CAPACITANCE
Remote Temperature Error (°C)
3.0
GND Collector-Connected Transistor (Auto)
2.5
2.0
1.5
Low-Beta Transistor (Disabled)
1.0
0.5
0
-0.5
GND Collector-Connected Transistor (Disabled)
Diode-Connected Transistor (Auto, Disabled)
-1.0
Low-Beta Transistor
(Auto)
-1.5
-2.0
-2.5
NOTE: See Figure 11 for schematic configuration.
-3.0
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Capacitance (nF)
Figure 9.
SERIES RESISTANCE CONFIGURATION
DIFFERENTIAL CAPACITANCE CONFIGURATION
(a) GND Collector-Connected Transistor
(a) GND Collector-Connected Transistor
(1)
RS
DXP
DXP
CDIFF
(1)
DXN
DXN
(1)
RS
(b) Diode-Connected Transistor
(b) Diode-Connected Transistor
(1)
RS
DXP
DXP
CDIFF
(1)
DXN
DXN
(1)
RS
(1)
RS should be less than 1kΩ; see Filtering
section.
Figure 10.
(1)
CDIFF should be less than 300pF; see Filtering
section.
Figure 11.
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TMP442
SBOS425A – DECEMBER 2008 – REVISED MARCH 2009 .............................................................................................................................................. www.ti.com
APPLICATION INFORMATION
For proper remote temperature sensing operation, the
TMP441 requires only a transistor connected
between DXP and DXN; the TMP442 requires
transistors connected between DXP1 and DXN1 and
between DXP2 and DXN2. The SCL and SDA
interface pins require pull-up resistors as part of the
communication bus. A 0.1µF power-supply bypass
capacitor is recommended for good local bypassing.
Figure 12 shows a typical configuration for the
TMP441; Figure 13 shows a typical configuration for
the TMP442.
The TMP441/42 are digital temperature sensors that
combine a local die temperature measurement
channel and one (TMP441) or two (TMP442) remote
junction temperature measurement channels in a
single SOT23-8 package. The TMP441/42 are
Two-Wire- and SMBus interface-compatible and are
specified over a temperature range of –40°C to
+125°C. The TMP441/42 contain multiple registers
for holding configuration information and temperature
measurement results.
+5V
GND collector-connected transistor configuration:(1)
0.1mF
Series Resistance
RS(2)
RS(2)
8
1
CDIFF(3)
2
3
4
V+
SCL
DXP
DXN
TMP441
SDA
10kW
(typ)
10kW
(typ)
7
SMBus
Controller
6
A1
A0
GND
Diode-connected transistor configuration(1):
5
RS(2)
RS(2)
CDIFF(3)
NOTES: (1) Diode-connected transistor configuration provides better settling time.
GND collector-connected transistor configuration provides better series resistance cancellation.
(2) RS should be < 1kW in most applications. Selection of RS depends on application; see the Filtering section.
(3) CDIFF should be < 500pF in most applications. Selection of CDIFF depends on application;
see the Filtering section and Figure 9, Remote Temperature Error vs Differential Capacitance.
Figure 12. TMP441 Basic Connections
+5V
GND collector-connected transistor configuration:(1)
0.1mF
Series Resistance
RS(2)
DXP1
RS(2)
8
1
CDIFF(3)
2
V+
DXN1
DXN1
RS(2)
DXP2
RS(2)
3
CDIFF(3)
4
SCL
DXP1
SDA
10kW
(typ)
10kW
(typ)
7
6
SMBus
Controller
TMP442
DXP2
DXN2
DXN2
GND
5
Diode-connected transistor configuration(1):
RS(2)
RS(2)
CDIFF(3)
NOTES: (1) Diode-connected transistor configuration provides better settling time.
GND collector-connected transistor configuration provides better series resistance cancellation.
(2) RS should be < 1kW in most applications. Selection of RS depends on application; see the Filtering section.
(3) CDIFF should be < 500pF in most applications. Selection of CDIFF depends on application;
see the Filtering section and Figure 9, Remote Temperature Error vs Differential Capacitance.
Figure 13. TMP442 Basic Connections
8
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BETA COMPENSATION
TEMPERATURE MEASUREMENT DATA
Previous generations of remote junction temperature
sensors were operated by controlling the emitter
current of the sensing transistor. However,
examination of the physics of a transistor shows that
VBE is actually a function of the collector current. If
beta is independent of the collector current, then VBE
may be calculated from the emitter current. In earlier
generations of processors that contained PNP
transistors connected to these temperature sensors,
controlling the emitter current provided acceptable
temperature measurement results. At 90nm process
geometry and below, the beta factor continues to
decrease and the premise that it is independent of
collector current becomes less certain.
Temperature measurement data are taken over a
default range of –55°C to +127°C for both local and
remote locations. However, measurements from
–55°C to +150°C can be made both locally and
remotely by reconfiguring the TMP441/42 for the
extended temperature range, as described in this
section. Temperature data resulting from conversions
within the default measurement range are
represented in binary form, as shown in Table 1,
Standard Binary column. Note that any temperature
below –64°C results in a data value of –64 (C0h).
Likewise, temperatures above +127°C result in a
value of 127 (7Fh). The device can be set to measure
over an extended temperature range by changing bit
2 (RANGE) of Configuration Register 1 from low to
high. The change in measurement range and data
format from standard binary to extended binary
occurs at the next temperature conversion. For data
captured in the extended temperature range
configuration, an offset of 64 (40h) is added to the
standard binary value, as shown in the Extended
Binary column of Table 1. This configuration allows
measurement of temperatures as low as –64°C, and
as
high
as
+191°C;
however,
most
temperature-sensing diodes only measure with the
range of –55°C to +150°C. Additionally, the
TMP441/42 are rated only for ambient temperatures
ranging from –40°C to +125°C. Parameters in the
Absolute Maximum Ratings table must be observed.
To manage this increasing temperature measurement
error, the TMP441/42 control the collector current
instead of the emitter current. The TMP441/42
automatically detect and choose the correct range
depending on the beta factor of the external
transistor. This auto-ranging is performed at the
beginning of each temperature conversion in order to
correct for any changes in the beta factor as a result
of temperature variation. The device can operate a
PNP transistor with a beta factor as low as 0.1. See
the Beta Compensation Configuration Register
Section for further information.
SERIES RESISTANCE CANCELLATION
Series resistance in an application circuit that typically
results from printed circuit board (PCB) trace
resistance and remote line length (see Figure 12) is
automatically
cancelled
by
the
TMP441/42,
preventing what would otherwise result in a
temperature offset. A total of up to 1kΩ of series line
resistance is cancelled by the TMP441/42 if beta
correction is disabled and up to 300Ω of series line
resistance is cancelled if beta correction is enabled,
eliminating the need for additional characterization
and temperature offset correction. See the two
Remote Temperature Error vs Series Resistance
typical characteristic curves (Figure 7 and Figure 8)
for details on the effect of series resistance on
sensed remote temperature error.
DIFFERENTIAL INPUT CAPACITANCE
The TMP441/42 can tolerate differential input
capacitance of up to 500pF if beta correction is
enabled, and 1000pF if beta correction is disabled
with minimal change in temperature error. The effect
of capacitance on sensed remote temperature error is
illustrated in Figure 9, Remote Temperature Error vs
Differential Capacitance. See the Filtering section for
suggested component values where filtering
unwanted coupled signals is needed.
Table 1. Temperature Data Format (Local and
Remote Temperature High Bytes)
LOCAL/REMOTE TEMPERATURE REGISTER
HIGH BYTE VALUE (1°C RESOLUTION)
TEMP
(°C)
STANDARD BINARY(1)
EXTENDED BINARY(2)
BINARY
HEX
BINARY
–64
1100 0000
C0
0000 0000
HEX
00
–50
1100 1110
CE
0000 1110
0E
–25
1110 0111
E7
0010 0111
27
0
0000 0000
00
0100 0000
40
1
0000 0001
01
0100 0001
41
5
0000 0101
05
0100 0101
45
10
0000 1010
0A
0100 1010
4A
25
0001 1001
19
0101 1001
59
50
0011 0010
32
0111 0010
72
75
0100 1011
4B
1000 1011
8B
100
0110 0100
64
1010 0100
A4
125
0111 1101
7D
1011 1101
BD
127
0111 1111
7F
1011 1111
BF
150
0111 1111
7F
1101 0110
D6
175
0111 1111
7F
1110 1111
EF
191
0111 1111
7F
1111 1111
FF
(1) Resolution is 1°C/count. Negative numbers are represented in
twos complement format.
(2) Resolution is 1°C/count. All values are unsigned with a –64°C
offset.
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Both local and remote temperature data use two
bytes for data storage. The high byte stores the
temperature with 1°C resolution. The second or low
byte stores the decimal fraction value of the
temperature and allows a higher measurement
resolution, as shown in Table 2. The measurement
resolution for both the local and remote channels is
0.0625°C, and cannot be adjusted.
Table 2. Decimal Fraction Temperature Data
Format (Local and Remote Temperature Low
Bytes)
TEMPERATURE REGISTER LOW BYTE
VALUE
(0.0625°C RESOLUTION)(1)
TEMP
(°C)
STANDARD AND EXTENDED
BINARY
HEX
0
0000 0000
00
0.0625
0001 0000
10
0.1250
0010 0000
20
0.1875
0011 0000
30
0.2500
0100 0000
40
0.3125
0101 0000
50
0.3750
0110 0000
60
0.4375
0111 0000
70
0.5000
1000 0000
80
0.5625
1001 0000
90
0.6250
1010 0000
A0
0.6875
1011 0000
B0
0.7500
1100 0000
C0
0.8125
1101 0000
D0
0.8750
1110 0000
E0
0.9375
1111 0000
F0
(1) Resolution is 0.0625°C/count. All possible values are shown.
10
Standard Binary to Decimal Temperature Data
Calculation Example
High byte conversion (for example, 0111 0011):
Convert the right-justified binary high byte to
hexadecimal.
From hexadecimal, multiply the first number by
160 = 1 and the second number by 161 = 16.
The sum equals the decimal equivalent.
0111 0011b → 73h → (3 × 160) + (7 × 161) = 115
Low byte conversion (for example, 0111 0000):
To convert the left-justified binary low-byte to
decimal, use bits 7 through 4 and ignore bits 3
through 0 because they do not affect the value of
the number.
0111b → (0 × 1/2)1 + (1 × 1/2)2 +
(1 × 1/2)3 + (1 × 1/2)4 = 0.4375
Note that the final numerical result is the sum of the
high byte and low byte. In negative temperatures, the
unsigned low byte adds to the negative high byte to
result in a value more than the high byte (for
instance, –15 + 0.75 = –14.25, not –15.75).
Standard Decimal to Binary Temperature Data
Calculation Example
For positive temperatures (for example, +20°C):
(+20°C)/(1°C/count) = 20 → 14h → 0001 0100
Convert the number to binary code with 8-bit,
right-justified format, and MSB = '0' to denote a
positive sign.
+20°C is stored as 0001 0100 → 14h.
For negative temperatures (for example, –20°C):
(|–20°C|)/(1°C/count) = 20 → 14h → 0001 0100
Generate the twos complement of a negative
number by complementing the absolute value
binary number and adding 1.
–20°C is stored as 1110 1100 → ECh.
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REGISTER INFORMATION
Pointer Register
The TMP441/42 contain multiple registers for holding
configuration information, temperature measurement
results, and status information. These registers are
described in Figure 14 and Table 3.
Local and Remote Temperature Registers
Status Register
SDA
Configuration Registers
POINTER REGISTER
One-Shot Start Register
Figure 14 shows the internal register structure of the
TMP441/42. The 8-bit Pointer Register is used to
address a given data register. The Pointer Register
identifies which of the data registers should respond
to a read or write command on the Two-Wire bus.
This register is set with every write command. A write
command must be issued to set the proper value in
the Pointer Register before executing a read
command. Table 3 describes the pointer address of
the TMP441/42 registers. The power-on reset (POR)
value of the Pointer Register is 00h (0000 0000b).
Conversion Rate Register
I/O
Control
Interface
SCL
h-Factor Correction Registers
Identification Registers
Software Reset
b-Compensation Register
Figure 14. Internal Register Structure
Table 3. Register Map
BIT DESCRIPTION
POINTER
(HEX)
POR
(HEX)
7
6
5
4
3
2
1
0
00
00
LT11
LT10
LT9
LT8
LT7
LT6
LT5
LT4
Local Temperature (High Byte) (1)
01
00
RT11
RT10
RT9
RT8
RT7
RT6
RT5
RT4
Remote Temperature 1 (High Byte) (1)
02
00
RT11
RT10
RT9
RT8
RT7
RT6
RT5
RT4
Remote Temperature 2 (High Byte) (1) (2)
08
BUSY
0
0
0
0
0
0
0
Status Register
09
00
0
SD
0
0
0
RANGE
0
0
Configuration Register 1
0A
1C/3C (2)
0
0
REN2 (2)
REN
LEN
RC
0
0
Configuration Register 2
0B
07
0
0
0
0
0
R2
R1
R0
0C
08/88 (2)
BC23 (2)
BC22 (2)
BC21 (2)
BC20 (2)
BC13
BC12
BC11
BC10
X
X
X
X
X
X
X
X
One-Shot Start (3)
Local Temperature (Low Byte)
0F
Conversion Rate Register
Beta Compensation
10
00
LT3
LT2
LT1
LT0
0
0
nPVLD
0
11
00
RT3
RT2
RT1
RT0
0
0
nPVLD
OPEN
Remote Temperature 1 (Low Byte)
12
00
RT3
RT2
RT1
RT0
0
0
nPVLD
OPEN
Remote Temperature 2 (Low Byte) (2)
21
00
NC7
NC6
NC5
NC4
NC3
NC2
NC1
NC0
η Correction 1
22
00
NC7
NC6
NC5
NC4
NC3
NC2
NC1
NC0
η Correction 2 (2)
X
X
X
X
X
X
X
X
Software Reset (4)
55
0
1
0
1
0
1
0
1
Manufacturer ID
41
0
1
0
0
0
0
0
1
TMP441 Device ID
42
0
1
0
0
0
0
1
0
TMP442 Device ID
FC
FE
FF
(1)
(2)
(3)
(4)
REGISTER DESCRIPTION
Compatible with Two-Byte Read; see Figure 18.
TMP442 only.
X = undefined. Writing any value to this register initiates a one-shot start; see the One-Shot Conversion section.
X = undefined. Writing any value to this register initiates a software reset; see the Software Reset section.
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TEMPERATURE REGISTERS
STATUS REGISTER
The TMP441/42 have four 8-bit registers that hold
temperature measurement results. Both the local
channel and the remote channel have a high byte
register that contains the most significant bits (MSBs)
of the temperature analog-to-digital converter (ADC)
result and a low byte register that contains the least
significant bits (LSBs) of the temperature ADC result.
The local channel high byte address is 00h; the local
channel low byte address is 10h. The remote channel
high byte is at address 01h; the remote channel low
byte address is 11h. For the TMP442, the second
remote channel high byte address is 02h; the second
remote channel low byte is 12h. These registers are
read-only and are updated by the ADC each time a
temperature measurement is completed.
The Status Register reports the state of the
temperature ADCs. Table 4 shows the Status
Register bits. The Status Register is read-only, and is
read by accessing pointer address 08h. The BUSY bit
= '1' if the ADC is making a conversion; it is set to '0'
if the ADC is not converting.
CONFIGURATION REGISTER 1
Configuration Register 1 (pointer address 09h) sets
the temperature range and controls shutdown mode.
The Configuration Register is set by writing to pointer
address 09h and read by reading from pointer
address 09h. The shutdown (SD) bit (bit 6) enables or
disables the temperature measurement circuitry. If
SD = '0', the TMP441/42 convert continuously at the
rate set in the conversion rate register. When SD is
set to '1', the TMP441/42 stop converting when the
current conversion sequence is complete and enters
a shutdown mode. When SD is set to '0' again, the
TMP441/42 resume continuous conversions. When
SD = '1', a single conversion can be started by writing
to the One-Shot Register.
The TMP441/42 contain circuitry to assure that a low
byte register read command returns data from the
same ADC conversion as the immediately preceding
high byte read command. This condition remains
valid only until another register is read. For proper
operation, the high byte of a temperature register
should be read first. The low byte register should be
read in the next read command. The low byte register
may be left unread if the LSBs are not needed.
Alternatively, the temperature registers may be read
as a 16-bit register by using a single two-byte read
command from address 00h for the local channel
result, or from address 01h for the remote channel
result (02h for the second remote channel result).
The high byte is output first, followed by the low byte.
Both bytes of this read operation are from the same
ADC conversion. The power-on reset value of all
temperature registers is 00h.
The temperature range is set by configuring bit 2 of
the Configuration Register. Setting this bit low
configures the TMP441/42 for the standard
measurement range (–55°C to +127°C); temperature
conversions are stored in the standard binary format.
Setting bit 2 high configures the TMP441/42 for the
extended measurement range (–55°C to +150°C);
temperature conversions are stored in the extended
binary format (see Table 1). The remaining bits of the
Configuration Register are reserved and must always
be set to '0'. The power-on reset value for this
register is 00h. Table 5 summarizes the bits of
Configuration Register 1.
Table 4. Status Register Format
STATUS REGISTER (Read = 08h, Write = NA)
BIT #
BIT NAME
POR VALUE
(1)
D7
D6
D5
D4
D3
D2
D1
D0
BUSY
0
0
0
0
0
0
0
0 (1)
0
0
0
0
0
0
0
The BUSY changes to '1' almost immediately (< 100µs) following power-up, as the TMP441/42 begins the first temperature conversion.
It is high whenever the TMP441/42 converts a temperature reading.
Table 5. Configuration Register 1 Bit Descriptions
CONFIGURATION REGISTER 1 (Read/Write = 09h, POR = 00h)
12
BIT
NAME
FUNCTION
POWER-ON RESET VALUE
7
Reserved
—
0
6
SD
0 = Run
1 = Shut down
0
5, 4, 3
Reserved
—
0
2
Temperature Range
0 = –55°C to +127°C
1 = –55°C to +150°C
0
1, 0
Reserved
—
0
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ONE-SHOT CONVERSION
When the TMP441/42 are in shutdown mode (SD = 1
in the Configuration Register 1), a single conversion
can start on all enabled channels by writing any value
to the One-Shot Start Register, pointer address 0Fh.
This write operation starts one conversion; the
TMP441/42 return to shutdown mode when that
conversion completes. The value of the data sent in
the write command is irrelevant and is not stored by
the TMP441/42. When the TMP441/42 are in
shutdown mode, the conversion sequence currently
in process must be completed before a one-shot
command can be issued. One-shot commands issued
during a conversion are ignored.
CONFIGURATION REGISTER 2
Configuration Register 2 (pointer address 0Ah)
controls which temperature measurement channels
are enabled and whether the external channels have
the resistance correction feature enabled or not.
The RC bit enables the resistance correction feature
for the external temperature channels. If RC = '1',
series resistance correction is enabled; if RC = '0',
resistance correction is disabled. Resistance
correction should be enabled for most applications.
However, disabling the resistance correction may
yield slightly improved temperature measurement
noise performance, and reduce conversion time by
about 50%, which could lower power consumption
when conversion rates of two per second or less are
selected.
The LEN bit enables the local temperature
measurement channel. If LEN = '1', the local channel
is enabled; if LEN = '0', the local channel is disabled.
The REN bit enables external temperature
measurement channel 1 (connected to pins 1 and 2.)
If REN = '1', the external channel is enabled; if REN =
'0', the external channel is disabled.
For the TMP442 only, the REN2 bit enables the
second external measurement channel (connected to
pins 3 and 4.) If REN2 = '1', the second external
channel is enabled; if REN2 = '0', the second external
channel is disabled.
The temperature measurement sequence is local
channel, external channel 1, external channel 2,
shutdown, and delay (to set conversion rate, if
necessary). The sequence starts over with the local
channel. If any of the channels are disabled, they are
skipped in the sequence. Table 6 summarizes the
bits of Configuration Register 2.
CONVERSION RATE REGISTER
The Conversion Rate Register (pointer address 0Bh)
controls the rate at which temperature conversions
are performed. This register adjusts the idle time
between conversions but not the conversion timing
itself, thereby allowing the TMP441/42 power
dissipation to be balanced with the temperature
register update rate. Table 7 shows the conversion
rate options and corresponding current consumption.
A one-shot command can be used during the idle
time between conversions to immediately start
temperature conversions on all enabled channels.
Table 6. Configuration Register 2 Bit Descriptions
CONFIGURATION REGISTER 2 (Read/Write = 0Ah, POR = 1Ch for TMP441; 3Ch for TMP442)
BIT
NAME
FUNCTION
7, 6
Reserved
—
POWER-ON RESET VALUE
0
5
REN2
0 = External channel 2 disabled
1 = External channel 2 enabled
1 (TMP442)
0 (TMP441)
4
REN
0 = External channel 1 disabled
1 = External channel 1 enabled
1
3
LEN
0 = Local channel disabled
1 = Local channel enabled
1
2
RC
0 = Resistance correction disabled
1 = Resistance correction enabled
1
1, 0
Reserved
—
0
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BETA COMPENSATION CONFIGURATION
REGISTER
If the Beta Compensation Configuration Register is
set to '1xxx' (beta compensation enabled) for a given
channel at the beginning of each temperature
conversion, the TMP441/42 automatically detects if
the
sensor
is
diode-connected
or
GND
collector-connected, selects the proper beta range,
and measures the sensor temperature appropriately.
If the Beta Compensation Configuration Register is
set to '0111' (beta compensation disabled) for a given
channel, the automatic detection is bypassed and the
temperature
is
measured
assuming
a
diode-connected sensor. A PNP transistor may
continue to be GND collector-connected in this mode,
but no beta compensation is applied. When the beta
compensation configuration is set to '0111' or the
sensor is diode-connected (base shorted to collector),
the η-factor used by the TMP441/42 is 1.008. When
the beta compensation configuration is set to '1xxx'
(beta compensation enabled) and the sensor is GND
collector-connected (PNP collector to ground), the
η-factor used by the TMP441/42 is 1.000. Table 8
shows the read values for the selected beta ranges
and the appropriate η-Factor used for each
conversion.
Table 7. Conversion Rate Register
CONVERSION RATE REGISTER (Read/Write = 0Bh, POR = 07h)
AVERAGE IQ (TYP) (µA),
VS = 5.5V
(1)
R7
R6
R5
R4
R3
R2
R1
R0
CONVERSIONS/SEC
TMP441
TMP442
0
0
0
0
0
0
0
0
0.0625
30
35
0
0
0
0
0
0
0
1
0.125
35
44
0
0
0
0
0
0
1
0
0.25
45
62
0
0
0
0
0
0
1
1
0.5
65
99
0
0
0
0
0
1
0
0
1
103
162
0
0
0
0
0
1
0
1
2
181
272
0
0
0
0
0
1
1
0
4
332
437
0
0
0
0
0
1
1
1
8 (1)
634
652
Conversion rate depends on which channels are enabled.
Table 8. Beta Compensation Configuration Register
BCx3-BCx0
14
N
TIME
1000
Automatically selected range 0 (0.10 < beta < 0.18)
BETA RANGE DESCRIPTION
1.000
126ms
1001
Automatically selected range 1 (0.16 < beta < 0.26)
1.000
126ms
1010
Automatically selected range 2 (0.24 < beta < 0.43)
1.000
126ms
1011
Automatically selected range 3 (0.35 < beta < 0.78)
1.000
126ms
1100
Automatically selected range 4 (0.64 < beta < 1.8)
1.000
126ms
1101
Automatically selected range 5 (1.4 < beta < 9.0)
1.000
126ms
1110
Automatically selected range 6 (6.7 < beta < 40.0)
1.000
126ms
1111
Automatically selected range 7 (beta > 27.0)
1.000
126ms
1111
Automatically detected diode connected sensor
1.008
93ms
0000
Manually selected range 0 (0.10 < beta < 0.5)
1.000
93ms
0001
Manually selected range 1 (0.13 < beta < 1.0)
1.000
93ms
0010
Manually selected range 2 (0.18 < beta < 2.0)
1.000
93ms
0011
Manually selected range 3 (0.3 < beta < 25)
1.000
93ms
0100
Manually selected range 4 (0.5 < beta < 50)
1.000
93ms
0101
Manually selected range 5 (1.1 < beta < 100)
1.000
93ms
0110
Manually selected range 6 (2.4 < beta < 150)
1.000
93ms
0111
Manually disabled beta correction
1.008
93ms
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η-FACTOR CORRECTION REGISTER
Table 9. η-Factor Range
The TMP441/42 allow for a different η-factor value to
be
used
for
converting
remote
channel
measurements to temperature. The remote channel
uses sequential current excitation to extract a
differential VBE voltage measurement to determine
the temperature of the remote transistor. Equation 1
relates this voltage and temperature.
( )
I
hkT
ln 2
VBE2 - VBE1 =
q
I1
(1)
The value η in Equation 1 is a characteristic of the
particular transistor used for the remote channel.
When the beta compensation configuration is set to
'0111' (beta compensation disabled) or the sensor is
diode-connected (base shorted to collector), the
η-factor used by the TMP441/42 is 1.008. When the
beta compensation configuration is set to '1000' (beta
compensation enabled) and the sensor is GND
collector-connected (PNP collector to ground), the
η-factor used by the TMP441/42 is 1.000. If the
η-factor used for the temperature conversion does
not match the characteristic of the sensor, then
temperature offset is observed. The value in the
η-Factor Correction Register may be used to adjust
the effective η-factor according to Equation 2 and
Equation 3 for disabled beta compensation or a
diode-connected sensor. Equation 4 and Equation 5
may be used for enabled beta compensation and a
GND collector-connected sensor.
1.008 ´ 300
heff =
300 - NADJUST
(2)
NADJUST = 300 -
heff =
300 ´ 1.008
heff
1.000 ´ 300
300 - NADJUST
NADJUST = 300 -
300 ´ 1.000
heff
(3)
(4)
(5)
The η-correction value must be stored in twos
complement format, yielding an effective data range
from –128 to +127. Table 9 shows the η-factor range
for both 1.008 and 1.000. The η-correction value may
be written to and read from pointer address 21h. (The
η-correction value for the second remote channel is
read to/written from pointer address 22h.) The
register power-on reset value is 00h, thus having no
effect unless the register is written to.
NADJUST
HEX
DECIMAL
η-FACTOR
= 1.008
η-FACTOR
= 1.000
0111 1111
7F
127
1.747977
1.734104
0000 1010
0A
10
1.042759
1.034482
0000 1000
08
8
1.035616
1.027397
0000 0110
06
6
1.028571
1.020408
0000 0100
04
4
1.021622
1.013513
0000 0010
02
2
1.014765
1.006711
0000 0001
01
1
1.011371
1.003344
0000 0000
00
0
1.008
1.000
1111 1111
FF
–1
1.004651
0.996677
1111 1110
FE
–2
1.001325
0.993377
1111 1100
FC
–4
0.994737
0.986842
1111 1010
FA
–6
0.988235
0.980392
1111 1000
F8
–8
0.981818
0.974025
1111 0110
F6
–10
0.975484
0.967741
1000 0000
80
–128
0.706542
0.700934
BINARY
SOFTWARE RESET
The TMP441/42 may be reset by writing any value to
the Software Reset Register (pointer address FCh).
This action restores the power-on reset state to all of
the TMP441/42 registers as well as aborts any
conversion in process. The TMP441/42 also support
reset via the Two-Wire general call address (0000
0000). The TMP441/42 acknowledge the general call
address and respond to the second byte. If the
second byte is 0000 0110, the TMP441/42 execute a
software reset. The TMP441/42 do not respond to
other values in the second byte.
IDENTIFICATION REGISTERS
The TMP441/42 allow for the Two-Wire bus controller
to query the device for manufacturer and device IDs
to enable software identification of the device at the
particular Two-Wire bus address. The manufacturer
ID is obtained by reading from pointer address FEh.
The device ID is obtained by reading from pointer
address FFh. The TMP441/42 both return 55h for the
manufacturer code. The TMP441 returns 41h for the
device ID and the TMP442 returns 42h for the device
ID. These registers are read-only.
space
space
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Table 10. TMP441 Slave Address Options
BUS OVERVIEW
The TMP441/42 are SMBus interface-compatible. In
SMBus protocol, 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, a START condition is
initiated. START is indicated by pulling the data line
(SDA) from a high-to-low logic level while SCL is
high. All slaves on the bus shift in the slave address
byte, with the last bit indicating whether a read or
write operation is intended. During the ninth clock
pulse, the slave being addressed responds to the
master by generating an Acknowledge 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 control signal.
Once all data have been transferred, the master
generates a STOP condition. STOP is indicated by
pulling SDA from low to high, while SCL is high.
SERIAL INTERFACE
The TMP441/42 operate only as a slave device on
either the Two-Wire bus or the SMBus. Connections
to either bus are made via 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 TMP441/42 support the transmission
protocol for fast (1kHz to 400kHz) and high-speed
(1kHz to 3.4MHz) modes. All data bytes are
transmitted MSB first.
SERIAL BUS ADDRESS
To communicate with the TMP441/42, the master
must first address slave devices via a slave address
byte. The slave address byte consists of seven
address bits, and a direction bit indicating the intent
of executing a read or write operation.
TWO-WIRE INTERFACE SLAVE DEVICE
ADDRESSES
The TMP441 supports nine slave device addresses.
The TMP442A and TMP442B are available in two
different fixed serial interface addresses.
The slave device address for the TMP441 is set by
the A1 and A0 pins, as summarized in Table 10.
16
TWO-WIRE SLAVE
ADDRESS
A1
A0
0011 100
Float
0
0011 101
Float
1
0011 110
0
Float
0011 111
1
Float
0101 010
Float
Float
1001 100
0
0
1001 101
0
1
1001 110
1
0
1001 111
1
1
The TMP442 has a factory-preset slave address. The
TMP442A slave address is 1001100b, and the
TMP442B slave address is 1001101b. The
configuration of the DXP and DXN channels are
independent of the address. Unused DXP channels
can be left open or tied to GND.
READ/WRITE OPERATIONS
Accessing a particular register on the TMP441/42 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
TMP441/42 requires a value for the Pointer Register
(see Figure 16).
When reading from the TMP441/42, 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 transaction 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 18 for details of this sequence. If repeated
reads from the same register are desired, it is not
necessary to continually send the Pointer Register
bytes, because the TMP441/42 retain the Pointer
Register value until it is changed by the next write
operation. Note that register bytes are sent MSB first,
followed by the LSB.
Read operations should be terminated by issuing a
Not-Acknowledge command at the end of the last
byte to be read. For a single-byte operation, the
master should leave the SDA line high during the
Acknowledge time of the first byte that is read from
the slave. For a two-byte read operation, the master
must pull SDA low during the Acknowledge time of
the first byte read, and should leave SDA high during
the Acknowledge time of the second byte read from
the slave.
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TIMING DIAGRAMS
The
TMP441/42
are
Two-Wire
and
SMBus-compatible. Figure 15 to Figure 18 describe
the various operations on the TMP441/42.
Parameters for Figure 15 are defined in Table 11.
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
terminates with a repeated START or STOP
condition.
t(LOW)
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 data transfer.
Acknowledge: Each receiving device, when
addressed, is obliged to generate an Acknowledge
bit. A device that acknowledges must pull down the
SDA line during the Acknowledge clock pulse in such
a way 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. On a master
receive, data transfer termination can be signaled by
the master generating a Not-Acknowledge on the last
byte that has been transmitted by the slave.
tF
tR
t(HDSTA)
SCL
t(HDSTA)
t(HIGH)
t(HDDAT)
t(SUSTO)
t(SUSTA)
t(SUDAT)
SDA
t(BUF)
P
S
S
P
Figure 15. Two-Wire Timing Diagram
Table 11. Timing Characteristics for Figure 15
FAST MODE
PARAMETER
HIGH-SPEED MODE
MIN
MAX
MIN
MAX
UNIT
0.4
0.001
3.4
MHz
SCL operating frequency
f(SCL)
0.001
Bus free time between STOP and START conditions
t(BUF)
600
160
ns
t(HDSTA)
100
100
ns
Repeated START condition setup time
t(SUSTA)
100
100
ns
STOP condition setup time
t(SUSTO)
100
100
ns
Data hold time
t(HDDAT)
0
0
ns
Data setup time
t(SUDAT)
100
10
ns
SCL clock LOW period
t(LOW)
1300
160
ns
SCL clock HIGH period
t(HIGH)
600
60
ns
Hold time after repeated START condition. After this period, the first clock
is generated.
Clock/Data fall time
tF
300
160
ns
Clock/Data rise time
tR
300
160
ns
tR
1000
for SCL ≤ 100kHz
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17
TMP441
TMP442
SBOS425A – DECEMBER 2008 – REVISED MARCH 2009 .............................................................................................................................................. www.ti.com
1
9
9
1
SCL
¼
1
SDA
0
0
1
1
0
0(1)
R/W
Start By
Master
P7
P6
P5
P4
P3
P2
P1
P0
ACK By
TMP441/42
¼
ACK By
TMP441/42
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
D1
ACK By
TMP441/42
D0
ACK By
TMP441/42
Frame 3 Data Byte 1
Stop By
Master
Frame 4 Data Byte 2
NOTE: (1) Slave address 1001100 shown.
Figure 16. Two-Wire Timing Diagram for Write Word Format
1
9
1
9
SCL
¼
SDA
1
0
0
1
1
0
0(1)
R/W
Start By
Master
P7
P6
P5
P4
P3
P2
P1
P0
¼
ACK By
TMP441/42
ACK By
TMP441/42
Frame 1 Two-Wire Slave Address Byte
Frame 2 Pointer Register Byte
1
9
1
9
SCL
(Continued)
¼
SDA
(Continued)
1
0
0
1
1
0
0(1)
R/W
Start By
Master
D7
D6
D5
ACK By
TMP441/42
Frame 3 Two-Wire Slave Address Byte
D4
D3
D2
D1
D0
From
TMP441/42
¼
NACK By
Master(2)
Frame 4 Data Byte 1 Read Register
NOTES: (1) Slave address 1001100 shown.
(2) Master should leave SDA high to terminate a single-byte read operation.
Figure 17. Two-Wire Timing Diagram for Single-Byte Read Format
18
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1
9
1
9
SCL
¼
SDA
1
0
0
1
1
0
0(1)
P7
R/W
Start By
Master
P6
P5
P4
P3
P2
P1
P0
¼
ACK By
TMP441/42
ACK By
TMP441/42
Frame 1 Two-Wire Slave Address Byte
Frame 2 Pointer Register Byte
1
9
1
9
SCL
(Continued)
¼
SDA
(Continued)
1
0
0
1
1
0
0(1)
R/W
Start By
Master
D7
D6
D5
ACK By
TMP441/42
Frame 3 Two-Wire Slave Address Byte
1
D4
D3
D2
D1
D0
From
TMP441/42
¼
ACK By
Master
Frame 4 Data Byte 1 Read Register
9
SCL
(Continued)
SDA
(Continued)
D7
D6
D5
D4
D3
D2
From
TMP441/42
D1
D0
NACK By
Master(2)
Stop By
Master
Frame 5 Data Byte 2 Read Register
NOTES: (1) Slave address 1001100 shown.
(2) Master should leave SDA high to terminate a two-byte read operation.
Figure 18. Two-Wire Timing Diagram for Two-Byte Read Format
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TMP441
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SBOS425A – DECEMBER 2008 – REVISED MARCH 2009 .............................................................................................................................................. www.ti.com
HIGH-SPEED MODE
In order for the Two-Wire bus to operate at
frequencies above 400kHz, the master device must
issue a High-Speed mode (Hs-mode) master code
(0000 1xxx) as the first byte after a START condition
to switch the bus to high-speed operation. The
TMP441/42 acknowledge this byte, but switch the
input filters on SDA and SCL and the output filter on
SDA to operate in Hs-mode, allowing transfers at up
to 3.4MHz. 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 TMP441/42 switch the input and
output filters back to fast mode operation.
When not using the remote sensor with the
TMP441/42, the DXP and DXN inputs must be
connected together to prevent meaningless fault
warnings.
UNDERVOLTAGE LOCKOUT
The TMP441/42 sense when the power-supply
voltage has reached a minimum voltage level for the
ADC to function. The detection circuitry consists of a
voltage comparator that enables the ADC after the
power supply (V+) exceeds 2.45V (typical). The
comparator output is continuously checked during a
conversion. The TMP441/42 do not perform a
temperature conversion if the power supply is not
valid. The PVLD bit (bit 1, see Table 3) of the
Local/Remote Temperature Register is set to '1' and
the temperature result may be incorrect.
TIMEOUT FUNCTION
The TMP441/42 reset the serial interface if either
SCL or SDA are held low for 32ms (typical) between
a START and STOP condition. If the TMP441/42 are
holding the bus low, they release the bus and waits
for a START condition. To avoid activating the
timeout function, it is necessary to maintain a
communication speed of at least 1kHz for the SCL
operating frequency.
SHUTDOWN MODE (SD)
The TMP441/42 Shutdown Mode allows maximum
power to be saved by shutting down all device
circuitry other than the serial interface, reducing
current consumption to typically less than 3µA; see
Figure 6, Shutdown Quiescent Current vs Supply
Voltage. Shutdown Mode is enabled when the SD bit
of the Configuration Register is high; the device shuts
down once the current conversion is completed.
When SD is low, the device maintains a continuous
conversion state.
SENSOR FAULT
The TMP441/42 can sense a fault at the DXP input
resulting from incorrect diode connection and can
sense an open circuit. Short-circuit conditions return a
value of –64°C. The detection circuitry consists of a
voltage comparator that trips when the voltage at
DXP exceeds (V+) – 0.6V (typical). The comparator
output is continuously checked during a conversion. If
a fault is detected, the OPEN bit (bit 0) in the
temperature result register is set to '1' and the rest of
the register bits should be ignored.
20
GENERAL CALL RESET
The TMP441/42 support reset via the Two-Wire
General Call address 00h (0000 0000b). The
TMP441/42 acknowledge the General Call address
and respond to the second byte. If the second byte is
06h (0000 0110b), the TMP441/42 execute a
software reset. This software reset restores the
power-on reset state to all TMP441/42 registers, and
aborts any conversion in progress. The TMP441/42
take no action in response to other values in the
second byte.
FILTERING
Remote junction temperature sensors are usually
implemented in a noisy environment. Noise is
frequently generated by fast digital signals and if not
filtered properly will induce errors that can corrupt
temperature measurements. The TMP441/42 have a
built-in 65kHz filter on the inputs of DXP and DXN to
minimize the effects of noise. However, a differential
low-pass filter can help attenuate unwanted coupled
signals. If filtering is needed, suggested component
values are 100pF and 50Ω on each input; exact
values
are
application-specific.
It
is
also
recommended that the capacitor value remains
between 0pF to 330pF with a series resistance less
than 1kΩ.
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REMOTE SENSING
The TMP441/42 are designed to be used with either
discrete transistors or substrate transistors built into
processor chips and ASICs. Either NPN- or PNP-type
transistors can be used, as long as the base-emitter
junction is used as the remote temperature sense.
NPN transistors must be diode-connected. PNP
transistors
can
either
be
transistoror
diode-connected (see Figure 12).
Errors in remote temperature sensor readings are
typically the consequence of the ideality factor and
current excitation used by the TMP441/42 versus the
manufacturer-specified operating current for a given
transistor. Some manufacturers specify a high-level
and low-level current for the temperature-sensing
substrate transistors. The TMP441/42 use 6µA for
ILOW and 120µA for IHIGH. The TMP441/42 allow for
different η-factor values; see the η-Factor Correction
Register section. The ideality factor (η) is a measured
characteristic of a remote temperature sensor diode
as compared to an ideal diode.
The ideality factor for the TMP441/42 is trimmed to
be 1.008. For transistors that have an ideality factor
that does not match the TMP441/42, Equation 6 can
be used to calculate the temperature error. Note that
for the equation to be used correctly, actual
temperature (°C) must be converted to kelvins (K).
Terr =
- 1.008
( h 1.008
) ´ (273.15 + T (°C))
(6)
Where:
η = ideality factor of remote temperature sensor
T(°C) = actual temperature
TERR = error in TMP441/42 due to n ≠ 1.008
Degree delta is the same for °C and K
For η = 1.004 and T(°C) = 100°C:
ǒ
Ǔ
T ERR + 1.004 * 1.008
1.008
ǒ273.15 ) 100°CǓ
T ERR + 1.48°C
(7)
If a discrete transistor is used as the remote
temperature sensor with the TMP441/42, the best
accuracy can be achieved by selecting the transistor
according to the following criteria:
1. Base-emitter voltage > 0.25V at 6µA, at the
highest sensed temperature.
2. Base-emitter voltage < 0.95V at 120µA, at the
lowest sensed temperature.
3. Base resistance < 100Ω.
4. Tight control of VBE characteristics indicated by
small variations in hFE (that is, 50 to 150).
Based on these criteria, two recommended
small-signal transistors are the 2N3904 (NPN) or
2N3906 (PNP).
MEASUREMENT ACCURACY AND THERMAL
CONSIDERATIONS
The temperature measurement accuracy of the
TMP441/42 depends on the remote and/or local
temperature sensor being at the same temperature
as the system point being monitored. Clearly, if the
temperature sensor is not in good thermal contact
with the part of the system being monitored, then
there will be a delay in the response of the sensor to
a temperature change in the system. For remote
temperature-sensing applications that use a substrate
transistor (or a small, SOT23 transistor) placed close
to the device being monitored, this delay is usually
not a concern.
The local temperature sensor inside the TMP441/42
monitors the ambient air around the device. The
thermal time constant for the TMP441/42 is
approximately two seconds. This constant implies
that if the ambient air changes quickly by 100°C, it
would take the TMP441/42 approximately 10 seconds
(that is, five thermal time constants) to settle to within
1°C of the final value. In most applications, the
TMP441/42 package is in electrical, and therefore
thermal, contact with the printed circuit board (PCB),
as well as subjected to forced airflow. The accuracy
of the measured temperature directly depends on
how accurately the PCB and forced airflow
temperatures represent the temperature that the
TMP441/42 is measuring. Additionally, the internal
power dissipation of the TMP441/42 can cause the
temperature to rise above the ambient or PCB
temperature. The internal power dissipated as a
result of exciting the remote temperature sensor is
negligible because of the small currents used. For a
5.5V supply and maximum conversion rate of eight
conversions per second, the TMP441/42 dissipate
5.2mW (PDIQ = 5.5V × 950µA). A θJA of 100°C/W
causes the junction temperature to rise approximately
+0.23°C above the ambient.
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TMP441
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LAYOUT CONSIDERATIONS
Remote temperature sensing on the TMP441/42
measures very small voltages using very low
currents; therefore, noise at the IC inputs must be
minimized. Most applications using the TMP441/42
will have high digital content, with several clocks and
logic level transitions creating a noisy environment.
Layout should adhere to the following guidelines:
1. Place the TMP441/42 as close to the remote
junction sensor as possible.
2. Route the DXP and DXN traces next to each
other and shield them from adjacent signals
through the use of ground guard traces, as
shown in Figure 19. If a multilayer PCB is used,
bury these traces between ground or VDD planes
to shield them from extrinsic noise sources. 5 mil
(0.005 in, or 0,127 mm) PCB traces are
recommended.
3. Minimize additional thermocouple junctions
caused by copper-to-solder connections. If these
junctions are used, make the same number and
approximate
locations
of
copper-to-solder
connections in both the DXP and DXN
connections to cancel any thermocouple effects.
4. Use a 0.1µF local bypass capacitor directly
between the V+ and GND of the TMP441/42, as
shown in Figure 20. Minimize filter capacitance
between DXP and DXN to 330pF or less for
optimum measurement performance. This
capacitance includes any cable capacitance
between the remote temperature sensor and
TMP441/42.
5. If the connection between the remote
temperature sensor and the TMP441/42 is less
than 8 in (20,32 cm) long, use a twisted-wire pair
connection. Beyond 8 in, use a twisted, shielded
pair with the shield grounded as close to the
TMP441/42 as possible. Leave the remote sensor
connection end of the shield wire open to avoid
ground loops and 60Hz pickup.
6. Thoroughly clean and remove all flux residue in
and around the pins of the TMP441/42 to avoid
temperature offset readings as a result of leakage
paths between DXP or DXN and GND, or
between DXP or DXN and V+.
V+
DXP
Ground or V+ layer
on bottom and/or
top, if possible.
DXN
GND
NOTE: Use minimum 5 mil traces with 5 mil spacing.
Figure 19. Suggested PCB Layer Cross-Section
0.1mF Capacitor
GND
PCB Via
DXP
1
8
DXN
2
7
A1
3
6
A0
4
5
V+
TMP441
0.1mF Capacitor
GND
PCB Via
DXP1
1
8
DXN1
2
7
DXP2
3
6
DXN2
4
5
V+
TMP442
Figure 20. Suggested Bypass Capacitor
Placement and Trace Shielding
22
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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)
TMP441AIDCNR
ACTIVE
SOT-23
DCN
8
3000
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 125
DIGI
TMP441AIDCNT
ACTIVE
SOT-23
DCN
8
250
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 125
DIGI
TMP442ADCNR
ACTIVE
SOT-23
DCN
8
3000
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 125
DIHI
TMP442ADCNT
ACTIVE
SOT-23
DCN
8
250
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 125
DIHI
TMP442BDCNR
ACTIVE
SOT-23
DCN
8
3000
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 125
DIJI
TMP442BDCNT
ACTIVE
SOT-23
DCN
8
250
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 125
DIJI
(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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