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TMP421-Q1, TMP422-Q1, TMP423-Q1
SBOS821 – NOVEMBER 2016
TMP42x-Q1 ±1°C Remote and Local Temperature Sensor
1 Features
3 Description
•
The TMP421-Q1, TMP422-Q1, and TMP423-Q1
devices are single, dual, and triple remote,
automotive-qualified temperature sensor monitors
with a built-in local temperature sensor. The 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).
1
•
•
•
•
•
•
•
•
•
AEC-Q100 Qualified with the Following Results
– Temperature Grade 1: –40°C to +125°C
– Device HBM ESD Classification Level 2
– Device CDM ESD Classification Level C5
SOT23-8 Package
±1°C Remote Diode Sensor (Maximum)
±1.5°C Local Temperature Sensor (Maximum)
Series Resistance Cancellation
n-Factor Correction
Two-Wire I2C or SMBus™ Compatible Serial
Interface
Multiple Interface Addresses
Diode Fault Detection
RoHS Compliant and No Sb/Br
2 Applications
•
•
•
•
•
Processor and FPGA Temperature Monitoring
LCD, DLP, and LCOS Projectors
Servers
Central Office Telecom Equipment
Storage Area Networks (SAN)
Remote accuracy is ±1°C for multiple device
manufacturers, with no calibration needed. The twowire serial interface accepts SMBus write byte, read
byte, send byte, and receive byte commands to
configure the device.
The TMP421-Q1, TMP422-Q1, and TMP423-Q1
include series resistance cancellation, programmable
non-ideality factor, wide remote temperature
measurement range (up to +150°C), and diode fault
detection.
The TMP421-Q1, TMP422-Q1, and TMP423-Q1 are
all available in an 8-pin SOT-23 package.
Device Information(1)
PART NUMBER
TMP421-Q1
TMP422-Q1
TMP423-Q1
PACKAGE
BODY SIZE (NOM)
SOT-23 (8)
2.90 mm × 1.63 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Diode Input Configurations for the TMP421-Q1, TMP422-Q1, and TMP423-Q1
5V
TMP421-Q1
1
2
3
4
DXP
DXN
TMP422-Q1
1
2
A1
3
A0
4
DX1
DX2
DX3
DX4
TMP423-Q1
1
2
3
4
8
V+
SCL
DXP1
SDA
DXP2
7
6
SMBus
Controller
DXP3
DXN
GND
5
1 Channel Local
1 Channel Remote
1 Channel Local
2 Channels Remote
1 Channel Local
3 Channels Remote
Copyright © 2016, Texas Instruments Incorporated
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.
TMP421-Q1, TMP422-Q1, TMP423-Q1
SBOS821 – NOVEMBER 2016
www.ti.com
Table of Contents
1
2
3
4
5
6
7
8
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Device Comparison Table.....................................
Pin Configuration and Functions .........................
Specifications.........................................................
1
1
1
2
3
3
5
7.1
7.2
7.3
7.4
7.5
7.6
7.7
5
5
5
5
6
7
8
Absolute Maximum Ratings ......................................
ESD Ratings..............................................................
Recommended Operating Conditions.......................
Thermal Information ..................................................
Electrical Characteristics...........................................
Timing Requirements ................................................
Typical Characteristics ..............................................
8.5 Programming........................................................... 14
8.6 Register Maps ......................................................... 21
9
9.1 Application Information............................................ 25
9.2 Typical Applications ................................................ 25
10 Power Supply Recommendations ..................... 29
11 Layout................................................................... 29
11.1 Layout Guidelines ................................................. 29
11.2 Layout Example .................................................... 30
11.3 Measurement Accuracy and Thermal
Considerations ......................................................... 30
12 Device and Documentation Support ................. 31
12.1
12.2
12.3
12.4
12.5
12.6
Detailed Description ............................................ 10
8.1
8.2
8.3
8.4
Overview .................................................................
Functional Block Diagram .......................................
Feature Description.................................................
Device Functional Modes........................................
Application and Implementation ........................ 25
10
10
12
14
Related Links ........................................................
Receiving Notification of Documentation Updates
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
31
31
31
31
31
31
13 Mechanical, Packaging, and Orderable
Information ........................................................... 31
4 Revision History
2
DATE
REVISION
NOTES
November 2016
*
Initial release.
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SBOS821 – NOVEMBER 2016
5 Device Comparison Table
PART NUMBER
TWO-WIRE
ADDRESS
DESCRIPTION
TMP421-Q1
Single-channel remote junction temperature sensor
100 11xx
TMP422-Q1
Dual-channel remote junction temperature sensor
100 11xx
TMP423-Q1
Triple-channel remote junction temperature sensor
100 1100
6 Pin Configuration and Functions
TMP421-Q1 DCN Package
8-Pin SOT-23
Top View
DXP
1
8
V+
DXN
2
7
SCL
A1
3
6
SDA
A0
4
5
GND
TMP421-Q1 Pin Functions
PIN
NO.
NAME
TYPE
DESCRIPTION
1
DXP
Analog input
Positive connection to remote temperature sensor
2
DXN
Analog input
Negative connection to remote temperature sensor
3
A1
Digital input
Address pin
4
A0
Digital input
Address pin
5
GND
Ground
6
SDA
Bidirectional digital input-output
Serial data line for SMBus, open-drain; requires pullup resistor to V+
7
SCL
Digital input
Serial clock line for SMBus, open-drain; requires pullup resistor to V+
8
V+
Power supply
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Ground
Positive supply voltage (2.7 V to 5.5 V for the TMP421-Q1)
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TMP422-Q1 DCN Package
8-Pin SOT-23
Top View
DX1
1
8
V+
DX2
2
7
SCL
DX3
3
6
SDA
DX4
4
5
GND
TMP422-Q1 Pin Functions
PIN
NO.
NAME
TYPE
DESCRIPTION
1
DX1
Analog input
Channel 1 remote temperature sensor connection pin.
Also sets the TMP422-Q1 address; see Table 4.
2
DX2
Analog input
Channel 1 remote temperature sensor connection pin.
Also sets the TMP422-Q1 address; see Table 4.
3
DX3
Analog input
Channel 2 remote temperature sensor connection pin.
Also sets the TMP422-Q1 address; see Table 4.
4
DX4
Analog input
Channel 2 remote temperature sensor connection pin.
Also sets the TMP422-Q1 address; see Table 4.
5
GND
Ground
6
SDA
Bidirectional digital input-output
Serial data line for SMBus, open-drain; requires pullup resistor to V+.
7
SCL
Digital input
Serial clock line for SMBus, open-drain; requires pullup resistor to V+.
8
V+
Power supply
Ground
Positive supply voltage (2.7 V to 5.5 V).
TMP423-Q1 DCN Package
8-Pin SOT-23
Top View
DXP1
1
8
V+
DXP2
2
7
SCL
DXP3
3
6
SDA
DXN
4
5
GND
TMP423-Q1 Pin Functions
PIN
TYPE
DESCRIPTION
NO.
NAME
1
DXP1
Analog input
Channel 1 positive connection to remote temperature sensor
2
DXP2
Analog input
Channel 2 positive connection to remote temperature sensor
3
DXP3
Analog input
Channel 3 positive connection to remote temperature sensor
4
DXN
Analog input
Common negative connection to remote temperature sensors, channel 1, channel 2, and channel 3
5
GND
Ground
6
SDA
Bidirectional digital input-output
Serial data line for SMBus, open-drain; requires pullup resistor to V+
7
SCL
Digital input
Serial clock line for SMBus, open-drain; requires pullup resistor to V+
8
V+
Power supply
4
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Ground
Positive supply voltage (2.7 V to 5.5 V)
Copyright © 2016, Texas Instruments Incorporated
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SBOS821 – NOVEMBER 2016
7 Specifications
7.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted) (1)
MIN
MAX
UNIT
7
V
Power supply, VS
Input voltage
Pins 1, 2, 3, and 4 only
–0.5
VS + 0.5
Pins 6 and 7 only
–0.5
7
Input current
Operational temperature
–55
Junction temperature, TJ max
Storage temperature, Tstg
(1)
–60
V
10
mA
127
°C
150
°C
130
°C
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.
7.2 ESD Ratings
VALUE
V(ESD)
(1)
Electrostatic discharge
Human-body model (HBM), per AEC Q100-002 (1)
±3000
Charged-device model (CDM), per AEC Q100-011
±750
UNIT
V
AEC Q100-002 indicates that HBM stressing shall be in accordance with the ANSI/ESDA/JEDEC JS-001 specification.
7.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)
MIN
MAX
UNIT
Temperature
–40
125
°C
Power-supply voltage
2.7
5.5
V
7.4 Thermal Information
TMP42x-Q1
THERMAL METRIC (1)
DCN (SOT-23)
UNIT
8 PINS
RθJA
Junction-to-ambient thermal resistance
147
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
115
°C/W
RθJB
Junction-to-board thermal resistance
33
°C/W
ψJT
Junction-to-top characterization parameter
38
°C/W
ψJB
Junction-to-board characterization parameter
33
°C/W
(1)
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report.
Copyright © 2016, Texas Instruments Incorporated
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7.5 Electrical Characteristics
at TA = –40°C to +125°C and V+ = 2.7 V to 5.5 V (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
TA = –40°C to +125°C
–2.5
±1.25
2.5
TA = 15°C to 85°C, V+ = 3.3 V
–1.5
±0.25
1.5
TA = 15°C to 85°C, TD = –40°C to +150°C, V+ = 3.3 V
–1
±0.25
1
TA = –40°C to +100°C, TD = –40°C to +150°C, V+ = 3.3 V
–3
±1
3
TA = –40°C to +125°C, TD = –40°C to +150°C
–5
±3
5
–0.5
±0.2
0.5
°C/V
100
115
130
ms
TEMPERATURE ERROR
TELOCAL
Local temperature sensor
TEREMOTE
Remote temperature sensor (1)
Local and remote power-supply
sensitivity
PSS
V+ = 2.7 V to 5.5 V
°C
°C
TEMPERATURE MEASUREMENT
Conversion time (per channel)
Resolution
Local temperature sensor (programmable)
12
Remote temperature sensor
12
High, series resistance = 3 kΩ maximum
Remote sensor source currents
120
Medium high
60
Medium low
12
Low
Remote transistor ideality factor
η
Bits
μA
6
TMP42x-Q1 optimized ideality factor
1.008
SMBus INTERFACE
VIH
Logic input high voltage (SCL, SDA)
VIL
Logic input low voltage (SCL, SDA)
2.1
Hysteresis
500
SMBus output low sink current
VOL
V
0.8
6
SDA output low voltage
IOUT = 6 mA
Logic input current
0 ≤ VIN ≤ 6 V
V
mV
mA
0.15
–1
0.4
V
1
μA
DIGITAL INPUTS
Input capacitance
VIH
Input logic high voltage
VIL
Input logic low voltage
IIN
Leakage input current
3
pF
0.7(V+)
(V+)+0.5
–0.5
0.3(V+)
V
1
μA
5.5
V
0 V ≤ VIN ≤ V+
V
POWER SUPPLY
V+
Specified voltage range
2.7
0.0625 conversions per second
Eight conversions per second
IQ
Quiescent current
UVLO
Undervoltage lockout
POR
Power-on-reset threshold
(1)
6
Serial bus inactive, shutdown mode
32
38
μA
400
525
μA
3
10
μA
Serial bus active, fS = 400 kHz, shutdown mode
90
Serial bus active, fS = 3.4 MHz, shutdown mode
350
2.3
μA
μA
2.4
2.6
V
1.6
2.3
V
Tested with less than 5-Ω effective series resistance and 100-pF differential input capacitance.
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7.6 Timing Requirements
at –40°C to +125°C and V+ = 2.7 V to 5.5 V (unless otherwise noted); values are based on statistical analysis of samples
tested during initial release
FAST MODE
HIGH-SPEED MODE
MIN
MAX
MIN
MAX
0.4
0.001
2.56
UNIT
f(SCL)
SCL operating frequency
0.001
t(BUF)
Bus free time between STOP and START condition
1300
160
ns
t(HD;STA)
Hold time after repeated START condition.
After this period, the first clock is generated.
600
160
ns
t(SU;STA)
Repeated START condition setup time
600
160
ns
t(SU;STO)
STOP condition setup time
600
160
t(HD;DAT)
Data hold time
25
t(VD.DAT)
Data valid time (data response time)
t(SU;DAT)
Data setup time
t(LOW)
See
(2)
(1)
900
MHz
ns
5
90
ns
Not applicable
ns
100
10
ns
SCL clock LOW period
1300
250
ns
t(HIGH)
SCL clock HIGH period
600
tF – SDA
Data fall time
300
150
ns
tF – SCL
Clock fall time
300
40
ns
tR
Clock, data rise time
ns
1000
Serial bus timeout
(1)
(2)
60
25
35
ns
25
35
ms
The maximum tHD;DAT can be 0.9 μs for Fast-Mode, and is less than the maximum tVD;DAT by a transition time.
tVDDATA = time for data signal from SCL LOW to SDA output (HIGH to LOW, depending on which is worse).
tLOW
tF
tHIGH
tR
VIH
SCL
VIL
tHD;STA
tBUF
tHD;DAT
tVD;DAT
tSU;STA
tSU;DAT
tSU;STO
VIH
SDA
VIL
P
S
S
P
Figure 1. Two-Wire Timing Diagram
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7.7 Typical Characteristics
at TA = 25°C and V+ = 5 V (unless otherwise noted)
3
V+ = 3.3V
TREMOTE = +25°C
2
30 Typical Units Shown
h = 1.008
1
0
-1
-2
2
1
0
-1
-2
-3
-3
-50
0
-25
25
50
75
100
125
-50
-25
Ambient Temperature, TA (°C)
0
25
100
125
Figure 3. Local Temperature Error vs Temperature
20
1.5
Remote Temperature Error (°C)
40
R - GND
0
R - V+
-20
-40
V+ = 2.7V
1.0
0.5
0
V+ = 5.5V
-0.5
-1.0
-1.5
-2.0
-60
0
5
10
15
20
25
30
0
500
1000
1500
Leakage Resistance (MW )
2000
2500
3000
3500
RS ( W )
Figure 4. Remote Temperature Error vs Leakage Resistance
Figure 5. Remote Temperature Error vs Series Resistance
(Diode-Connected Transistor, 2N3906 PNP)
2.0
3
1.5
V+ = 2.7V
1.0
0.5
V+ = 5.5V
0
-0.5
-1.0
-1.5
-2.0
Remote Temperature Error (°C)
Remote Temperature Error (°C)
75
2.0
60
2
1
0
-1
-2
-3
0
500
1000
1500
2000
2500
3000
3500
0
0.5
1.0
Figure 6. Remote Temperature Error vs Series Resistance
(GND Collector-Connected Transistor, 2N3906 PNP)
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1.5
2.0
2.5
3.0
Capacitance (nF)
RS (W)
8
50
Ambient Temperature, TA (°C)
Figure 2. Remote Temperature Error vs Temperature
Remote Temperature Error (°C)
50 Units Shown
V+ = 3.3V
Local Temperature Error (°C)
Remote Temperature Error (°C)
3
Figure 7. Remote Temperature Error vs Differential
Capacitance
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Typical Characteristics (continued)
at TA = 25°C and V+ = 5 V (unless otherwise noted)
25
15
10
450
400
350
5
IQ (mA)
Temperature Error (°C)
500
Local 100mVPP Noise
Remote 100mVPP Noise
Local 250mVPP Noise
Remote 250mVPP Noise
20
0
-5
300
200
-10
150
-15
100
-20
50
5
10
V+ = 2.7V
0
0.0625
-25
0
V+ = 5.5V
250
15
0.125
Frequency (MHz)
Figure 8. Temperature Error vs Power-Supply Noise
Frequency
0.5
1
2
4
8
Figure 9. Quiescent Current vs Conversion Rate
500
8
450
7
400
6
350
5
300
250
IQ (mA)
IQ (mA)
0.25
Conversion Rate (conversions/sec)
V+ = 5.5V
200
4
3
150
2
100
1
50
V+ = 3.3V
0
0
1k
10k
100k
1M
10M
2.5
3.0
3.5
4.0
4.5
5.0
5.5
SCL CLock Frequency (Hz)
V+ (V)
Figure 10. Shutdown Quiescent Current vs SCL Clock
Frequency
Figure 11. Shutdown Quiescent Current vs Supply Voltage
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8 Detailed Description
8.1 Overview
The TMP421-Q1 is a two-channel digital temperature sensor that combines a local die temperaturemeasurement channel and a remote-junction temperature-measurement channel, and is available in an 8-pin
SOT-23 package. The TMP422-Q1 (three-channel), and TMP423-Q1 (four-channel) are digital temperature
sensors that combine a local die temperature measurement channel and two or three remote junction
temperature measurement channels, respectively, in a single 8-pin SOT-23 package. These devices are twowire- and SMBus interface-compatible and are specified over a temperature range of –40°C to +125°C. The
TMP421-Q1, TMP422-Q1, and TMP423-Q1 each contain multiple registers for holding configuration information
and temperature measurement results.
For proper remote temperature sensing operation, the TMP421-Q1 requires only a transistor connected between
DXP and DXN pins. If the remote channel is not utilized, DXP can be left open or tied to GND.
The TMP422-Q1 requires transistors connected between DX1 and DX2 and between DX3 and DX4. Unused
channels on the TMP422-Q1 must be connected to GND. The TMP423-Q1 requires a transistor connected to
each positive channel (DXP1, DXP2, and DXP3), with the base of each channel tied to the common negative,
DXN. For an unused channel, the TMP423-Q1 DXP pin can be left open or tied to GND.
8.2 Functional Block Diagram
V+
8
A1 3
A0 4
Serial
Interface
SCL 7
Register
Bank
SDA 6
Oscillator
V+
Control
Logic
20 × I
Local
Thermal BJT
5×I
2×I
I
MUX
M
U
X
DXP 1
DXN 2
ADC
Voltage
Reference
5
GND
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Figure 12. The TMP421-Q1 Supports Multiple Slave Addresses and a Single Remote Diode Input
10
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Functional Block Diagram (continued)
V+
8
SCL 7
Serial
Interface
SDA 6
Register
Bank
Oscillator
V+
Control
Logic
Local
Thermal BJT
20 × I
2×I
5×I
I
MUX
M
U
X
DX1 1
DX2 2
ADC
DX3 3
Voltage
Reference
DX4 4
5
GND
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Figure 13. The TMP422-Q1 With Four Possible Remote Diode Inputs
V+
8
SCL 7
Serial
Interface
Register
Bank
SDA 6
Oscillator
V+
Control
Logic
Local
Thermal BJT
20 × I
5×I
2×I
I
MUX
M
U
X
DXP1 1
DXP2 2
ADC
DXP3 3
Voltage
Reference
DXN 4
5
GND
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Figure 14. The TMP423-Q1 With Three Remote Diode Inputs
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8.3 Feature Description
8.3.1 Temperature Measurement Data
Temperature measurement data can be taken over an operating range of –40°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
TMP421-Q1, TMP422-Q1, and TMP423-Q1 for the extended temperature range, as described as follows.
Temperature data that result from conversions within the default measurement range are represented in binary
form, as shown in Table 1, 2s Complement Standard Binary column. Note that although the device is rated to
only measure temperatures down to –55°C, the device can read temperatures below this level. However, 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 TMP421-Q1, TMP422-Q1, and TMP423-Q1 are rated only for ambient temperatures
ranging from –40°C to +125°C. Parameters in the Absolute Maximum Ratings table must be observed.
Table 1. Temperature Data Format (Local and Remote Temperature High Bytes)
TEMPERATURE
(°C)
(1)
(2)
12
LOCAL/REMOTE TEMPERATURE REGISTER
HIGH BYTE VALUE (1°C RESOLUTION)
2s COMPLEMENT 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
Resolution is 1°C/count. Negative numbers are represented in 2s-complement format.
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 the both the local and
remote channels is 0.0625°C, and is not adjustable.
Table 2. Decimal Fraction Temperature Data Format (Local and Remote Temperature Low Bytes)
TEMPERATURE REGISTER LOW BYTE VALUE
(0.0625°C RESOLUTION) (1)
TEMPERATURE
(°C)
(1)
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
0.9385
1111 0000
F0
Resolution is 0.0625°C/count. All possible values are shown.
8.3.2 Remote Sensing
The TMP421-Q1, TMP422-Q1, and TMP423-Q1 are designed to be used with either discrete transistors or
substrate transistors built into processor chips and ASICs. Either NPN or PNP transistors can be used, as long
as the base-emitter junction is used as the remote temperature sense. NPN transistors must be diodeconnected. PNP transistors can either be transistor- or diode-connected (see Figure 20, Figure 21, and
Figure 22).
8.3.3 Series Resistance Cancellation
Series resistance in an application circuit that typically results from printed circuit board (PCB) trace resistance
and remote line length is automatically cancelled by the TMP421-Q1, TMP422-Q1, and TMP423-Q1, preventing
what would otherwise result in a temperature offset. A total of up to 3 kΩ of series line resistance is cancelled by
the TMP421-Q1, TMP422-Q1, and TMP423-Q1, eliminating the need for additional characterization and
temperature offset correction. See the two Remote Temperature Error vs Series Resistance typical characteristic
curves (Figure 5 and Figure 6) for details on the effects of series resistance and power-supply voltage on sensed
remote temperature error.
8.3.4 Differential Input Capacitance
The TMP421-Q1, TMP422-Q1, and TMP423-Q1 tolerate differential input capacitance of up to 1000 pF with
minimal change in temperature error. The effect of capacitance on sensed remote temperature error is illustrated
in Figure 7, Remote Temperature Error vs Differential Capacitance.
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8.3.5 Filtering
Remote junction temperature sensors are usually implemented in a noisy environment. Noise is most often
created by fast digital signals, and can corrupt measurements. The TMP421-Q1, TMP422-Q1, and TMP423-Q1
have a built-in 65-kHz filter on the inputs of DXP and DXN (TMP421-Q1 and TMP423-Q1), or on the inputs of
DX1 through DX4 (TMP422-Q1), to minimize the effects of noise. However, a bypass capacitor placed
differentially across the inputs of the remote temperature sensor is recommended to make the application more
robust against unwanted coupled signals. The value of this capacitor must be between 100 pF and 1 nF. Some
applications attain better overall accuracy with additional series resistance; however, this increased accuracy is
application-specific. When series resistance is added, the total value must not be greater than 3 kΩ. If filtering is
needed, suggested component values are 100 pF and 50 Ω on each input; exact values are application-specific.
8.3.6 Sensor Fault
The TMP421-Q1 can sense a fault at the DXP input resulting from incorrect diode connection. The TMP421-Q1,
TMP422-Q1, and TMP423-Q1 can all 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 must be ignored.
When not using the remote sensor with the TMP421-Q1, the DXP and DXN inputs must be connected together
to prevent meaningless fault warnings. When not using a remote sensor with the TMP422-Q1, connect the DX
pins (see Table 4) such that DXP connections are grounded and DXN connections are left open (unconnected).
Unused TMP423-Q1 DXP pins can be left open or connected to GND.
8.3.7 Undervoltage Lockout
The TMP421-Q1, TMP422-Q1, and TMP423-Q1 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 2.45 V (typical). The comparator output is continuously checked during
a conversion. The TMP421-Q1, TMP422-Q1, and TMP423-Q1 do not perform a temperature conversion if the
power supply is not valid. The PVLD bit (bit 1, see Table 6) of the individual Local/Remote Temperature Register
is set to 1 and the temperature result may be incorrect.
8.3.8 Timeout Function
The TMP421-Q1, TMP422-Q1, and TMP423-Q1 reset the serial interface if the SCL or SDA lines are held low for
30 ms (typical) between a START and STOP condition. If the TMP421-Q1, TMP422-Q1, and TMP423-Q1 are
holding the bus low, the device releases the bus and waits for a START condition. To avoid activating the
timeout function, a communication speed of at least 1 kHz must be maintained for the SCL operating frequency.
8.4 Device Functional Modes
8.4.1 Shutdown Mode (SD)
The TMP421-Q1, TMP422-Q1, and TMP423-Q1 Shutdown Mode allows the user to save maximum power by
shutting down all device circuitry other than the serial interface, reducing current consumption to typically less
than 3 μA; see Figure 11, Shutdown Quiescent Current vs Supply Voltage. Shutdown Mode is enabled when the
SD bit (bit 6) of Configuration Register 1 is high; the device shuts down when the current conversion is
completed. When SD is low, the device maintains a continuous conversion state.
8.5 Programming
8.5.1 Serial Interface
The TMP421-Q1, TMP422-Q1, and TMP423-Q1 operate only as a slave device on the two-wire bus (I2C or
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 TMP421-Q1, TMP422-Q1, and TMP423-Q1 support the transmission protocol for fast (1 kHz to
400 kHz) and high-speed (1 kHz to 3.4 MHz) modes. All data bytes are transmitted MSB first.
14
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Programming (continued)
8.5.2 Bus Overview
The TMP421-Q1, TMP422-Q1, and TMP423-Q1 are SMBus or I2C 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 when 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 when SCL is high, because any change in SDA when SCL is high is interpreted
as a control signal.
When all data are transferred, the master generates a STOP condition. STOP is indicated by pulling SDA from
low to high, when SCL is high.
8.5.3 Bus Definitions
The TMP421-Q1, TMP422-Q1, and TMP423-Q1 are two-wire and SMBus-compatible. Figure 1 and Figure 15 to
Figure 17 describe the timing for various operations on the TMP421-Q1, TMP422-Q1, and TMP423-Q1.
Parameters for Figure 1 are defined in Timing Requirements. 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 when the SCL line is high defines a
START condition. Each data transfer initiates with a START condition. Denoted as S in Figure 1.
Stop Data Transfer A change in the state of the SDA line from low to high when the SCL line is high defines a
STOP condition. Each data transfer terminates with a repeated START or STOP condition.
Denoted as P in Figure 1.
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 transmitted by the slave.
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Programming (continued)
1
9
9
1
SCL
¼
SDA
1
0
0
1
1
0(1)
0
R/W
Start By
Master
P7
P6
P5
P4
P3
P2
P1
ACK By
TMP42x-Q1
P0
¼
ACK By
TMP42x-Q1
Frame 2 Pointer Register Byte
Frame 1 Two-Wire Slave Address Byte
9
1
SCL
(Continued)
SDA
(Continued)
D7
D6
D5
D4
D3
D2
D1
D0
ACK By
TMP42x-Q1
Stop By
Master
Frame 3 Data Byte 1
(1)
Slave address 1001100 shown.
Figure 15. Two-Wire Timing Diagram for Write Word Format
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
TMP42x-Q1
ACK By
TMP42x-Q1
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
D4
D3
ACK By
TMP42x-Q1
Frame 3 Two-Wire Slave Address Byte
D2
D1
D0
From
TMP42x-Q1
¼
NACK By
Master(2)
Frame 4 Data Byte 1 Read Register
(1)
Slave address 1001100 shown.
(2)
The master must leave the SDA high to terminate a single-byte read operation.
Figure 16. Two-Wire Timing Diagram for Single-Byte Read Format
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Programming (continued)
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
TMP42x-Q1
ACK By
TMP42x-Q1
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
D4
D3
ACK By
TMP42x-Q1
Frame 3 Two-Wire Slave Address Byte
1
D2
D1
D0
From
TMP42x-Q1
¼
ACK By
Master
Frame 4 Data Byte 1 Read Register
9
SCL
(Continued)
SDA
(Continued)
D7
D6
D5
D4
D3
D2
From
TMP42x-Q1
D1
D0
NACK By
Master(2)
Stop By
Master
Frame 5 Data Byte 2 Read Register
(1)
Slave address 1001100 shown.
(2)
The master must leave the SDA high to terminate a two-byte read operation.
Figure 17. Two-Wire Timing Diagram for Two-Byte Read Format
8.5.4 Serial Bus Address
To communicate with the TMP421-Q1, TMP422-Q1, and TMP423-Q1, 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.
8.5.5 Two-Wire Interface Slave Device Addresses
The TMP421-Q1 supports nine slave device addresses and the TMP422-Q1 supports four slave device
addresses. The TMP423-Q1 has one of two factory-preset slave addresses.
The slave device address for the TMP421-Q1 is set by the A1 and A0 pins according to Table 3.
The slave device address for the TMP422-Q1 is set by the connections between the external transistors and the
TMP422-Q1 according to Figure 18 and Table 4. If one of the channels is unused, the respective DXP
connection must be connected to GND, and the DXN connection must be left unconnected. The polarity of the
transistor for external channel 2 (pins 3 and 4) sets the least significant bit of the slave address. The polarity of
the transistor for external channel 1 (pins 1 and 2) sets the next least significant bit of the slave address.
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Programming (continued)
Table 3. TMP421-Q1 Slave Address Options
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
Table 4. TMP422-Q1 Slave Address Options
TWO-WIRE SLAVE ADDRESS
DX1
DX2
DX3
DX4
1001 100
DXP1
DXN1
DXP2
DXN2
1001 101
DXP1
DXN1
DXN2
DXP2
1001 110
DXN1
DXP1
DXP2
DXN2
1001 111
DXN1
DXP1
DXN2
DXP2
SCL
SDA
V+
DX1
Q0
Q1
V+
DX2
SCL
DX3
SDA
DX4
GND
DX1
Q2
Q3
Address = 1001100
V+
DX2
SCL
DX3
SDA
DX4
GND
Address = 1001101
DX1
Q4
Q5
V+
DX2
SCL
DX3
SDA
DX4
GND
DX1
Q6
Q7
Address = 1001110
V+
DX2
SCL
DX3
SDA
DX4
GND
Address = 1001111
Figure 18. TMP422-Q1 Connections for Device Address Setup
The TMP422-Q1 checks the polarity of the external transistor at power-on, or after software reset, by forcing
current to pin 1 when connecting pin 2 to approximately 0.6 V. If the voltage on pin 1 does not pull up to near the
V+ of the TMP422-Q1, pin 1 functions as DXP for channel 1, and the second LSB of the slave address is 0. If the
voltage on pin 1 does pull up to near V+, the TMP422-Q1 forces current to pin 2 when connecting pin 1 to 0.6 V.
If the voltage on pin 2 does not pull up to near V+, the TMP422-Q1 uses pin 2 for the DXP of channel 1, and sets
the second LSB of the slave address to 1. If both pins are shorted to GND or if both pins are open, the TMP422Q1 uses pin 1 as the DXP and sets the address bit to 0. This process is then repeated for channel 2 (pins 3 and
4).
If the TMP422-Q1 is to be used with transistors that are located on another device (such as a CPU, DSP, or
graphics processor), Pin 1 or pin 3 are recommended to be used as the DXP to ensure correct address
detection. If the other device has a lower supply voltage or is not powered when the TMP422-Q1 tries to detect
the slave address, a protection diode can turn on during the detection process and the TMP422-Q1 can
incorrectly choose the DXP pin and corresponding slave address. Using pin 1 or pin 3 for transistors that are on
other devices ensures the correct operation independent of supply sequencing or levels.
The TMP423-Q1 has a factory-preset slave address. The TMP423A-Q1 slave address is 1001100b, and the
TMP423B-Q1 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.
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8.5.6 Read and Write Operations
Accessing a particular register on the TMP421-Q1, TMP422-Q1, and TMP423-Q1 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 TMP421-Q1, TMP422-Q1, and TMP423-Q1
requires a value for the Pointer Register (see Figure 15).
When reading from the TMP421-Q1, TMP422-Q1, and TMP423-Q1, 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 which register is
read 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 17 for details of this sequence. If repeated reads from the same
register are desired, the Pointer Register bytes do not have to be continually sent because the TMP421-Q1,
TMP422-Q1, and TMP423-Q1 retain the Pointer Register value until that value is changed by the next write
operation. Note that register bytes are sent MSB first, followed by the LSB.
Read operations must 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 must 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 must leave SDA high during the Acknowledge time of the second
byte read from the slave.
8.5.7 High-Speed Mode
In order for the two-wire bus to operate at frequencies above 400 kHz, the master device must issue a HighSpeed mode (Hs-mode) master code (0000 1xxx) as the first byte after a START condition to switch the bus to
high-speed operation. The TMP421-Q1, TMP422-Q1, and TMP423-Q1 do not 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
3.4 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 TMP421-Q1, TMP422-Q1, and TMP423-Q1 switch the input and
output filters back to fast mode operation.
8.5.8 One-Shot Conversion
When the TMP421-Q1, TMP422-Q1, and TMP423-Q1 are in shutdown mode (SD = 1 in the Configuration
Register 1), a single conversion is started on all enabled channels by writing any value to the One-Shot Start
Register, pointer address 0Fh. This write operation starts one conversion; the TMP421-Q1, TMP422-Q1, and
TMP423-Q1 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 TMP421-Q1, TMP422-Q1, and TMP423-Q1. When the TMP421Q1, TMP422-Q1, and TMP423-Q1 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.
8.5.9 η-Factor Correction Register
The TMP421-Q1, TMP422-Q1, and TMP423-Q1 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
describes this voltage and temperature.
VBE2 - VBE1 =
hkT
I
ln 2
q
I1
(1)
The value η in Equation 1 is a characteristic of the particular transistor used for the remote channel. The poweron reset value for the TMP421-Q1, TMP422-Q1, and TMP423-Q1 is η = 1.008. The value in the η-Factor
Correction Register can be used to adjust the effective η-factor according to Equation 2 and Equation 3.
heff =
1.008 ´ 300
300 - NADJUST
(2)
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300 ´ 1.008
heff
(3)
The η-correction value must be stored in two's-complement format, yielding an effective data range from –128 to
+127. The n-correction value can be written to and read from pointer address 21h. The η-correction value for the
second remote channel (TMP422-Q1 and TMP423-Q1) can be written and read from pointer address 22h. The ηcorrection value for the third remote channel (TMP423-Q1 only) can be written to and read from pointer address
23h. The register power-on reset value is 00h, thus having no effect unless the register is written to.
8.5.10 Software Reset
The TMP421-Q1, TMP422-Q1, and TMP423-Q1 can 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 TMP421-Q1, TMP422Q1, and TMP423-Q1 registers as well as aborts any conversion in process. The TMP421-Q1, TMP422-Q1, and
TMP423-Q1 also support reset via the two-wire general call address (0000 0000). The General Call Reset
section contains more information.
Table 5. η-Factor Range
NADJUST
η
BINARY
HEX
DECIMAL
0111 1111
7F
127
1.747977
0000 1010
0A
10
1.042759
0000 1000
08
8
1.035616
0000 0110
06
6
1.028571
0000 0100
04
4
1.021622
0000 0010
02
2
1.014765
0000 0001
01
1
1.011371
0000 0000
00
0
1.008
1111 1111
FF
–1
1.004651
1111 1110
FE
–2
1.001325
1111 1100
FC
–4
0.994737
1111 1010
FA
–6
0.988235
1111 1000
F8
–8
0.981818
1111 0110
F6
–10
0.975484
1000 0000
80
–128
0.706542
8.5.11 General Call Reset
The TMP421-Q1, TMP422-Q1, and TMP423-Q1 support reset via the two-wire General Call address 00h (0000
0000b). The TMP421-Q1, TMP422-Q1, and TMP423-Q1 acknowledge the General Call address and respond to
the second byte. If the second byte is 06h (0000 0110b), the TMP421-Q1, TMP422-Q1, and TMP423-Q1
execute a software reset. This software reset restores the power-on reset state to all TMP421-Q1, TMP422-Q1,
and TMP423-Q1 registers, and aborts any conversion in progress. The TMP421-Q1, TMP422-Q1, and TMP423Q1 take no action in response to other values in the second byte.
8.5.12 Identification Registers
The TMP421-Q1, TMP422-Q1, and TMP423-Q1 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 TMP421-Q1, TMP422-Q1, and TMP423-Q1 each return 55h for the
manufacturer code. The TMP421-Q1 returns 21h for the device ID; the TMP422-Q1 returns 22h for the device
ID; and the TMP423-Q1 returns 23h for the device ID. These registers are read-only.
20
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8.6 Register Maps
The TMP421-Q1, TMP422-Q1, and TMP423-Q1 contain multiple registers for holding configuration information,
temperature measurement results, and status information. These registers are described in Figure 19 and
Table 6.
8.6.1 Pointer Register
Figure 19 shows the internal register structure of the TMP421-Q1, TMP422-Q1, and TMP423-Q1. The 8-bit
Pointer Register is used to address a given data register. The Pointer Register identifies which of the data
registers must 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 6 describes the pointer address of the TMP421-Q1, TMP422-Q1, and TMP423-Q1
registers. The power-on reset (POR) value of the Pointer Register is 00h (0000 0000b).
Pointer Register
Local and Remote Temperature Registers
Status Register
SDA
Configuration Registers
I/O
Control
Interface
One-Shot Start Register
Conversion Rate Register
SCL
N-Factor Correction Registers
Identification Registers
Software Reset
Figure 19. Internal Register Structure
Table 6. Register Map
POINTER
(HEX)
POR (HEX)
00
REGISTER DESCRIPTION
7
6
5
4
3
2
1
0
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) (3)
03
00
RT11
RT10
RT9
RT8
RT7
RT6
RT5
RT4
Remote Temperature 3
(High Byte) (1) (3)
BUSY
0
0
0
0
0
0
0
Status Register
0
SD
0
0
0
RANGE
0
0
Configuration Register 1
REN
LEN
RC
0
0
Configuration Register 2
08
09
00
0A
1C/3C (2)/
7C (3)
0B
07
0F
(1)
(2)
(3)
(4)
BIT DESCRIPTION
0
REN3
(3)
REN2
(2) (3)
0
0
0
0
0
R2
R1
R0
X
X
X
X
X
X
X
X
Conversion Rate Register
One-Shot Start (4)
Local Temperature (Low Byte)
10
00
LT3
LT2
LT1
LT0
0
0
PVLD
0
11
00
RT3
RT2
RT1
RT0
0
0
PVLD
OPEN
Remote Temperature 1 (Low Byte)
12
00
RT3
RT2
RT1
RT0
0
0
PVLD
OPEN
Remote Temperature 2
(Low Byte) (2) (3)
13
00
RT3
RT2
RT1
RT0
0
0
PLVD
OPEN
Remote Temperature 3 (Low Byte) (3)
21
00
NC7
NC6
NC5
NC4
NC3
NC2
NC1
NC0
N Correction 1
22
00
NC7
NC6
NC5
NC4
NC3
NC2
NC1
NC0
N Correction 2 (2)
23
00
NC7
NC6
NC5
NC4
NC3
NC2
NC1
NC0
N Correction 3 (3)
(3)
Compatible with Two-Byte Read; see Figure 17.
TMP422-Q1.
TMP423-Q1.
X = undefined. Writing any value to this register initiates a one-shot start; see the One-Shot Conversion section.
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Register Maps (continued)
Table 6. Register Map (continued)
POINTER
(HEX)
POR (HEX)
FC
FE
55
FF
(5)
21
BIT DESCRIPTION
REGISTER DESCRIPTION
7
6
5
4
3
2
1
0
X
X
X
X
X
X
X
X
Software Reset (5)
0
1
0
1
0
1
0
1
Manufacturer ID
0
0
1
0
0
0
0
1
TMP421-Q1 Device ID
0
0
1
0
0
0
1
0
TMP422-Q1 Device ID
0
0
1
0
0
0
1
1
TMP423-Q1 Device ID
X = undefined. Writing any value to this register initiates a software reset; see the Software Reset section.
8.6.2 Temperature Registers
The TMP421-Q1, TMP422-Q1, and TMP423-Q1 have multiple 8-bit registers that hold temperature measurement
results. The local channel and each of the remote channels 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 TMP422-Q1, the second remote channel high byte address is 02h; the
second remote channel low byte is 12h. The TMP 423 uses the same local and remote address as the TMP421Q1 and TMP422-Q1, with the third remote channel high byte of 03h; the third remote channel low byte is 13h.
These registers are read-only and are updated by the ADC each time a temperature measurement is completed.
The TMP421-Q1, TMP422-Q1, and TMP423-Q1 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 assurance remains valid only until another register is read. For proper operation, the high byte of a
temperature register must be read first. The low byte register must be read in the next read command. The low
byte register can be left unread if the LSBs are not needed. Alternatively, the temperature registers can 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, and 03h for the third
remote channel). 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.
8.6.3 Status Register
The Status Register reports the state of the temperature ADCs. Table 7 summarizes 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; BUSY is set to 0 if the ADC is not converting.
Table 7. Status Register Format
STATUS REGISTER ( READ = 08h, WRITE = NA)
BIT #
BIT NAME
POR VALUE
(1)
22
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
FOR TMP421-Q1 AND TMP423-Q1: BUSY changes to 1 almost immediately (< 100 μs) following power-up, when the TMP421-Q1 and
TMP423-Q1 begin the first temperature conversion. BUSY is high whenever the TMP421-Q1 and TMP423-Q1 convert a temperature
reading.
FOR TMP422-Q1: The BUSY bit changes to 1 approximately 1 ms following power-up. BUSY is high whenever the TMP422-Q1
converts a temperature reading.
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8.6.4 Configuration Register 1
Configuration Register 1 (pointer address 09h) sets the temperature range and controls the shutdown mode. The
Configuration Register is set by writing to pointer address 09h and read by reading from pointer address 09h.
Table 8 summarizes the bits of Configuration Register 1.
The shutdown (SD) bit (bit 6) enables or disables the temperature measurement circuitry. If SD = 0, the TMP421Q1, TMP422-Q1, and TMP423-Q1 convert continuously at the rate set in the conversion rate register. When SD
is set to 1, the TMP421-Q1, TMP422-Q1, and TMP423-Q1 stop converting when the current conversion
sequence is complete and enter a shutdown mode. When SD is set to 0 again, the TMP421-Q1, TMP422-Q1,
and TMP423-Q1 resume continuous conversions. When SD = 1, a single conversion can be started by writing to
the One-Shot Register. See the One-Shot Conversion section for more information.
The temperature range is set by configuring the RANGE bit (bit 2) of the Configuration Register. Setting this bit
low configures the TMP421-Q1, TMP422-Q1, and TMP423-Q1 for the standard measurement range (–40°C to
+127°C); temperature conversions are stored in the standard binary format. Setting bit 2 high configures the
TMP421-Q1, TMP422-Q1, and TMP423-Q1 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 8. Configuration Register 1 Bit Descriptions
CONFIGURATION REGISTER 1 (Read/Write = 09h, POR = 00h)
FUNCTION
POWER-ON RESET
VALUE
Reserved
—
0
6
SD
0 = Run
1 = Shut Down
0
5, 4, 3
Reserved
—
0
2
Temperature Range
0 = –40°C to +127°C
1 = –55°C to +150°C
0
1, 0
Reserved
—
0
BIT
NAME
7
8.6.5 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 disabled. Table 9
summarizes the bits of Configuration Register 2.
The RC bit (bit 2) 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 must
be enabled for most applications. However, disabling the resistance correction can yield slightly improved
temperature measurement noise performance, and reduce conversion time by about 50%, which can lower
power consumption when conversion rates of two per second or less are selected.
The LEN bit (bit 3) 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 (bit 4) enables external temperature measurement for channel 1. If REN = 1, the first external
channel is enabled; if REN = 0, the external channel is disabled.
For the TMP422-Q1 and TMP423-Q1 only, the REN2 bit (bit 5) enables the second external measurement
channel. If REN2 = 1, the second external channel is enabled; if REN2 = 0, the second external channel is
disabled.
For the TMP423-Q1 only, the REN3 bit (bit 6) enables the third external measurement channel. If REN3 = 1, the
third external channel is enabled; if REN3 = 0, the third external channel is disabled.
The temperature measurement sequence is: local channel, external channel 1, external channel 2, external
channel 3, 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 bypassed in the sequence.
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Table 9. Configuration Register 2 Bit Descriptions
CONFIGURATION REGISTER 2 (Read/Write = 0Ah, POR = 1Ch for TMP421-Q1; 3Ch for TMP422-Q1; 7Ch for TMP423-Q1)
POWER-ON RESET
VALUE
BIT
NAME
FUNCTION
7
Reserved
—
0
6
REN3
0 = External channel 3 disabled
1 = External channel 3 enabled
1 (TMP423-Q1)
0 (TMP421-Q1,
TMP422-Q1)
5
REN2
0 = External channel 2 disabled
1 = External channel 2 enabled
1 (TMP422-Q1,
TMP423-Q1)
0 (TMP421-Q1)
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
8.6.6 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 TMP421-Q1, TMP422-Q1, and TMP423-Q1 power dissipation to be balanced with the temperature
register update rate. Table 10 describes 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 10. Conversion Rate Register
CONVERSION RATE REGISTER (Read/Write = 0Bh, POR = 07h)
(1)
(2)
24
R7
R6
R5
R4
R3
R2
R1
R0
CONVERSIONS/SEC
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
AVERAGE IQ (TYP) (μA)
V+ = 2.7 V
V+ = 5.5 V
0.0625
11
32
1
0.125
17
38
1
0
0.25
28
49
0
1
1
0.5
47
69
0
1
0
0
1
80
103
0
1
0
1
2
128
155
(1)
190
220
373
413
0
0
0
0
0
1
1
0
4
0
0
0
0
0
1
1
1
8 (2)
Conversion rate shown is for only one or two enabled measurement channels. When three channels are enabled, the conversion rate is
2 and 2/3 conversions-per-second. When four channels are enabled, the conversion rate is 2 per second.
Conversion rate shown is for only one enabled measurement channel. When two channels are enabled, the conversion rate is 4
conversions-per-second. When three channels are enabled, the conversion rate is 2.667 conversions-per-second. When four channels
are enabled, the conversion rate is 2 conversions-per-second.
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9 Application and Implementation
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
9.1 Application Information
The TMP42x-Q1 require a transistor connected between the DXP and DXN pins for remote temperature
measurement. The SDA (and SCL if driven by an open-drain output) require pulllup resistors as part of the
communication bus. The TMP421-Q1 includes slave address select pins (A1 and A0) allowing more than one
device to reside on the same bus.
9.2 Typical Applications
9.2.1 TMP421-Q1 Basic Connections
The TMP421-Q1, TMP422-Q1, and TMP423-Q1 SCL and SDA interface pins each require pull-up resistors as
part of the communication bus. A 0.1-μF power-supply bypass capacitor is recommended for local bypassing.
Figure 20, Figure 21, and Figure 22 illustrate typical configurations for the TMP421-Q1, TMP422-Q1, and
TMP423-Q1, respectively.
+5 V
Transistor-connected configuration(1):
0.1 mF
Series Resistance
RS(2)
RS(2)
8
1
CDIFF(3)
2
3
4
Diode-connected configuration(1):
V+
SCL
DXP
DXN TMP421-Q1 SDA
10 kW
(typ)
10 kW
(typ)
7
SMBus
Controller
6
A1
A0
GND
5
RS(2)
RS(2)
CDIFF(3)
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(1)
Diode-connected configuration provides better settling time. Transistor-connected configuration provides better series
resistance
cancellation.
(2)
RS (optional) must be < 1.5 kΩ in most applications. Selection of RS depends on application; see the Filtering section.
(3)
CDIFF (optional) must be < 1000 pF in most applications. Selection of CDIFF depends on application; see the Filtering
section and
Figure 7, Remote Temperature Error vs Differential Capacitance.
Figure 20. TMP421-Q1 Basic Connections
9.2.1.1 Design Requirements
The TMP421-Q1, TMP422-Q1, and TMP423-Q1 are designed to be used with either discrete transistors or
substrate transistors built into processor chips, field programmable gate arrays (FPGAs) and application-specific
integrated circuits (ASICs). Either NPN or PNP 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
transistor or diode-connected.
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Errors in remote temperature sensor readings are typically the consequence of the ideality factor and current
excitation used by the TMP421-Q1, TMP422-Q1, and TMP423-Q1 versus the manufacturer-specified operating
current for a given transistor. Some manufacturers specify a high-level and low-level current for the temperaturesensing substrate transistors. The TMP421-Q1, TMP422-Q1, and TMP423-Q1 use 6 μA for ILOW and 120 μA for
IHIGH.
The ideality factor (η-factor) is a measured characteristic of a remote temperature sensor diode as compared to
an ideal diode. The TMP421-Q1, TMP422-Q1, and TMP423-Q1 allow for different η-factor values; see the ηFactor Correction Register section.
The ideality factor for the TMP421-Q1, TMP422-Q1, and TMP423-Q1 is trimmed to be 1.008. For transistors that
have an ideality factor that does not match the TMP421-Q1, TMP422-Q1, and TMP423-Q1, Equation 4 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 =
h - 1.008
´ (273.15 + T(°C))
1.008
where
•
•
•
•
η = ideality factor of remote temperature sensor
T(°C) = actual temperature
TERR = error in TMP421-Q1, TMP422-Q1, and TMP423-Q1 because η ≠ 1.008
Degree delta is the same for °C and K
(4)
For η = 1.004 and T (°C) = 100°C:
æ 1.004 - 1.008 ö
TERR = ç
÷ ´ 273.15 + 100°C
1.008
è
ø
TERR = 1.48°C
(5)
If a discrete transistor is used as the remote temperature sensor with the TMP421-Q1, TMP422-Q1, and
TMP423-Q1, the best accuracy can be achieved by selecting the transistor according to the following criteria:
1. Base-emitter voltage > 0.25 V at 6 μA, at the highest sensed temperature.
2. Base-emitter voltage < 0.95 V at 120 μA, at the lowest sensed temperature.
3. Base resistance < 100 Ω.
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).
9.2.1.2 Detailed Design Procedure
The local temperature sensor inside the TMP421-Q1, TMP422-Q1, and TMP423-Q1 is influenced by the ambient
air around the device but mainly monitors the PCB temperature that it is mounted to. In most applications, the
TMP421-Q1, TMP422-Q1, and TMP423-Q1 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
TMP421-Q1, TMP422-Q1, and TMP423-Q1 is measuring. Additionally, the internal power dissipation of the
TMP421-Q1, TMP422-Q1, and TMP423-Q1 can cause the temperature to rise above the ambient or PCB
temperature. The internal power is negligible because of the small current drawn by TMP421-Q1, TMP422-Q1,
and TMP423-Q1 (see the Measurement Accuracy and Thermal Considerations section for more details).
For this design example a diode connected 2N3906 transistor was used thus the default setting of the n-factor
and offset can be used.
26
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9.2.1.3 Application Curve
The following curve shows the typical accuracy of the TMP421-Q1, TMP422-Q1, and TMP423-Q1 when
connected to a 2N3906 remote transistor. All three TMP421-Q1, TMP422-Q1, and TMP423-Q1 will have the
same performance and have identical design requirements when it comes to the accuracy of the remote sensor.
Remote Temperature Error (°C)
3
V+ = 3.3V
TREMOTE = +25°C
2
30 Typical Units Shown
h = 1.008
1
0
-1
-2
-3
-50
0
-25
25
50
75
100
125
Ambient Temperature, TA (°C)
9.2.2 TMP422-Q1 Basic Connections
+5V
Transistor-connected configuration(1):
0.1 mF
Series Resistance
RS(2)
DXP1
RS(2)
8
1
CDIFF(3)
2
DXN1
RS
(2)
SCL
DX2(4)
SDA
10 kW
(typ)
7
SMBus
Controller
6
TMP422-Q1
RS(2)
DXP2
V+
DX1(4)
10 kW
(typ)
3
CDIFF
DX3(4)
(3)
DXN2
4
DX4(4)
GND
5
Diode-connected configuration(1):
RS(2)
RS(2)
CDIFF(3)
Copyright © 2016, Texas Instruments Incorporated
(1)
Diode-connected configuration provides better settling time. Transistor-connected configuration provides better series
resistance
cancellation.
(2)
RS (optional) must be < 1.5 kΩ in most applications. Selection of RS depends on application; see the Filtering section.
(3)
CDIFF (optional) must be < 1000 pF in most applications. Selection of CDIFF depends on application; see the Filtering
section and
Figure 7, Remote Temperature Error vs Differential Capacitance.
(4)
TMP422-Q1 SMBus slave address is 1001 100 when connected as shown.
Figure 21. TMP422-Q1 Basic Connections
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9.2.3 TMP423-Q1 Basic Connections
+5V
(1)
Transistor-connected configuration :
8
RS(2)
RS
(2)
RS(2)
RS(2)
RS(2)
1
CDIFF
V+
2
10 kW
(typ)
7
DXP1
SCL
DXP2
SDA 6
SMBus
Controller
(3)
CDIFF(3)
TMP423-Q1
3
CDIFF(3)
RS(2)
10 kW
(typ)
0.1 mF
Series Resistance
4
DXP3
DXN
GND
5
Diode-connected configuration(1):
RS(2)
DXP
RS(2)
CDIFF(3)
DXN
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(1)
Diode-connected configuration provides better settling time. Transistor-connected configuration provides better series
resistance
cancellation.
(2)
RS (optional) must be < 1.5 kΩ in most applications. Selection of RS depends on application; see the Filtering section.
(3)
CDIFF (optional) must be < 1000 pF in most applications. Selection of CDIFF depends on application; see the Filtering
section and
Figure 7, Remote Temperature Error vs Differential Capacitance.
Figure 22. TMP423-Q1 Basic Connections
28
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10 Power Supply Recommendations
The TMP421-Q1, TMP422-Q1, and TMP423-Q1 operates with a power-supply range of 2.7 V to 5.5 V. The
device is optimized for operation at a 3.3 V supply but can measure temperature accurately in the full supply
range. TI recommends a power-supply bypass capacitor. 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 0.1 μF. Applications with noisy
or high-impedance power supplies may require additional decoupling capacitors to reject power-supply noise.
11 Layout
11.1 Layout Guidelines
Remote temperature sensing on the TMP421-Q1, TMP422-Q1, and TMP423-Q1 measures very small voltages
using very low currents; therefore, noise at the device inputs must be minimized. Most applications using the
TMP421-Q1, TMP422-Q1, and TMP423-Q1 have high digital content, with several clocks and logic level
transitions creating a noisy environment. Layout must adhere to the following guidelines:
1. Place the TMP421-Q1, TMP422-Q1, and TMP423-Q1 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 23. If a multilayer PCB is used, bury these traces between ground
or V+ planes to shield them from extrinsic noise sources. 5 mil (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 0.1-μF local bypass capacitor directly between the V+ and GND of the TMP421-Q1, TMP422-Q1, and
TMP423-Q1; see Figure 24. Minimize filter capacitance between DXP and DXN to 1000 pF or less for
optimum measurement performance. This capacitance includes any cable capacitance between the remote
temperature sensor and the TMP421-Q1, TMP422-Q1, and TMP423-Q1.
5. If the connection between the remote temperature sensor and the TMP421-Q1, TMP422-Q1, and TMP423Q1 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 TMP421-Q1, TMP422-Q1, and TMP423-Q1 as possible. Leave
the remote sensor connection end of the shield wire open to avoid ground loops and 60-Hz pickup.
6. Thoroughly clean and remove all flux residue in and around the pins of the TMP421-Q1, TMP422-Q1, and
TMP423-Q1 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
top, if possible.
DXN
GND
NOTE: Use minimum 5 mil (0.127mm) traces with 5 mil spacing.
Figure 23. Suggested PCB Layer Cross-Section
Copyright © 2016, Texas Instruments Incorporated
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29
TMP421-Q1, TMP422-Q1, TMP423-Q1
SBOS821 – NOVEMBER 2016
www.ti.com
11.2 Layout Example
0.1-mF Capacitor
DXP
1
8
DXN
2
A1
A0
0.1-mF Capacitor
GND
GND
PCB Via
PCB Via
V+
DX1
1
8
7
DX2
2
7
3
6
DX3
3
6
4
5
DX4
4
5
TMP421-Q1
V+
TMP422-Q1
0.1-mF Capacitor
GND
PCB Via
DXP1
1
8
DXP2
2
7
DXP3
3
6
DXN
4
5
V+
TMP423-Q1
Figure 24. Suggested Bypass Capacitor Placement and Trace Shielding
11.3 Measurement Accuracy and Thermal Considerations
The temperature measurement accuracy of the TMP421-Q1, TMP422-Q1, and TMP423-Q1 depends on the
remote and 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 is a delay in the response of the sensor to a temperature change in the system. For remote
temperature-sensing applications using a substrate transistor (or a small, SOT-23 transistor) placed close to the
device being monitored, this delay is usually not a concern.
The local temperature sensor inside the TMP421-Q1, TMP422-Q1, and TMP423-Q1 monitors the ambient air
around the device. The thermal time constant for the TMP421-Q1, TMP422-Q1, and TMP423-Q1 is
approximately two seconds. This constant implies that if the ambient air changes quickly by 100°C, then the
TMP421-Q1, TMP422-Q1, and TMP423-Q1 requires approximately 10 seconds (that is, five thermal time
constants) to settle to within 1°C of the final value. In most applications, the TMP421-Q1, TMP422-Q1, and
TMP423-Q1 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 TMP421-Q1, TMP422-Q1, and
TMP423-Q1 is measuring. Additionally, the internal power dissipation of the TMP421-Q1, TMP422-Q1, and
TMP423-Q1 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 5.5-V supply and maximum conversion rate of eight conversions per second, the TMP421-Q1, TMP422Q1, and TMP423-Q1 dissipate 2.3 mW (PDIQ = 5.5 V × 415 μA). A θJA of 100°C/W (for SOT-23 package) causes
the junction temperature to rise approximately 0.23°C above the ambient.
30
Submit Documentation Feedback
Copyright © 2016, Texas Instruments Incorporated
Product Folder Links: TMP421-Q1 TMP422-Q1 TMP423-Q1
TMP421-Q1, TMP422-Q1, TMP423-Q1
www.ti.com
SBOS821 – NOVEMBER 2016
12 Device and Documentation Support
12.1 Related Links
The table below lists quick access links. Categories include technical documents, support and community
resources, tools and software, and quick access to sample or buy.
Table 11. Related Links
PARTS
PRODUCT FOLDER
SAMPLE & BUY
TECHNICAL
DOCUMENTS
TOOLS &
SOFTWARE
SUPPORT &
COMMUNITY
TMP421-Q1
Click here
Click here
Click here
Click here
Click here
TMP422-Q1
Click here
Click here
Click here
Click here
Click here
TMP423-Q1
Click here
Click here
Click here
Click here
Click here
12.2 Receiving Notification of Documentation Updates
To receive notification of documentation updates, navigate to the device product folder on ti.com. In the upper
right corner, click on Alert me to register and receive a weekly digest of any product information that has
changed. For change details, review the revision history included in any revised document.
12.3 Community Resources
The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective
contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of
Use.
TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration
among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help
solve problems with fellow engineers.
Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and
contact information for technical support.
12.4 Trademarks
E2E is a trademark of Texas Instruments.
SMBus is a trademark of Intel Corporation.
All other trademarks are the property of their respective owners.
12.5 Electrostatic Discharge Caution
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.
12.6 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
13 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.
Copyright © 2016, Texas Instruments Incorporated
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Product Folder Links: TMP421-Q1 TMP422-Q1 TMP423-Q1
31
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)
TMP421AQDCNRQ1
ACTIVE
SOT-23
DCN
8
3000
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 125
421Q
TMP421AQDCNTQ1
ACTIVE
SOT-23
DCN
8
250
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 125
421Q
TMP422AQDCNRQ1
ACTIVE
SOT-23
DCN
8
3000
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 125
422Q
TMP422AQDCNTQ1
ACTIVE
SOT-23
DCN
8
250
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 125
422Q
TMP423AQDCNRQ1
ACTIVE
SOT-23
DCN
8
3000
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 125
423Q
TMP423AQDCNTQ1
ACTIVE
SOT-23
DCN
8
250
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 125
423Q
(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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