Texas Instruments TMP421, TMP422, TMP423A, TMP423B Schematic [ru]

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+5V

SCL

GND

SDA

V+

SMBus

Controller

TMP421

DXP

DXN

1ChannelLocal

1ChannelRemote

TMP422

DX1

DX2

DX3

DX4

1ChannelLocal

2ChannelsRemote

TMP423

DXP1

DXP2

DXP3

DXN

1ChannelLocal

3ChannelsRemote

TMP421 TMP422

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SBOS398B – JULY 2007 – REVISED MARCH 2008

TMP423

± 1 ° C Remote and Local TEMPERATURE SENSOR

in SOT23-8

FEATURES DESCRIPTION

234

• SOT23-8 PACKAGE

• ± 1 ° C REMOTE DIODE SENSOR (MAX)

• ± 1.5 ° C LOCAL TEMPERATURE SENSOR (MAX)

• SERIES RESISTANCE CANCELLATION

• n-FACTOR CORRECTION integral part of microcontrollers, microprocessors, or

• TWO-WIRE/ SMBus™ SERIAL INTERFACE

• MULTIPLE INTERFACE ADDRESSES

• DIODE FAULT DETECTION

• RoHS COMPLIANT AND NO Sb/Br

APPLICATIONS

• PROCESSOR/FPGA TEMPERATURE

MONITORING

• LCD/ DLP

• SERVERS

• CENTRAL OFFICE TELECOM EQUIPMENT

• STORAGE AREA NETWORKS (SAN)

/LCOS PROJECTORS

The TMP421, TMP422, and TMP423 are remote 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

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 TMP421, TMP422, and TMP423 include series resistance cancellation, programmable non-ideality factor, wide remote temperature measurement range (up to +150 ° C), and diode fault detection.

The TMP421, TMP422, and TMP423 are all available in a SOT23-8 package.

2 DLP is a registered trademark of Texas Instruments. 3 SMBus is a trademark of Intel Corporation. 4 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.

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.

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TMP421 TMP422 TMP423

SBOS398B – JULY 2007 – REVISED MARCH 2008

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

PRODUCT DESCRIPTION ADDRESS PACKAGE-LEAD DESIGNATOR MARKING

TMP421 Remote Junction 100 11xx SOT23-8 DCN DACI

TMP422 Remote Junction 100 11xx SOT23-8 DCN DADI

TMP423A Triple Channel 100 1100 SOT23-8 DCN DAEI TMP423B 100 1101 SOT23-8 DCN DAFI

(1) 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

Single Channel

Temperature Sensor

Dual Channel

Temperature Sensor

Remote Junction

Temperature Sensor

(1)

TWO-WIRE PACKAGE PACKAGE

(1)

Over operating free-air temperature range, unless otherwise noted.

TMP421, TMP422, TMP423 UNIT

Power Supply, V

Input Voltage

Input Current 10 mA Operating Temperature Range – 55 to +127 ° C Storage Temperature Range – 60 to +130 ° C Junction Temperature (T

ESD Rating Charged Device Model (CDM) 1000 V

(1) 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.

Pins 1, 2, 3, and 4 only – 0.5 to VS+ 0.5 V Pins 6 and 7 only – 0.5 to 7 V

max) +150 ° C

Human Body Model (HBM) 3000 V

Machine Model (MM) 200 V

+7 V

Product Folder Link(s): TMP421 TMP422 TMP423

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TMP421 TMP422 TMP423

SBOS398B – JULY 2007 – REVISED MARCH 2008

ELECTRICAL CHARACTERISTICS

At TA= – 40 ° C to +125 ° C and VS= 2.7V to 5.5V, unless otherwise noted.

TMP421, TMP422, TMP423

PARAMETER CONDITIONS MIN TYP MAX UNIT

TEMPERATURE ERROR

Local Temperature Sensor TE

Remote Temperature Sensor

vs Supply (Local/Remote) VS= 2.7V to 5.5V ± 0.2 ± 0.5 ° C/V

TEMPERATURE MEASUREMENT

Conversion Time (per channel) 100 115 130 ms Resolution

Local Temperature Sensor (programmable) 12 Bits Remote Temperature Sensor 12 Bits

Remote Sensor Source Currents

High Series Resistance 3k Ω Max 120 µ A Medium High 60 µ A Medium Low 12 µ A Low 6 µ A

Remote Transistor Ideality Factor η TMP421/22/23 Optimized Ideality Factor 1.008

SMBus INTERFACE

Logic Input High Voltage (SCL, SDA) V Logic Input Low Voltage (SCL, SDA) V Hysteresis 500 mV SMBus Output Low Sink Current 6 mA SDA Output Low Voltage V Logic Input Current 0 ≤ VIN≤ 6V – 1 +1 µ A SMBus Input Capacitance (SCL, SDA) 3 pF SMBus Clock Frequency 3.4 MHz SMBus Timeout 25 30 35 ms SCL Falling Edge to SDA Valid Time 1 µ s

DIGITAL INPUTS

Input Capacitance 3 pF Input Logic Levels

Input High Voltage V Input Low Voltage V Leakage Input Current I

POWER SUPPLY

Specified Voltage Range V Quiescent Current I

Undervoltage Lockout UVLO 2.3 2.4 2.6 V Power-On Reset Threshold POR 1.6 2.3 V

TEMPERATURE RANGE

Specified Range – 40 +125 ° C Storage Range – 60 +130 ° C Thermal Resistance, SOT23 θ

(1)

LOCAL

REMOTE

TA= +15 ° C to +85 ° C, TD= – 40 ° C to +150 ° C, VS= 3.3V ± 0.25 ± 1 ° C

TA= – 40 ° C to +100 ° C, TD= – 40 ° C to +150 ° C, VS= 3.3V ± 1 ± 3 ° C

TA= – 40 ° C to +125 ° C, TD= – 40 ° C to +150 ° C ± 3 ± 5 ° C

Serial Bus Active, fS= 400kHz, Shutdown Mode 90 µ A Serial Bus Active, fS= 3.4MHz, Shutdown Mode 350 µ A

(1) Tested with less than 5 Ω effective series resistance and 100pF differential input capacitance.

TA= – 40 ° C to +125 ° C ± 1.25 ± 2.5 ° C

TA= +15 ° C to +85 ° C, VS= 3.3V ± 0.25 ± 1.5 ° C

2.1 V

0.8 V

= 6mA 0.15 0.4 V

OUT

0.7(V+) (V+)+0.5 V – 0.5 0.3(V+) V

0V ≤ VIN≤ V

0.0625 Conversions per Second 32 38 µ A Eight Conversions per Second 400 525 µ A

Serial Bus Inactive, Shutdown Mode 3 10 µ A

2.7 5.5 V

100 ° C/W

1 µ A

Product Folder Link(s): TMP421 TMP422 TMP423

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V+

SCL

GND

DXP

DXN

SDA

TMP421

V+

SCL

GND

DX1

DX2

DX3

DX4

SDA

TMP422

TMP421 TMP422 TMP423

SBOS398B – JULY 2007 – REVISED MARCH 2008

TMP421 PIN CONFIGURATION

DCN PACKAGE

SOT23-8

(TOP VIEW)

TMP421 PIN ASSIGNMENTS

TMP421

NO. NAME DESCRIPTION

1 DXP 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)

TMP422 PIN CONFIGURATION

DCN PACKAGE

SOT23-8

(TOP VIEW)

TMP422 PIN ASSIGNMENTS

TMP422

NO. NAME DESCRIPTION

1 DX1 Channel 1 remote temperature sensor connection pin. Also sets the TMP422 address; see Table 10 . 2 DX2 Channel 1 remote temperature sensor connection pin. Also sets the TMP422 address; see Table 10 . 3 DX3 Channel 2 remote temperature sensor connection pin. Also sets the TMP422 address; see Table 10 . 4 DX4 Channel 2 remote temperature sensor connection pin. Also sets the TMP422 address; see Table 10 . 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)

Product Folder Link(s): TMP421 TMP422 TMP423

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V+

SCL

GND

DXP1

DXP2

DXP3

DXN

SDA

TMP423

SBOS398B – JULY 2007 – REVISED MARCH 2008

TMP423 PIN CONFIGURATION

DCN PACKAGE

SOT23-8

(TOP VIEW)

TMP423 PIN ASSIGNMENTS

TMP423

NO. NAME DESCRIPTION

1 DXP1 Channel 1 positive connection to remote temperature sensor. 2 DXP2 Channel 2 positive connection to remote temperature sensor. 3 DXP3 Channel 3 positive connection to remote temperature sensor. 4 DXN Common negative connection to remote temperature sensors, Channel 1, Channel 2, Channel 3. 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)

TMP421 TMP422 TMP423

Product Folder Link(s): TMP421 TMP422 TMP423

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-1

-2

-3

AmbientTemperature,T ( C)°

-50 -25 1251007550250

RemoteTemperatureError( C)°

V =3.3V

T =+25 C

REMOTE

30TypicalUnitsShown h =1.008

LocalTemperatureError( )

°C

AmbientTemperature,T (A°C)

-1

-2

-3

-50 125-25 0 25 50 75 100

50UnitsShown

V =3.3V

-20

-40

-60

LeakageResistance(M )W

0 5 10 15 20 25 30

RemoteT

emperatureError( C)°

R GND-

R V-

RemoteTemperatureError( )

°C

R W( )

2.0

1.5

1.0

0.5

-0.5

-1.0

-1.5

-2.0

0 3500500 1000 1500 2000 2500 3000

V =2.7V

V =5.5V

-1

-2

-3

Capacitance(nF)

0 0.5 1.0 1.5 2.0 2.5 3.0

RemoteTemperatureError( C)°

RemoteTemperatureError( )

°C

R (W)

2.0

1.5

1.0

0.5

-0.5

-1.0

-1.5

-2.0

0 3500500 1000 1500 2000 2500 3000

V =2.7V

V =5.5V

TMP421 TMP422 TMP423

SBOS398B – JULY 2007 – REVISED MARCH 2008

REMOTE TEMPERATURE ERROR LOCAL TEMPERATURE ERROR

vs TEMPERATURE vs TEMPERATURE

TYPICAL CHARACTERISTICS

At TA= +25 ° C and VS= +5.0V, unless otherwise noted.

Figure 1. Figure 2.

REMOTE TEMPERATURE ERROR REMOTE TEMPERATURE ERROR vs SERIES RESISTANCE

vs LEAKAGE RESISTANCE (Diode-Connected Transistor, 2N3906 PNP)

Figure 3. Figure 4.

REMOTE TEMPERATURE ERROR vs SERIES RESISTANCE REMOTE TEMPERATURE ERROR

(GND Collector-Connected Transistor, 2N3906 PNP) vs DIFFERENTIAL CAPACITANCE

Figure 5. Figure 6.

Product Folder Link(s): TMP421 TMP422 TMP423

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500

450

400

350

300

250

200

150

100

ConversionRate(conversions/sec)

0.0625 0.125 0.25 0.5 1 2 4 8

I (mA)

V =2.7V

V =5.5V

-5

-10

-15

-20

-25

Frequency(MHz)

0 5 10 15

TemperatureError( C)°

Local100mV Noise

Remote100mV Noise

Local250mV Noise

Remote250mV Noise

500

450

400

350

300

250

200

150

100

SCLCLockFrequency(Hz)

1k 10k 100k 1M 10M

( A)m

V =3.3V

V =5.5V

I ( )

V (SV)

4.53.0 3.5 4.0 5.55.02.5

TYPICAL CHARACTERISTICS (continued)

At TA= +25 ° C and VS= +5.0V, unless otherwise noted.

TMP421 TMP422 TMP423

SBOS398B – JULY 2007 – REVISED MARCH 2008

vs POWER-SUPPLY NOISE FREQUENCY vs CONVERSION RATE

TEMPERATURE ERROR QUIESCENT CURRENT

Figure 7. Figure 8.

SHUTDOWN QUIESCENT CURRENT SHUTDOWN QUIESCENT CURRENT

vs SCL CLOCK FREQUENCY vs SUPPLY VOLTAGE

Figure 9. Figure 10.

Product Folder Link(s): TMP421 TMP422 TMP423

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0.1 Fm

10kW (typ)

TMP421

DXP

DXN

V+

(2)

DIFF

(3)

DIFF

(3)

(2)

GND

SCL

SDA

+5V

SMBus

Controller

Diode-connectedconfiguration :

(1)

SeriesResistance

Transistor-connectedconfiguration :

(1)

TMP421 TMP422 TMP423

SBOS398B – JULY 2007 – REVISED MARCH 2008

APPLICATION INFORMATION

The TMP421 (two-channel), TMP422 (three-channel), The TMP422 requires transistors connected between and TMP423 (four-channel) are digital temperature DX1 and DX2 and between DX3 and DX4. Unused sensors that combine a local die temperature channels on the TMP422 must be connected to GND. measurement channel and one, two, or three remote The TMP423 requires a transistor connected to each junction temperature measurement channels in a positive channel (DXP1, DXP2, and DXP3), with the single SOT23-8 package. These devices are base of each channel tied to the common negative, two-wire- and SMBus interface-compatible and are DXN. For an unused channel, the TMP423 DXP pin specified over a temperature range of – 40 ° C to can be left open or tied to GND. +125 ° C. The TMP421/22/23 each contain multiple registers for holding configuration information and temperature measurement results.

For proper remote temperature sensing operation, the recommended for local bypassing. Figure 11 shows a TMP421 requires only a transistor connected typical configuration for the TMP421; Figure 12 between DXP and DXN pins. If the remote channel is illustrates a typical application for the TMP422. not utilized, DXP can be left open or tied to GND. Figure 13 illustrates a typical application for the

The TMP421/22/23 SCL and SDA interface pins each require pull-up resistors as part of the communication bus. A 0.1 µ F power-supply bypass capacitor is

TMP423.

(1) Diode-connected configuration provides better settling time. Transistor-connected configuration provides better series resistance cancellation.

(2) RS(optional) should be < 1.5k Ω in most applications. Selection of RSdepends on application; see the Filtering section. (3) C

(optional) should be < 1000pF in most applications. Selection of C

DIFF

Figure 6 , Remote Temperature Error vs Differential Capacitance.

depends on application; see the Filtering section and

DIFF

Figure 11. TMP421 Basic Connections

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TMP422

DX1

(4)

DX2

(4)

(2)

DIFF

(3)

DIFF

(3)

(2)

GND

Diode-connectedconfiguration :

(1)

SeriesResistance

Transistor-connectedconfiguration :

(1)

DX3

(4)

DX4

(4)

(2)

DIFF

(3)

0.1 Fm

10kW (typ)

V+

SCL

SDA

+5V

SMBus

Controller

DXP1

DXN1

DXP2

DXN2

+5V

TMP423

DXP1

DXP2

DXP3

DXP

DXN

SCL

GND

SDA

V+

(2)

DIFF

(3)

DIFF

(3)

DIFF

(3)

Transistor-connectedconfiguration :

(1)

DIFF

(3)

(2)

Diode-connectedconfiguration :

(1)

0.1 Fm

10kW (typ)

SMBus

Controller

SeriesResistance

TMP421 TMP422 TMP423

SBOS398B – JULY 2007 – REVISED MARCH 2008

(1) Diode-connected configuration provides better settling time. Transistor-connected configuration provides better series resistance cancellation.

(2) RS(optional) should be < 1.5k Ω in most applications. Selection of RSdepends on application; see the Filtering section. (3) C

(optional) should be < 1000pF in most applications. Selection of C

DIFF

Figure 6 , Remote Temperature Error vs Differential Capacitance.

(4) TMP422 SMBus slave address is 1001 100 when connected as shown.

(1) Diode-connected configuration provides better settling time. Transistor-connected configuration provides better series resistance cancellation.

(2) RS(optional) should be < 1.5k Ω in most applications. Selection of RSdepends on application; see the Filtering section. (3) C

Figure 6 , Remote Temperature Error vs Differential Capacitance.

(optional) should be < 1000pF in most applications. Selection of C

DIFF

Figure 12. TMP422 Basic Connections

Figure 13. TMP423 Basic Connections

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DIFF

depends on application; see the Filtering section and

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TMP421 TMP422 TMP423

SBOS398B – JULY 2007 – REVISED MARCH 2008

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 TMP421/22/23, preventing what would otherwise result in a temperature offset. A total of up to 3k Ω of series line resistance is cancelled by the TMP421/22/23, eliminating the need for additional characterization and temperature offset correction. See the two Remote Temperature Error vs Series Resistance typical characteristic curves (Figure 4 and

Figure 5 ) for details on the effects of series resistance

and power-supply voltage on sensed remote temperature error.

DIFFERENTIAL INPUT CAPACITANCE

The TMP421/22/23 tolerate differential input capacitance of up to 1000pF with minimal change in temperature error. The effect of capacitance on sensed remote temperature error is illustrated in

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 TMP421/22/23 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)

LOCAL/REMOTE TEMPERATURE REGISTER

HIGH BYTE VALUE (1 ° C RESOLUTION)

TEMP

STANDARD BINARY

(1)

EXTENDED BINARY

Figure 6 , Remote Temperature Error vs Differential ( ° C) BINARY HEX BINARY HEX

Capacitance.

TEMPERATURE MEASUREMENT DATA

Temperature measurement data may 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 TMP421/22/23 for the extended temperature range, as described below.

Temperature data that result from conversions within the default measurement range are represented in binary form, as shown in Table 1 , Standard Binary column. Note that although the device is rated to only measure temperatures down to – 55 ° C, it may read temperatures below this level. However, any

– 64 1100 0000 C0 0000 0000 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

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

(1) Resolution is 1 ° C/count. Negative numbers are represented in

two's complement format.

(2) Resolution is 1 ° C/count. All values are unsigned with a – 64 ° C

changing bit 2 (RANGE) of Configuration Register 1 offset.

(2)

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One-ShotStartRegister

ConfigurationRegisters

StatusRegister

IdentificationRegisters

N-FactorCorrectionRegisters

ConversionRateRegister

LocalandRemoteTemperatureRegisters

SDA

SCL

PointerRegister

I/O

Control

Interface

SoftwareReset

TMP421 TMP422 TMP423

SBOS398B – JULY 2007 – REVISED MARCH 2008

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

TEMPERATURE REGISTER LOW BYTE VALUE

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

0.9385 1111 0000 F0

(1) Resolution is 0.0625 ° C/count. All possible values are shown.

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

= 1 and the second number by 16 The sum equals the decimal equivalent. 0111 0011b → 73h → (3 × 16

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)

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 less than the high byte (for instance, – 15 + 0.75 = – 14.25, not – 15.75).

1/2)

= 0.4375

Bytes)

+ (1 × 1/2)

(0.0625 ° C RESOLUTION)

= 16.

) + (7 × 16

+ (1 × 1/2)

Product Folder Link(s): TMP421 TMP422 TMP423

) = 115

+ (1 ×

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|)/(+1 ° C/count) = 20 → 14h → 0001 0100 Generate the two's complement of a negative

number by complementing the absolute value binary number and adding 1.

– 20 ° C is stored as 1110 1100 → ECh.

REGISTER INFORMATION

The TMP421/22/23 contain multiple registers for holding configuration information, temperature measurement results, and status information. These registers are described in Figure 14 and Table 3 .

POINTER REGISTER

Figure 14 shows the internal register structure of the

TMP421/22/23. 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 TMP421/22/23 registers. The power-on reset (POR) value of the Pointer Register is 00h (0000 0000b).

Figure 14. Internal Register Structure

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TMP421 TMP422 TMP423

SBOS398B – JULY 2007 – REVISED MARCH 2008

Table 3. Register Map

POINTER

(HEX) POR (HEX) 7 6 5 4 3 2 1 0 REGISTER DESCRIPTION

00 00 LT11 LT10 LT9 LT8 LT7 LT6 LT5 LT4 Local Temperature (High Byte) 01 00 RT11 RT10 RT9 RT8 RT7 RT6 RT5 RT4

02 00 RT11 RT10 RT9 RT8 RT7 RT6 RT5 RT4

03 00 RT11 RT10 RT9 RT8 RT7 RT6 RT5 RT4 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 0 REN3 0B 07 0 0 0 0 0 R2 R1 R0 Conversion Rate Register

0F X X X X X X X X One-Shot Start 10 00 LT3 LT2 LT1 LT0 0 0 PVLD 0 Local Temperature (Low Byte) 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 13 00 RT3 RT2 RT1 RT0 0 0 PLVD OPEN Remote Temperature 3 (Low Byte)

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 23 00 NC7 NC6 NC5 NC4 NC3 NC2 NC1 NC0 N Correction 3

FC X X X X X X X X Software Reset

FE 55 0 1 0 1 0 1 0 1 Manufacturer ID

FF 21 0 0 1 0 0 0 1 0 TMP422 Device ID

(1) Compatible with Two-Byte Read; see Figure 19 . (2) TMP422. (3) TMP423. (4) X = undefined. Writing any value to this register initiates a one-shot start; see the One-Shot Conversion section. (5) X = undefined. Writing any value to this register initiates a software reset; see the Software Reset section.

(2)

1C/3C

(3)

0 0 1 0 0 0 0 1 TMP421 Device ID

0 0 1 0 0 0 1 1 TMP423 Device ID

(3)

REN2

TEMPERATURE REGISTERS

The TMP421/22/23 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, 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 TMP421 and TMP422, 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.

BIT DESCRIPTION

Remote Temperature 1 (High Byte)

Remote Temperature 2 (High Byte)

Remote Temperature 3 (High Byte)

(2) (3)

REN LEN RC 0 0 Configuration Register 2

Remote Temperature 2 (Low Byte)

(2) (3)

The TMP421/22/23 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 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, 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.

(1)

(1) (2) (3)

(1) (3)

(4)

(3)

(2) (3) (3)

(5)

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STATUS REGISTER

The Status Register reports the state of the temperature ADCs. Table 4 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; 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 the shutdown mode. The Configuration Register is set by writing to pointer address 09h and read by reading from pointer address 09h. Table 5 summarizes the bits of Configuration Register 1.

The shutdown (SD) bit (bit 6) enables or disables the temperature measurement circuitry. If SD = '0', the TMP421/22/23 convert continuously at the rate set in the conversion rate register. When SD is set to '1', the TMP421/22/23 stop converting when the current conversion sequence is complete and enter a shutdown mode. When SD is set to '0' again, the TMP421/22/23 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 TMP421/22/23 for the standard measurement range ( – 40 ° C to +127 ° C); temperature conversions will be stored in the standard binary format. Setting bit 2 high configures the TMP421/22/23 for the extended measurement range ( – 55 ° C to +150 ° C); temperature conversions will be 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.

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.

Table 6 summarizes the bits of Configuration

Table 4. Status Register Format

STATUS REGISTER (Read = 08h, Write = NA)

BIT # D7 D6 D5 D4 D3 D2 D1 D0

BIT NAME BUSY 0 0 0 0 0 0 0

POR VALUE 0

(1) FOR TMP421/TMP423: The BUSY changes to '1' almost immediately (< 100 µ s) following power-up, as the TMP421/TMP423 begin the

first temperature conversion. It is high whenever the TMP421/TMP423 convert a temperature reading. FOR TMP422: The BUSY bit changes to '1' approximately 1ms following power-up. It is high whenever the TMP422 converts a temperature reading.

(1)

0 0 0 0 0 0 0

Table 5. Configuration Register 1 Bit Descriptions

CONFIGURATION REGISTER 1 (Read/Write = 09h, POR = 00h)

BIT NAME FUNCTION VALUE

7 Reserved — 0 6 SD 0

5, 4, 3 Reserved — 0

2 Temperature Range 0

1, 0 Reserved — 0

0 = Run

1 = Shut Down

0 = – 55 ° C to +127 ° C 1 = – 55 ° C to +150 ° C

POWER-ON RESET

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The RC bit (bit 2) enables the resistance correction For the TMP423 only, the REN3 bit (bit 6) enables feature for the external temperature channels. If RC = the third external measurement channel. If REN3 = '1', series resistance correction is enabled; if RC = '0', '1', the third external channel is enabled; if REN3 = resistance correction is disabled. Resistance '0', the third external channel is disabled. 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 (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 and TMP423 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.

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.

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 TMP421/22/23 power dissipation to be balanced with the temperature register update rate. Table 7 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 6. Configuration Register 2 Bit Descriptions

CONFIGURATION REGISTER 2 (Read/Write = 0Ah, POR = 1Ch for TMP421; 3Ch for TMP422; 7Ch for TMP423)

BIT NAME FUNCTION VALUE

7 Reserved — 0 6 REN3

5 REN2

4 REN 1

3 LEN 1

2 RC 1

1, 0 Reserved — 0

0 = External Channel 3 Disabled 1 (TMP423)

1 = External Channel 3 Enabled 0 (TMP421, TMP422)

0 = External Channel 2 Disabled 1 (TMP422, TMP423)

1 = External Channel 2 Enabled 0 (TMP421)

0 = External Channel 1 Disabled

1 = External Channel 1 Enabled

0 = Local Channel Disabled

1 = Local Channel Enabled

0 = Resistance Correction Disabled

1 = Resistance Correction Enabled

POWER-ON RESET

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BE2*VBE1

nkT

eff

1.008 300

300* N

ADJUST

+ 300 *

300 1.008

eff

TMP421 TMP422 TMP423

SBOS398B – JULY 2007 – REVISED MARCH 2008

Table 7. Conversion Rate Register

CONVERSION RATE REGISTER (Read/Write = 0Bh, POR = 07h)

AVERAGE IQ(TYP) ( µ A)

R7 R6 R5 R4 R3 R2 R1 R0 CONVERSIONS/SEC VS= 2.7V VS= 5.5V

0 0 0 0 0 0 0 0 0.0625 11 32 0 0 0 0 0 0 0 1 0.125 17 38 0 0 0 0 0 0 1 0 0.25 28 49 0 0 0 0 0 0 1 1 0.5 47 69 0 0 0 0 0 1 0 0 1 80 103 0 0 0 0 0 1 0 1 2 128 155 0 0 0 0 0 1 1 0 4 0 0 0 0 0 1 1 1 8

(1) 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.

(2) 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 and 2/3 conversions-per-second. When four channels are enabled, the conversion rate is 2 conversions-per-second.

(1) (2)

190 220 373 413

ONE-SHOT CONVERSION

When the TMP421/22/23 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 TMP421/22/23 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 TMP421/22/23. When the TMP421/22/23 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.

n-FACTOR CORRECTION REGISTER

The TMP421/22/23 allow for a different n-factor value to be used for converting remote channel measurements to temperature. The remote channel uses sequential current excitation to extract a differential V the temperature of the remote transistor. Equation 1 describes this voltage and temperature.

voltage measurement to determine

(1)

The value n in Equation 1 is a characteristic of the particular transistor used for the remote channel. The power-on reset value for the TMP421/22/23 is n =

1.008. The value in the n-Factor Correction Register may be used to adjust the effective n-factor according to Equation 2 and Equation 3 .

(2)

(3)

The n-correction value must be stored in two's-complement format, yielding an effective data range from – 128 to +127. The n-correction value may be written to and read from pointer address 21h. The n-correction value for the second remote channel (TMP422 and TMP423) may be written and read from pointer address 22h. The n-correction value for the third remote channel (TMP423 only) may 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.

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SOFTWARE RESET

The TMP421/22/23 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 TMP421/22/23 registers as well as aborts any conversion in process. The TMP421/22/23 also support reset via the two-wire general call address (0000 0000). The General Call Reset section contains more information.

Table 8. n-Factor Range

ADJUST

BINARY HEX DECIMAL n

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

GENERAL CALL RESET

The TMP421/22/23 support reset via the two-wire General Call address 00h (0000 0000b). The TMP421/22/23 acknowledge the General Call address and respond to the second byte. If the second byte is 06h (0000 0110b), the TMP421/22/23 execute a software reset. This software reset restores the power-on reset state to all TMP421/22/23 registers, and aborts any conversion in progress. The TMP421/22/23 take no action in response to other values in the second byte.

IDENTIFICATION REGISTERS

The TMP421/22/23 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 TMP421/22/23 each return 55h for the manufacturer code. The TMP421 returns 21h for the device ID; the TMP422 returns 22h for the device ID; and the TMP423 returns 23h for the device ID. These registers are read-only.

BUS OVERVIEW

The TMP421/22/23 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 TMP421/22/23 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 TMP421/22/23 support the transmission protocol for fast (1kHz to 400kHz) and high-speed (1kHz to

3.4MHz) modes. All data bytes are transmitted MSB first.

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DX1

DX2

DX3

DX4

SCL

SDA

V+

Address=1001100 Address=1001101 Address=1001110 Address=1001111

V+

SCL

SDA

GND

DX1

DX2

DX3

DX4

V+

SCL

SDA

GND

DX1

DX2

DX3

DX4

V+

SCL

SDA

GND

DX1

DX2

DX3

DX4

V+

SCL

SDA

GND

TMP421 TMP422 TMP423

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SERIAL BUS ADDRESS

To communicate with the TMP421/22/23, 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 TMP421 supports nine slave device addresses and the TMP422 supports four slave device addresses. The TMP423 has one of two factory-preset slave addresses.

The slave device address for the TMP421 is set by the A1 and A0 pins according to Table 9 .

The slave device address for the TMP422 is set by the connections between the external transistors and the TMP422 according to Figure 15 and Table 10 . If one of the channels is unused, the respective DXP connection should be connected to GND, and the

DXN connection should 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.

Table 9. TMP421 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 10. TMP422 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

Figure 15. TMP422 Connections for Device Address Setup

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The TMP422 checks the polarity of the external transistor at power-on, or after software reset, by forcing current to pin 1 while connecting pin 2 to approximately 0.6V. If the voltage on pin 1 does not pull up to near the V+ of the TMP422, 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 forces current to pin 2 while connecting pin 1 to 0.6V. If the voltage on pin 2 does not pull up to near V+, the TMP422 uses pin 2 for 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 TMP422 uses pin 1 as DXP and sets the address bit to '0'. This process is then repeated for channel 2 (pins 3 and 4).

If the TMP422 is to be used with transistors that are located on another IC (such as a CPU, DSP, or graphics processor), it is recommended to use pin 1 or pin 3 as DXP to ensure correct address detection. If the other IC has a lower supply voltage or is not powered when the TMP422 tries to detect the slave address, a protection diode may turn on during the detection process and the TMP422 may incorrectly choose the DXP pin and corresponding slave address. Using pin 1 and/or pin 3 for transistors that are on other ICs ensures correct operation independent of supply sequencing or levels.

The TMP423 has a factory-preset slave address. The TMP423A slave address is 1001100b, and the TMP423B 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 TMP421/22/23 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 TMP421/22/23 requires a value for the Pointer Register (see Figure 17 ).

When reading from the TMP421/22/23, 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 19 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 TMP421/22/23 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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SCL

SDA

(LOW)

(HDSTA)

(HDDAT)

(BUF)

(SUDAT)

(HIGH)

(SUSTA)

(SUSTO)

P S S P

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SBOS398B – JULY 2007 – REVISED MARCH 2008

TIMING DIAGRAMS

The TMP421/22/23 are two-wire and SMBus-compatible. Figure 16 to Figure 19 describe the timing for various operations on the

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.

TMP421/22/23. Parameters for Figure 16 are defined Acknowledge: Each receiving device, when in Table 11 . Bus definitions are: addressed, is obliged to generate an Acknowledge

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 initiates with a START condition. Denoted as S in

Figure 16 .

Stop Data Transfer: A change in the state of the

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.

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. Denoted as P in Figure 16 .

Figure 16. Two-Wire Timing Diagram

Table 11. Timing Characteristics for Figure 16

FAST MODE HIGH-SPEED MODE

PARAMETER MIN MAX MIN MAX UNIT

SCL Operating Frequency f Bus Free Time Between STOP and START Condition t Hold time after repeated START condition. After this period, the first clock

is generated. Repeated START Condition Setup Time t STOP Condition Setup Time t Data Hold Time t Data Setup Time t SCL Clock LOW Period t SCL Clock HIGH Period t Clock/Data Fall Time t Clock/Data Rise Time t

for SCL ≤ 100kHz t

(HDSTA)

(SUSTA) (SUSTO) (HDDAT) (SUDAT)

(LOW)

(HIGH)

(1) For cases with fall time of SCL less than 20ns and/or the rise or fall time of SDA less than 20ns, the hold time should be greater than

20ns.

(2) For cases with a fall time of SCL less than 10ns and/or the rise or fall time of SDA less than 10ns, the hold time should be greater than

10ns.

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0.001 0.4 0.001 3.4 MHz

(SCL) (BUF)

600 160 ns 100 100 ns 100 100 ns

100 100 ns

(1)

0 100 10 ns

1300 160 ns

600 60 ns

F R R

(2)

300 160 ns 300 160

1000

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Frame1Two-WireSlaveAddressByte

Frame2PointerRegisterByte

StartBy

Master

ACKBy

TMP421/22/23

ACKBy

TMP421/22/23

1 9 1

Frame3DataByte1

ACKBy

TMP421/22/23

SDA

(Continued)

SCL

(Continued)

D6 D5 D4 D3 D2 D1 D0

SDA

SCL

0 0 1 1 0 0

(1)

R/W P7 P6 P5 P4 P3 P2 P1 P0

StopBy

Master

Frame1Two-WireSlaveAddressByte Frame2PointerRegisterByte

StartBy

Master

ACKBy

TMP421/22/23

ACKBy

TMP421/22/23

Frame3Two-WireSlaveAddressByte Frame4DataByte1ReadRegister

StartBy

Master

ACKBy

TMP421/22/23

NACKBy

Master

(2)

From

TMP421/22/23

1 9 1

SDA

SCL

0 0 1 R/

W P7 P6 P5 P4 P3 P2 P1 P0

SDA

(Continued)

SCL

(Continued)

1 0 0 1

1 0 0

(1)

1 0 0

(1)

R/W D7 D6 D5 D4 D3 D2 D1 D0

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SBOS398B – JULY 2007 – REVISED MARCH 2008

(1) Slave address 1001100 shown.

Figure 17. Two-Wire Timing Diagram for Write Word Format

(1) Slave address 1001100 shown. (2) Master should leave SDA high to terminate a single-byte read operation.

Figure 18. Two-Wire Timing Diagram for Single-Byte Read Format

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Frame1Two-WireSlaveAddressByte Frame2PointerRegisterByte

StartBy

Master

ACKBy

TMP421/22/23

ACKBy

TMP421/22/23

Frame3Two-WireSlaveAddressByte Frame4DataByte1ReadRegister

StartBy

Master

ACKBy

TMP421/22/23

ACKBy

Master

From

TMP421/22/23

1 9 1

SDA

SCL

0 0 1 R/

W P7 P6 P5 P4 P3 P2 P1 P0

SDA

(Continued)

SCL

(Continued)

SDA

(Continued)

SCL

(Continued)

1 0 0 1

1 0 0

(1)

1 0 0

(1)

R/W D7 D6 D5 D4 D3 D2 D1 D0

Frame5DataByte2ReadRegister

StopBy

Master

NACKBy

Master

(2)

From

TMP421/22/23

D7 D6 D5 D4 D3 D2 D1 D0

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SBOS398B – JULY 2007 – REVISED MARCH 2008

(1) Slave address 1001100 shown. (2) Master should leave SDA high to terminate a two-byte read operation.

Figure 19. Two-Wire Timing Diagram for Two-Byte Read Format

HIGH-SPEED MODE TIMEOUT FUNCTION

In order for the two-wire bus to operate at frequencies The TMP421/22/23 reset the serial interface if either above 400kHz, the master device must issue a SCL or SDA are held low for 30ms (typical) between High-Speed mode (Hs-mode) master code (0000 a START and STOP condition. If the TMP421/22/23 1xxx) as the first byte after a START condition to are holding the bus low, the device releases the bus switch the bus to high-speed operation. The and waits for a START condition. To avoid activating TMP421/22/23 do not acknowledge this byte, but the timeout function, it is necessary to maintain a switch the input filters on SDA and SCL and the communication speed of at least 1kHz for the SCL output filter on SDA to operate in Hs-mode, allowing operating frequency. 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 TMP421/22/23 switch the input and output filters back to fast mode operation.

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ERR

n * 1.008

1.008

273.15) Tǒ°C

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SBOS398B – JULY 2007 – REVISED MARCH 2008

SHUTDOWN MODE (SD)

The TMP421/22/23 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 µ A; see

Figure 10 , 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 once the current conversion is completed. When SD is low, the device maintains a continuous conversion state.

SENSOR FAULT

The TMP421 can sense a fault at the DXP input resulting from incorrect diode connection. The TMP421/22/23 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 should be ignored.

When not using the remote sensor with the TMP421, the DXP and DXN inputs must be connected together to prevent meaningless fault warnings. When not using a remote sensor with the TMP422, the DX pins should be connected (refer to Table 10 ) such that DXP connections are grounded and DXN connections are left open (unconnected). Unused TMP423 DXP pins can be left open or connected to GND.

UNDERVOLTAGE LOCKOUT

The TMP421/22/23 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 TMP421/22/23 do not perform a temperature conversion if the power supply is not valid. The PVLD bit (bit 1, see Table 3 ) of the individual Local/Remote Temperature Register is set to '1' and the temperature result may be incorrect.

FILTERING

Remote junction temperature sensors are usually implemented in a noisy environment. Noise is most often created by fast digital signals, and it can corrupt measurements. The TMP421/22/23 have a built-in 65kHz filter on the inputs of DXP and DXN (TMP421/TMP423), or on the inputs of DX1 through

DX4 (TMP422), 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 should be between 100pF and 1nF. 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 should not be greater than 3k Ω . If filtering is needed, suggested component values are 100pF and 50 Ω on each input; exact values are application-specific.

REMOTE SENSING

The TMP421/22/23 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 diode-connected. PNP transistors can either be transistor- or diode-connected (see Figure 11 , Figure 12 , and

Figure 13 ).

Errors in remote temperature sensor readings are typically the consequence of the ideality factor and current excitation used by the TMP421/22/23 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 TMP421/22/23 use 6 µ A for I

The ideality factor ( n) is a measured characteristic of a remote temperature sensor diode as compared to an ideal diode. The TMP421/22/23 allow for different n-factor values; see the N-Factor Correction Register section.

The ideality factor for the TMP421/22/23 is trimmed to be 1.008. For transistors that have an ideality factor that does not match the TMP421/22/23,

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).

Where:

n = ideality factor of remote temperature sensor T( ° C) = actual temperature T

= error in TMP421/22/23 because n ≠ 1.008

ERR

Degree delta is the same for ° C and K

and 120 µ A for I

LOW

HIGH

(4)

Product Folder Link(s): TMP421 TMP422 TMP423

www.ti.com

ERR

1.004* 1.008

1.008

273.15) 100°C

ERR

+ 1.48°C

TMP421 TMP422 TMP423

SBOS398B – JULY 2007 – REVISED MARCH 2008

For n = 1.004 and T( ° C) = 100 ° C: 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 TMP421/22/23 dissipate 2.3mW (PD

If a discrete transistor is used as the remote temperature sensor with the TMP421/22/23, the best accuracy can be achieved by selecting the transistor according to the following criteria:

1. Base-emitter voltage > 0.25V at 6 µ A, at the highest sensed temperature.

2. Base-emitter voltage < 0.95V at 120 µ A, at the lowest sensed temperature.

3. Base resistance < 100 Ω .

4. Tight control of V small variations in h

Based on these criteria, two recommended small-signal transistors are the 2N3904 (NPN) or 2N3906 (PNP).

characteristics indicated by

(that is, 50 to 150).

MEASUREMENT ACCURACY AND THERMAL

(5)

415 µ A). A θ temperature to rise approximately +0.23 ° C above the ambient.

of 100 ° C/W causes the junction

LAYOUT CONSIDERATIONS

Remote temperature sensing on the TMP421/22/23 measures very small voltages using very low currents; therefore, noise at the IC inputs must be minimized. Most applications using the TMP421/22/23 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 TMP421/22/23 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; see

CONSIDERATIONS Figure 20 . If a multilayer PCB is used, bury these

The temperature measurement accuracy of the TMP421/22/23 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 using a substrate transistor (or a small, SOT23 transistor) placed close 4. Use a 0.1 µ F local bypass capacitor directly to the device being monitored, this delay is usually between the V+ and GND of the TMP421/22/23; not a concern. see Figure 21 . Minimize filter capacitance

The local temperature sensor inside the TMP421/22/23 monitors the ambient air around the device. The thermal time constant for the TMP421/22/23 is approximately two seconds. This constant implies that if the ambient air changes quickly by 100 ° C, it would take the TMP421/22/23 about 10 seconds (that is, five thermal time constants) to settle to within 1 ° C of the final value. In most applications, the TMP421/22/23 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 6. Thoroughly clean and remove all flux residue in temperature that the TMP421/22/23 is measuring. and around the pins of the TMP421/22/23 to Additionally, the internal power dissipation of the avoid temperature offset readings as a result of TMP421/22/23 can cause the temperature to rise leakage paths between DXP or DXN and GND, above the ambient or PCB temperature. The internal or between DXP or DXN and V+.

traces between ground or V them from extrinsic noise sources. 5 mil (0.127mm) 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.

between DXP and DXN to 1000pF or less for optimum measurement performance. This capacitance includes any cable capacitance between the remote temperature sensor and the TMP421/22/23.

5. If the connection between the remote temperature sensor and the TMP421/22/23 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 TMP421/22/23 as possible. Leave the remote sensor connection end of the shield wire open to avoid ground loops and 60Hz pickup.

planes to shield

= 5.5V ×

Product Folder Link(s): TMP421 TMP422 TMP423

www.ti.com

V+

DXP

DXN

GND

GroundorV+layer onbottomand/or top,ifpossible.

TMP421

0.1mFCapacitor

V+

GND

PCBVia

DXP

DXN

TMP422

0.1mFCapacitor

V+

GND

PCBVia

DX1

DX2

DX3

DX4

TMP423

0.1mFCapacitor

V+

GND

PCBVia

DXP1

DXP2

DXP3

DXN

TMP421 TMP422 TMP423

SBOS398B – JULY 2007 – REVISED MARCH 2008

NOTE: Use minimum 5 mil (0.127mm) traces with 5 mil spacing.

Figure 20. Suggested PCB Layer Cross-Section

Figure 21. Suggested Bypass Capacitor Placement and Trace Shielding

Product Folder Link(s): TMP421 TMP422 TMP423

PACKAGE OPTION ADDENDUM

www.ti.com

27-Mar-2008

PACKAGING INFORMATION

Orderable Device Status

(1)

Package

Type

Package

Drawing

Pins Package

Qty

Eco Plan

TMP421AIDCNR ACTIVE SOT-23 DCN 8 3000 Green (RoHS &

no Sb/Br)

TMP421AIDCNRG4 ACTIVE SOT-23 DCN 8 3000 Green (RoHS &

no Sb/Br)

TMP421AIDCNT ACTIVE SOT-23 DCN 8 250 Green (RoHS &

no Sb/Br)

TMP421AIDCNTG4 ACTIVE SOT-23 DCN 8 250 Green (RoHS &

no Sb/Br)

TMP422AIDCNR ACTIVE SOT-23 DCN 8 3000 Green (RoHS &

no Sb/Br)

TMP422AIDCNRG4 ACTIVE SOT-23 DCN 8 3000 Green (RoHS &

no Sb/Br)

TMP422AIDCNT ACTIVE SOT-23 DCN 8 250 Green (RoHS &

no Sb/Br)

TMP422AIDCNTG4 ACTIVE SOT-23 DCN 8 250 Green (RoHS &

no Sb/Br)

TMP423AIDCNR ACTIVE SOT-23 DCN 8 3000 Green (RoHS &

no Sb/Br)

TMP423AIDCNT ACTIVE SOT-23 DCN 8 250 Green (RoHS &

no Sb/Br)

TMP423BIDCNR ACTIVE SOT-23 DCN 8 3000 Green (RoHS &

no Sb/Br)

TMP423BIDCNT ACTIVE SOT-23 DCN 8 250 Green (RoHS &

no Sb/Br)

(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)

Lead/Ball Finish MSL Peak Temp

CU NIPDAU Level-2-260C-1 YEAR

(3)

(2)

Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check

http://www.ti.com/productcontent for the latest availability information and additional product content details.

TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements

for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material)

(3)

MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder

temperature.

Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.

Addendum-Page 1

PACKAGE OPTION ADDENDUM

www.ti.com

In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.

27-Mar-2008

Addendum-Page 2

PACKAGE MATERIALS INFORMATION

www.ti.com

TAPE AND REEL INFORMATION

13-May-2008

*All dimensions are nominal

Device Package

Type

TMP421AIDCNR SOT-23 DCN 8 3000 179.0 8.4 3.2 3.2 1.4 4.0 8.0 Q1 TMP421AIDCNT SOT-23 DCN 8 250 179.0 8.4 3.2 3.2 1.4 4.0 8.0 Q1 TMP422AIDCNR SOT-23 DCN 8 3000 179.0 8.4 3.2 3.2 1.4 4.0 8.0 Q1 TMP422AIDCNT SOT-23 DCN 8 250 179.0 8.4 3.2 3.2 1.4 4.0 8.0 Q1 TMP423AIDCNR SOT-23 DCN 8 3000 179.0 8.4 3.2 3.2 1.4 4.0 8.0 Q1 TMP423AIDCNT SOT-23 DCN 8 250 179.0 8.4 3.2 3.2 1.4 4.0 8.0 Q1 TMP423BIDCNR SOT-23 DCN 8 3000 179.0 8.4 3.2 3.2 1.4 4.0 8.0 Q1 TMP423BIDCNT SOT-23 DCN 8 250 179.0 8.4 3.2 3.2 1.4 4.0 8.0 Q1

Package Drawing

Pins SPQ Reel

Diameter

(mm)

Reel

Width

W1 (mm)

A0 (mm) B0 (mm) K0 (mm) P1

(mm)W(mm)

Pin1

Quadrant

Pack Materials-Page 1

PACKAGE MATERIALS INFORMATION

www.ti.com

13-May-2008

*All dimensions are nominal

Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm)

TMP421AIDCNR SOT-23 DCN 8 3000 195.0 200.0 45.0 TMP421AIDCNT SOT-23 DCN 8 250 195.0 200.0 45.0 TMP422AIDCNR SOT-23 DCN 8 3000 195.0 200.0 45.0 TMP422AIDCNT SOT-23 DCN 8 250 195.0 200.0 45.0 TMP423AIDCNR SOT-23 DCN 8 3000 195.0 200.0 45.0 TMP423AIDCNT SOT-23 DCN 8 250 195.0 200.0 45.0 TMP423BIDCNR SOT-23 DCN 8 3000 195.0 200.0 45.0 TMP423BIDCNT SOT-23 DCN 8 250 195.0 200.0 45.0

Pack Materials-Page 2

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Texas Instruments TMP421, TMP422, TMP423A, TMP423B Schematic [ru]

Specifications and Main Features

Frequently Asked Questions

User Manual

FEATURES DESCRIPTION

APPLICATIONS

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

TMP421 PIN CONFIGURATION

TMP422 PIN CONFIGURATION

TMP423 PIN CONFIGURATION

TYPICAL CHARACTERISTICS

APPLICATION INFORMATION

SERIES RESISTANCE CANCELLATION

DIFFERENTIAL INPUT CAPACITANCE

TEMPERATURE MEASUREMENT DATA

Standard Binary to Decimal Temperature Data Calculation Example

Standard Decimal to Binary Temperature Data Calculation Example

REGISTER INFORMATION

POINTER REGISTER

TEMPERATURE REGISTERS

STATUS REGISTER

CONFIGURATION REGISTER 1

CONFIGURATION REGISTER 2

CONVERSION RATE REGISTER

ONE-SHOT CONVERSION

n-FACTOR CORRECTION REGISTER

SOFTWARE RESET

GENERAL CALL RESET

IDENTIFICATION REGISTERS

BUS OVERVIEW

SERIAL INTERFACE

SERIAL BUS ADDRESS

Two-Wire Interface Slave Device Addresses

READ/WRITE OPERATIONS

TIMING DIAGRAMS

SHUTDOWN MODE (SD)

SENSOR FAULT

UNDERVOLTAGE LOCKOUT

FILTERING

REMOTE SENSING

LAYOUT CONSIDERATIONS