TMP400
 
  
1
FEATURES DESCRIPTION
APPLICATIONS
DeviceIDRegister
ManufacturerIDRegister
ConsecutiveAlert
ConfigurationRegister
TR
TL
StatusRegister
ConversionRate
Register
N-Factor
Correction
D+
2
7,8
12
14
3
4
BusInterface PointerRegister
ResolutionRegister
ConfigurationRegister
LocalTempLowLimit
LocalTempHighLimit
RemoteTempLowLimit
RemoteTempHighLimit
Remote
Temperature
Register
Local
Temperature
Register
Temperature
Comparators
Interrupt
Configuration
SCL
GND
11 ALERT
V+
V+
SDA
D-
TMP400
RemoteTemperatureMin/MaxRegister
LocalTemperatureMin/MaxRegister
STBY
A1A0
15
610
TMP400
SBOS404 – DECEMBER 2007
± 1 °C Remote and Local TEMPERATURE SENSORwith N-Factor and Series Resistance Correction
234
•± 1 °C REMOTE DIODE SENSOR
The TMP400 is a remote temperature sensor monitorwith a built-in local temperature sensor. The remote•± 1 °C LOCAL TEMPERATURE SENSOR
temperature sensor diode-connected transistors are•PROGRAMMABLE NON-IDEALITY FACTOR
typically low-cost, NPN- or PNP-type transistors or•PROGRAMMABLE SERIES RESISTANCE
diodes that are an integral part of microcontrollers,CANCELLATION
microprocessors, or FPGAs.•ALERT FUNCTION
Remote accuracy is ± 1 °C for multiple IC•PROGRAMMABLE RESOLUTION: 9 to 12 Bits
manufacturers, with no calibration needed. TheTwo-Wire serial interface accepts SMBus write byte,•PROGRAMMABLE THRESHOLD LIMITS
read byte, send byte, and receive byte commands to•TWO-WIRE/ SMBus™ SERIAL INTERFACE
program the alarm thresholds and to read•MINIMUM AND MAXIMUM TEMPERATURE
temperature data.MONITORS
The TMP400 is customizable with programmable:•MULTIPLE INTERFACE ADDRESSES
series resistance cancellation, non-ideality factor,•ALERT PIN CONFIGURATION
resolution, and threshold limits. Other features are:minimum and maximum temperature monitors, wide•DIODE FAULT DETECTION
remote temperature measurement range (up to+127.9375 °C), diode fault detection, and temperaturealert function.•LCD/ DLP
®
/LCOS PROJECTORS
The TMP400 is available in a QSSOP-16 package.•SERVERS
•INDUSTRIAL CONTROLLERS•CENTRAL OFFICE TELECOM EQUIPMENT•DESKTOP AND NOTEBOOK COMPUTERS•STORAGE AREA NETWORKS (SAN)•INDUSTRIAL AND MEDICAL EQUIPMENT•PROCESSOR/FPGA TEMPERATUREMONITORING
1
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications ofTexas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
2DLP is a registered trademark of Texas Instruments.3SMBus is a trademark of Intel Corp.4All other trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date.
Copyright © 2007, Texas Instruments IncorporatedProducts conform to specifications per the terms of the TexasInstruments standard warranty. Production processing does notnecessarily include testing of all parameters.
www.ti.com
ABSOLUTE MAXIMUM RATINGS
(1)
PIN CONFIGURATION
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
NC
STBY
SCL
NC
SDA
ALERT
A0
NC
NC
V+
D+
D-
NC
A1
GND
GND
TMP400
TMP400
SBOS404 – DECEMBER 2007
This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled withappropriate 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 moresusceptible to damage because very small parametric changes could cause the device not to meet its published specifications.
ORDERING INFORMATION
(1)
PRODUCT PACKAGE-LEAD PACKAGE DESIGNATOR PACKAGE MARKING
TMP400 QSSOP-16 DBQ TMP400
(1) For the most current package and ordering information see the Package Option Addendum at the end of this document, or see the TIweb site at www.ti.com .
TMP400 UNIT
Power Supply, V
S
7 VInput Voltage, pins 3, 4, 6, 10, and 15 only – 0.5 to V
S
+ 0.5 VInput Voltage, pins 11, 12, and 14 only – 0.5 to +7 VInput Current 10 mAOperating Temperature Range – 55 to +127 °CStorage Temperature Range – 60 to +130 °CJunction Temperature (T
J
max) +150 °CHuman Body Model (HBM) 3000 VESD Rating Charged Device Model (CDM) 1000 VMachine Model (MM) 200 V
(1) Stresses above these ratings may cause permanent damage. Exposure to absolute maximum conditions for extended periods maydegrade device reliability. These are stress ratings only, and functional operation of the device at these or any other conditions beyondthose specified is not supported.
TERMINAL FUNCTIONS
PIN NAME DESCRIPTIONQSSOP-16
Top View
1, 5, 9,
NC No internal connection13, 16
2 V+ Positive supply (2.7V to 5.5V)Positive connection to remote temperature3 D+
sensor
Negative connection to remote temperature4 D –
sensor6 A1 Address pin7, 8 GND Ground10 A0 Address pinAlert, active low, open-drain; requires pull-up11 ALERT
resistor to V+Serial data line for SMBus, open-drain;12 SDA
requires pull-up resistor to V+Serial clock line for SMBus, open-drain;14 SCL
requires pull-up resistor to V+15 STBY Standby pin
2Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated
Product Folder Link(s): TMP400
www.ti.com
ELECTRICAL CHARACTERISTICS
TMP400
SBOS404 – DECEMBER 2007
At T
A
= – 40 °C to +125 °C and V
S
= 2.7V to 5.5V, unless otherwise noted.
TMP400
PARAMETER CONDITIONS MIN TYP MAX UNIT
TEMPERATURE ERROR
Local Temperature Sensor TE
LOCAL
T
A
= – 40 °C to +125 °C ± 1.25 ± 2.5 °C
V
S
= 3.3V, T
A
= +15 °C to +85 °C ± 0.0625 ± 1 °C
Remote Temperature Sensor
(1) (2)
TE
REMOTE
V
S
= 3.3V, T
A
= +15 °C to +75 °C, T
D
= – 40 °C to +125 °C
(3)
± 0.0625 ± 1 °C
V
S
= 3.3V, T
A
= – 40 °C to +100 °C, T
D
= – 40 °C to +125 °C
(3)
± 1 ± 3 °C
T
A
= – 40 °C to +125 °C, T
D
= – 40 °C to +125 °C
(3)
± 3 ± 10 °C
vs Supply
Local/Remote V
S
= 2.7V to 5.5V ± 0.2 ± 0.5 °C/V
TEMPERATURE MEASUREMENT
Conversion Time (per channel)
(4)
105 115 125 ms
Resolution
Local Temperature Sensor (programmable) 9 12 Bits
Remote Temperature Sensor 12 Bits
Remote Sensor Source Currents
High Series Resistance 3k ΩMaximum 120 µA
Medium High 60 µA
Medium Low 12 µA
Low 6 µA
Remote Transistor Ideality Factor ηTMP400 Optimized Ideality Factor 1.008
SMBus INTERFACE
Logic Input High Voltage (SCL, SDA) V
IH
2.1 V
Logic Input Low Voltage (SCL, SDA) V
IL
0.8 V
Hysteresis 500 mV
SMBus Output Low Sink Current 6 mA
Logic Input Current – 1 +1 µA
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 µs
DIGITAL OUTPUTS
Output Low Voltage V
OL
I
OUT
= 6mA 0.15 0.4 V
High-Level Output Leakage Current I
OH
V
OUT
= V
S
0.1 1 µA
ALERT Output Low Sink Current ALERT Forced to 0.4V 6 mA
POWER SUPPLY
Specified Voltage Range V
S
2.7 5.5 V
Quiescent Current I
Q
0.0625 Conversions per Second 30 38 µA
Eight Conversions per Second 420 525 µA
Serial Bus Inactive, Shutdown Mode 3 10 µA
Serial Bus Active, f
S
= 400kHz, Shutdown Mode 90 µA
Serial Bus Active, f
S
= 3.4MHz, Shutdown Mode 350 µA
Undervoltage Lock Out 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, QSSOP 70 °C/W
(1) Tested with less than 5 Ωeffective series resistance and 100pF differential input capacitance.(2) RC = '1'.(3) T
D
is the remote temperature measured at the diode.(4) RES1 = '1' and RES0 = '1' for 12-bit resolution.
Copyright © 2007, Texas Instruments Incorporated Submit Documentation Feedback 3
Product Folder Link(s): TMP400
www.ti.com
TYPICAL CHARACTERISTICS
3
2
1
0
-1
-2
-3
AmbientTemperature,T ( C)°
A
-50 -25 1251007550250
RemoteTemperatureError( C)°
V =3.3V
S
T =+25 C
REMOTE °
30TypicalUnitsShown
h=1.008
RC=1
LocalTemperatureError( )
°C
AmbientTemperature,T (
A°C)
3.0
2.0
1.0
0
-1.0
-2.0
-3.0
-50 125-25 0 25 50 75 100
50UnitsShown
V =3.3V
S
60
40
20
0
-20
-40
-60
LeakageResistance(M )W
0 5 10 15 20 25
RemoteTemperatureError( C)°
R GND-
R VS
-
RemoteTemperatureError( )
°C
RW( )
S
2.0
1.5
1.0
0.5
0
-0.5
-1.0
-1.5
-2.0
0 3000500 1000 1500 2000 2500
V =2.7V
S
V =5.5V
S
RC=1
3
2
1
0
-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)
S
2.0
1.5
1.0
0.5
0
-0.5
-1.0
-1.5
-2.0
0 3000500 1000 1500 2000 2500
V =2.7V
S
V =5.5V
S
RC=1
TMP400
SBOS404 – DECEMBER 2007
At T
A
= +25 °C and V
S
= 5.0V, unless otherwise noted.
REMOTE TEMPERATURE ERROR LOCAL TEMPERATURE ERRORvs TEMPERATURE vs TEMPERATURE
Figure 1. Figure 2.
REMOTE TEMPERATURE ERROR REMOTE TEMPERATURE ERROR vs SERIES RESISTANCEvs 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.
4Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated
Product Folder Link(s): TMP400
www.ti.com
500
450
400
350
300
250
200
150
100
50
0
SCLClockFrequency(Hz)
1k 10k 100k 1M 10M
I ( A)m
Q
V =3.3V
S
V =5.5V
S
I )(
QmA
V (
SV)
8
7
6
5
4
3
2
1
0
4.53.0 3.5 4.0 5.55.02.5
TMP400
SBOS404 – DECEMBER 2007
TYPICAL CHARACTERISTICS (continued)At T
A
= +25 °C and V
S
= 5.0V, unless otherwise noted.
TEMPERATURE ERROR QUIESCENT CURRENTvs POWER-SUPPLY NOISE FREQUENCY vs CONVERSION RATE
Figure 7. Figure 8.
SHUTDOWN QUIESCENT CURRENT SHUTDOWN QUIESCENT CURRENTvs SCL CLOCK FREQUENCY vs SUPPLY VOLTAGE
Figure 9. Figure 10.
Copyright © 2007, Texas Instruments Incorporated Submit Documentation Feedback 5
Product Folder Link(s): TMP400
www.ti.com
APPLICATION INFORMATION
SERIES RESISTANCE CANCELLATION
0.1mF
10kW
(typ)
10kW
(typ)
10kW
(typ)
TMP400
D+
D-
V+
2
14
12
11
7,8
4
3
R(2)
S
R(2)
SC(3)
DIFF
C(3)
DIFF
R(2)
S
R(2)
S
GND
SCL
SDA
ALERT
+5V
Two-WireBus/
SMBus Controller
Diode-connectedconfiguration :
(1)
SeriesResistance
Transistor-connectedconfiguration :
(1)
STBY
A0
A1
15
10
6
TMP400
SBOS404 – DECEMBER 2007
other devices if desired for a wired-ORThe TMP400 is a dual-channel digital temperature
implementation. A 0.1 µF power-supply bypasssensor that combines a local die temperature
capacitor is recommended for good local bypassing.measurement channel and a remote junction
Figure 11 shows a typical configuration for thetemperature measurement channel in a QSSOP-16
TMP400.package. The TMP400 is Two-Wire and SMBusinterface-compatible, and is specified over atemperature range of – 40 °C to +125 °C. The TMP400contains multiple registers for holding configuration
Series resistance in an application circuit that typicallyinformation, temperature measurement results,
results from printed circuit board (PCB) tracetemperature comparator maximum/minimum limits,
resistance and remote line length (see Figure 11 ) canand status information.
be automatically programmed to be cancelled by theTMP400 by setting the RC bit to '1' in the ResolutionUser-programmed high and low temperature limits
Register, preventing what would otherwise result in astored in the TMP400 can be used to monitor local
temperature offset.and remote temperatures to trigger an over/undertemperature alarm ( ALERT).
A total of up to 3k Ωof series line resistance iscancelled by the TMP400 if the RC bit is enabled,The TMP400 requires only a transistor connected
eliminating the need for additional characterizationbetween D+ and D – for proper remote temperature
and temperature offset correction. Upon power-up,sensing operation. The SCL and SDA interface pins
the RC bit is disabled (RC = 0).require pull-up resistors as part of the communicationbus, while ALERT is an open-drain output that also
See the two Remote Temperature Error vs Seriesneeds a pull −up resistor. ALERT may be shared with
Resistance typical characteristics curves (Figure 4and Figure 5 ) for details on the effect of seriesresistance and power-supply voltage on sensedremote temperature error.
(1) Diode-connected configuration provides better settling time. Transistor-connected configuration provides better series resistancecancellation.
(2) R
S
should be less than 1.5k Ωin most applications.(3) C
DIFF
should be less than 1000pF in most applications.
Figure 11. Basic Connections
6Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated
Product Folder Link(s): TMP400
www.ti.com
DIFFERENTIAL INPUT CAPACITANCE
REGISTER INFORMATIONTEMPERATURE MEASUREMENT DATA
POINTER REGISTER
ResolutionRegister
ConfigurationRegister
StatusRegister
IdentificationRegisters
ConsecutiveAlertRegister
LocalTemperatureMin/Max
ConversionRateRegister
RemoteTemperatureMin/Max
LocalandRemoteLimitRegisters
LocalandRemoteTemperatureRegisters
SDA
SCL
PointerRegister
I/O
Control
Interface
TMP400
SBOS404 – DECEMBER 2007
byte stores the decimal fraction value of thetemperature and allows a higher measurementThe TMP400 tolerates differential input capacitance
resolution. The measurement resolution for theof up to 1000pF if RC = 1 (if RC = 0, input
remote channel is 0.0625 °C, and is not adjustable.capacitance can be as high as 2200pF) with minimal
The measurement resolution for the local channel ischange in temperature error. The effect of
adjustable; it can be set for 0.5 °C, 0.25 °C, 0.125 °C,capacitance on sensed remote temperature error is
or 0.0625 °C by setting the RES1 and RES0 bits ofillustrated in the typical characteristic curve, Remote
the Resolution Register; see the Resolution RegisterTemperature Error vs Differential Capacitance
section (Table 5 ).(Figure 6 ).
The TMP400 contains multiple registers for holdingTemperature measurement data are taken over a
configuration information, temperature measurementdefault range of – 55 °C to +127.9375 °C for both local
results, temperature comparator maximum/minimum,and remote locations.
limits, and status information. These registers aredescribed in Figure 12 and Table 2 .Temperature data resulting from conversions withinthe default measurement range are represented inbinary form, as shown in Table 1 , Binary column.Note that any temperature above +127.9375 °C
Figure 12 shows the internal register structure of theresults in a value of 127.9375 (7Fh/F0h).
TMP400. The 8-bit Pointer Register is used toTemperatures below – 65 °C results in a value of – 65
address a given data register. The Pointer Register(BF/00h). The TMP400 is specified only for ambient
identifies which of the data registers should respondtemperatures ranging from – 40 °C to +125 °C.
to a read or write command on the Two-Wire bus.Parameters in the Absolute Maximum Ratings table
This register is set with every write command. A writemust be observed.
command must be issued to set the proper value inthe Pointer Register before executing a readTable 1. Temperature Data Format
command. Table 2 describes the pointer address ofREMOTE TEMPERATURE REGISTER
the registers available in the TMP400. The power-onreset (POR) value of the Pointer Register is 00hDIGITAL OUTPUT
(BINARY)
(0000 0000b).TEMPERATURE
(°C) HIGH BYTE LOW BYTE HEX
128 0111 1111 1111 0000 7F/F0127.9375 0111 1111 1111 0000 7F/F0100 0110 0100 0000 0000 64/0080 0101 0000 0000 0000 50/0075 0100 1011 0000 0000 4B/0050 0011 0010 0000 0000 32/0025 0001 1001 0000 0000 19/000.25 0000 0000 0100 0000 00/400 0000 0000 0000 0000 00/00– 0.25 1111 1111 1100 0000 FF/C0– 25 1110 0111 0000 0000 E7/00– 55 1100 1001 0000 0000 C9/00– 65 1011 1111 0000 0000 BF/00
Both local and remote temperature data use two
Figure 12. Internal Register Structurebytes for data storage. The high byte stores thetemperature with 1 °C resolution. The second (or low)
Copyright © 2007, Texas Instruments Incorporated Submit Documentation Feedback 7
Product Folder Link(s): TMP400
www.ti.com
TMP400
SBOS404 – DECEMBER 2007
Table 2. Register MapPOINTER
ADDRESS (HEX) BIT DESCRIPTIONSPOWER-ONREAD WRITE RESET (HEX) D7 D6 D5 D4 D3 D2 D1 D0 REGISTER DESCRIPTIONS
Local Temperature00 NA
(1)
00 LT11 LT10 LT9 LT8 LT7 LT6 LT5 LT4
(High Byte)
Remote Temperature01 NA 00 RT11 RT10 RT9 RT8 RT7 RT6 RT5 RT4
(High Byte)
02 NA 00 BUSY LHIGH LLOW RHIGH RLOW OPEN 0 0 Status Register
03 09 00 MASK1 SD 0 0 0 0 0 0 Configuration Register
04 0A 02 0 0 0 0 R3 R2 R1 R0 Conversion Rate Register
Local Temperature High05 0B 7F LTH11 LTH10 LTH9 LTH8 LTH7 LTH6 LTH5 LTH4
Limit (High Byte)
Local Temperature Low Limit06 0C C9 LTL11 LTL10 LTL9 LTL8 LTL7 LTL6 LTL5 LTL4
(High Byte)
Remote Temperature High07 0D 7F RTH11 RTH10 RTH9 RTH8 RTH7 RTH6 RTH5 RTH4
Limit (High Byte)
Remote Temperature Low08 0E C9 RTL11 RTL10 RTL9 RTL8 RTL7 RTL6 RTL5 RTL4
Limit (High Byte)
NA 0F XX X
(2)
X X X X X X X One-Shot Start
Remote Temperature10 NA 00 RT3 RT2 RT1 RT0 0 0 0 0
(Low Byte)
Remote Temperature High13 13 00 RTH3 RTH2 RTH1 RTH0 0 0 0 0
Limit (Low Byte)
Remote Temperature Low14 14 00 RTL3 RTL2 RTL1 RTL0 0 0 0 0
Limit (Low Byte)
Local Temperature15 NA 00 LT3 LT2 LT1 LT0 0 0 0 0
(Low Byte)
Local Temperature High16 16 00 LTH3 LTH2 LTH1 LTH0 0 0 0 0
Limit (Low Byte)
Local Temperature Low Limit17 17 00 LTL3 LTL2 LTL1 LTL0 0 0 0 0
(Low Byte)
18 18 00 NC7 NC6 NC5 NC4 NC3 NC2 NC1 NC0 N-factor Correction
1A 1A 18 0 0 0 1 1 RC RES1 RES0 Resolution Register
22 22 01 TO_EN 0 0 0 C2 C1 C0 0 Consecutive Alert Register
Local Temperature Minimum30 30 7F LMT11 LMT10 LMT9 LMT8 LMT7 LMT6 LMT5 LMT4
(High Byte)
Local Temperature Minimum31 31 F0 LMT3 LMT2 LMT1 LMT0 0 0 0 0
(Low Byte)
Local Temperature Maximum32 32 80 LXT11 LXT10 LXT9 LXT8 LXT7 LXT6 LXT5 LXT4
(High Byte)
Local Temperature Maximum33 33 00 LXT3 LXT2 LXT1 LXT0 0 0 0 0
(Low Byte)
Remote Temperature34 34 7F RMT11 RMT10 RMT9 RMT8 RMT7 RMT6 RMT5 RMT4
Minimum (High Byte)
Remote Temperature35 35 F0 RMT3 RMT2 RMT1 RMT0 0 0 0 0
Minimum (Low Byte)
Remote Temperature36 36 80 RXT11 RXT10 RXT9 RXT8 RXT7 RXT6 RXT5 RXT4
Maximum (High Byte)
Remote Temperature37 37 00 RXT3 RXT2 RXT1 RXT0 0 0 0 0
Maximum (Low Byte)
NA FC FF X
(2)
X X X X X X X Software Reset
FE NA 55 0 1 0 1 0 1 0 1 Manufacturer ID
FF NA 01 0 0 0 0 0 0 0 1 Device ID
(1) NA = not applicable; register is write- or read-only.(2) X = indeterminate state. Writing any value to this register indicates a software reset; see the Software Reset section.
8Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated
Product Folder Link(s): TMP400
www.ti.com
TEMPERATURE REGISTERS
LIMIT REGISTERS
STATUS REGISTER
TMP400
SBOS404 – DECEMBER 2007
byte first) to pointer address 0Bh. The localtemperature high limit is obtained by reading the highThe TMP400 has four 8-bit registers that hold
byte from pointer address 05h and the low byte fromtemperature measurement results. Both the local
pointer address 16h. The power-on reset value of thechannel and the remote channel have a high byte
local temperature high limit is 7Fh/00h (+127 °C).register that contains the most significant bits (MSBs)of the temperature analog-to-digital converter (ADC) Similarly, the local temperature low limit is set byresult, and a low byte register that contains the least writing the high byte to pointer address 0Ch andsignificant bits (LSBs) of the temperature ADC result. writing the low byte to pointer address 17h, or byThe local channel high byte address is 00h; the local using a single two-byte write command to pointerchannel low byte address is 15h. The remote channel address 0Ch. The local temperature low limit is readhigh byte is at address 01h; the remote channel low by reading the high byte from pointer address 06hbyte address is 10h. These read-only registers are and the low byte from pointer address 17h, or byupdated by the ADC each time a temperature using a two-byte read from pointer address 06h. Themeasurement is completed. power-on reset value of the local temperature lowlimit register is C9h/00h ( – 55 °C).The TMP400 contains circuitry to assure that a lowbyte register read command returns data from the The remote temperature high limit is set by writing thesame ADC conversion as the immediately preceding high byte to pointer address 0Dh and writing the lowhigh byte read command. This assurance remains byte to pointer address 13h, or by using a two-bytevalid only until another register is read. For proper write command to pointer address 0Dh. The remoteoperation, the high byte of a temperature register temperature high limit is obtained by reading the highshould be read first. The low byte register should be byte from pointer address 07h and the low byte fromread in the next read command. The low byte register pointer address 13h, or by using a two-byte readmay be left unread if the LSBs are not needed. command from pointer address 07h. The power-onAlternatively, the temperature registers may be read reset value of the Remote Temperature High Limitas a 16-bit register by using a single two-byte read Register is 7Fh/00h (+127 °C).command from address 00h for the local channel
The remote temperature low limit is set by writing theresult or from address 01h for the remote channel
high byte to pointer address 0Eh and writing the lowresult. The high byte is output first, followed by the
byte to pointer address 14h, or by using a two-bytelow byte. Both bytes of this read operation are from
write to pointer address 0Eh. The remote temperaturethe same ADC conversion. The power-on reset value
low limit is read by reading the high byte from pointerof both temperature registers is 00h.
address 08h and the low byte from pointer address14h, or by using a two-byte read from pointer address08h. The power-on reset value of the RemoteTemperature Low Limit Register is C9h/00h ( – 55 °C).The TMP400 has eight registers for settingcomparator limits for both the local and remotemeasurement channels. These registers have readand write capability. The High and Low Limit
The TMP400 has a Status Register to report the stateRegisters for both channels span two registers, as do
of the temperature comparators. Table 3 shows thethe temperature registers. The local temperature high
Status Register bits. The Status Register is read-onlylimit is set by writing the high byte to pointer address
and is read by reading from pointer address 02h.0Bh and writing the low byte to pointer address 16h,or by using a single two-byte write command (high
Table 3. Status Register Format
STATUS REGISTER (Read = 02h, Write = NA)
BIT # D7 D6 D5 D4 D3 D2 D1 D0
BIT NAME BUSY LHIGH LLOW RHIGH RLOW OPEN — —
POR VALUE 0
(1)
0000000
(1) The BUSY bit will change to ‘ 1 ’ almost immediately (<< 100 µs) following power-up, as the TMP400 begins the first temperatureconversion. It is high whenever the TMP400 converts a temperature reading.
Copyright © 2007, Texas Instruments Incorporated Submit Documentation Feedback 9
Product Folder Link(s): TMP400
www.ti.com
CONFIGURATION REGISTER
TMP400
SBOS404 – DECEMBER 2007
The BUSY bit is ‘ 1 ’ if the ADC makes a conversion. It The TMP400 NORs LHIGH, LLOW, RHIGH, RLOW,is ‘ 0 ’ if the ADC is not converting. and OPEN, so a status change for any of these flagsfrom ‘ 0 ’ to ‘ 1 ’ automatically causes the ALERT pin toThe OPEN bit is ‘ 1 ’ if the remote transistor was
go low.detected as open since the last read of the StatusRegister. The OPEN status is only detected when theADC attempts to convert a remote temperature.
The Configuration Register controls shutdown modeThe LHIGH bit is ‘ 1 ’ if the local high limit was
and disables the ALERT pin. The Configurationexceeded since the last clearing of the Status
Register is set by writing to pointer address 09h andRegister. The RHIGH bit is ‘ 1 ’ if the remote high limit
read by reading from pointer address 03h.was exceeded since the last clearing of the StatusRegister.
The MASK bit (bit 7) enables or disables the ALERTpin output. If MASK is set to ‘ 0 ’ , the ALERT pin goesThe LLOW bit is ‘ 1 ’ if the local low limit was exceeded
low when one of the temperature measurementsince the last clearing of the Status Register. The
channels exceeds its high or low limits for the chosenRLOW bit is ‘ 1 ’ if the remote low limit was exceeded
number of consecutive conversions. If the MASK bitsince the last clearing of the Status Register.
is set to ‘ 1 ’ , the TMP400 retains the ALERT pinThe values of the LLOW, RLOW, and OPEN bits are status, but the ALERT pin does not go low.latched and read as ‘ 1 ’ until the Status Register is
The shutdown (SD) bit (bit 6) enables or disables theread or a device reset occurs. These bits are cleared
temperature measurement circuitry. If SD = 0, theby reading the Status Register, provided that the
TMP400 converts continuously at the rate set in thecondition causing the flag to be set no longer exists.
conversion rate register. When SD is set to ‘ 1 ’ , theThe BUSY bit is not latched and is not cleared by
TMP400 immediately stops converting and enters areading the Status Register. The BUSY bit always
shutdown mode. When SD is set to ‘ 0 ’ again, theindicates the current state and updates appropriately
TMP400 resumes continuous conversions.at the end of the corresponding ADC conversion.Clearing the Status Register bits does not clear the
The remaining bits of the Configuration Register arestate of the ALERT pin; an SMBus alert response
reserved and must always be set to ‘ 0 ’ . The power-onaddress command must be used to clear the ALERT
reset value for this register is 00h. Table 4pin.
summarizes the bits of the Configuration Register.
Table 4. Configuration Register Bit Descriptions
CONFIGURATION REGISTER (Read = 03h, Write = 09h, POR = 00h)
BIT NAME FUNCTION POWER-ON RESET VALUE
0 = ALERT Enabled7 MASK 01 = ALERT Masked
0 = Run6 SD 01 = Shut Down5, 4, 3, 2, 1, 0 Reserved — 0
10 Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated
Product Folder Link(s): TMP400
www.ti.com
RESOLUTION REGISTER
CONVERSION RATE REGISTER
N-FACTOR CORRECTION REGISTER
V V =-
BE2 BE1
nkT
qln l2
l1
(1)
ONE-SHOT (OS)
n=
eff
1.008 300´
(300 N )-ADJUST
(2)
N =300 -
ADJUST
300 1.008´
neff
(3)
TMP400
SBOS404 – DECEMBER 2007
conversion. This mode is useful to reduce powerconsumption in the TMP400 when continuousThe RES1 and RES0 bits (resolution bits 1 and 0,
temperature monitoring is not required. When therespectively) of the Resolution Register set the
configuration register is read, the OS bit always readsresolution of the local temperature measurement
'0'channel. Remote temperature measurement channelresolution is not affected. Changing the local channelresolution also affects the conversion time and rate ofthe TMP400. The Resolution Register is set by
The Conversion Rate Register controls the rate atwriting to pointer address 1Ah and is read by reading
which temperature conversions are performed. Thisfrom pointer address 1Ah. Table 5 shows the
register adjusts the idle time between conversions butresolution bits for the Resolution Register.
not the conversion timing itself, thereby allowing theTMP400 power dissipation to be balanced with theTable 5. Resolution Register: Local Channel
temperature register update rate. Table 6 shows theProgrammable Resolution
conversion rate options and corresponding currentconsumption. By default, the TMP400 converts everyRESOLUTION REGISTER
four seconds.(Read = 1Ah, Write = 1Ah, POR = 18h)
CONVERSIONRES1 RES0 RESOLUTION TIME (Typical)
0 0 9 Bits (0.5 °C) 12.5ms
The TMP400 allows for a different n-factor value to0 1 10 Bits (0.25 °C) 25ms
be used for converting remote channelmeasurements to temperature. The remote channel1 0 11 Bits (0.125 °C) 50ms
uses sequential current excitation to extract a1 1 12 Bits (0.0625 °C) 100ms
differential V
BE
voltage measurement to determinethe temperature of the remote transistor. Equation 1Bits 3 and 4 of the Resolution Register must always
relates this voltage and temperature.be set to ‘ 1 ’ . Bits 5 through 7 of the ResolutionRegister must always be set to ‘ 0 ’ . The power-onreset value of this register is 18h. Resistancecorrection (RC) is not automatically enabled onpower-on; see the Series Resistance Cancellation
The value nin Equation 1 is a characteristic of thesection for information on RC.
particular transistor used for the remote channel. Thedefault value for the TMP400 is n= 1.008. The valuein the N-Factor Correction Register may be used toThe TMP400 features a One-Shot Temperature
adjust the effective n-factor according to Equation 2Measurement Mode. When the device is in Shutdown
and Equation 3 .Mode, writing a ‘ 1 ’ to the OS bit starts a singletemperature conversion. The device returns to theshutdown state at the completion of the single
Table 6. Conversion Rate Register
CONVERSION RATE REGISTER (Read = 04h, Write = 0Ah, POR = 02h)
AVERAGE I
Q
(TYP)(µA)
R7 R6 R5 R4 R3 R2 R1 R0 CONVERSION/SEC V
S
= 2.7V V
S
= 5.5V
0 0 0 0 0 0 0 0 0.0625 11 320 0 0 0 0 0 0 1 0.125 17 380 0 0 0 0 0 1 0 0.25 28 490 0 0 0 0 0 1 1 0.5 47 690 0 0 0 0 1 0 0 1 80 1030 0 0 0 0 1 0 1 2 128 1550 0 0 0 0 1 1 0 4 190 22007h to 0Fh 8 373 413
Copyright © 2007, Texas Instruments Incorporated Submit Documentation Feedback 11
Product Folder Link(s): TMP400
www.ti.com
MINIMUM AND MAXIMUM REGISTERS
SOFTWARE RESET
TMP400
SBOS404 – DECEMBER 2007
The n-correction value must be stored in The Local Temperature Maximum Register may betwo ’ s-complement format, yielding an effective data read by reading the high byte from pointer addressrange from – 128 to +127. The n-correction value may 32h and the low byte from pointer address 33h. Thebe written to and read from pointer address 18h. The Local Temperature Maximum Register may also beregister power-on reset value is 00h; thus, the read by using a two-byte read command from pointerregister has no effect unless written to. The n-factor address 32h. The Local Temperature Maximumrange is shown in Table 7 . Register is reset at power-on by executing the chipreset command, or by writing any value to any ofTable 7. N-Factor Range pointer addresses 30h through 37h. The reset valuefor these registers is 80h/00h.N
ADJUST
The Remote Temperature Minimum Register may beBINARY HEX DECIMAL N
read by reading the high byte from pointer address01111111 7F 127 1.747977
34h and the low byte from pointer address 35h. The00001010 0A 10 1.042759
Remote Temperature Minimum Register may also be00001000 08 8 1.035616
read by using a two-byte read command from pointer00000110 06 6 1.028571
address 34h. The Remote Temperature MinimumRegister is reset at power-on by executing the chip00000100 04 4 1.021622
reset command, or by writing any value to any of00000010 02 2 1.014765
pointer addresses 30h through 37h. The reset value00000001 01 1 1.011371
for these registers is 7Fh/F0h.00000000 00 0 1.008
The Remote Temperature Maximum Register may be11111111 FF – 1 1.004651
read by reading the high byte from pointer address11111110 FE – 2 1.001325
36h and the low byte from pointer address 37h. The11111100 FC – 4 0.994737
Remote Temperature Maximum Register may also be11111010 FA – 6 0.988235
read by using a two-byte read command from pointeraddress 36h. The Remote Temperature Maximum11111000 F8 – 8 0.981818
Register is reset at power-on by executing the chip11110110 F6 – 10 0.975484
reset command, or by writing any value to any of10000000 80 – 128 0.706542
pointer addresses 30h through 37h. The reset valuefor these registers is 80h/00h.
The TMP400 stores the minimum and maximumtemperatures measured since power-on, chip-reset,
The TMP400 may be reset by writing any value toor minimum and maximum register reset for both the
Pointer Register FCh. A reset restores the power-onlocal and remote channels. The Local Temperature
reset state to all of the TMP400 registers as well asMinimum Register may be read by reading the high
aborts any conversion in process and clears thebyte from pointer address 30h and the low byte from
ALERT pin.pointer address 31h. The Local Temperature
The TMP400 also supports reset via the Two-WireMinimum Register may also be read by using a
general call address (00000000). The TMP400two-byte read command from pointer address 30h.
acknowledges the general call address and respondsThe Local Temperature Minimum Register is reset at
to the second byte. If the second byte is 00000110,power-on, by executing the chip-reset command, or
the TMP400 latches the status of the address pinsby writing any value to any of pointer addresses 30h
and executes a software reset. A 500 µs time delaythrough 37h. The reset value for these registers is
must be observed after a general-call command. The7Fh/F0h.
TMP400 takes no action in response to other valuesin the second byte.
12 Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated
Product Folder Link(s): TMP400
www.ti.com
CONSECUTIVE ALERT REGISTER SERIAL INTERFACE
SERIAL BUS ADDRESS
BUS OVERVIEW
READ/WRITE OPERATIONS
TMP400
SBOS404 – DECEMBER 2007
The value in the Consecutive Alert Register (address The TMP400 operates only as a slave device on22h) determines how many consecutive out-of-limit either the Two-Wire bus or the SMBus. Connectionsmeasurements must occur on a measurement to either bus are made via the open-drain I/O lines,channel before the ALERT signal is activated. The SDA, and SCL. The SDA and SCL pins featurevalue in this register does not affect bits in the Status integrated spike suppression filters and SchmittRegister. Values of one, two, three, or four triggers to minimize the effects of input spikes andconsecutive conversions can be selected; one bus noise. The TMP400 supports the transmissionconversion is the default. This function allows protocol for fast (1kHz to 400kHz) and high-speedadditional filtering for the ALERT pin. The consecutive (1kHz to 3.4MHz) modes. All data bytes arealert bits are shown in Table 8 . transmitted MSB first.
Table 8. Consecutive Alert Register
CONSECUTIVE ALERT REGISTER
To communicate with the TMP400, the master must(READ = 22h, WRITE = 22h, POR = 01h)
first address slave devices via a slave address byte.NUMBER OF CONSECUTIVE
The slave address byte consists of seven addressOUT-OF-LIMIT
bits, and a direction bit indicating the intent ofC2 C1 C0 MEASUREMENTS
executing a read or write operation. The address of0 0 0 1
the TMP400 is set by the A0 and A1 pins. TMP4000 0 1 2
addresses and corresponding A0 and A1configurations are shown in Table 9 .0 1 1 31 1 1 4
Table 9. Device Addresses(1) Note that bit 7 of the Consecutive Alert Register controls the
A0 A1 ADDRESSenable/disable of the timeout function. See the TimeoutFunction section for a description of this feature.
GND GND 0011 000GND High-Z 0011 001GND V
CC
0011 010The TMP400 is SMBus interface-compatible. In
High-Z GND 0101 001SMBus protocol, the device that initiates the transfer
High-Z High-Z 0101 010is called a master, and the devices controlled by the
High-Z V
CC
0101 011master are slaves. The bus must be controlled by a
V
CC
GND 1001 100master device that generates the serial clock (SCL),controls the bus access, and generates the START
V
CC
High-Z 1001 101and STOP conditions.
V
CC
V
CC
1001 110To address a specific device, a START condition isinitiated. START is indicated by pulling the data line(SDA) from a high to low logic level while SCL is
Accessing a particular register on the TMP400 ishigh. All slaves on the bus shift in the slave address
accomplished by writing the appropriate value to thebyte, with the last bit indicating whether a read or
Pointer Register. The value for the Pointer Register iswrite operation is intended. During the ninth clock
the first byte transferred after the slave address bytepulse, the slave being addressed responds to the
with the R/ W bit low. Every write operation to themaster by generating an Acknowledge and pulling
TMP400 requires a value for the Pointer RegisterSDA low.
(see Figure 14 ).Data transfer is then initiated and sent over eight
When reading from the TMP400, the last value storedclock pulses followed by an Acknowledge bit. During
in the Pointer Register by a write operation is used todata transfer, SDA must remain stable while SCL is
determine which register is read by a read operation.high, because any change in SDA while SCL is high
To change the register pointer for a read operation, ais interpreted as a control signal.
new value must be written to the Pointer Register.Once all data have been transferred, the master
This transaction is accomplished by issuing a slavegenerates a STOP condition. STOP is indicated by
address byte with the R/ W bit low, followed by thepulling SDA from low to high, while SCL is high.
Pointer Register byte. No additional data arerequired. The master can then generate a STARTcondition and send the slave address byte with theR/ W bit high to initiate the read command. SeeFigure 16 for details of this sequence. If repeated
Copyright © 2007, Texas Instruments Incorporated Submit Documentation Feedback 13
Product Folder Link(s): TMP400
www.ti.com
TIMING DIAGRAMS
SCL
SDA
t(LOW) tRtFt(HDSTA)
t(HDSTA)
t(HDDAT)
t(BUF)
t(SUDAT)
t(HIGH) t(SUSTA) t(SUSTO)
P S S P
TMP400
SBOS404 – DECEMBER 2007
reads from the same register are desired, it is not Stop Data Transfer: A change in the state of thenecessary to continually send the Pointer Register SDA line from low to high while the SCL line is highbytes, because the TMP400 retains the Pointer defines a STOP condition. Each data transferRegister value until it is changed by the next write terminates with a repeated START or STOPoperation. Note that register bytes are sent MSB first, condition.followed by the LSB.
Data Transfer: The number of data bytes transferredbetween a START and a STOP condition is notlimited and is determined by the master device. Thereceiver acknowledges the transfer of data.Figure 13 to Figure 16 describe various operations onthe TMP400. Bus definitions are given below.
Acknowledge: Each receiving device, whenParameters for Figure 13 are defined in Table 10 .
addressed, is obliged to generate an Acknowledgebit. A device that acknowledges must pull down theBus Idle: Both SDA and SCL lines remain high.
SDA line during the Acknowledge clock pulse in suchStart Data Transfer: A change in the state of the
a way that the SDA line is stable low during the highSDA line, from high to low, while the SCL line is high,
period of the Acknowledge clock pulse. Setup anddefines a START condition. Each data transfer
hold times must be taken into account. On a masterinitiates with a START condition.
receive, data transfer termination can be signaled bythe master generating a Not-Acknowledge on the lastbyte that has been transmitted by the slave.
Figure 13. Two-Wire Timing Diagram
Table 10. Timing Diagram Definitions for Figure 13
FAST MODE HIGH-SPEED MODE
PARAMETER MIN MAX MIN MAX UNIT
SCL Operating Frequency f
(SCL)
0.001 0.4 0.001 3.4 MHzBus Free Time Between STOP and START Condition t
(BUF)
600 160 nsHold time after repeated START condition.
t
(HDSTA)
100 100 nsAfter this period, the first clock is generated.Repeated START Condition Setup Time t
(SUSTA)
100 100 nsSTOP Condition Setup Time t
(SUSTO)
100 100 nsData Hold Time t
(HDDAT)
0
(1)
0
(2)
nsData Setup Time t
(SUDAT)
100 10 nsSCL Clock LOW Period t
(LOW)
1300 160 nsSCL Clock HIGH Period t
(HIGH)
600 60 nsClock/Data Fall Time t
F
300 nsClock/Data Rise Time t
R
300 160
nsfor SCL ≤100kHz t
R
1000 160
(1) For cases with fall time of SCL less than 20ns and/or the rise time or fall time of SDA less than 20ns, the hold time should be greaterthan 20ns.(2) For cases with 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 than10ns.
14 Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated
Product Folder Link(s): TMP400
www.ti.com
Frame2PointerRegisterByte
Frame4DataByte2
1
StartBy
Master
ACKBy
TMP400
ACKBy
TMP400
ACKBy
TMP400
StopBy
Master
1 9 1
1
D7 D6 D5 D4 D3 D2 D1 D0
9
Frame3DataByte1
ACKBy
TMP400
1
D7
SDA
(Continued)
SCL
(Continued)
D6 D5 D4 D3 D2 D1 D0
9
9
SDA
SCL
0 0 1 1 0 0 R/W P7 P6 P5 P4 P3 P2 P1 P0
¼
¼
Frame1Two-WireSlaveAddressByte(1)
Frame2PointerRegisterByte
1
StartBy
Master
ACKBy
TMP400
ACKBy
TMP400
Frame4DataByte1ReadRegister
StartBy
Master
ACKBy
TMP400
NACKBy
Master(2)
From
TMP400
1 9 1 9
1 9 1 9
SDA
SCL
0 0 1 R/WP7 P6 P5 P4 P3 P2 P1 P0
SDA
(Continued)
SCL
(Continued)
1 0 0 1
1 0 0
1 0 0 R/WD7 D6 D5 D4 D3 D2 D1 D0
Frame1T WireSlaveAddressBytewo- (1)
Frame3T WireSlaveAddressBytewo- (1)
TMP400
SBOS404 – DECEMBER 2007
(1) See Table 9 for all available addresses. A0 = 1 and A1 = 0 in this example.
Figure 14. Two-Wire Timing Diagram for Write Word Format
(1) See Table 9 for all available addresses. A0 = 1 and A1 = 0 in this example.(2) Master should leave SDA high to terminate a single-byte read operation.
Figure 15. Two-Wire Timing Diagram for Single-Byte Read Format
Copyright © 2007, Texas Instruments Incorporated Submit Documentation Feedback 15
Product Folder Link(s): TMP400
www.ti.com
Frame2PointerRegisterByte
1
StartBy
Master
ACKBy
TMP400
ACKBy
TMP400
Frame4DataByte1ReadRegister
StartBy
Master
ACKBy
TMP400
ACKBy
Master
From
TMP400
1 9 1 9
1 9 1 9
SDA
SCL
0 0 1 R/WP7 P6 P5 P4 P3 P2 P1 P0 ¼
¼
¼
¼
SDA
(Continued)
SCL
(Continued)
SDA
(Continued)
SCL
(Continued)
1 0 0 1
1 0 0
1 0 0 R/WD7 D6 D5 D4 D3 D2 D1 D0
Frame5DataByte2ReadRegister
StopBy
Master
ACKBy
Master
From
TMP400
19
D7 D6 D5 D4 D3 D2 D1 D0
Frame1Two-WireSlaveAddressByte(1)
Frame3Two-WireSlaveAddressByte(1)
Frame1SMBusALERTResponseAddressByte
StartBy
Master
ACKBy
TMP400
From
TMP400
NACKBy
Master
StopBy
Master
1 9 1 9
SDA
SCL
ALERT
0 0 0 1 1 0 0 R/W1 0 0 1 1 0 0 Status
Frame2Two-WireSlaveAddressByte(1)
TMP400
SBOS404 – DECEMBER 2007
(1) See Table 9 for all available addresses. A0 = 1 and A1 = 0 in this example.
Figure 16. Two-Wire Timing Diagram for Two-Byte Read Format
(1) See Table 9 for all available addresses. A0 = 1 and A1 = 0 in this example.
Figure 17. Timing Diagram for SMBus ALERT
16 Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated
Product Folder Link(s): TMP400
www.ti.com
HIGH-SPEED MODE ALERT (PIN 11)
TIMEOUT FUNCTION
STBY (PIN 15)
Measured
Temperature
ALERTHighLimit
ALERTLowLimitHysteresis
ALERT
SMBusALERT
Read Read
Time
Read
TMP400
SBOS404 – DECEMBER 2007
In order for the Two-Wire bus to operate at The ALERT pin of the TMP400 is dedicated to alarmfrequencies above 400kHz, the master device must functions. This pin has an open-drain output thatissue a High-speed mode (Hs-mode) master code requires a pull-up resistor to V+. It can be wire-ORed(00001XXX) as the first byte after a START condition together with other alarm pins for system monitoringto switch the bus to high-speed operation. The of multiple sensors. The ALERT pin is intended forTMP400 does not acknowledge this byte, but use as an earlier warning interrupt, and can beswitches the input filters on SDA and SCL and the software disabled, or masked.output filter on SDA to operate in Hs-mode, allowing
The ALERT pin (pin 11) asserts low when either thetransfers at up to 3.4MHz. After the Hs-mode master
measured local or remote temperature violates thecode has been issued, the master transmits a
range limit set by the corresponding Local/RemoteTwo-Wire slave address to initiate a data transfer
Temperature High/Low Limit Registers. This alertoperation. The bus continues to operate in Hs-mode
function can be configured to assert only if the rangeuntil a STOP condition occurs on the bus. Upon
is violated a specified number of consecutive timesreceiving the STOP condition, the TMP400 switches
(1, 2, 3, or 4). The consecutive violation limit is set inthe input and output filter back to fast-mode
the Consecutive Alert Register. False alerts thatoperation.
occur as a result of environmental noise can beprevented by requiring consecutive faults. ALERTalso asserts low if the remote temperature sensor isopen-circuit. When the MASK function is enabledWhen bit 7 of the Consecutive Alert Register is set
(Configuration Register: bit 7 = 1), ALERT is disabledhigh, the TMP400 timeout function is enabled. The
(that is, masked). ALERT resets when the masterTMP400 resets the serial interface if either SCL or
reads the device address, as long as the conditionSDA are held low for 30ms (typical) between a
that caused the alert no longer persists, and theSTART and STOP condition. If the TMP400 is
Status Register has been reset.holding the bus low, it releases the bus and waits fora START condition. To avoid activating the timeoutfunction, it is necessary to maintain a communicationspeed of at least 1kHz for the SCL operating
The TMP400 features a standby pin ( STBY) that,frequency. The default state of the timeout function is
when pulled low, disables the device. During normalenabled (bit 7 = high).
operation STBY should be tied high (V+). WhenSTBY is pulled low, the TMP400 is immediatelydisabled. If the TMP400 receives a One-Shotcommand when STBY is pulled low, the command isignored and the TMP400 continues to be disableduntil STBY is pulled high.
Figure 18. SMBus Alert Timing Diagram
Copyright © 2007, Texas Instruments Incorporated Submit Documentation Feedback 17
Product Folder Link(s): TMP400
www.ti.com
SMBUS ALERT FUNCTION UNDERVOLTAGE LOCKOUT
GENERAL CALL RESET
SHUTDOWN MODE (SD)
IDENTIFICATION REGISTERS
SENSOR FAULT
FILTERING
TMP400
SBOS404 – DECEMBER 2007
The TMP400 supports the SMBus Alert function. The The TMP400 senses when the power-supply voltageALERT pin of the TMP400 may be connected as an has reached a minimum voltage level for the ADCSMBus Alert signal. When a master detects an alert converter to function. The detection circuitry consistscondition on the ALERT line, the master sends an of a voltage comparator that enables the ADCSMBus Alert command (00011001) on the bus. If the converter after the power supply (V+) exceeds 2.45VALERT pin of the TMP400 is active, the device (typical). The comparator output is continuouslyacknowledges the SMBus Alert command and checked during a conversion. The TMP400 does notrespond by returning its slave address on the SDA perform a temperature conversion if the power supplyline. The eighth bit (LSB) of the slave address byte is not valid. The last valid measured temperature isindicates whether the temperature exceeding one of used for the temperature measurement result.the temperature high limit settings or falling belowone of the temperature low limit settings caused thealert condition. This bit is high if the temperature is
The TMP400 supports reset via the Two-Wiregreater than or equal to one of the temperature high
General Call address 00h (0000 0000b). Thelimit settings; this bit is low if the temperature is less
TMP400 acknowledges the General Call address andthan one of the temperature low limit settings. See
responds to the second byte. If the second byte isFigure 17 for details of this sequence.
06h (0000 0110b), the TMP400 executes a softwareIf multiple devices on the bus respond to the SMBus
reset, while latching the status of the address pins.Alert command, arbitration during the slave address
This software reset restores the power-on reset stateportion of the SMBus Alert command determines
to all TMP400 registers, aborts any conversion inwhich device will clear its alert status. If the TMP400
progress, and clears the ALERT pin. If the secondwins the arbitration, its ALERT pin becomes inactive
byte is 04h ( 0000 0100b), the TMP400 latches theat the completion of the SMBus Alert command. If the
status of the address pins, but does not reset. TheTMP400 loses the arbitration, the ALERT pin remains
TMP400 takes no action in response to other valuesactive.
in the second byte. A 500 µs time delay must be takenafter a general call command.
The TMP400 Shutdown Mode allows the user to savemaximum power by shutting down all device circuitry
The TMP400 allows for the Two-Wire bus controllerother than the serial interface, reducing current
to query the device for manufacturer and device IDsconsumption to typically less than 3 µA; see typical
to allow for software identification of the device at thecharacteristic curve Shutdown Quiescent Current vs
particular Two-Wire bus address. The manufacturerSupply Voltage (Figure 10 ). Shutdown Mode is
ID is obtained by reading from pointer address FEh.enabled when the SD bit of the Configuration
The device ID is obtained by reading from pointerRegister is high; the device shuts down once the
address FFh. The TMP400 returns 55h for thecurrent conversion is completed. When SD is low, the
manufacturer code and 01h for the device ID. Thesedevice maintains a continuous conversion state.
registers are read-only.
The TMP400 senses a fault at the D+ input resulting
Remote junction temperature sensors are usuallyfrom incorrect diode connection or an open circuit.
implemented in a noisy environment. Noise is mostThe detection circuitry consists of a voltage
often created by fast digital signals, and it can corruptcomparator that trips when the voltage at D+ exceeds
measurements. The TMP400 has a built-in 65kHz(V+) – 0.6V (typical). The comparator output is
filter on the inputs of D+ and D – to minimize thecontinuously checked during a conversion. If a fault is
effects of noise. However, a bypass capacitor placeddetected, the result reads 7FFh (0111 1111 1111b)
differentially across the inputs of the remoteand is used for the temperature measurement result;
temperature sensor is recommended to make thethe OPEN bit (Status Register, bit 2) is set high, and,
application more robust against unwanted coupledif the alert function is enabled, ALERT asserts low.
signals. The value of the capacitor should bebetween 100pF and 1nF. Some applications attainWhen not using the remote sensor with the TMP400,
better overall accuracy with additional seriesthe D+ and D – inputs must be connected together to
resistance; however, this increased accuracy isprevent meaningless fault warnings.
setup-specific. When series resistance is added, thevalue should not be greater than 3k Ωand resistancecorrection must be enabled (RC = 1).
18 Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated
Product Folder Link(s): TMP400
www.ti.com
REMOTE SENSING
MEASUREMENT ACCURACY AND THERMAL
T =
ERR
n1.008-
1.008 ´ °[273.15+T( C)]
(4)
T =
ERR
1.004 1.008-
1.008 ´ °(273.15+100 C)
T = 1.48-
ERR °C
(5)
TMP400
SBOS404 – DECEMBER 2007
If filtering is needed, the suggested component 2. Base-emitter voltage < 0.95V at 120 µA, at thevalues are 100pF and 50 Ωon each input. Exact lowest sensed temperature.values are application specific. Resistance correction
3. Base resistance < 100 Ω.must be enabled to avoid offset correction.
4. Tight control of V
BE
characteristics indicated bysmall variations in h
FE
(that is, 50 to 150).
Based on these criteria, two recommendedThe TMP400 is designed to be used with either
small-signal transistors are the 2N3904 (NPN) ordiscrete transistors or substrate transistors built into
2N3906 (PNP).processor chips and ASICs. Either NPN or PNPtransistors can be used, as long as the base-emitterjunction is used as the remote temperature sense.
CONSIDERATIONSEither a transistor or diode connection can also beused; see Figure 11 .
The temperature measurement accuracy of theTMP400 depends on the remote and/or localErrors in remote temperature sensor readings are
temperature sensor being at the same temperaturegenerally the consequence of the ideality factor and
as the system point being monitored. Clearly, if thecurrent excitation used by the TMP400 versus the
temperature sensor is not in good thermal contactmanufacturer-specified operating current for a given
with the part of the system being monitored, thentransistor. Some manufacturers specify a high-level
there will be a delay in the response of the sensor toand low-level current for the temperature-sensing
a temperature change in the system. For remotesubstrate transistors. The TMP400 uses 6 µA for I
LOW
temperature sensing applications using a substrateand 120 µA for I
HIGH
. The TMP400 allows for different
transistor (or a small, SOT23 transistor) placed closen-factor values; see the N-Factor Correction Register
to the device being monitored, this delay is usuallysection.
not a concern.The ideality factor ( n) is a measured characteristic of
The local temperature sensor inside the TMP400a remote temperature sensor diode as compared to
monitors the ambient air around the device. Thean ideal diode. The ideality factor for the TMP400 is
thermal time constant for the TMP400 istrimmed to be 1.008. For transistors whose ideality
approximately two seconds. This constant impliesfactor does not match the TMP400, Equation 4 can
that if the ambient air changes quickly by 100 °C, itbe used to calculate the temperature error. Note that
would take the TMP400 about 10 seconds (that is,for the equation to be used correctly, actual
five thermal time constants) to settle to within 1 °C oftemperature ( °C) must be converted to Kelvin ( °K).
the final value. In most applications, the TMP400package is in electrical (and therefore, thermal)contact with the printed circuit board (PCB), as wellas subjected to forced airflow. The accuracy of theWhere: measured temperature directly depends on howaccurately the PCB and forced airflow temperaturesn= Ideality factor of remote temperature sensor
represent the temperature that the TMP400 isT( °C) = actual temperature
measuring. Additionally, the internal power dissipationT
ERR
= Error in TMP400 reading due to n≠1.008
of the TMP400 can cause the temperature to riseDegree delta is the same for °C and °K
above the ambient or PCB temperature. The internalpower dissipated as a result of exciting the remoteFor n= 1.004 and T( °C) = 100 °C:
temperature sensor is negligible because of the smallcurrents used. For a 5.5V supply and maximumconversion rate of eight conversions per second, theTMP400 dissipates 1.82mW (PD
IQ
= 5.5V ×420 µA).If the ALERT pin is sinking 1mA, an additional powerof 0.4mW is dissipated (PD
OUT
= 1mA ×0.4V =If a discrete transistor is used as the remote
0.4mW). Total power dissipation is then 2.22mWtemperature sensor with the TMP400, the best
(PD
IQ
+ PD
OUT
) and, with an θ
JA
of 150 °C/W, causesaccuracy can be achieved by selecting the transistor
the junction temperature to rise approximatelyaccording to the following criteria:
0.333 °C above the ambient.1. Base-emitter voltage > 0.25V at 6 µA, at thehighest sensed temperature.
Copyright © 2007, Texas Instruments Incorporated Submit Documentation Feedback 19
Product Folder Link(s): TMP400
www.ti.com
LAYOUT CONSIDERATIONS
GND(1)
D+(1)
D-(1)
GND(1)
GroundorV+layer
onbottomand/or
top,ifpossible.
1
2
3
4
16
15
14
13
TMP400
0.1 FCapacitorm
PCBVia PCBVia
V+ GND
5
6
7
12
11
10
89
TMP400
SBOS404 – DECEMBER 2007
Remote temperature sensing on the TMP400measures very small voltages using very lowcurrents; therefore, noise at the IC inputs must beminimized. Most applications using the TMP400 willhave high digital content, with several clocks andlogic level transitions creating a noisy environment.Layout should adhere to the following guidelines:1. Place the TMP400 as close to the remotejunction sensor as possible.2. Route the D+ and D – traces next to each otherand shield them from adjacent signals throughthe use of ground guard traces, as shown inFigure 19 . If a multilayer PCB is used, bury thesetraces between ground or V
DD
planes to shieldthem from extrinsic noise sources. 5 mil(0.127mm) PCB traces are recommended.
(1) 5mil traces with 5mil spacing.3. Minimize additional thermocouple junctionscaused by copper-to-solder connections. If these
Figure 19. Example Signal Tracesjunctions are used, make the same number andapproximate locations of copper-to-solderconnections in both the D+ and D – connectionsto cancel any thermocouple effects.4. Use a 0.1 µF local bypass capacitor directlybetween the V+ and GND of the TMP400, asshown in Figure 20 . Minimize filter capacitancebetween D+ and D – to 1000pF or less foroptimum measurement performance. Thiscapacitance includes any cable capacitancebetween the remote temperature sensor andTMP400.
5. If the connection between the remotetemperature sensor and the TMP400 is less than8 inches (203.2mm), use a twisted-wire pairconnection. Beyond 8 inches, use a twisted,shielded pair with the shield grounded as close tothe TMP400 as possible. Leave the remotesensor connection end of the shield wire open to
Figure 20. Suggested Bypass Capacitoravoid ground loops and 60Hz pickup.
Placement
20 Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated
Product Folder Link(s): TMP400
PACKAGE OPTION ADDENDUM
www.ti.com 16-Aug-2012
Addendum-Page 1
PACKAGING INFORMATION
Orderable Device Status (1) Package Type Package
Drawing Pins Package Qty Eco Plan (2) Lead/
Ball Finish MSL Peak Temp (3) Samples
(Requires Login)
TMP400AIDBQR ACTIVE SSOP DBQ 16 2500 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
TMP400AIDBQRG4 ACTIVE SSOP DBQ 16 2500 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
TMP400AIDBQT ACTIVE SSOP DBQ 16 250 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
TMP400AIDBQTG4 ACTIVE SSOP DBQ 16 250 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
(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) 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.
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.
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device Package
Type Package
Drawing Pins SPQ Reel
Diameter
(mm)
Reel
Width
W1 (mm)
A0
(mm) B0
(mm) K0
(mm) P1
(mm) W
(mm) Pin1
Quadrant
TMP400AIDBQR SSOP DBQ 16 2500 330.0 12.4 6.4 5.2 2.1 8.0 12.0 Q1
TMP400AIDBQT SSOP DBQ 16 250 180.0 12.4 6.4 5.2 2.1 8.0 12.0 Q1
PACKAGE MATERIALS INFORMATION
www.ti.com 16-Aug-2012
Pack Materials-Page 1
*All dimensions are nominal
Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm)
TMP400AIDBQR SSOP DBQ 16 2500 367.0 367.0 35.0
TMP400AIDBQT SSOP DBQ 16 250 210.0 185.0 35.0
PACKAGE MATERIALS INFORMATION
www.ti.com 16-Aug-2012
Pack Materials-Page 2
IMPORTANT NOTICE
Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other
changes to its semiconductor products and services per JESD46C and to discontinue any product or service per JESD48B. Buyers should
obtain the latest relevant information before placing orders and should verify that such information is current and complete. All
semiconductor products (also referred to herein as “components”) are sold subject to TI’s terms and conditions of sale supplied at the time
of order acknowledgment.
TI warrants performance of its components to the specifications applicable at the time of sale, in accordance with the warranty in TI’s terms
and conditions of sale of semiconductor products. Testing and other quality control techniques are used to the extent TI deems necessary
to support this warranty. Except where mandated by applicable law, testing of all parameters of each component is not necessarily
performed.
TI assumes no liability for applications assistance or the design of Buyers’ products. Buyers are responsible for their products and
applications using TI components. To minimize the risks associated with Buyers’ products and applications, Buyers should provide
adequate design and operating safeguards.
TI does not warrant or represent that any license, either express or implied, is granted under any patent right, copyright, mask work right, or
other intellectual property right relating to any combination, machine, or process in which TI components or services are used. Information
published by TI regarding third-party products or services does not constitute a license to use such products or services or a warranty or
endorsement thereof. Use of such information may require a license from a third party under the patents or other intellectual property of the
third party, or a license from TI under the patents or other intellectual property of TI.
Reproduction of significant portions of TI information in TI data books or data sheets is permissible only if reproduction is without alteration
and is accompanied by all associated warranties, conditions, limitations, and notices. TI is not responsible or liable for such altered
documentation. Information of third parties may be subject to additional restrictions.
Resale of TI components or services with statements different from or beyond the parameters stated by TI for that component or service
voids all express and any implied warranties for the associated TI component or service and is an unfair and deceptive business practice.
TI is not responsible or liable for any such statements.
Buyer acknowledges and agrees that it is solely responsible for compliance with all legal, regulatory and safety-related requirements
concerning its products, and any use of TI components in its applications, notwithstanding any applications-related information or support
that may be provided by TI. Buyer represents and agrees that it has all the necessary expertise to create and implement safeguards which
anticipate dangerous consequences of failures, monitor failures and their consequences, lessen the likelihood of failures that might cause
harm and take appropriate remedial actions. Buyer will fully indemnify TI and its representatives against any damages arising out of the use
of any TI components in safety-critical applications.
In some cases, TI components may be promoted specifically to facilitate safety-related applications. With such components, TI’s goal is to
help enable customers to design and create their own end-product solutions that meet applicable functional safety standards and
requirements. Nonetheless, such components are subject to these terms.
No TI components are authorized for use in FDA Class III (or similar life-critical medical equipment) unless authorized officers of the parties
have executed a special agreement specifically governing such use.
Only those TI components which TI has specifically designated as military grade or “enhanced plastic” are designed and intended for use in
military/aerospace applications or environments. Buyer acknowledges and agrees that any military or aerospace use of TI components
which have not been so designated is solely at the Buyer's risk, and that Buyer is solely responsible for compliance with all legal and
regulatory requirements in connection with such use.
TI has specifically designated certain components which meet ISO/TS16949 requirements, mainly for automotive use. Components which
have not been so designated are neither designed nor intended for automotive use; and TI will not be responsible for any failure of such
components to meet such requirements.
Products Applications
Audio www.ti.com/audio Automotive and Transportation www.ti.com/automotive
Amplifiers amplifier.ti.com Communications and Telecom www.ti.com/communications
Data Converters dataconverter.ti.com Computers and Peripherals www.ti.com/computers
DLP® Products www.dlp.com Consumer Electronics www.ti.com/consumer-apps
DSP dsp.ti.com Energy and Lighting www.ti.com/energy
Clocks and Timers www.ti.com/clocks Industrial www.ti.com/industrial
Interface interface.ti.com Medical www.ti.com/medical
Logic logic.ti.com Security www.ti.com/security
Power Mgmt power.ti.com Space, Avionics and Defense www.ti.com/space-avionics-defense
Microcontrollers microcontroller.ti.com Video and Imaging www.ti.com/video
RFID www.ti-rfid.com
OMAP Mobile Processors www.ti.com/omap TI E2E Community e2e.ti.com
Wireless Connectivity www.ti.com/wirelessconnectivity
Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265
Copyright © 2012, Texas Instruments Incorporated