SEMTECH SX8743

SX8733/SX8743/SX8744
DATASHEET
ADVANCED COMMUNICATIONS & SENSING
Precision Diode Digital Temperature
For Up To 3 External Sensors
SX8733
P1
1
AL1 AL2
6
P2
5
VDD
4
SMBCLK
ALARM
2 D2+
D2-
SMBDAT
VDD
SX8743
1
+
+
-
MUX
VSS
D1+
D1-
3
8
+ ADC
-
SMBUS
SMBCLK
VDD
SX8744
1
AL1 AL2
P3
2
P1
4
+-
+ ADC
-
SMBUS
7
SMBDAT
P1
2
6
P4
P2
3
5
VSS
NC
4
ALARM
D1+
D1-
+-
D2+
D2-
+
-
MUX
3
++-
MUX
P2
ALARM
D1+
D1D2+
D2D3+
D3-
8
SMBCLK
7
SMBDAT
6
P4
5
VSS
AL1 AL2
+ ADC
-
SMBUS
General Description
Key Product Features
The SX8733, SX8743 and SX8744 are digital temperature
sensors with a 2-wire SMBus interface. It provides a lowcost solution to monitor the temperature of remote diodes
as well as its own temperature with an on-chip PN junction
sensor.
1 Internal and Up To 3 External Sensors
2 Temp. Output Formats: 0°C to 127°C and -40°C to
140°C With 0.125°C Resolution
Depending on the device version, 2, 3 or 4 programmable
ports are included. They offer the possibility to trig under- /
over- temperature alarms which can be used as an interrupt
or to connect up to 3 external sensors in single-ended
mode or 2 external sensors in differential mode.
Parasitic Series Resistance Cancellation: Algorithmic, 3point and Kelvin (4-wire)
Under-/ Over- Temp. Alarms With Programmable
Thresholds
Programmable Conversion Rate For Optimal Power
Consumption
250 uA Active Current @ 10Hz Sampling Rate
V
The parasitic resistances in series with the temperature
monitoring diode can be cancelled by an algorithmic, a 3point or a Kelvin (4-wire) method.
The SX8744 is pin-to-pin compatible with the LM86 part.
The SX8733 (2 programmable ports) is available in MLPD6 package. The SX8743 (4 programmable ports) and
SX8744 (3 programmable ports) are available in MSOP-8
package.
Applications
Printer
Server
Set Top Box
Projector
Remote Diode Temp. Accuracy of ±0.5°C on the Temp.
Range 25°C to 100°C
SMBus v2.0 Interface Supports TIMEOUT
Pb-Free, Halogen Free, RoHS/WEEE Compliant
Product
Ordering Information
Part Number
Feature
Package
SX8733EWLTRT
2 Programmable ports
MLPD-6
SX8743EMSTRT
4 Programmable ports
MSOP-8
SX8744EMSTRT
3 Programmable ports
MSOP-8
Batteries charger monitoring
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ADVANCED COMMUNICATIONS & SENSING
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Table of contents
Section
Page
1.
Electrical Characteristics ......................................................................................................................................... 3
2.
3.
4.
1.1.
Sensor Temperature Definition ........................................................................................................................ 3
1.2.
Absolute Maximum Ratings ............................................................................................................................. 3
1.3.
Electrical Specification ..................................................................................................................................... 4
1.4.
SMBus Timing Characteristics......................................................................................................................... 5
1.5.
SMBus Timing Waveforms .............................................................................................................................. 5
Pin Configuration ..................................................................................................................................................... 6
2.1.
Pinout............................................................................................................................................................... 6
2.2.
Pin Description................................................................................................................................................. 6
Configuration ........................................................................................................................................................... 7
3.1.
General Presentation ....................................................................................................................................... 7
3.2.
Modes .............................................................................................................................................................. 7
3.3.
Differential and Single-Ended External Sensor.............................................................................................. 10
3.4.
Measurement Principle .................................................................................................................................. 10
3.5.
Parasitic Track Resistance Cancellation........................................................................................................ 10
3.5.1.
Algorithmic Track Resistance Cancellation............................................................................................ 10
3.5.2.
3-Point Track Resistance Cancellation ................................................................................................... 10
3.5.3.
The Kelvin (4-wire) Track Resistance Cancellation ................................................................................ 11
3.6.
Temperature Acquisition Sequence............................................................................................................... 11
3.7.
Alarm.............................................................................................................................................................. 12
3.8.
Temperature Data Format ............................................................................................................................. 12
3.9.
Continuous Time Vs. Single Shot .................................................................................................................. 13
Application Note .................................................................................................................................................... 13
4.1.
Typical Temperature Sensing System With A SX8743.................................................................................. 13
5.
Power-Up Sequence and Standby Mode .............................................................................................................. 14
6.
Serial Interface ...................................................................................................................................................... 14
7.
8.
6.1.
Register Write - Combined Format ................................................................................................................ 14
6.2.
Register Write - Direct Format ....................................................................................................................... 14
6.3.
Register Read - Combined Format ................................................................................................................ 15
6.4.
Register Read - Direct Format ....................................................................................................................... 15
6.5.
Soft Reset ...................................................................................................................................................... 15
Register / Memory Map ......................................................................................................................................... 16
7.1.
Memory Map .................................................................................................................................................. 16
7.2.
Registers Description..................................................................................................................................... 16
Packaging Information ........................................................................................................................................... 20
8.1.
MLPD-W6-EP2 Package Outline Drawing..................................................................................................... 20
8.2.
MLPD-W6-EP2 Land Pattern Drawing........................................................................................................... 21
8.3.
Package Outline Drawing: MSOP-8............................................................................................................... 22
8.4.
Land Pattern Drawing: MSOP-8 .................................................................................................................... 23
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SX8733/SX8743/SX8744
Digital temperature sensor
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ADVANCED COMMUNICATIONS & SENSING
1. Electrical Characteristics
1.1. Sensor Temperature Definition
Parameter
Symbol
Local sensor diode temperature (chip junction temperature)
TJ
External diode temperature (remote diode junction temperature)
TD
1.2. Absolute Maximum Ratings
Stresses above the values listed below may cause permanent device failure. Exposure to absolute maximum ratings for
extended periods may affect device reliability. Operation outside the parameters specified in the Electrical Characteristics
section is not implied.
Parameter
Symbol
Conditions
Min
Max
Unit
Power supply to VSS
VDD,ABSMAX
-0.5
5.75
V
Storage temperature
TJ,STORE
-50
150
°C
Ambient operating temperature
TJ,ABSMAX
-40
140
°C
Input voltage on programmable
pin
VPIN,ABSMAX
P1, P2, P3, P4
-0.5
VDD + 0.25
V
Input voltage on SMBUS pin
VPIN,SMBUS
SMBCLK, SMBDAT
-0.5
5.75
V
Input current on any pin
IPIN,ABSMAX
-10
10
mA
Peak reflow temperature
TPKG
260
°C
Latchup
ILUP
100
mA
2
kV
ESD
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HBM
Human Body Model
MM
Machine Model
200
V
CDM
Charged Device Model
500
V
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Digital temperature sensor
DATASHEET
ADVANCED COMMUNICATIONS & SENSING
1.3. Electrical Specification
All values valid within the operating conditions unless otherwise specified.
Parameter
Symbol
Conditions
Min
Typ
Max
Unit
2.7
3.3
5.5
V
125
°C
250
400
uA
40
uA
Operating Conditions
Power supply
VDD
TJ
Operating temperature =
Junction temperature
Active current
IVDD,ACTIVE
10 Hz sampling rate
No track cancellation mode
Current in standby mode
IVDD,STDBY
10
TRESOL
0.125
Operating temperature
-40
Current Consumption
Temperature to Digital Converter
Temperature resolution
°C
TD,ERR1
TJ = 25°C to 85°C
TD = 25°C to 100°C
-1.5
±0.5
1.5
°C
TD,ERR2
TJ = 25°C to 85°C
TD = - 40°C to 125°C
-3
±1.5
3
°C
TJ,ERR1
TJ = 25°C to 85°C
-2
±0.75
2
°C
TJ,ERR2
TJ = - 40°C to 125°C
±1.5
°C
tCONV
10Hz sampling rate
100
ms
I2
High level
100
uA
I1
Low level
10
uA
Alarm output low voltage
VOL,AL
IOL< 4mA
Leakage current
ID,LEAK
Standby mode
Remote temperature error1
Local temperature error1
Conversion time
Remote-diode source current
-1
0.4
V
1
uA
SMBus - Compatible Interface SMBCLK & SMBDAT
Input logic high
VIH
Input logic low
VIL
Output logic low
VOL
Current leakage on SMBCLK/
SMBDAT
ILEAK,SMB
Capacitive load on SMBCLK/
SMBDAT
CBUS
2.1
V
IOL< 4mA
-1
5
0.8
V
0.4
V
1
uA
pF
1. Specification with VDD=3.0V to 3.6V and track resistance cancellation disabled.
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Digital temperature sensor
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1.4. SMBus Timing Characteristics
Parameter
Symbol
Conditions
Min
Typ
Max
Unit
400
kHz
SMBus clock frequency
fSMB
10
SMBus clock low time
tLOW
1.3
us
SMBus clock high time
tHIGH
0.6
us
SMBus rise time
tR,SMB
300
ns
SMBus fall time
tF,SMB
300
ns
35
ms
SMBDAT and SMBCLK time low
for reset of serial interface
tTIMEOUT
25
Data setup time
tSU,DAT
100
ns
Data hold time1
tHD,DAT
0
ns
Start condition hold time
(SMBDAT low to SMBCLK low)
tHD,STA
0.6
us
Stop condition hold time
(SMBCLK high to SMBDAT high)
tSU,STO
0.6
us
Repeated start-condition setup
time
(SMBCLK high to SMBDAT low)
tSU,STA
0.6
us
tBUF
1.3
us
SMBus free time between stop
and start conditions
1. The device provides a hold time of at least 300ns for the SMBDAT signal to bridge the undefined region of the falling edge of SMBCLK.
1.5. SMBus Timing Waveforms
SMBDAT
SMBCLK
tSU,STA
tHD,STA
tLOW
tHIGH
tHD,DAT
Start
tSU,DAT
tSU,STO
tBUF
Stop
Figure 1. SMBUS Timing
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2. Pin Configuration
2.1. Pinout
SX8743
SX87331
P1
VSS
SMBDAT
SMBCLK
VDD
P2
-
Pin #
1
2
3
4
5
6
7
8
SX8744
VDD
P1
P2
NC
VSS
P4
SMBDAT
SMBCLK
VDD
P3
P2
P1
VSS
P4
SMBDAT
SMBCLK
1. MLPD exposed pad is not connected internally. It is connected to ground plane for
thermal dissipation
Table 1 Pinout
2.2. Pin Description
Pin
Type
SMBCLK
SMBDAT
VDD
VSS
DIGITAL
DIGITAL
POWER
POWER
Description
SMBus serial clock input, open drain
SMBus serial data input/output, open drain
Positive power supply
Negative power supply
Table 2 Power and SMBus Pin Description
Pin
P1
P2
P3
P4
VSS
Type
Description
ANALOG
DIGITAL
ANALOG
Ext. diode current source
Alarm output, pseudo-open drain
Ext. diode current source
ANALOG
Ext. diode return current sink
DIGITAL
ANALOG
Alarm output, pseudo-open drain
Ext. diode current source
ANALOG
Ext. diode return current sink
DIGITAL
ANALOG
Alarm output, pseudo-open drain
Ext. diode return current sink
DIGITAL
POWER
0
2
1
D1+ D1+
3
Mode
4
6
8
11
13
16
10
15
18
20
5
7
9
12
14
17
D1+ D1+ D1+ D1+ D1+ D1+ D1+ D1+ D1+ D1+
AL1
D2+
D2+ D2+ D2+
D1- D1-
D1AL2
D1-
D1-
D2+ D2+
D3+ D3+ D1+
D1D2-
AL1 AL1
D2-
Alarm output, pseudo-open drain
Ext. diode return current sink
D1-
AL1
AL2 AL2
D1-
D1D2-
D1-
D1-
D1D1AL1 AL1 D2D3D1- D1D1- D1D2- D2D2- D2D3- D3-
Table 3 Programmable Pin Description
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3. Configuration
3.1. General Presentation
SX8733 / SX8743 / SX8744 include an onchip PN junction to measure local temperaAL1
ture TJ.
AL2
4
3
1
6
P1
P2
P3
2
DECODER
3
2
D1+
D1D2+
6
+
+
-
P4
D3+
D3-
MUX
D2-
6
The device has a 2-level current source
and an ADC to measure each diode’s
forward
voltage
to
compute
the
temperature. The input multiplexer allows 3
external and 1 internal sensors to be
connected to the ADC.
ALARM
+
ADC
-
+
SMBUS
SMBCLK
4
8
SMBDAT
3
7
VDD
5
1
VSS
2
5
SX8733
SX8744
SX8743
Two alarms can provide to the system the
information that a sensor temperature has
reached the programmable threshold.
The chip is configured with a 2-wire
SMBUS serial line.
The functional
Figure 2.
diagram
is
shown in
Figure 2. Functional Diagram
3.2. Modes
The mode set in RegConfig allows numerous circuit configurations described in Figure 3 and Figure 4.
Up to 3 external sensors can be connected. Theses are configured with differential or single-ended connections.
Some modes provide a track resistance cancellation feature to decrease temperature inaccuracy linked to long PCB traces
connecting the external sensor to the chip. This is set in RegControl (bits Point3 or Algo). Table 4 presents the mode for the
SX8743.
Mode
External sensor
Differential
Single-ended
Algorithmic track resistance cancellation
3-point track resistance cancellation
Kelvin (4-wire) track resistance cancellation
Alarm #
0
1
x
1
1
x
2
1
3
0
x
4
2
5
2
6
1
7
1
x
x
x
x
x
x
0
1
x
8
1
x
9
1
x
x
x
0
0
0
2
0
1
2
2
10 11 12 13 14 15 16 17 18 20
1 2 2 2 2 2 3 3 3 1
x x
x
x
x x x x x x
x
x
x
x
x
x
x
2 0 0 2 2 1 1 1 0 0
Table 4 Features Available With SX8743
Due to their limited number of ports, SX8733 and SX8744 do not offer all theses features. SX8733 does not provide ports
P3 and P4 so modes 8 to 20 should not be used. Also port P3 is not available on SX8744 and this typically reduces the
number of alarm or the number of external sensors.
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Digital temperature sensor
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ADVANCED COMMUNICATIONS & SENSING
P1
P1
TD1
P2
TD1
P2
Mode 0, Mode 1
Mode 2
VDD
P1
TD1
P1
P2
ALARM1
TD2
P2
VSS
ALARM2
Mode 3
Mode 4, Mode 5
P1
P1
TD1
VSS
P2
TD1
VDD
VDD
P2
P3
ALARM1
P4
ALARM2
ALARM1
Mode 8, Mode 9
Mode 6, Mode 7
P1
P1
TD1
P2
P2
VDD
TD1
P3
P3
ALARM1
P4
ALARM2
P4
Mode 10
TD2
Mode 11, Mode 12
Figure 3. Mode Connection Diagrams (Modes 0 to 12)
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P1
P1
TD1
P2
TD1
P2
VDD
TD2
TD2
P3
VSS
VDD
P3
ALARM1
P4
P4
ALARM2
Mode 13, Mode 14
Mode 15
P1
P1
TD1
P2
P2
TD2
P3
P3
TD3
VSS
ALARM1
P4
VDD
P4
TD1
TD2
TD3
ALARM1
Mode 18
Mode 16, Mode 17
P1
TD1
P2
P3
P4
Mode 20
Figure 4. Mode Connection Diagrams (Modes 13 to 18 and 20)
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3.3. Differential and Single-Ended External Sensor
Table 4 indicates whether the external sensors are connected differentially or in single-ended configuration with grounded
cathode.
Differential modes have better common-mode rejection of external noise pickup. The external noise pickup is present
equally on the anode and the cathode therefore differential noise is minimized.
Single-ended modes allow more sensors to be connected to the chip but they are more prone to noise pickup since the
cathode is connected to a common VSS and, therefore, any external noise pickup tends to be developed mainly across the
anode which will be measured as temperature noise.
A filtering capacitor is recommended to decrease measurement noise especially if the external sensor is connected to the
chip by a long trace. A capacitor with a value of 100 pF should be placed as close as possible to the chip pins.
3.4. Measurement Principle
The circuit uses the intrinsic thermal property of a diode to measure temperature. Temperature is calculated by measuring
the base-emitter voltage of a transistor. Two different currents are sourced to the diodes. The base-emitter voltage is
measured in each case. With a fixed current ratio, temperature is accurately calculated by measuring the difference in the
base-emitter voltage at the two currents.
The excitation current I2 of 100uA is passed through the diode first. The base-emitter voltage of the transistor is measured
by the ADC. The measurement is then repeated using the excitation current divided by a fixed value. This current I1 has a
value of 10uA. The following equation relates the VBE difference voltage with current and temperature T where:
k is the Boltzmann’s constant (1.381 x 10-23 J/K)
q is the charge on the electron (1.602 x 10-19 Cb).
Tabs is the absolute temperature in Kelvins. (Tabs=273.15 + T
where T is the temperature in Celsius).
n is the pn junction ideality factor (1.00 for an ideal diode)
For a current ratio I2/I1=10 and an ideality factor n=1.010, this gives a
fixed relationship between ∆VBE and temperature of 200uV/ºC. The
voltage is then converted to digital with an ADC.
kT abs I 2
∆V BE = V BE2 – V BE1 = n ⋅ ------------- ln  ----
q
I1
3.5. Parasitic Track Resistance Cancellation
The temperature measurement method described previously assumes
a very low series impedance in the sensor path.With a typical ∆VBE
around 200uV/ºC and the ∆I=I2-I1=90uA, 1 ohm of parasitic resistance
in the sensor path gives approximately 0.45ºC of temperature error.
This may result in a significant error if the external sensor is located
some distance away from the chip. Track resistance cancellation
schemes decrease temperature error due to high resistance in the
tracks from the device to the sensors.
I2 – I1
∆T Rtrack = R Track ⋅ -----------------------200uV ⁄ C
3.5.1. Algorithmic Track Resistance Cancellation
The use of the algorithmic track resistance cancellation allows automatic cancellation of resistances in series with the
temperature diode by using current modulation to bias the external diode. This is done transparently to the user. This
method may cancel up to 1 kOhm of series resistance. The best accuracy is in the TD range 20ºC to 70ºC.
3.5.2. 3-Point Track Resistance Cancellation
The 3-point track resistance cancellation requires one additional connection to the external PN junction so that an
additional current source can be used to cancel out the error voltage due to the track resistance.
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Track resistances up to 1 kOhm may be cancelled. It is important that the track resistance values in the cathode or anode
path of the external sensor are made equal. Care must be taken during PCB layout to match track resistances between the
device and the sensor. Any resistance difference will lead to cancellation errors.
In this mode, VSS is used for the current return path from the cathode. This connection must be placed close to the diode’s
cathode. One port supply the current modulation to the anode and another port supply the cancellation current to the
cathode. The resulting junction voltage modulation is measured between the 2 used ports. Figure 5 explains the method:
I
P1
V1
V2
I
P2
V1
2I
VSS
Assume sensor Q1 is being measured in mode 2 with 3-point
track resistance cancellation enabled. The PCB trace linking the
device to the external sensor must be matched which means the
PCB track resistance are the same. The same current is forced
out of P1 and P2.
The voltages developed on P1 and P2 traces are the same
therefore the differential voltage seen on P1-P2 is not impacted by
the track resistance.
Figure 5. 3-Point Track Resistance Cancellation
3.5.3. The Kelvin (4-wire) Track Resistance Cancellation
P1
P2
P3
The sensor is connected to the chip via 4 wires. Two comes from
the current source (force : P3, P4) and two are used for the
voltage measurement (sense : P1, P2).
Sense (+)
Sense (-)
Force (+)
The Kelvin connection avoids the measurement error caused by
the voltage drop in the force path.
I
I
P4
Sense leads are attached directly accross the external sensor.
The P1 and P2 connections must be as close as possible to
sensor anode and cathode respectively.
Force (-)
Figure 6. Kelvin (4-wire) Track Resistance Cancellation
3.6. Temperature Acquisition Sequence
The SX8743 monitors up to 4 sensors (3 remote and 1 internal). Theses can be scanned in sequence to make an
automatic reading of the sensors one after the other. The result of each conversion is stored in the temperature registers
(see Table 6). The register RegSensor defines which sensors are scanned in the sequence. When all the sensors are
selected, the sequence is the following: Int→ Ext1→ Ext2→ Ext3→Int→etc.
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3.7. Alarm
VDD
ALARM
VSS
Alarm threshold registers (RegAlarm1 and RegAlarm2) contain the value the user wishes
the alarms to trip on. The alarm data format is the same as the temperature data format
which is set in RegControl (bit TempOffsetMode). In other words, in binary mode alarm
value is set in degree; in offset binary mode alarm is set in with an offset of 64.
The alarm calculation is performed at the end of the temperature sensing cycle.
Therefore, if TempOffsetMode bit or alarm values are changed, a temperature sensor
measurement must be run to update the alarm outputs.
Depending on the selected mode, the chip can have two alarm outputs: Alarm1 and
Alarm2. If the external or internal temperature exceeds or goes under a programmed
temperature threshold, the alarm is activated. Any remote or local sensor may be
selected to trigger Alarm1 and Alarm2.
Figure 7. Alarm Output Internal Simplified Schematics
The pseudo-open drain output shown in Figure 7 requires a pull-up resistor connected to VDD. It allows connection to a
GPIO, a system shutdown or other thermal management circuitry.
The alarm polarity can be set active low or high
and, the over or under temperature can also be
set with RegAlarmSet register.
Temperature
Alarm threshold
Hysteresis
Remote or local
temperature
Alarm(1 or 2)
To prevent alarm outputs to trig constantly when
the
limit
temperature
is
reached,
the
RegAlarmHyst register holds a hysteresis value.
The alarm remains active while the temperature is
superior to the alarm threshold minus the value
programmed in the RegAlarmHyst register (for a
trig on over-temperature) as described on
Figure 8.
Over-temperature
Time
Figure 8. Alarm Output
3.8. Temperature Data Format
Temperature output code from the internal and external sensors are made of 2 bytes. The temperature high byte has an
LSB representing 1ºC and contains the integer part of the temperature while the low byte contains the fractional value with
a resolution of 0.125ºC.
The SX8733 has 2 temperature data formats. By default, the format is binary and the measurement range is from 0ºC to
127ºC. To extend the measurement range to -40ºC to +140ºC, an offset of 64ºC is added to the binary code.
When a conversion is complete, the main temperature register and the extended temperature register are updated
simultaneously. Ensure that no conversions are completed between reading the main register and the extended register,
so that both registers contain the result of the same conversion.
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Digital temperature sensor
DATASHEET
ADVANCED COMMUNICATIONS & SENSING
Temperature High Byte
Temperature (ºC)
Offset Binary
0001 1000
1
Temperature (ºC)
Binary or
Offset Binary
0000 0000
0
0000 00002
0000 0000
0100 0000
x.000
1
0000 0001
0100 0001
x.125
0000 0001
50
0011 0010
0111 0010
x.250
0000 0010
-40 or less
1.
2.
3.
4.
Temperature Low Byte
Binary
64
0100 0000
0000 0000
x.375
0000 0011
100
0110 0100
1010 0100
x.500
0000 0100
127
0111 1111
1011 1111
x.625
0000 0101
140 or more
0111 11113
1100 1100
x.750
0000 0110
Diode fault
1111 11114
1111 11114
x.875
0000 0111
Offset binary scale temperature values are offset by 64ºC
Binary scale returns 0ºC for all temperatures <0ºC
Binary scale returns 127ºC for all temperatures >127ºC
A diode fault is detected when the temperature ADC hard limits at 0% or 100% pulse density
3.9. Continuous Time Vs. Single Shot
The chip can be operated in 2 distinct modes: continuous time or one-shot.
The one-shot mode performs one temperature measurement of all sensors selected in RegSensor. After completion, it
returns to standby.
In continuous temperature sampling, temperature measurements are taken at regular intervals and the result held in
internal registers accessible by SMBUS. The RegADCRate register controls the sampling time period.
4. Application Note
4.1. Typical Temperature Sensing System With A SX8743
VBUS
10k
3.3V
1
10k
7
SMBus
Interface
8
100nF
VDD
SMBDAT
SMBCLK
P1
4
SX8743
HOST
10k
GPIO
100pF
P2 3
10k
ALARM1
2
ALARM2
6
MMBT3906
P3
P4
VSS
5
VSS
Figure 9. SX8743 Performs Remote Temperature Measurement In Mode 8
When the remote-sensing diode is a discrete transistor, its collector and base should be connected together. An external
capacitor of 100pF across the PN junction smoothes out external noise interference. The capacitor must be located very
close to the pins.
The ideality factor is a measure of the deviation of the thermal diode from ideal behavior. The chips are trimmed for the
PNP device described in Table 5.
ACS Revision 2.91/February 2010
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Digital temperature sensor
DATASHEET
ADVANCED COMMUNICATIONS & SENSING
A different ideality factor causes a change in the slope of the linear
equation ∆VBE=f(T).
n nom
∆T nfact =  --------------- – 1 ⋅ ( T D + 273.15 )
 n actual 
Gain and offset can be adjusted with the registers RegExtGain and
RegExtOffset to compensate for small variations in n. Large power
transistors must not be used.
Part Number
Manufacturer
Package
MMBT3906
Fairchild
SOT23-3
Table 5 Recommended device
5. Power-Up Sequence and Standby Mode
At power-up, the device is in one-shot mode waiting for an SMBUS command to start conversion. The measurement
interval and the alarm thresholds will default to a set value at power-up but may be reconfigured to different values with
SMBUS command.
Between temperature measurements, to decrease power consumption, the chip will shut down into its low-power standby
state with most functions disabled.
6. Serial Interface
6.1. Register Write - Combined Format
Write to single register (combined format)
SA SA SA
2
1
0
Slave address 0x4C
WD WD WD WD WD WD WD WD
7
6
5
4
3
2
1
0
R/
W
Write Data
Stop by Master
Register Address
SA SA
4
3
Slave ACK driven
by SX8733
R/
W
Slave address 0x4C
SA SA
6
5
Slave ACK driven
by SX8733
RA RA RA RA RA RA RA RA
7
6
5
4
3
2
1
0
Restart by Master
SA SA
1
0
Slave ACK driven
by SX8733
SA SA
3
2
Slave ACK driven
by SX8733
Start by Master
SA SA SA
6
5
4
6.2. Register Write - Direct Format
Write to single register (direct format)
SA2
SA1
Slave address 0x4C
ACS Revision 2.91/February 2010
©2010 Semtech Corp.
SA0
RA7
R/W
RA6
RA5
RA4
RA3
RA2
Register Address
Page 14
RA1
RA0
WD7 WD6 WD5 WD4 WD3 WD2 WD1 WD0
Write Data
Stop by Master
SA3
Slave ACK driven
by SX8733
SA4
Slave ACK driven
by SX8733
SA5
Slave ACK driven
by SX8733
Start by Master
SA6
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ADVANCED COMMUNICATIONS & SENSING
6.3. Register Read - Combined Format
Read from single register (combined format)
Register Address
SA
4
SA
3
SA
2
SA
1
SA
0
RD RD RD RD RD RD RD RD
7
6
5
4
3
2
1
0
R/
W
Slave address 0x4C
Read data driven by SX8733
Stop by Master
R/
W
Slave address 0x4C
SA SA
6
5
NACK driven by
master
RA RA RA RA RA RA RA RA
7
6
5
4
3
2
1
0
Slave ACK driven
by SX8733
SA
0
Restart by Master
SA SA
2
1
Slave ACK driven
by SX8733
SA SA
4
3
Slave ACK driven
by SX8733
Start by Master
SA SA
6
5
6.4. Register Read - Direct Format
Read from single register (short format)
Read data driven by SX8733
Stop by Master
R/
W
Slave address 0x4C
NACK driven by
master
RD RD RD RD RD RD RD RD
7
6
5
4
3
2
1
0
Slave ACK driven
by SX8733
Start by Master
SA SA SA SA SA SA SA
6
5
4
3
2
1
0
6.5. Soft Reset
The user may reset the circuit via SMBus by sending a general call address at slave address 0x00 followed by the reset
command 0x06. In other words, as illustrated in the figure below, a soft reset can be generated by sending a command at
slave address 0x00 (rather than the regular 0x4C slave address) to IC register address 0x06 with any data (0xXX).
The soft reset command sets the circuit and registers in the same state as after a power-up.
Reset
SA2
SA1
Slave address
0x00
ACS Revision 2.91/February 2010
©2010 Semtech Corp.
SA0
RA7
R/W
RA6
RA5
RA4
RA3
RA2
Register Address
0x06
Page 15
RA1
RA0
WD7 WD6 WD5 WD4 WD3 WD2 WD1 WD0
Write Data
0xXX
Stop by Master
SA3
Slave ACK driven
by SX8733
SA4
Slave ACK driven
by SX8733
SA5
Slave ACK driven
by SX8733
Start by Master
SA6
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Digital temperature sensor
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DATASHEET
7. Register / Memory Map
Each register is described in the following register memory map. These are identified by a Register Name and
corresponding hexadecimal register address.
7.1. Memory Map
0x00
0x06
0x07
0x20
0x21
RegConfig
RegExtGain
RegExtOffset
RegDeviceID
RegDeviceVersion
0x22
0x23
0x24
RegSensor
RegAlarm1
RegAlarm2
0x25
RegAlarmSet
0x26
0x27
RegAlarmHyst
RegADCRate
0x28
RegIntTempMSB
Identification Registers
Determines the chip variant and the communication interface (I2C or SMBus)
Sets the calibration gain for remote temperature measurement
Sets the calibration offset for remote temperature measurement
Read-only ID = 0x33
Read-only circuit revision
Configuration Registers
Defines which sensors are scanned in sequence
Alarm1 threshold
Alarm2 threshold
Defines which sensors control alarms 1 and 2, and whether over-/under- temperature triggers for
each alarm
Alarm hysteresis
Temperature conversion rate
Temperature Registers
TJ temperature reading for internal sensor, integer part, LSB = 1ºC
0x29
RegIntTempLSB
TJ temperature reading for internal sensor, fractional part, LSB = 0.125ºC
0x2A
RegExtTemp1MSB
TD1 temperature reading for external sensor 1, integer part, LSB = 1ºC
0x2B
RegExtTemp1LSB
TD1 temperature reading for external sensor 1, fractional part, LSB = 0.125ºC
0x2C
RegExtTemp2MSB
TD2 temperature reading for external sensor 2, integer part, LSB = 1ºC
0x2D
RegExtTemp2LSB
TD2 temperature reading for external sensor 2, fractional part, LSB = 0.125ºC
0x2E
RegExtTemp3MSB
TD3 temperature reading for external sensor 3, integer part, LSB = 1ºC
0x2F
RegExtTemp3LSB
TD3 temperature reading for external sensor 3, fractional part, LSB = 0.125ºC
0x30
0x31
RegControl
RegStatus
General Registers
General Control register
General Status register
Table 6 Memory map
7.2. Registers Description
Addr: 0x00 RegConfig
Bits
Name
Mode
Reset
7:6
Reserved
rw
00
5
SetInterface
rw
1
4:0
Mode
rw
00000
ACS Revision 2.91/February 2010
©2010 Semtech Corp.
Description
Write to 00
Select between I2C or SMBus interface
0: I2C (Time Out Disabled)
1: SMBUS
Select the configuration mode
00000: Mode 0
00001: Mode 1
...
10010: Mode 18
10100: Mode 20
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Digital temperature sensor
ADVANCED COMMUNICATIONS & SENSING
DATASHEET
Addr: 0x06 RegExtGain
Bits
Name
Mode
Reset
Description
7:6
Reserved
rw
00
5:0
ExtGain
rw
xxxxxx
Bits
Name
Mode
Reset
7:0
ExtOffset
rw
xxxxxxxx
Bits
Name
Mode
Reset
Description
7:4
Reserved
rw
0000
Write to 0000
3
SelExt3
rw
0
2
SelExt2
rw
0
1
SelExt1
rw
0
0
SelInt
rw
1
Bits
Name
Mode
Reset
7:0
Threshold1
rw
01000000
Bits
Name
Mode
Reset
7:0
Threshold2
rw
01000000
Bits
Name
Mode
Reset
7
Reserved
rw
0
Write to 00
Gain adjustement for external temperature measurement
Do not write to avoid production calibration altering
Addr: 0x07 RegExtOffset
Description
Offset adjustement for external temperature measurement.
Do not write to avoid production calibration altering
Addr: 0x22 RegSensor
0: External sensor 3 not in temp. scan sequence
1: Enable external sensor 3 to be in temp. scan sequence
0: External sensor 2 not in temp. scan sequence
1: Enable external sensor 2 to be in temp. scan sequence
0: External sensor 1 not in temp. scan sequence
1: Enable external sensor 1 to be in temp. scan sequence
0: Internal sensor not in temp. scan sequence
1: Enable internal sensor to be in temp. scan sequence
Addr: 0x23 RegAlarm1
Description
Alarm1 temperature threshold. The data is coherent with the binary and offset format.
1LSB=1ºC
Addr: 0x24 RegAlarm2
Description
Alarm2 temperature threshold. The data is coherent with the binary and offset format.
1LSB=1ºC
Addr: 0x25 RegAlarmSet
6
AlarmPolarity
rw
0
5
Direction2
rw
0
4
Direction1
rw
0
Description
Write to 0
0: Alarm1, Alarm2 outputs active high
1: Alarm1, Alarm2 outputs active low
0: Trigger on over-temperature for Alarm2
1: Trigger on under-temperature for Alarm2
0: Trigger on over-temperature for Alarm1
1: Trigger on under-temperature for Alarm1
3:2
Select2
rw
00
00: External 1 sensor controls Alarm2
01: External 2 sensor controls Alarm2
10: External 3 sensor controls Alarm2
11: Internal sensor controls Alarm2
1:0
Select1
rw
11
00: External 1 sensor controls Alarm1
01: External 2 sensor controls Alarm1
10: External 3 sensor controls Alarm1
11: Internal sensor controls Alarm1
Bits
Name
Mode
Reset
Description
7:4
Hysteresis2
rw
0100
Defines Alarm2 hysteresis with 1ºC resolution. (0 to 15ºC)
3:0
Hysteresis1
rw
0100
Defines Alarm1 hysteresis with 1ºC resolution. (0 to 15ºC)
Addr: 0x26 RegAlarmHyst
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Digital temperature sensor
ADVANCED COMMUNICATIONS & SENSING
DATASHEET
Addr: 0x27 RegADCRate
Bits
Name
Mode
Reset
Description
7:5
Reserved
rw
000
Write to 000
4
OneShot
rw
0
3
Regular
rw
0
2:0
Rate
rw
0: Standby
1: Perform one temperature measurement
0: Disable continuous temperature sampling
1: Enable continuous temperature sampling
Temperature sampling rate
000: 0.1 second (continuous sampling)
001: 0.25 second
010: 0.50 second
011: 1 second
100: 2 seconds
101: 4 seconds
110: 8 seconds
111: 16 seconds
000
Addr: 0x28 RegIntTempMSB
Bits
Name
Mode
Reset
7:0
IntTempMSB
r
00000000
Bits
Name
Mode
Reset
7:3
Reserved
r
00000
2:0
IntTempLSB
r
000
Bits
Name
Mode
Reset
7:0
ExtTemp1MSB
r
00000000
Bits
Name
Mode
Reset
7:3
Reserved
r
00000
2:0
ExtTemp1LSB
r
000
Bits
Name
Mode
Reset
7:0
ExtTemp2MSB
r
00000000
Description
MSB of Internal Temperature TJ. LSB=1ºC
Addr: 0x29 RegIntTempLSB
Description
LSB of Internal Temperature TJ. LSB=0.125ºC
Addr: 0x2A RegExtTemp1MSB
Description
MSB of External Temperature TD1. LSB=1ºC
Addr: 0x2B RegExtTemp1LSB
Description
LSB of External Temperature TD1. LSB=0.125ºC
Addr: 0x2C RegExtTemp2MSB
Description
MSB of External Temperature TD2. LSB=1ºC
Addr: 0x2D RegExtTemp2LSB
Bits
Name
Mode
Reset
7:3
Reserved
r
00000
Description
2:0
ExtTemp2LSB
r
000
Bits
Name
Mode
Reset
7:0
ExtTemp3MSB
r
00000000
Bits
Name
Mode
Reset
7:3
Reserved
r
00000
2:0
ExtTemp3LSB
r
000
LSB of External Temperature TD2. LSB=0.125ºC
Addr: 0x2E RegExtTemp3MSB
Description
MSB of External Temperature TD3. LSB=1ºC
Addr: 0x2F RegExtTemp3LSB
ACS Revision 2.91/February 2010
©2010 Semtech Corp.
Description
LSB of External Temperature TD3. LSB=0.125ºC
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Digital temperature sensor
ADVANCED COMMUNICATIONS & SENSING
DATASHEET
Addr: 0x30 RegControl
Bits
Name
Mode
Reset
7:5
Reserved
rw
000
Description
Write to 000
0: No clock stretching
1: Enable clock stretching
0: Binary mode
1: Offset binary mode
0: Disable 3-point track resistance cancellation
1: Enable 3-point track resistance cancellation
0: Disable algorithmic track cancellation
1: Enable algorithmic track cancellation
4
ClockStretching
rw
1
3
TempOffsetMode
rw
0
2
Point3
rw
0
1
Algo
rw
0
0
Bit0
rw
1
Bits
Name
Mode
Reset
Description
7:4
Reserved
w
0000
Write to 0000
3
ExtTemp3End
0
1: External temperature 3 conversion complete
2
ExtTemp2End
w1
w1
0
1: External temperature 2 conversion complete
1
ExtTemp1End
w
1
0
1: External temperature 1 conversion complete
0
IntTempEnd
w
1
0
1: Internal temperature conversion complete
This bit must be set to 1
Addr: 0x31 RegStatus
1. write logic 1 to register bit to clear
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Digital temperature sensor
DATASHEET
ADVANCED COMMUNICATIONS & SENSING
8. Packaging Information
8.1. MLPD-W6-EP2 Package Outline Drawing
A
D
DIMENSIONS
B
DIM
A
A1
A2
b
D
E
D1
E1
e
L
N
aaa
bbb
E
PIN 1
INDICATOR
(LASER MARK)
A
aaa C
A1
1
SEATING
PLANE
C
A2
D1
MILLIMETERS
MIN NOM MAX
0.70 0.75 0.80
0.00 0.02 0.05
(0.20)
0.30 0.40 0.45
2.90 3.00 3.10
2.90 3.00 3.10
2.23 2.38 2.48
1.50 1.65 1.75
0.95 BSC
0.30 0.40 0.50
6
0.08
0.10
2
LxN
E/2
E1
N
bxN
e
bbb
C A B
D/2
NOTES:
1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES).
2. COPLANARITY APPLIES TO THE EXPOSED PAD AS WELL AS TERMINALS.
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Digital temperature sensor
DATASHEET
ADVANCED COMMUNICATIONS & SENSING
8.2. MLPD-W6-EP2 Land Pattern Drawing
R
K
DIMENSIONS
DIM
(C)
G
H
C
G
H
K
P
R
X
Y
Z
Z
Y
X
P
MILLIMETERS
(2.95)
2.20
1.65
2.38
0.95
0.225
0.45
0.75
3.70
NOTES:
1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES).
2. THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY.
CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR
COMPANY'S MANUFACTURING GUIDELINES ARE MET.
3. THERMAL VIAS IN THE LAND PATTERN OF THE EXPOSED PAD
SHALL BE CONNECTED TO A SYSTEM GROUND PLANE.
FAILURE TO DO SO MAY COMPROMISE THE THERMAL AND/OR
FUNCTIONAL PERFORMANCE OF THE DEVICE.
ACS Revision 2.91/February 2010
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SX8733/SX8743/SX8744
Digital temperature sensor
DATASHEET
ADVANCED COMMUNICATIONS & SENSING
8.3. Package Outline Drawing: MSOP-8
DIMENSIONS
INCHES
MILLIMETERS
DIM
MIN NOM MAX MIN NOM MAX
e/2
A
A
A1
A2
b
c
D
E1
E
e
L
L1
N
01
aaa
bbb
ccc
D
N
2X E/2
E1
E
PIN 1
INDICATOR
ccc C
2X N/2 TIPS
1 2
e
B
aaa C
D
C
1.10
0.00
0.15
0.75
0.95
0.22
0.38
0.08
0.23
2.90 3.00 3.10
2.90 3.00 3.10
4.90 BSC
0.65 BSC
0.40 0.60 0.80
(.95)
8
0°
8°
0.10
0.13
0.25
H
A2
SEATING
PLANE
.043
.000
.006
.030
.037
.009
.015
.003
.009
.114 .118 .122
.114 .118 .122
.193 BSC
.026 BSC
.016 .024 .032
(.037)
8
0°
8°
.004
.005
.010
A
c
GAGE
PLANE
A1
bxN
bbb
C A-B D
0.25
L
DETAIL
SIDE VIEW
01
(L1)
SEE DETAIL
A
A
NOTES:
1.
CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES).
2. DATUMS -A- AND -B- TO BE DETERMINED AT DATUM PLANE -H3. DIMENSIONS "E1" AND "D" DO NOT INCLUDE MOLD FLASH, PROTRUSIONS
OR GATE BURRS.
4. REFERENCE JEDEC STD MO-187, VARIATION AA.
ACS Revision 2.91/February 2010
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SX8733/SX8743/SX8744
Digital temperature sensor
DATASHEET
ADVANCED COMMUNICATIONS & SENSING
8.4. Land Pattern Drawing: MSOP-8
X
DIM
(C)
G
Y
Z
C
G
P
X
Y
Z
DIMENSIONS
INCHES
MILLIMETERS
(.161)
.098
.026
.016
.063
.224
(4.10)
2.50
0.65
0.40
1.60
5.70
P
NOTES:
1.
THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY.
CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR
COMPANY'S MANUFACTURING GUIDELINES ARE MET.
ACS Revision 2.91/February 2010
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DATASHEET
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