SMSC EMC1023 1â°c triple temperature sensor with resistance error correction Datasheet

EMC1023
1°C Triple Temperature
Sensor with Resistance
Error Correction
Datasheet
General Description
Features
The EMC1023 is a System Management Bus (SMBus)
temperature sensor that is capable of monitoring three
temperature zones. Four unique part numbers can be
ordered, each with a different SMBus Address. The
three temperature zones consist of two external diodes
and one internal monitor.
■
Extended features include resistance error correction
and ideality factor configuration eliminating both major
sources of temperature measurement error.1 The 11-bit
delta-sigma temperature-to-digital converter provides
superb linearity, excellent noise immunity and
repeatable temperature readings. An extended
temperature format may be selected for compatibility
with a broad range of CPUs. Selectable conversion
rates and standby mode support low-power operation.
■
■
■
■
Resistance Error Correction
Ideality Factor Configuration
Accepts 2200pF cap for noise suppression
Remote Thermal Zones
— ±1°C Accuracy (40°C to 80°C)
— 0.125°C resolution
Internal Thermal Zone
— ±3°C Accuracy (0°C to 85°C)
— 0.125°C resolution
■
■
■
■
Low Power; 3.0V to 3.6V Supply
Four Unique SMBus Addresses Available
Programmable Conversion Rate
MSOP-8 3x3mm Package; Green, Lead-Free
Package also available.
Applications
■
■
■
■
1.Patents pending.
Desktop and Notebook Computers
Thermostats
Smart batteries
Industrial/Automotive
Simplified Block Diagram
EMC1023
Switching
Current
Configuration
Register
Analog Mux
DN1
DP2
11-bit
delta-sigma
ADC
Remote Temp
Register 2
Digital Mux
and
Byte Interlock
DN2
Local Temp
Diode
Local Temp
Register
SMCLK
Status Register
SMSC EMC1023
DATASHEET
SMBus Interface
Remote Temp
Register 1
DP1
SMDATA
Revision 1.2 (04-15-05)
1°C Triple Temperature Sensor with Resistance Error Correction
Datasheet
ORDER NUMBERS
EMC1023-1-ACZB-TR FOR 8 PIN, MSOP PACKAGE (Address - 1001100b)
EMC1023-2-ACZB-TR FOR 8 PIN, MSOP PACKAGE (Address - 1001101b)
EMC1023-3-ACZB-TR FOR 8 PIN, MSOP PACKAGE (Address - 1001000b)
EMC1023-4-ACZB-TR FOR 8 PIN, MSOP PACKAGE (Address - 1001001b)
EMC1023-1-ACZL-TR FOR 8 PIN, MSOP PACKAGE (Address - 1001100b) (Green, Lead-Free)
EMC1023-2-ACZL-TR FOR 8 PIN, MSOP PACKAGE (Address - 1001101b) (Green, Lead-Free)
EMC1023-3-ACZL-TR FOR 8 PIN, MSOP PACKAGE (Address - 1001000b) (Green, Lead-Free)
EMC1023-4-ACZL-TR FOR 8 PIN, MSOP PACKAGE (Address - 1001001b) (Green, Lead-Free)
Reel size is 4,000 pieces.
Evaluation Board available upon request. (EVB-EMC1023)
80 Arkay Drive
Hauppauge, NY 11788
(631) 435-6000
FAX (631) 273-3123
Copyright © SMSC 2005. All rights reserved.
Circuit diagrams and other information relating to SMSC products are included as a means of illustrating typical applications. Consequently, complete
information sufficient for construction purposes is not necessarily given. Although the information has been checked and is believed to be accurate, no
responsibility is assumed for inaccuracies. SMSC reserves the right to make changes to specifications and product descriptions at any time without
notice. Contact your local SMSC sales office to obtain the latest specifications before placing your product order. The provision of this information does
not convey to the purchaser of the described semiconductor devices any licenses under any patent rights or other intellectual property rights of SMSC
or others. All sales are expressly conditional on your agreement to the terms and conditions of the most recently dated version of SMSC's standard
Terms of Sale Agreement dated before the date of your order (the "Terms of Sale Agreement"). The product may contain design defects or errors
known as anomalies which may cause the product's functions to deviate from published specifications. Anomaly sheets are available upon request.
SMSC products are not designed, intended, authorized or warranted for use in any life support or other application where product failure could cause
or contribute to personal injury or severe property damage. Any and all such uses without prior written approval of an Officer of SMSC and further
testing and/or modification will be fully at the risk of the customer. Copies of this document or other SMSC literature, as well as the Terms of Sale
Agreement, may be obtained by visiting SMSC’s website at http://www.smsc.com. SMSC is a registered trademark of Standard Microsystems
Corporation (“SMSC”). Product names and company names are the trademarks of their respective holders.
SMSC DISCLAIMS AND EXCLUDES ANY AND ALL WARRANTIES, INCLUDING WITHOUT LIMITATION ANY AND ALL IMPLIED WARRANTIES
OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, TITLE, AND AGAINST INFRINGEMENT AND THE LIKE, AND ANY AND
ALL WARRANTIES ARISING FROM ANY COURSE OF DEALING OR USAGE OF TRADE.
IN NO EVENT SHALL SMSC BE LIABLE FOR ANY DIRECT, INCIDENTAL, INDIRECT, SPECIAL, PUNITIVE, OR CONSEQUENTIAL DAMAGES;
OR FOR LOST DATA, PROFITS, SAVINGS OR REVENUES OF ANY KIND; REGARDLESS OF THE FORM OF ACTION, WHETHER BASED ON
CONTRACT; TORT; NEGLIGENCE OF SMSC OR OTHERS; STRICT LIABILITY; BREACH OF WARRANTY; OR OTHERWISE; WHETHER OR
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ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
Revision 1.2 (04-15-05)
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DATASHEET
SMSC EMC1023
1°C Triple Temperature Sensor with Resistance Error Correction
Datasheet
Chapter 1 Pin Configuration
DP1
1
DN1
2
8
S M C LK
DP2
E M C 1023 7
3 TO P V IE W 6
VDD
DN2
4
GND
S M D A TA
5
Figure 1.1 EMC1023 Pin Configuration
Table 1.1 Pin Description
PIN
PIN NO.
DP1
1
Positive Analog Input for External Temperature Diode 1
DN1
2
Negative Analog Input for External Temperature Diode 1
DP2
3
Positive Analog Input for External Temperature Diode 2
DN2
4
Negative Analog Input for External Temperature Diode 2
GND
5
Ground
VDD
6
Supply Voltage
SMDATA
7
System Management Bus Data Input/Output, open drain output
SMCLK
8
System Management Bus Clock Input
SMSC EMC1023
DESCRIPTION
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DATASHEET
Revision 1.2 (04-15-05)
1°C Triple Temperature Sensor with Resistance Error Correction
Datasheet
Table 1.2 Absolute Maximum Ratings
DESCRIPTION
RATING
UNIT
Supply Voltage VDD
-0.3 to 5.0
V
Voltage on SMDATA and SMCLK pins
-0.3 to 5.5
V
-0.3 to VDD+0.3
V
0 to 85
°C
-55 to 150
°C
Voltage on any other pin
Operating Temperature Range
Storage Temperature Range
Lead Temperature Range
Refer to JEDEC
Spec. J-STD-020
Package Thermal Characteristics for MSOP-8
Power Dissipation
TBD
Thermal Resistance (at 0 air flow)
135.9
°C/W
ESD Rating, All Pins Human Body Model
2000
V
Note: Stresses above those listed could cause damage to the device. This is a stress rating only
and functional operation of the device at any other condition above those indicated in the
operation sections of this specification is not implied. When powering this device from
laboratory or system power supplies, it is important that the Absolute Maximum Ratings not be
exceeded or device failure can result. Some power supplies exhibit voltage spikes on their
outputs when the AC power is switched on or off. In addition, voltage transients on the AC
power line may appear on the DC output. If this possibility exists, it is suggested that a clamp
circuit be used.
Revision 1.2 (04-15-05)
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DATASHEET
SMSC EMC1023
1°C Triple Temperature Sensor with Resistance Error Correction
Datasheet
Chapter 2 Electrical Characteristics
Table 2.1 Electrical Characteristics
VDD=3.0V to 3.6V, TA= 0°C to +85°C, Typical values at TA = 27°C unless otherwise noted
PARAMETER
SYMBOL
MIN
TYP
MAX
UNITS
3.3
3.6
V
CONDITIONS
DC Power
Supply Voltage
VDD
Average Operating Current
IDD
36
42
µA
1 conversions/s
IPD
2
4
µA
Standby mode
°C
0°C≤TA≤85°C
3.0
Internal Temperature Monitor
±1
Temperature Accuracy
Temperature Resolution
±3
°C
0.125
External Temperature Monitor
Temperature Accuracy
Remote Diode 40°C to 80°C
Remote Diode 0°C to 125°C
±1
±3
Temperature Resolution
°C
°C
15°C≤TA≤70°C
0°C≤TA≤85°C
0.125
°C
62
ms
ADC
Conversion Time for all three sensors
Wake-up from STOP mode
(During one shot command or
transition to RUN mode)
1
ms
Voltage Tolerance (SMDATA,SMCLK)
Voltage at pin
VTOL
-0.3
5.5
V
SMBus Interface (SMDATA,SMCLK)
Input High Level
VIH
Input Low Level
VIL
Input High/Low Current
IIH/IIL
2.0
V
-1
0.8
V
1
µA
Hysteresis
500
mV
Input Capacitance
5
pF
Output Low Sink Current
6
mA
SMDATA = 0.6V
SMBus Timing
Clock Frequency
FSMB
10
Spike Suppression
400
kHz
50
ns
Bus free time Start to Stop
TBUF
1.3
µs
Hold time Start
THD:STA
0.6
µs
SMSC EMC1023
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DATASHEET
Revision 1.2 (04-15-05)
1°C Triple Temperature Sensor with Resistance Error Correction
Datasheet
Table 2.1 Electrical Characteristics (continued)
VDD=3.0V to 3.6V, TA= 0°C to +85°C, Typical values at TA = 27°C unless otherwise noted
PARAMETER
SYMBOL
MIN
TYP
MAX
UNITS
CONDITIONS
Setup time Start
TSU:STA
0.6
µs
Setup time Stop
TSU:STO
0.6
µs
Data Hold Time
THD:DAT
0.3
µs
Data Setup Time
TSU:DAT
100
ns
Clock Low Period
TLOW
1.3
µs
Clock High Period
THIGH
0.6
µs
Clock/Data Fall Time
TF
*
300
ns
*Min = 20+0.1Cb ns
Clock/Data Rise Time
TR
*
300
Note
2.1
ns
*Min = 20+0.1Cb ns
Capacitive Load (each bus line)
Cb
0.6
400
pF
Note 2.1
Revision 1.2 (04-15-05)
300nS rise time max is required for 400kHz bus operation. For lower clock frequencies,
the maximum rise time is (0.1/FSMB)+50nS
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DATASHEET
SMSC EMC1023
1°C Triple Temperature Sensor with Resistance Error Correction
Datasheet
Chapter 3 System Management Bus Interface Protocol
A host controller, such as an SMSC I/O controller, communicates with the EMC1023 via the two wire
serial interface named SMBus. The SMBus interface is used to read and write registers in the
EMC1023, which is a slave-only device. A detailed timing diagram is shown in Figure 3.1.
TLOW
THIGH
THD:STA
TR
SMCLK
THD:STA
TSU:STO
TF
THD:DAT TSU:DAT
TSU:STA
SMDATA
TBUF
S
P
S
S - Start Condition
P - Stop Condition
P
Figure 3.1 System Management Bus Timing Diagram
The EMC1023 implements a subset of the SMBus specification and supports Write Byte, Read Byte,
Send Byte, Receive Byte, and Alert Response Address protocols. as shown. In the tables that describe
the protocol, the “gray” columns indicate that the slave is driving the bus.
3.1
Write Byte
The Write Byte protocol is used to write one byte of data to the registers as shown below:
Table 3.1 SMBus Write Byte Protocol
START
SLAVE ADDRESS
WR
ACK
COMMAND
ACK
DATA
ACK
STOP
1
7
1
1
8
1
8
1
1
3.2
Read Byte
The Read Byte protocol is used to read one byte of data from the registers as shown below:
Table 3.2 SMBus Read Byte Protocol
START
SLAVE ADDRESS
WR
ACK
COMMAND
ACK
START
SLAVE ADDRESS
RD
ACK
DATA
NACK
STOP
1
7
1
1
8
1
1
7
1
1
8
1
1
3.3
Send Byte
The Send Byte protocol is used to set the Internal Address Register to the correct Address. The Send
Byte can be followed by the Receive Byte protocol described below in order to read data from the
register. The send byte protocol cannot be used to write data - if data is to be written to a register then
the write byte protocol must be used as described in subsection above. The send byte protocol is
shown in Table 3.3, “SMBus Send Byte Protocol,” on page 7.
Table 3.3 SMBus Send Byte Protocol
FIELD:
START
SLAVE ADDR
WR
ACK
REG. ADDR
ACK
STOP
Bits:
1
7
1
1
8
1
1
SMSC EMC1023
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DATASHEET
Revision 1.2 (04-15-05)
1°C Triple Temperature Sensor with Resistance Error Correction
Datasheet
3.4
Receive Byte
The Receive Byte protocol is used to read data from a register when the internal register address
pointer is known to be at the right location (e.g. set via Send Byte). This can be used for consecutive
reads of the same register as shown below:
Table 3.4 SMBus Receive Byte Protocol
FIELD:
START
SLAVE ADDR
RD
ACK
REG. DATA
NACK
STOP
Bits:
1
7
1
1
8
1
1
3.5
SMBus Addresses
The EMC1023 may be ordered with one of four 7-bit slave addresses as shown in Order Numbers.
Attempting to communicate with the EMC1023 SMBus interface with an invalid slave address or invalid
protocol results in no response from the device and does not affect its register contents. The EMC1023
supports stretching of the SMCLK signal by other devices on the SMBus but will not perform this
operation itself.
3.6
SMBus Timeout
The EMC1023 includes an SMBus timeout feature. Following a 25 ms period of inactivity on the
SMBus, the device will timeout and reset the SMBus interface.
Revision 1.2 (04-15-05)
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DATASHEET
SMSC EMC1023
1°C Triple Temperature Sensor with Resistance Error Correction
Datasheet
Chapter 4 Product Description
The EMC1023 is an SMBus sensor that is capable of monitoring three temperature zones for use in
a personal computer or embedded environment. The part may be used as a companion to one of
SMSC’s broad line of SIO host circuits, or other devices capable of performing the SMBus host
function.
EMC1023
Host
(SMSC SIO)
DP1
DN1
DP2
SMBus
Interface
SMBus
DN2
Internal
Diode
Figure 4.1 System Overview
In cooperation with the host device, thermal management can be performed as outlined in Figure 4.1
above. Thermal management consists of the host reading the temperature data from the remote and
internal temperature diodes of the EMC1023 and controlling the speed of one or multiple fans. Since
the EMC1023 incorporates one internal and two external temperature diodes, three separate thermal
zones can be monitored and controlled with this application. Also, measured temperature levels can
quickly be compared to preset limits within the host device which in turn will take the appropriate action
when values are found to be out of limit.
The EMC1023 has two basic modes of operation:
4.1
■
Run Mode: In this mode, the EMC1023 continuously converts temperature data and updates its
registers. The conversion rate is configured by the lower bits in the configuration register as
described in Section Table 4.8, "Configuration Register, Conversion Rate," on page 14.
■
Standby Mode: In this mode, the EMC1023 is powered down, drawing a maximum current of only
3uA. The SMBus is still operational and a one-shot command can be given which will force the
circuit to complete one full set of temperature conversions. The EMC1023 will return to Standby
Mode after the one shot conversion has finished.
Temperature Monitors
Thermal diode temperature measurements are based on the change in forward bias voltage (∆VBE) of
a diode when operated at two different currents:
where:
∆VBE = VBE _ HIGH − VBE _ LOW =
I
ln HIGH
q
 I LOW
ηkT



k = Boltzmann’s constant
T = absolute temperature in Kelvin
q = electron charge
η = diode ideality factor
The change in
SMSC EMC1023
∆VBE voltage is proportional to absolute temperature T.
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DATASHEET
Revision 1.2 (04-15-05)
1°C Triple Temperature Sensor with Resistance Error Correction
Datasheet
VDD
Ihigh
Internal or
Remote Diode
Ilow
Ibias
Bias
Diode
Delta Vbe
Sample
&
Hold
1-bit
delta-sigma
Modulator
Digital
Averaging
Filter
11-bit Output
Figure 4.2 Detailed Block Diagram
Figure 4.2 shows a detailed block diagram of the temperature measurement circuit. The EMC1023
incorporates switched capacitor technology that integrates the temperature diode ∆VBE from different
bias currents. The negative terminal, DN, for the temperature diode is internally biased with a forward
diode voltage referenced to ground.
The advantages of this architecture over Nyquist rate FLASH or SAR converters are superb linearity
and inherent noise immunity. The linearity can be directly attributed to the delta-sigma ADC single-bit
comparator while the noise immunity is achieved by the ~20ms integration time which translates to
50Hz input noise bandwidth.
The 11 bit conversion can be displayed in either legacy format or in extended range format. In Legacy
format, the temperature range covers –64ºC to 127ºC while in extended format, temperature readings
span -64ºC to 191ºC. It should be noted that the latter range is really meant to cover thermal diodes
with a non ideal curvature caused by factor n in equation (1) not being equal to exactly 1.000. In
general, it is not recommended to run silicon based thermal diodes at temperatures above 150ºC.
4.2
Resistance Error Correction
The EMC1023 includes resistance error correction implemented in the analog front end of the chip.
Without this automatic feature, voltage developed across the parasitic resistance in the remote diode
path causes the temperature to read higher than the true zone temperature. The error introduced by
parasitic resistance is approximately +0.7ºC per ohm. Sources of parasitic resistance include bulk
resistance in the remote temperature transistor junctions along with resistance in the printed circuit
board traces and package leads.
Resistance error correction in the EMC1023 eliminates the need to characterize and compensate for
parasitic resistance in the remote diode path.
4.3
Programmable Ideality Factor Configuration
Temperature sensors like the EMC1023 are typically designed for remote diodes with an ideality factor
of 1.008. When the diode does not have this exact factor, an error is introduced in the temperature
measurement. Programmable offset registers are sometimes used to compensate for this error, but
this correction is only perfect at one temperature since the error introduced by ideality factor mismatch
is a function of temperature. The higher the temperature measured, the greater the error introduced.
To provide maximum flexibility to the user, the EMC1023 provides a 6-bit ideality factor register for
each remote diode. The ideality factor of the remote diode is programmed in these registers to
eliminate errors across all temperatures. See Section 4.10, "Ideality Factor Register," on page 15 for
details on programming these registers.
Revision 1.2 (04-15-05)
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DATASHEET
SMSC EMC1023
1°C Triple Temperature Sensor with Resistance Error Correction
Datasheet
4.4
Register Allocation
See Table 4.1, “Register Table,” on page 11 for a description of registers that are accessible through
the SMBus:
Table 4.1 Register Table
DEFAULT
VALUE
(HEX)
READ
ADDRESS
(HEX)
WRITE
ADDRESS
(HEX)
00
N/A
Legacy Format Internal Temperature High Byte
00
23
N/A
Legacy Format Internal Temperature Low Byte
00
01
N/A
Legacy Format Remote Temperature 1 High Byte
00
10
N/A
Legacy Format Remote Temperature 1 Low Byte
00
F8
N/A
Legacy Format Remote Temperature 2 High Byte
00
F9
N/A
Legacy Format Remote Temperature 2 Low Byte
00
FA
N/A
Extended Format Remote Temperature 1 High Byte
00
FB
N/A
Extended Format Remote Temperature 1 Low Byte
00
FC
N/A
Extended Format Remote Temperature 2 High Byte
00
FD
N/A
Extended Format Remote Temperature 2 Low Byte
00
02
N/A
Status register
00
03
09
Configuration register
47
N/A
0F
One Shot Command
--
27
27
Remote 1 Ideality Factor
12
28
28
Remote 2 Ideality Factor
12
ED
N/A
Product ID
FE
N/A
Manufacturer ID
5D
FF
N/A
Revision Number
01
REGISTER NAME
04
05
06
07
(-1)
(-2)
(-3)
(-4)
During Power on Reset (POR), the default values are stored in the registers. A POR is initiated when
power is first applied to the part and the voltage on the VDD supply surpasses the POR level as
specified in the electrical characteristics. Any reads to undefined registers will return 00h. Writes to any
undefined registers will not have an effect.
The EMC1023 uses an interlock mechanism that prevents changes in register content when fresh
readings come in from the ADC during successive reads from a host. When the High Byte is read, the
last conversion value is latched into the High Byte and Low Byte. Please note that the interlock
mechanism is only effective when reading the High Byte first.
SMSC EMC1023
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DATASHEET
Revision 1.2 (04-15-05)
1°C Triple Temperature Sensor with Resistance Error Correction
Datasheet
4.5
Temperature Monitor Registers
As shown in Table 4.1, each temperature monitor has two byte wide data registers. The external
monitors are equipped with both legacy and extended data format. The 11 bit data temperature is
stored aligned to the left resulting in the High Byte to contain temperature in 1°C steps and the Low
Byte to contain fractions of °C as outlined below:
Table 4.2 High Byte Temperature Register
REGISTER
Temperature High Byte Registers
00h, 01h, F8h, FAh, FCh
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
SIGN
64
32
16
8
4
2
1
Table 4.3 Low Byte Temperature Register
REGISTER
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Temperature Low Byte Registers 23h,
10h, F9h, FBh, FDh
0.500
0.250
0.125
0
0
0
0
0
4.6
Legacy Temperature Data Format Registers 00h, 23h, 01h,
10h, F8h, F9h:
For registers displaying legacy temperature data format, the temperature range spans from –63.875ºC
to +127.875ºC with 0.125ºC resolution. Temperatures outside this range are clipped to –63.875ºC and
+127.875ºC. Data is stored in the registers in 2’s complement as shown in Table 4.4:
Table 4.4 Legacy Temperature Data Format
TEMPERATURE (°C)
2’S COMPLEMENT
HEX
Diode Fault
100 0000 0000
400
= -63.875
110 0000 0001
601
-63
110 0000 1000
608
-1
111 1111 1000
7F8
0
000 0000 0000
000
+0.125
000 0000 0001
001
+1
000 0000 1000
008
+127
011 1111 1000
3F8
≥ +127.875
011 1111 1111
3FF
Revision 1.2 (04-15-05)
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SMSC EMC1023
1°C Triple Temperature Sensor with Resistance Error Correction
Datasheet
4.7
Extended Temperature Data Format Registers FAh, FBh, FCh,
FDh
For registers displaying extended temperature data format, a value of 64d is subtracted from the
Legacy Format output. This effectively extends the range to cover higher external temperature
measurements while still maintaining the 2’s complement format. Obviously, the host will have to
compensate and add 64d to the read temperature data. This format spans from –63.875ºC to
+191.875ºC with 0.125ºC resolution. Temperatures outside this range are limited to –63.875ºC and
+191.875ºC. Table 4.5 shows example temperature readings and register content for this data format.
Table 4.5 Extended Temperature Data Format
ACTUAL TEMP.
(°C)
-64°C OFFSET
(°C)
Diode Fault
2’S COMPLEMENT
OF -64°C OFFSET
HEX
100 0000 0000
400
= -63.875
-127.875
100 0000 0001
401
-63
-127
100 0000 1000
408
-1
-65
101 1111 1000
5F8
0
-64
110 0000 0000
600
+0.125
-63.875
110 0000 0001
601
+1
-63
110 0000 1000
608
+63
-1
111 1111 1000
7F8
+64
0
000 0000 0000
000
+65
1
000 0000 1000
008
+191
127
011 1111 1000
3F8
= +191.875
127.875
011 1111 1111
3FF
Table 4.4 and Table 4.5 show that temperature data is stored in 2’s complement in both Legacy and
Extended Temperature Data Format. Both extended and legacy temperature formats are updated
simultaneously after every conversion cycle. Code 400h is reserved for diode fault signaling which
occurs when open or short conditions are present between the external DP and DN pins.
4.8
Status Register
Table 4.6 Status Register
REGISTER
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
DEF
Status
Busy
-
-
-
-
-
D2
D1
00h
The Status register is a read only register and returns the operational status of the part. It indicates an
external diode fault conditions through bit 0 and 1. When either D1 or D2 is set, a faulty diode
connection is detected for external diode 1 or external diode 2 respectively. Also, when diode faults
are detected, temperature readings for the faulty external diode will return 400h. The EMC1023 detects
both open and short conditions for all diode pins. Bit 7 of the status register will be set when the
internal ADC is busy converting data.
SMSC EMC1023
13
DATASHEET
Revision 1.2 (04-15-05)
1°C Triple Temperature Sensor with Resistance Error Correction
Datasheet
4.9
Configuration Register
Table 4.7 Configuration Register
REGISTER
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
DEF
Configuration
-
nRun/Stop
-
-
-
CR2
CR1
CR0
47h
Bits 0 through bit 2 of the configuration register set the ADC conversion rate of the part. See Table 4.8,
“Configuration Register, Conversion Rate,” on page 14
Table 4.8 Configuration Register, Conversion Rate
CR2, CR1, CR0
CONVERSION RATE
000
Reserved
001
Reserved
010
Reserved
011
1 Conversions per second
100
2 Conversions per second
101
4 Conversions per second
110
8 Conversions per second
111
16 Conversions per second
A conversion for all 3 temperature readings takes about 60ms. Therefore, the maximum conversion
rate, equals 16 conversions per second.
Bits 6 set of the Configuration Register sets the power mode of the part:
Table 4.9 Configuration Registers Data Format
NRUN/STOP
0
1
DESCRIPTION
Run Mode
Standby Mode
In Run Mode, the EMC1023 will operate at the preset conversion rate. In Standby Mode, the part is
powered down to minimize current consumption. The SMBus is fully operational in either mode. In
Standby Mode, a WRITE command to the One Shot register will trigger a one time conversion of the
3 temperature monitors. After the part finishes the conversion, it will go back to Standby Mode. The
host can now read the updated temperature information.
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SMSC EMC1023
1°C Triple Temperature Sensor with Resistance Error Correction
Datasheet
4.10
Ideality Factor Register
The ideality factor registers are used to program the remote diode ideality factor into the EMC1023 so
that this error source can be eliminated. The default ideality factor is 1.008 and has a value of
XX010010b or 12h.
Table 4.10 Diode Ideality Factor Values
DIODE
IDEALITY
FACTOR
VALUE
DIODE
IDEALITY
FACTOR
DIODE
IDEALITY
FACTOR
VALUE
VALUE
DIODE
IDEALITY
FACTOR
VALUE
0.9850
XX00 0000
1.0054
XX01 0000
1.0267
XX10 0000
1.0489
XX11 0000
0.9862
XX00 0001
1.0067
XX01 0001
1.0280
XX10 0001
1.0503
XX11 0001
0.9875
XX00 0010
1.0080
XX01 0010
1.0294
XX10 0010
1.0517
XX11 0010
0.9888
XX00 0011
1.0093
XX01 0011
1.0308
XX10 0011
1.0531
XX11 0011
0.9900
XX00 0100
1.0106
XX01 0100
1.0321
XX10 0100
1.0546
XX11 0100
0.9913
XX00 0101
1.0119
XX01 0101
1.0335
XX10 0101
1.0560
XX11 0101
0.9925
XX00 0110
1.0133
XX01 0110
1.0349
XX10 0110
1.0574
XX11 0110
0.9938
XX00 0111
1.0146
XX01 0111
1.0363
XX10 0111
1.0589
XX11 0111
0.9951
XX00 1000
1.0159
XX01 1000
1.0377
XX10 1000
1.0603
XX11 1000
0.9964
XX00 1001
1.0173
XX01 1001
1.0391
XX10 1001
1.0618
XX11 1001
0.9976
XX00 1010
1.0186
XX01 1010
1.0404
XX10 1010
1.0632
XX11 1010
0.9989
XX00 1011
1.0199
XX01 1011
1.0418
XX10 1011
1.0647
XX11 1011
1.0002
XX00 1100
1.0213
XX01 1100
1.0432
XX10 1100
1.0661
XX11 1100
1.0015
XX00 1101
1.0226
XX01 1101
1.0446
XX10 1101
1.0676
XX11 1101
1.0028
XX00 1110
1.0240
XX01 1110
1.0460
XX10 1110
1.0690
XX11 1110
1.0041
XX00 1111
1.0253
XX01 1111
1.0475
XX10 1111
1.0705
XX11 1111
SMSC EMC1023
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Revision 1.2 (04-15-05)
1°C Triple Temperature Sensor with Resistance Error Correction
Datasheet
Chapter 5 Application Information
This chapter provides information on maintaining accuracy when using diodes as remote sensors with
SMSC Environmental Monitoring and Control devices. It is assumed that the users have some
familiarity with hardware design and transistor characteristics.
SMSC supplies a family Environmental Monitoring and Control (EMC) devices that are capable of
accurately measuring temperatures. Most devices include an internal temperature sensor along with
the ability to measure one or more external sensors. The characteristics of an appropriate diode for
use as the external sensor are listed in this chapter. Recommendations for the printed circuit board
layout are provided to help reduce error caused by electrical noise or trace resistance.
5.1
Maintaining Accuracy
5.1.1
Physical Factors
Temperature measurement is performed by measuring the change in forward bias voltage of a diode
when different currents are forced through the junction. The circuit board itself can impact the ability
to accurately measure these small changes in voltage.
5.1.1.1
Layout
Apply the following guidelines when designing the printed circuit board:
1. Route the remote diode traces on the top layer.
2. Place a ground guard signal on both sides of the differential pair. This guard band should be
connected to the ground plane at least every 0.25 inches.
3. Place a ground plane on the layer immediately below the diode traces.
4. Keep the diode traces as short as possible.
5. Keep the diode traces parallel, and the length of the two traces identical within 0.3 inches.
6. Use a trace width of 0.01 inches with a 0.01 inch guard band on each side.
7. Keep the diode traces away from sources of high frequency noise such as power supply filtering
or high speed digital signals.
8. When the diode traces must cross high speed digital signals, make them cross at a 90 degree
angle.
9. Avoid joints of copper to solder that can introduce thermocouple effects.
These recommendations are illustrated in Figure 5.1 Routing the Diode Traceson page 16.
.01 GAP MIN.
.01 WIDE MIN.
.01 WIDE MIN.
.01 GAP MIN.
DP or DN
GND PLANE
.01 GAP MIN.
DP or DN
COPPER TRACE
COPPER TRACE
GND PLANE
BOARD MATERIAL
COPPER PLANE (TO SHIELD FROM NOISE)
RECOMMEND VIA STICTCHING AT .25 INCH INTERVALS.
Figure 5.1 Routing the Diode Traces
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SMSC EMC1023
1°C Triple Temperature Sensor with Resistance Error Correction
Datasheet
5.1.1.2
Bypass Capacitors
Accurate temperature measurements require a clean, stable power supply. Locate a 0.1µF capacitor
as close as possible to the power pin with a good ground. A low ESR capacitor (such as a 10µF
ceramic) should be placed across the power source. Add additional power supply filtering in systems
that have a noisy power supply.
A capacitor may be placed across the DP/DN pair at the remote sensor in noisy environments. Do not
exceed a value of 2.2nF if this capacitor is installed.
5.1.1.3
Manufacturing
Circuit board assembly processes may leave a residue on the board. This residue can result in
unexpected leakage currents that may introduce errors if the circuit board is not clean. For example,
processes that use water-soluble soldering fluxes have been known to cause problems if the board is
not kept clean.
5.1.1.4
Thermal Considerations
Keep the sensor in good thermal contact with the component to be measured. The temperature of the
leads of a discrete diode will greatly impact the temperature of the diode junction. Make use of the
printed circuit board to disperse any self-heating that may occur.
5.1.1.5
Remote Sensors Connected by Cables
When connecting remote diodes with a cable (instead of traces on the PCB) use shielded twisted pair
cable. The shield should be attached to ground near the EMC1023, and should be left unconnected
at the sensor end. Belden 8451 cable is a good choice for this application.
5.1.2
Sensor Characteristics
The characteristics of the diode junction used for temperature sensing will affect the accuracy of the
measurement.
5.1.2.1
Selecting a Sensor
A diode connected small signal transistor is recommended. Silicon diodes are not a good choice for
remote sensors. Small signal transistors such as the 2N3904 or the 2N3906 are recommended. Select
a transistor with a constant value of hFE in the range of 2.5 to 220 microamps. The magnitude of hFE
is not critical, and the variation in hFE from one device to another cancels out of the temperature
equations.
5.1.2.2
Compensating for Ideality of the diode
The remote diode may have an ideality factor based on the manufacturing process. Inaccuracy in the
temperature measurement resulting from this ideality factor may be eliminated by configuring the
ideality factor register. The EMC1023 is trimmed to an ideality factor of 1.008.
5.1.2.3
Circuit Connections
The more negative terminal for the remote temperature diode, DN, is internally biased with a forward
diode voltage. Terminal DN is not referenced to ground. Remote temperature diodes can be
constructed as shown in Figure 5.2 Remote Temperature Diode Exampleson page 18.
SMSC EMC1023
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Revision 1.2 (04-15-05)
1°C Triple Temperature Sensor with Resistance Error Correction
Datasheet
To DP
To DP
To DP
To DN
To DN
To DN
Local Ground
Typical Remote Parasitic
Substrate Transistor
e.g. CPU substrate PNP
Typical Remote
Discrete PNP Transistor
e.g 2N3906
Typical Remote
Discrete NPN Transistor
e.g. 2N3904
Figure 5.2 Remote Temperature Diode Examples
Environmental Monitoring and Control (EMC) devices supplied by SMSC are designed to make
accurate temperature measurements. Careful design of the printed circuit board and proper selection
of the remote sensing diode will help to maintain the accuracy.
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DATASHEET
SMSC EMC1023
1°C Triple Temperature Sensor with Resistance Error Correction
Datasheet
Chapter 6 Package Outline
Figure 6.1 8-Pin MSOP Package Outline - 3x3mm Body 0.65mm Pitch
Table 6.1 8-Pin MSOP Package Parameters
MIN
NOMINAL
MAX
REMARKS
A
0.80
~
1.10
Overall Package Height
A1
0.05
~
0.15
Standoff
A2
0.75
0.85
0.95
Body Thickness
D
2.80
3.00
3.20
X Body Size
E
4.65
4.90
5.15
Y Span
E1
2.80
~
3.20
Y body Size
H
0.08
~
0.23
Lead Foot Thickness
L
0.40
~
0.80
Lead Foot Length
L1
0.95 REF
e
Lead Length
0.65 BSC
Lead Pitch
θ
0o
~
8o
Lead Foot Angle
W
0.22
~
0.38
Lead Width
ccc
~
~
0.10
Coplanarity
Notes:
1. Controlling Unit: millimeters.
2. Tolerance on the true position of the leads is ± 0.065 mm maximum.
3. Package body dimensions D and E1 do not include mold protrusion or flash. Dimensions D and
E1 to be determined at datum plane H. Maximum mold protrusion or flash is 0.15mm (0.006 inches)
per end, and 0.15mm (0.006 inches) per side.
4. Dimension for foot length L measured at the gauge plane 0.25 mm above the seating plane.
5. Details of pin 1 identifier are optional but must be located within the zone indicated.
SMSC EMC1023
19
DATASHEET
Revision 1.2 (04-15-05)
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