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EMC1002 1C Dual SMBus Sensor with Resistance Error Correction
PRODUCT FEATURES
General Description
The EMC1002 is an SMBus temperature sensor that monitors up to two temperature zones and can generate two system interrupts. With 1C measurement accuracy, the EMC1002 provides a low-cost solution for critical temperature monitoring applications. Extended features include automatic resistance error correction and programmable ideality factor configuration eliminating both major sources of temperature m e a s u r e m e n t e r r o r. 1 T h e 11 - b i t s i g m a d e l t a temperature-to-digital converter provides superb linearity, excellent noise immunity and repeatable temperature readings. The EMC1002 generates two separate interrupts with programmable thermal trip points. The THERM output operates as a thermostat with programmable threshold and hysteresis. The ALERT output can be configured as a maskable SMBus alert with programmable window comparator limits, or a second THERM output. The EMC1002 is pin compatible with the ADT7461, ADM1032, LM99, and the MAX6649.
1.Patents pending.
Datasheet
Features
Resistance Error Correction Ideality Factor Configuration Select 1 of 4 SMBus addresses with external resistor Remote Thermal Zones
-- 1C Accuracy (40C to 80C) -- 0.125C resolution
Internal Thermal Zone
-- 3C Accuracy (0C to 85C)
Maskable Interrupt using ALERT One-shot Command during standby Programmable temperature conversion rate Extended temperature (-64C to 191C) available Over-limit filtering with consecutive counter Small 8-pin SOIC or MSOP green, lead-free package
Applications
Desktop and Notebook Computers Smart batteries Industrial/Automotive Other Electronic Systems
Simplified Block Diagram
EMC1002
Address Pointer Register Switching Current DP
Analog Mux Digital Mux
Conversion Rate Register
Limit Comparator
High Limit Registers
Digital Mux
DN
11-bit delta-sigma ADC
Remote Temp Register Internal Temp Register
Low Limit Registers THERM Limit Register THERM Hysteresis Register Configuration Register
Internal Temp Diode
SMBus Interface
SMCLK SMDATA ALERT THERM
Status Register
Interrupt Masking
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ORDER NUMBER(S):
EMC1002-1-ACZT-TR FOR 8 PIN, SOIC GREEN, LEAD-FREE PACKAGE (Fixed Address, Tape and Reel) EMC1002-2-ACZT-TR FOR 8 PIN, SOIC GREEN, LEAD-FREE PACKAGE (Variable Address, Tape and Reel) EMC1002-1-ACZL-TR FOR 8 PIN, MSOP GREEN, LEAD-FREE PACKAGE (Fixed Address, Tape and Reel) EMC1002-2-ACZL-TR FOR 8 PIN, MSOP GREEN, LEAD-FREE PACKAGE (Variable Address, Tape and Reel) See Table 1.2, "Ordering Information," on page 3. Reel size is 4,000 pieces. Evaluation Board available upon request. (EVB-EMC1002)
80 Arkay Drive Hauppauge, NY 11788 (631) 435-6000 FAX (631) 273-3123
Copyright (c) 2006 SMSC or its subsidiaries. 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 NOT ANY REMEDY OF BUYER IS HELD TO HAVE FAILED OF ITS ESSENTIAL PURPOSE, AND WHETHER OR NOT SMSC HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
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Chapter 1 Pin Configuration
VDD DP DN ADDR/THERM
1 2 3 4
8
SMCLK SMDATA ALERT/THERM2 GND
EMC1002 TOP VIEW
7 6 5
Figure 1.1 EMC1002 Pin Configuration Table 1.1 Pin Description PIN VDD DP DN
ADDR/THERM
PIN NO. 1 2 3 4
DESCRIPTION Supply Voltage, 3.0V to 3.6V. Anode connection for remote temperature diode. Cathode connection for remote temperature diode. Logic output that can be used to turn on/off a fan or throttle a CPU clock in the event of an over-temperature condition. This is an open-drain output. For the EMC1002-2, this pin is sampled following power up and the value of the pull-up resistor determines the SMBus slave address per Table 1.2 on page 3. Total capacitance on this pin must not exceed 100 pf, and the pull-up resistor must be connected to the same supply voltage as VDD. Ground. Logic output used as interrupt, SMBus alert or as a second THERM output. This is an open-drain output. SMBus data input/output. This is an open-drain output. SMBus clock input. Table 1.2 Ordering Information
ADDR/THERM
GND
ALERT/THERM2
5 6 7 8
SMDATA SMCLK
PART NUMBER EMC1002-1 EMC1002-2
PULL-UP RESISTOR 1k or greater (If unused, connect to GND) 7.5k 5% Note 1.1 Note 1.2 12k 5% Note 1.2 20k 5% Note 1.2 33k 5% Note 1.2
SMBUS ADDRESS 1001 100b 1001 100b 1001 101b 0111 100b 0111 101b
Note 1.1 Note 1.2
.
This value must be greater than 1k 5% and less than or equal to 7.5k 5%. The pull-up resistor must be connected to VDD (pin 1), less than 100pf capacitance on pin.
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Table 1.3 Absolute Maximum Ratings PARAMETER Supply Voltage VDD Voltage on ALERT/THERM2, SMDATA and SMCLK pins Voltage on any other pin Operating Temperature Range Storage Temperature Range Lead Temperature Range Package Thermal Characteristics for MSOP-8 (TSSOP) Power Dissipation Thermal Resistance (at 0 air flow) Package Thermal Characteristics for SOIC-8 Power Dissipation Thermal Resistance (at 0 air flow) ESD Rating, All Pins (Human Body Model) TBD 135.9 2000 C/W V TBD 109.6 C/W RATING -0.3 to 5.0 -0.3 to 5.5 -0.3 to VDD+0.3 -40 to +125 -55 to +150 Refer to JEDEC Spec. J-STD-020 UNIT V V V C C
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.
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Chapter 2 Electrical Characteristics
Table 2.1 Electrical Characteristics
VDD=3.0V to 3.6V, TA= -40C to +125C, Typical values at TA = 27C unless otherwise noted
PARAMETER DC Power Supply Voltage Average Operating Current
SYMBOL
MIN
TYP
MAX
UNITS
CONDITIONS
VDD IDD
3.0
3.3 47
3.6 50
V A 0.0625 conversions/s See Table 4.6, "Conversion Rates," on page 15 Standby mode
IPD Internal Temperature Monitor Temperature Accuracy Temperature Resolution External Temperature Monitor Temperature Accuracy Remote Diode 40C to 80C Remote Diode 0C to 125C Temperature Resolution Voltage Tolerance Voltage at pin (ADDR/THERM, ) Voltage at pin (ALERT/THERM2, SMDATA,SMCLK) VTOL VTOL -0.3 -0.3
4.8
10
A
1 TBD 0.5
3
C C C
0CTA85C -40CTA125C
1 3 0.125
C C C
15CTA70C -40CTA125C
3.6 5.5
V V
Digital Outputs (ADDR/THERM, ALERT/THERM2) Output Low Voltage High Level Leakage Current SMBus Interface (SMDATA,SMCLK) Input High Level Input Low Level Input High/Low Current Hysteresis Input Capacitance Output Low Sink Current SMBus Timing Clock Frequency
SMSC EMC1002
VOL IOH 0.1
0.4 1
V A
IOUT=-4mA VOUT=VDD
VIH VIL IIH/IIL
2.0 0.8 -1 500 5 6 1
V V A mV pF mA SMDATA = 0.6V
FSMB
10
5
400
kHz
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Table 2.1 Electrical Characteristics (continued)
VDD=3.0V to 3.6V, TA= -40C to +125C, Typical values at TA = 27C unless otherwise noted
PARAMETER Spike Suppression Bus free time Start to Stop Hold time Start Setup time Start Setup time Stop Data Hold Time Data Setup Time Clock Low Period Clock High Period Clock/Data Fall Time Clock/Data Rise Time
SYMBOL
MIN
TYP
MAX 50
UNITS ns s s s s s ns s s
CONDITIONS
TBUF THD:STA TSU:STA TSU:STO THD:DAT TSU:DAT TLOW THIGH TF TR
1.3 0.6 0.6 0.6 0.3 100 1.3 0.6 * * 300 300 Note 2.1 400
ns ns
*Min = 20+0.1Cb ns *Min = 20+0.1Cb ns
Capacitive Load (each bus line) Note 2.1
Cb
0.6
pF
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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Chapter 3 System Management Bus Interface Protocol
A host controller, such as an SMSC I/O controller, communicates with the EMC1002 via the two wire serial interface named SMBus. The SMBus interface is used to read and write registers in the EMC1002, which is a slave-only device. A detailed timing diagram is shown in Figure 3.1.
T LO W T H IG H
T H D :STA TF
T SU :S TO
SM CLK
T H D :S TA
TR
T H D :D A T T S U :D AT
T SU :S TA
SM DA TA
TBUF
P
S
S - S tart Condition
S
P - Stop Condition
P
Figure 3.1 System Management Bus Timing Diagram The EMC1002 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 1
SLAVE ADDRESS 7
WR 1
ACK 1
COMMAND 8
ACK 1
DATA 8
ACK 1
STOP 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: Bits:
SMSC EMC1002
START 1
SLAVE ADDR 7
WR 1
7
ACK 1
REG. ADDR 8
ACK 1
STOP 1
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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: Bits:
START 1
SLAVE ADDR 7
RD 1
ACK 1
REG. DATA 8
NACK 1
STOP 1
3.5
Alert Response Address
The ALERT/THERM2 output can be used as an SMBALERT# as described in Section 4.5 on page 11. The Alert Response Address is polled by the Host whenever it detects an SMBALERT#, i.e. when the ALERT/THERM2 pin is asserted. The EMC1002 will acknowledge the Alert Response Address and respond with its device address as shown below: Table 3.5 Modified SMBus Receive Byte Protocol Response to ARA ALERT RESPONSE ADDRESS 7
FIELD: Bits:
START 1
RD 1
ACK 1
EMC1002 SLAVE ADDRESS 8
NACK 1
STOP 1
3.6
SMBus Addresses
The EMC1002-2 may be configured to one of four 7-bit slave addresses that are enabled based on the pull-up resistor on the ADDR/THERM pin. The value of this pull-up resistor determines the slave address per Table 1.2, "Ordering Information," on page 3. Attempting to communicate with the EMC1002 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 EMC1002 supports stretching of the SMCLK signal by other devices on the SMBus but will not perform this operation itself. The EMC1002 has an SMBus timeout feature. Bit 7 of the Consecutive Alert register enables this function when set to 1 (the default setting is 0). When this feature is enabled, the SMBus will timeout after approximately 25ms of inactivity.
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Chapter 4 Product Description
The EMC1002 is an SMBus sensor that can monitor internal temperature and one remote diode temperature. The sensor is typically used with an SMBus host such as an SMSC SIO device or an SMSC fan control chip. Thermal management is performed in cooperation with the host device. The host reads the temperature data from the EMC1002 and takes appropriate action such as controlling fan speed or processor clock frequency. The EMC1002 has programmable temperature limit registers that define a safe operating window. After the host has configured the temperature limits, the EMC1002 can perform as a free-running independent watchdog to warn the host of temperature hot spots without requiring the host to poll the device.
EMC1002 SMCLK DP DN SMDATA ALERT/THERM2 Internal Diode
Host
SMBus Interface
ADDR/THERM
Fan Driver
Figure 4.1 System Overview The EMC1002 has
two basic modes of operation:
Run Mode: In this mode, the EMC1002 continuously converts temperature data and updates its registers. The rate of temperature conversion is configured as shown in 4.11, "Conversion Rate Register," on page 15. Standby Mode: In this mode, the EMC1002 is placed in standby to conserve power as described in 4.7, "Standby Mode," on page 13.
4.1
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 =
kT
I ln HIGH I q LOW

k = Boltzmann's constant T = absolute temperature in Kelvin q = electron charge
= diode ideality factor
The change in
VBE voltage is proportional to absolute temperature T.
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VDD Ihigh Ilow Ibias
Internal or Remote Diode
Bias Diode
Delta Vbe Sample & Hold
1-bit DeltaSigma 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 EMC1002 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.
4.2
Resistance Error Correction
The EMC1002 includes active 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 +0.7C 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 EMC1002 eliminates the need to characterize and compensate for parasitic resistance in the remote diode path.
4.3
Ideality Factor Configuration
Temperature sensors like the EMC1002 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. The EMC1002 provides a 6-bit ideality factor register for the remote diode. The ideality factor of the remote diode is programmed in a register to eliminate errors across all temperatures. See section 4.16, "Ideality Factor Register," on page 16 for details on programming this register.
4.4
Temperature Measurement Results and Data
The 11-bit temperature measurement results are stored in temperature value registers. The EMC1002 has two temperature ranges and the default range is from 0 to 127C. This range uses binary number format, and the most significant bit is not used. The extended range is from -64C to +191C and is binary offset by 64C. Table 4.1 shows the two temperature data formats with an LSB equivalent to 0.125C. The format is selected as described in 4.10, "Configuration Register," on page 14.
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Table 4.1 Temperature Data Format ACTUAL TEMP. (C) -63 -0.125 0 +0.125 +0.250 +1 +127 +128 +190 +191 Note 4.1 Note 4.2 Note 4.3 Note 4.4 DEFAULT RANGE BINARY 0000 0000 000 Note 4.1 0000 0000 000 Note 4.1 0000 0000 000 Note 4.1 0000 0000 001 0000 0000 010 0000 0001 000 0111 1111 000 Note 4.3 0111 1111 000 Note 4.3 0111 1111 000 Note 4.3 0111 1111 000 Note 4.3 EXTENDED RANGE OFFSET BINARY 0000 0001 000 Note 4.2 0011 1111 111 0100 0000 000 0100 0000 001 0100 0000 010 0100 0001 000 1011 1110 000 1011 1111 000 1111 1110 000 1111 1111 000 Note 4.4
Data in Binary Format reads 0000 0000 000 for all temperatures 0.00C. Data in Offset Binary Format reads 0000 0000 000 for all temperatures -64C. Data in Binary Format reads 0111 1111 000 for all temperatures +127C. Data in Offset Binary Format reads 1111 1111 000 for all temperatures +191C.
The 11-bit temperature data is stored with the 8 most significant bits stored in the High Byte register and the 3 least significant bits in the Low Byte register. The Low Byte register contains the three least significant bits as outlined in Table 4.2. These bits are stored in the upper three bits of the register, and the five LSB positions of this register always read zero. In Table 4.2, the upper case "B" shows the bit position of a 16-bit word created by concatenating the High Byte and Low Byte, and the lower case "b" shows the bit position in the 11-bit temperature data. The resolution of the internal temperature is 0.5C and the b1 and b0 bits of the Internal Temperature Value Low Byte register will always read 0. Table 4.2 Bit Position of Two Byte Values HIGH BYTE B15 b10 B14 b9 B13 b8 B12 b7 B11 b6 B10 b5 B9 b4 B8 b3 B7 b2 B6 b1 B5 b0 LOW BYTE B4 0 B3 0 B2 0 B1 0 B0 0
4.5
ALERT/THERM2 Output
The ALERT/THERM2 output asserts if an out of limit measurement is detected as described in 4.12, "Limit Registers," on page 15. The ALERT/THERM2 pin is an open drain output and requires a pull-up resistor to VDD.The ALERT/THERM2 pin can be used as an SMBALERT#, or may be configured as a second THERM output. As described in the SMBus specification, an SMBus slave may inform the SMBus master that it wants to talk by asserting the SMBALERT# signal. One or more ALERT outputs can be hardwired together as a wired-or bus to a common input.
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The ALERT/THERM2 pin de-asserts when the EMC1002 responds to an alert response address (ARA=0001 100) sent by the host if the out of limit condition no longer exists, but it does not reset if the error condition remains. The ALERT/THERM2 pin can be masked so that it will not assert in the event of an out of limit temperature measurement, except when it is configured as a second THERM pin.
Temp
Temperature High Limit SMBus ARA Temperature Low Limit
Logic Level
Logic High
ALERT/THERM2 Time
Figure 4.3 ALERT/THERM2 Response to Temperature Limits Exceeded The ALERT/THERM2 pin can be configured as a second THERM pin that asserts when the temperature measurement exceeds the Temperature High Limit value. In this mode, the output will not de-assert until the temperature drops below the Temperature High Limit minus the THERM Hysteresis value.
4.6
ADDR/THERM Output
The ADDR/THERM output asserts if the temperature measurement exceeds the programmable THERM limit. It can be used to drive a fan or other fail-safe devices. The ADDR/THERM pin is open drain and requires a pull-up resistor to VDD. For the EMC1002-2, the value of this pull-up resistor determines the slave address per Table 1.2 on page 3. The ADDR/THERM pin cannot be masked. Do not exceed 100pf capacitance total on this pin. When the ADDR/THERM pin is asserted, it will not de-assert until the temperature drops below the THERM limit minus the THERM hysteresis value.
Temp
THERM Limit THERM Limit - THERM Hysterisis
THERM Hysteresis
Logic Level
Logic High
THERM Time
Figure 4.4 ADDR/THERM Output Response to Temperature Limit Exceeded
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4.7
Standby Mode
The EMC1002 can be set to standby mode (low power) by setting a bit in the Configuration Register as described in 4.10, "Configuration Register," on page 14. This shuts down all internal analog functions while the SMBus remains enabled. When the EMC1002 is in standby mode, a One-Shot command measurement can be initiated. The user may also write new values to the limit registers described in 4.12, "Limit Registers," on page 15 while in standby. If the previously stored temperature is outside any of the new limits, the ALERT/THERM2 output will respond as described in Section 4.5 and the ADDR/THERM output will respond as described in Section 4.6.
4.8
Register Allocation
The registers shown in Table 4.3 are accessible through the SMBus. Table 4.3 EMC1002 Register Map
READ ADDRESS (HEX) 00 01 02 03 04 05 06 07 08 N/A 10 11 12 13 14 19 20 21 22 27 29 FD FE FF
WRITE ADDRESS (HEX) N/A N/A N/A 09 0A 0B 0C 0D 0E 0F N/A 11 12 13 14 19 20 21 22 27 N/A
REGISTER NAME Internal Temperature Value High Byte Remote Temperature Value High Byte Status Configuration Conversion Rate Internal Temperature High Limit Internal Temperature Low Limit Remote Temperature High Limit High Byte Remote Temperature Low Limit High Byte One-Shot Remote Temperature Value Low Byte Scratchpad Byte 1 Scratchpad Byte 2 Remote Temperature High Limit Low Byte Remote Temperature Low Limit Low Byte Remote THERM Limit Internal THERM Limit THERM Hysteresis Consecutive ALERT Remote Ideality Factor Internal Temperature Value Low Byte Product ID Manufacture ID Revision Number
POWER-ON DEFAULT 0000 0000 0000 0000 undefined 0000 0000 0000 1000 0101 0101 0000 0000 0101 0101 0000 0000 0000 0000 0000 0000 0000 0101 0101 0000 0000 0001 0000 0000 0000 0101 0000
(85C) (0C) (85C) (0C)
N/A N/A Note 4.5
0000 0000 0000 0000 0000 0101 (85C) 0101 (85C) 1010 (10C) 0001 0010 (1.008) 0000 0010 - EMC1002-1 0011 - EMC1002-2 1101 0001 Note 4.5
Revision number may change. Please obtain the latest version of this document from the SMSC web site.
At device power-up, the default values are stored in registers as shown. A power-on-reset is initiated when power is first applied to the part and the VDD supply exceeds the POR threshold. Reads of undefined registers will return 00h and writes to undefined registers will be ignored. The EMC1002 uses an interlock mechanism that locks the low byte value when the high byte register is read. This prevents updates to the low byte register between high byte and low byte reads. This
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interlock mechanism requires that the high byte register always be read prior to reading the low byte register.
4.9
Status Register
The status register is a read only register that stores the operational status of the part. Table 4.4 Status Register STATUS REGISTER
BIT 7 6 5 4 3 2 1 0
NAME Busy LHIGH LLOW R1HIGH R1LOW FAULT R1THRM LTHRM 1 when ADC is converting
FUNCTION
1 when Internal Temperature High Limit is exceeded 1 when Internal Temperature Low Limit is exceeded 1 when Remote Temperature High Limit is exceeded 1 when Remote Temperature Low Limit is exceeded 1 when Remote is open circuit 1 when Remote THERM Limit is exceeded 1 when Internal THERM Limit is exceeded
Bit 7 indicates that the ADC is busy converting a value. Bits 6 and 5 indicate that the internal temperature is above or below its high or low limits respectively. Likewise, bits 4 and 3 indicate that remote temperature is above or below its limits. See 4.12, "Limit Registers," on page 15 for detail on the limits are compared. Bit 2 indicates that an open circuit on the remote diode anode connection has been detected. Bits 1 and 0 indicate that the remote temperature or the internal temperature has exceeded their respective THERM limits. If bits 1 or 0 go high the ADDR/THERM signal will be asserted. When the status register is read, bits 2 through 6 will individually clear provided that the error condition for that bit no longer exists. The ALERT/THERM2 output is latched and will not be reset until the host has responded to the SMBALERT# with an alert response address. The ALERT/THERM2 signal will not reset if the status register has not been cleared.
4.10
Configuration Register
The configuration register controls the functionality of the temperature measurements. Table 4.5 Configuration Register CONFIGURATION REGISTER
BIT 7 6 5
NAME MASK1 RUN/STOP
ALERT or THERM2
FUNCTION 0 = ALERT enabled 1 = ALERT disabled 0 = Active mode (continuously running) 1 = Standby mode 0 = ALERT 1 = THERM2
14
DEFAULT 0 0 0
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Table 4.5 Configuration Register (continued) CONFIGURATION REGISTER BIT 4-3 2 1-0 NAME Reserved Temperature Range Select Reserved 0 = 0C to 127C 1 = -64C to 191C FUNCTION DEFAULT 0 0 0
Bit 7 is used to mask the ALERT/THERM2 output. When this bit is set to 0, any out of limit condition will assert ALERT/THERM2. This bit is ignored if the ALERT/THERM2 pin is configured as THERM2 signal by bit 5. Bit 6 initiates ADC conversions. When this bit is low, the ADC will convert temperatures in a continuous mode. When this bit is high, the ADC will be in standby mode, thus reducing supply current significantly though the SMBus will still be active. If bit 6 is 1 and the one-shot register is written to, the ADC will execute a temperature measurement and then return to standby mode. Bit 5 sets the ALERT/THERM2 pin to act as either an SMBALERT# signal or as the THERM2 signal. If bit 5 is set to 1 the ALERT/THERM2 pin acts as the THERM2 signal and bit 7 is ignored. Bit 2 selects the range and format of the temperature as shown in Table 4.1, "Temperature Data Format," on page 11
4.11
Conversion Rate Register
The conversion rate register determines how many times the temperature value will be updated per second. The lowest 4 bits configure a programmable delay that waits between consecutive conversion cycles to obtain the desired conversion rate. Table 4.6 shows the conversion rate and the associated quiescent current. Table 4.6 Conversion Rates CONVERSION RATE VALUE 00h 01h 02h 03h 04h 05h 06h 07h 08h 09h 0Ah 0Bh to FFh CONVERSIONS/SECOND 0.0625 0.125 0.25 0.5 1 2 4 8 16 32 64 Reserved TYPICAL QUIESCENT CURRENT (A) 47 50 53 56 68 78 106 165 281 500 550
4.12
Limit Registers
The EMC1002 compares the limit registers to the measured temperature. The data format of the programmed limits for this comparison is the same as the measurement data format determined by
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the Configuration Register. The user is required to update the limit registers to the new format when changing between measurement data formats. The user can configure high and low temperature limits and an independent THERM limit. The temperature high limit (TH) is an 11-bit value that is set by the Temperature High Limit High Byte register and the Temperature High Limit Low Byte register. The Temperature High Limit Low Byte register contains the three least significant bits as shown in Table 4.2 on page 11. The temperature low limit (TL) is an 11-bit value that is set by the Temperature Low Limit High Byte register and the Temperature Low Limit Low Byte register as shown in Table 4.2 on page 11. The limits are automatically compared to the temperature measurement results (TM) and have been exceeded if (TM TL or TM > TH). If either limit is exceeded then the appropriate bit is set high in the status register and the ALERT/THERM2 output will respond as described in Section 4.5 on page 11. The THERM limit (TTH) is a single byte value set by the THERM Limit register. Exceeding the THERM limit asserts the ADDR/THERM signal as described in Section 4.6 on page 12. When the ALERT/THERM2 pin is configured as THERM2, then exceeding the high limit asserts this pin.
4.13
THERM Hysteresis Register
The THERM hysteresis register holds a hysteresis value that impacts the de-assertion of THERM as shown in Figure 4.4 on page 12. It defaults to 10C and can be set by the user at any time after power up. When the ALERT/THERM2 pin is configured as THERM2, then the output will not de-assert until the temperature drops below the Temperature High Limit minus the THERM Hysteresis value.
4.14
One-Shot Register
Writing to the one-shot register while in standby mode initiates a conversion and comparison cycle. The EMC1002 will execute a temperature measurement, compare the data to the limit registers and return to the standby mode. A write to the one-shot register will be ignored if it occurs while the EMC1002 is in run mode.
4.15
Scratchpad Registers
The scratchpad registers may be used to verify SMBus communications. These registers do not have any affect on the operation of the device, and may be written and read via the SMBus.
4.16
Ideality Factor Register
The ideality factor registers are used to program the remote diode ideality factor into the EMC1002 so that this error source can be eliminated. The default ideality factor is 1.008 and has a value of XX010010b or 12h. Table 4.7 Diode Ideality Factor Values
DIODE IDEALITY FACTOR 0.9850 0.9862 0.9875 0.9888 0.9900 0.9913
VALUE
DIODE IDEALITY FACTOR 1.0054 1.0067 1.0080 1.0093 1.0106 1.0119
VALUE XX01 0000 XX01 0001 XX01 0010 XX01 0011 XX01 0100 XX01 0101
16
DIODE IDEALITY FACTOR 1.0267 1.0280 1.0294 1.0308 1.0321 1.0335
VALUE XX10 0000 XX10 0001 XX10 0010 XX10 0011 XX10 0100 XX10 0101
DIODE IDEALITY FACTOR 1.0489 1.0503 1.0517 1.0531 1.0546 1.0560
VALUE XX11 0000 XX11 0001 XX11 0010 XX11 0011 XX11 0100 XX11 0101
SMSC EMC1002
XX00 0000 XX00 0001 XX00 0010 XX00 0011 XX00 0100 XX00 0101
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Table 4.7 Diode Ideality Factor Values (continued) DIODE IDEALITY FACTOR 0.9925 0.9938 0.9951 0.9964 0.9976 0.9989 1.0002 1.0015 1.0028 1.0041 DIODE IDEALITY FACTOR 1.0133 1.0146 1.0159 1.0173 1.0186 1.0199 1.0213 1.0226 1.0240 1.0253 DIODE IDEALITY FACTOR 1.0349 1.0363 1.0377 1.0391 1.0404 1.0418 1.0432 1.0446 1.0460 1.0475 DIODE IDEALITY FACTOR 1.0574 1.0589 1.0603 1.0618 1.0632 1.0647 1.0661 1.0676 1.0690 1.0705
VALUE
VALUE XX01 0110 XX01 0111 XX01 1000 XX01 1001 XX01 1010 XX01 1011 XX01 1100 XX01 1101 XX01 1110 XX01 1111
VALUE XX10 0110 XX10 0111 XX10 1000 XX10 1001 XX10 1010 XX10 1011 XX10 1100 XX10 1101 XX10 1110 XX10 1111
VALUE XX11 0110 XX11 0111 XX11 1000 XX11 1001 XX11 1010 XX11 1011 XX11 1100 XX11 1101 XX11 1110 XX11 1111
XX00 0110 XX00 0111 XX00 1000 XX00 1001 XX00 1010 XX00 1011 XX00 1100 XX00 1101 XX00 1110 XX00 1111
4.17
Consecutive ALERT Register
Bit 7 of the Consecutive ALERT register enables the SMBus timeout feature when set to 1 (the default setting is 0). When enabled, the SMBus will timeout after approximately 25ms of inactivity. Table 4.9 describes how bits 3-1 of the Consecutive ALERT register set how many consecutive error conditions must occur for each temperature measurement zone before the ALERT/THERM2 signal is asserted. These error conditions include diode faults and exceeding temperature limits. The default value is one which means that any out-of-limit measurement or any diode fault will cause the ALERT/THERM2 pin to be asserted. Any combination of bits 3-1 other than those shown will result in a value of one. Table 4.8 Consecutive ALERT Register
BIT 7 6-4 3-1 0
NAME SMBTE Reserved ALERTNUM Reserved See Table 4.9
FUNCTION 0 = SMBus timeout disabled 1 = SMBus timeout enabled
DEFAULT 0 0 0 0
Table 4.9 Consecutive ALERT Value VALUE NUMBER OF EVENTS REQUIRED 1 2 3 4 b3 0 0 0 1 b2 0 0 1 1 b1 0 1 1 1
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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
5.1.1
Maintaining Accuracy
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 Traces on page 18.
.01 GAP MIN.
.01 WIDE MIN.
.01 GAP MIN.
.01 WIDE MIN.
.01 GAP MIN.
DP or DN GND PLANE COPPER TRACE BOARD MATERIAL
DP or DN COPPER TRACE GND PLANE
COPPER PLANE (TO SHIELD FROM NOISE)
RECOMMEND VIA STICTCHING AT .25 INCH INTERVALS.
Figure 5.1 Routing the Diode Traces
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5.1.1.2
Bypass Capacitors
Accurate temperature measurements require a clean, stable power supply. Locate a 0.1F capacitor as close as possible to the power pin with a good ground. A low ESR capacitor (such as a 10F 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 EMC1002, 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 EMC1002 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 Examples on page 20.
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To DP To DN Local Ground
Typical Remote Parasitic Substrate Transistor e.g. CPU substrate PNP
To DP
To DP
To DN
To DN
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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Chapter 6 Package Outlines
Figure 6.1 8-Pin MSOP and 8-Pin MSOP (Lead-Free) Package Outline - 3x3mm Body 0.65mm Pitch Table 6.1 8-Pin MSOP and 8-Pin MSOP (Lead-Free) Package Parameters MIN A A1 A2 D E E1 H L L1 e 0.80 0.05 0.75 2.80 4.65 2.80 0.08 0.40 NOMINAL ~ ~ 0.85 3.00 4.90 ~ ~ ~ 0.95 REF 0.65 BSC 0o 0.22 ~ ~ ~ ~ 8o 0.38 0.10 MAX 1.10 0.15 0.95 3.20 5.15 3.20 0.23 0.80 REMARKS Overall Package Height Standoff Body Thickness X Body Size Y Span Y body Size Lead Foot Thickness Lead Foot Length Lead Length Lead Pitch Lead Foot Angle Lead Width Coplanarity
W ccc
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.
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REVISION HISTORY
REVISION A DESCRIPTION INITIAL RELEASE DATE 7/07/04 RELEASED BY S.K.ILIEV
D
3 e
SEE DETAIL "A"
8
3
E1
E
1 5 INDEX AREA (D/2 X E1/2)
2 4 8X b 2 4 c
TOP VIEW
END VIEW
C A2 SEATING PLANE ccc C A
A1
SIDE VIEW
3-D VIEW
NOTES: 1. ALL DIMENSIONS ARE IN MILLIMETER. 2. TRUE POSITION SPREAD TOLERANCE IS 0.125mm AT MAXIMUM MATERIAL CONDITION. 3. PACKAGE BODY DIMENSION "D" DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MAXIMUM MOLD FLASH, PROTRUSIONS OR GATE BURRS IS 0.15 mm PER END. DIMENSION "E1" DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSION. MAXIMUM INTERLEAD FLASH OR PROTRUSION IS 0.25 mm PER SIDE. "D1" & "E1" DIMENSIONS ARE DETERMINED AT DATUM PLANE "H". 4. DIMENSIONS "b" & "c" APPLY TO THE FLAT SECTION OF THE LEAD BETWEEN 0.10 TO 0.25 mm FROM THE LEAD TIP. 5. THE CHAMFER FEATURE IS OPTIONAL. IF IT IS NOT PRESENT, THEN A PIN 1 IDENTIFIER MUST BE LOCATED WITHIN THE INDEX AREA INDICATED.
H
0.25 GAUGE PLANE
L L1
0
UNLESS OTHERWISE SPECIFIED DIMENSIONS ARE IN MILLIMETERS AND TOLERANCES ARE: DECIMAL X.X 0.1 X.XX 0.05 X.XXX 0.025 ANGULAR 1
THIRD ANGLE PROJECTION
80 ARKAY DRIVE HAUPPAUGE, NY 11788 USA
DETAIL "A"
SCALE: 3/1
TITLE
DIM AND TOL PER ASME Y14.5M - 1994
MATERIAL
NAME
DRAWN
DATE
-
S.K.ILIEV
CHECKED
7/07/04 7/07/04
PACKAGE OUTLINE 8 PIN SOIC, 3.9mm BODY WIDTH, 1.27mm PITCH
DWG NUMBER
FINISH
S.K.ILIEV
APPROVED
MO-8-SOIC-4.9x3.9
STD COMPLIANCE SHEET
REV
A 1 OF 1
PRINT WITH "SCALE TO FIT" DO NOT SCALE DRAWING
SCALE
S.K.ILIEV
7/07/04
1:1
JEDEC: MS-012 / AA
Figure 6.2 8-Pin SOIC and 8-Pin SOIC (Lead-Free) Package Outline and Parameters - 3.9mm Body 1.27 mm Pitch
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