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. 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Revision 1.2 (04-15-05) 2 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 3 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) 4 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 5 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 6 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 7 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) 8 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. 9 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) 10 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 11 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) 12 DATASHEET 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. Revision 1.2 (04-15-05) 14 DATASHEET 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 15 DATASHEET 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 Revision 1.2 (04-15-05) 16 DATASHEET 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 17 DATASHEET 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. Revision 1.2 (04-15-05) 18 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)