LM95233 Dual Remote Diode and Local Temperature Sensor with SMBus Interface and TruTherm™ Technology General Description LM95233 is an 11-bit digital temperature sensor with a 2-wire System Management Bus (SMBus) interface that can monitor the temperature of two remote diodes as well as its own temperature. The LM95233 can be used to very accurately monitor the temperature of up to two external devices such as microprocessors, graphics processors or diode-connected 2N3904s. The LM95233's TruTherm™ BJT beta compensation technology allows sensing of 90nm or 65nm process thermal diodes accurately. The LM95233 reports temperature in two different formats for +127.875°C/–128°C range and 0°C/255°C range. The LM95233 TCRIT1, TCRIT2 and TCRIT3 outputs are triggered when any unmasked channel exceeds its corresponding programmable limit and can be used to shutdown the system, to turn on the system fans or as a microcontroller interrupt function. The current status of the TCRIT1, TCRIT2 and TCRIT3 pins can be read back from the status registers. Mask registers are available for further control of the TCRIT outputs. LM95233's remote temperature channels have programmable digital filters to minimize unwanted TCRIT events when temperature spikes are encountered. For optimum flexibility and accuracy each LM95233 channel includes, registers for sub-micron process or 2N3904 diode model selection as well as offset correction. A three level address pin allows connection of up to 3 LM95233s to the same SMBus master. The LM95233 includes power saving functions such as: programmable conversion rate, shutdown mode, and turn off of unused channels. ■ 0.125°C LSb temperature resolution ■ 0.03125°C LSb remote temperature resolution with digital ■ ■ ■ ■ ■ ■ ■ ■ ■ filter enabled +127.875°C/–128°C and 0°C/255°C remote ranges Programmable digital filters and analog front end filter Remote diode fault detection, model selection and offset correction Mask and status register support 3 programmable TCRIT outputs with programmable shared hysteresis Programmable conversion rate and shutdown mode oneshot conversion control SMBus 2.0 compatible interface, supports TIMEOUT Three-level address pin 14-pin LLP package Key Specifications ±2.0 °C (max) ■ Local Temperature Accuracy ■ Remote Diode Temperature Accuracy ±0.875 °C (max) 3.0 V to 3.6 V ■ Supply Voltage 0.57 mA (typ) ■ Average Supply Current (1Hz conversion rate) Applications ■ Processor/Computer System Thermal Management (e.g. Laptop, Desktop, Workstations, Server) ■ Electronic Test Equipment ■ Office Electronics Features ■ Accurately senses die temperature of 2 remote ICs or diode junctions and local temperature ■ TruTherm BJT beta compensation technology accurately senses sub-micron process thermal diodes Connection Diagram LLP-14 20206301 TOP VIEW TruTherm™ is a trademark of National Semiconductor Corporation. Intel™ is a trademark of Intel Corporation. Pentium™ is a trademark of Intel Corporation. © 2007 National Semiconductor Corporation 202063 www.national.com LM95233 Dual Remote Diode and Local Temperature Sensor with SMBus Interface and TruTherm Technology June 2007 LM95233 Ordering Information Package Marking NS Package Number Transport Media LM95233CISD 95233CI SDA14B (LLP-14) 1000 Units on Tape and Reel LM95233CISDX 95233CI SDA14B (LLP-14) 4500 Units on Tape and Reel Part Number Simplified Block Diagram 20206302 Pin Descriptions Label Pin # NC 1 No Connect Not connected. May be left floating, connected to GND or VDD. VDD 2 Positive Supply Voltage Input DC Voltage from 3.0 V to 3.6 V. VDD should be bypassed with a 0.1µF capacitor in parallel with 100pF. The 100pF capacitor should be placed as close as possible to the power supply pin. Noise should be kept below 200 mVp-p, a 10 µF capacitor may be required to achieve this. NC 3 No Connect Not connected. May be left floating, connected to GND or VDD. NC 4 No Connect Not connected. May be left floating, connected to GND or VDD. D− 5 Diode Return Current Sink To all Diode Cathodes. Common D- pin for all two remote diodes. www.national.com Function Typical Connection 2 Pin # Function Typical Connection D2+ 6 Diode Current Source To second Diode Anode. Connected to remote discrete diodeconnected transistor junction or to the diode-connected transistor junction on a remote IC whose die temperature is being sensed. A capacitor is not required between D2+ and D-. A 100 pF capacitor between D2+ and D- can be added and may improve perfomance in noisy systems. Float this pin if this thermal diode is not used. D1+ 7 Diode Current Source To first Diode Anode. Connected to remote discrete diodeconnected transistor junction or to the diode-connected transistor junction on a remote IC whose die temperature is being sensed. A capacitor is not required between D1+ and D-. A 100 pF capacitor between D1+ and D- can be added and may improve perfomance in noisy systems. Float this pin if this thermal diode is not used. GND 8 Power Supply Ground System low noise ground. A0 9 Dgital Input SMBus slave address select pin. Selects one of three addresses. Can be tied to VDD, GND, or to the middle of a resistor divider connected between VDD and GND. TCRIT1 10 Digital Output, Open-Drain Critical temperature output 1. Requires pull-up resistor. Active "LOW". TCRIT2 11 Digital Output, Open-Drain Critical temperature output 2. Requires pull-up resistor. Active "LOW". SMBDAT 12 SMBus Bi-Directional Data Line, Open-Drain Output From and to Controller; may require an external pull-up resistor SMBCLK 13 SMBus Clock Input From Controller; may require an external pull-up resistor TCRIT3 14 Digital Output, Open-Drain Critical temperature output 3. Requires pull-up resistor. Active "LOW". 3 www.national.com LM95233 Label LM95233 Typical Application 20206303 www.national.com 4 Supply Voltage −0.3V to 6.0V Voltage at SMBDAT, SMBCLK, TCRIT1, TCRIT2, TCRIT3 −0.5V to 6.0V Voltage at Other Pins −0.3V to (VDD + 0.3V) D− Input Current ±1 mA Input Current at All Other Pins (Note 2) ±5 mA Package Input Current (Note 2) 30 mA SMBDAT, TCRIT1, TCRIT2, TCRIT3 Output Sink Current 10 mA Storage Temperature −65°C to +150°C ESD Susceptibility (Note 4) Human Body Model 2000V Machine Model 200V Operating Ratings (Notes 1, 5) Operating Temperature Range Electrical Characteristics Temperature Range LM95233CISD −40°C to +140°C TMIN ≤ TA ≤ TMAX Supply Voltage Range (VDD) −40°C ≤ TA ≤ +125°C +3.0V to +3.6V Temperature-to-Digital Converter Electrical Characteristics Unless otherwise noted, these specifications apply for VDD = +3.0Vdc to 3.6Vdc. Boldface limits apply for TA = TJ = TMIN ≤ TA ≤ TMAX; all other limits TA = TJ = +25°C, unless otherwise noted. Parameter Conditions Typical (Note 6) Limits (Note 7) Units (Limit) ±1 ±2 °C (max) Temperature Error Using Local Diode TA = -40°C to +125°C, (Note 8) Temperature Error Using Remote Diode (Note 9) TA = +25°C to +85°C TD = +60°C to +100°C 65 nm Intel Processor ±0.875 °C (max) TA = +25°C to +85°C TD = +60°C to +100°C MMBT3904 Transistor ±1.1 °C (max) TA = +25°C to +85°C TD = 40°C to +125°C 65 nm Intel Processor ±1.0 °C (max) TA = +25°C to +85°C TD = −40°C to +125°C MMBT3904 Transistor ±1.3 °C (max) TA = −40°C to +85°C TD = −40°C to +125°C 65 nm Intel Processor ±3.2 °C (max) TA = −40°C to +85°C TD = −40°C to +125°C MMBT3904 Transistor ±3.0 °C (max) TA = −40°C to +85°C TD = 125°C to +140°C MMBT3904 Transistor ±3.3 °C (max) Local Diode Measurement Resolution Remote Diode Measurement Resolution 11 Digital Filter Off Digital Filter On (Remote Diodes 1 and 2 only) Conversion Time of All Temperatures at the Fastest Setting (Note 11) Quiescent Current (Note 10) °C 11 Bits 0.125 °C 13 Bits 0.03125 °C All Channels are Enabled in Default State 1100 1210 ms (max) 1 External Channel TruTherm Active 34 37 ms (max) 1 External Channel TruTherm Inactive 31 34 ms (max) Local only 30 33 ms (max) SMBus Inactive, 1Hz Conversion Rate, channels in default state 570 800 µA (max) Shutdown 360 D− Source Voltage Remote Diode Source Current Bits 0.125 µA 0.4 High level 160 Low level 10 5 V 230 µA (max) www.national.com LM95233 Charge Device Model 1000V Soldering process must comply with National’s reflow temperature profile specifications. Refer to http:// www.national.com/packaging/. (Note 3) Absolute Maximum Ratings (Note 1) LM95233 Parameter Conditions Typical (Note 6) Limits (Note 7) Units (Limit) 2.8 1.6 V (max) V (min) Power-On Reset Threshold Measured on VDD input, falling edge TCRIT1 Pin Temperature Threshold Default Diodes only +110 °C TCRIT2 Pin Temperature Threshold Default all channels +85 °C Logic Electrical Characteristics DIGITAL DC CHARACTERISTICS Unless otherwise noted, these specifications apply for VDD = +3.0Vdc to 3.6Vdc. Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits TA= TJ=+25°C, unless otherwise noted. Symbol Parameter Conditions Typical (Note 6) Limits (Note 7) Units (Limit) SMBDAT, SMBCLK INPUTS VIN(1) Logical “1” Input Voltage 2.1 V (min) VIN(0) Logical “0”Input Voltage 0.8 V (max) VIN(HYST) SMBDAT and SMBCLK Digital Input Hysteresis 400 mV IIN(1) Logical “1” Input Current VIN = VDD 0.005 10 µA (max) IIN(0) Logical “0” Input Current VIN = 0V −0.005 -10 µA (max) CIN Input Capacitance 5 pF A0 DIGITAL INPUT VIH Input High Voltage 0.90 × VDD V (min) VIM Input Middle Voltage 0.57 × VDD V (max) 0.43 × VDD V (min) 0.10 × VDD V (max) IIN(1) VIL Input Low Voltage Logical "1" Input Current VIN = VDD −0.005 −10 µA (min) IIN(0) Logical "0" Input Current VIN = 0V 0.005 10 µA (max) CIN Input Capacitance 5 pF SMBDAT, TCRIT1, TCRIT2, TCRIT3 DIGITAL OUTPUTS IOH High Level Output Current VOL(SMBDAT) SMBus Low Level Output Voltage VOL(TCRIT) COUT TCRIT1, TCRIT2, TCRIT3 Low Level Output Voltage VOH = VDD 10 µA (max) IOL = 4 mA IOL = 6 mA 0.4 0.6 V (max) V (max) IOL= 6 mA 0.4 V (max) Digital Output Capacitance www.national.com 5 6 pF Unless otherwise noted, these specifications apply for VDD=+3.0 Vdc to +3.6 Vdc, CL (load capacitance) on output lines = 80 pF. Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits TA = TJ = +25°C, unless otherwise noted. The switching characteristics of the LM95233 fully meet or exceed the published specifications of the SMBus version 2.0. The following parameters are the timing relationships between SMBCLK and SMBDAT signals related to the LM95233. They adhere to but are not necessarily the SMBus bus specifications. Symbol Parameter Conditions Typical (Note 6) Limits (Note 7) Units (Limit) 100 10 kHz (max) kHz (min) fSMB SMBus Clock Frequency tLOW SMBus Clock Low Time from VIN(0)max to VIN(0)max 4.7 25 µs (min) ms (max) tHIGH SMBus Clock High Time from VIN(1)min to VIN(1)min 4.0 µs (min) tR,SMB SMBus Rise Time (Note 12) 1 µs (max) tF,SMB SMBus Fall Time (Note 13) 0.3 µs (max) tOF Output Fall Time CL = 400 pF, IO = 3 mA, (Note 13) 250 ns (max) tTIMEOUT SMBDAT and SMBCLK Time Low for Reset of Serial Interface (Note 14) 25 35 ms (min) ms (max) tSU;DAT Data In Setup Time to SMBCLK High 250 ns (min) tHD;DAT Data Out Stable after SMBCLK Low 300 1075 ns (min) ns (max) tHD;STA Start Condition SMBDAT Low to SMBCLK Low (Start condition hold before the first clock falling edge) 100 ns (min) tSU;STO Stop Condition SMBCLK High to SMBDAT Low (Stop Condition Setup) 100 ns (min) tSU;STA SMBus Repeated Start-Condition Setup Time, SMBCLK High to SMBDAT Low 0.6 µs (min) SMBus Free Time Between Stop and Start Conditions 1.3 µs (min) tBUF SMBus Communication 20206309 Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. DC and AC electrical specifications do not apply when operating the device beyond its rated operating conditions. Note 2: When the input voltage (VI) at any pin exceeds the power supplies (VI < GND or VI > VDD), the current at that pin should be limited to 5 mA. Parasitic components and or ESD protection circuitry are shown in the table below for the LM95233's pins. 7 www.national.com LM95233 SMBus DIGITAL SWITCHING CHARACTERISTICS LM95233 Pin # Label Circuit 1 NC – 2 VDD A 3 NC – 4 NC – 5 D- A 6 D2+ A 7 D1+ A 8 GND – Circuits for Pin ESD Protection Structure Circuit A 9 A0 B 10 TCRIT1 B 11 TCRIT2 B 12 SMBDAT B 13 SMBCLK B 14 TCRIT2 B Circuit B Note 3: Reflow temperature profiles are different for packages containing lead (Pb) than for those that do not. Note 4: Human body model, 100 pF discharged through a 1.5 kΩ resistor. Machine model, 200 pF discharged directly into each pin. Charged Device Model (CDM) simulates a pin slowly acquiring charge (such as from a device sliding down the feeder in an automated assembler) then rapidly being discharged. Note 5: Thermal resistance junction-to-ambient when attached to a 4 layer printed circuit board per JEDEC standard JESD51-7: – 14-lead LLP = 90°C/W (no thermal vias, no airflow) – 14-lead LLP = 63°C/W (1 thermal via, no airflow) – 14-lead LLP = 43°C/W (6 thermal vias, no airflow) – 14-lead LLP = 31°C/W (6 thermal vias, 900 ln. ft. / min. airflow) Note, all quoted values include +15% error factor from nominal value. Note 6: Typicals are at TA = 25°C and represent most likely parametric norm. Note 7: Limits are guaranteed to National's AOQL (Average Outgoing Quality Level). Note 8: Local temperature accuracy does not include the effects of self-heating. The rise in temperature due to self-heating is the product of the internal power dissipation of the LM95233 and the thermal resistance. See (Note 5) for the thermal resistance to be used in the self-heating calculation. Note 9: The accuracy of the LM95233CISD is guaranteed when using a typical thermal diode of an Intel processor on a 65 nm process or an MMBT3904 diodeconnected transistor, as selected in the Remote Diode Model Select register. See typical performance curve for performance with Intel processor on a 90 nm process. For further information on other thermal diodes see applications Section 3.1 "Diode Non-ideality" or send email to [email protected]. Note 10: Quiescent current will not increase substantially with an SMBus communication. Note 11: This specification is provided only to indicate how often temperature data is updated. The LM95233 can be read at any time without regard to conversion state (and will yield last conversion result). Note 12: The output rise time is measured from (VIN(0)max − 0.15V) to (VIN(1)min + 0.15V). Note 13: The output fall time is measured from (VIN(1)min + 0.15V) to (VIN(0)max − 0.15V). Note 14: Holding the SMBDAT and/or SMBCLK lines Low for a time interval greater than tTIMEOUT will reset the LM95233's SMBus state machine, therefore setting SMBDAT and SMBCLK pins to a high impedance state. www.national.com 8 LM95233 Typical Performance Characteristics Conversion Rate Effect on Average Power Supply Current Thermal Diode Capacitor or PCB Leakage Current Effect on Remote Diode Temperature Reading 20206306 20206323 Remote Temperature Reading Sensitivity to Thermal Diode Filter Capacitance, TruTherm Disabled Remote Temperature Reading Sensitivity to Thermal Diode Filter Capacitance, TruTherm Enabled 20206307 20206308 Intel Processor on 65 nm Process or 90 nm Process Thermal Diode Performance Comparison 20206324 9 www.national.com LM95233 1.0 Functional Description LM95233 is an 11-bit digital temperature sensor with a 2-wire System Management Bus (SMBus) interface that can monitor the temperature of two remote diodes as well as its own temperature. The LM95233 can be used to very accurately monitor the temperature of up to two external devices such as microprocessors, graphics processors or diode-connected 2N3904 transistor. The LM95233 includes TruTherm BJT beta compensation technology that allows sensing of Intel processors 90 nm or 65 nm process thermal diodes accurately. The LM95233 reports temperature in two different formats for +127.875°C/–128°C range and 0°C/255°C range. The LM95233 has a Sigma-Delta ADC (Analog-to-Digital Converter) core which provides the first level of noise imunity. For improved performance in a noisy environment the LM95233 includes programmable digital filters for Remote Diode 1 and 2 temperature readings. When the digital filters are invoked the resolution for Remote Diode 1 and 2 readings increases to 0.03125°C. The LM95233 contains a diode model selection register that includes bits for each channel that select between thermal diodes of Intel™ processors on 65 nm process or 2N3904s. For maximum flexibility and best accuracy the LM95233 includes offset registers that allow calibration of other diode types. Diode fault detection circuitry in the LM95233 can detect the absence or fault state of a remote diode: whether D+ is shorted to VDD, D- or ground, or whether D+ is floating. The LM95233 TCRIT1, TCRIT2 and TCRIT3 active low outputs are triggered when any unmasked channel exceeds its corresponding programmable limit and can be used to shutdown the system, to turn on the system fans or as a microcontroller interrupt function. The current status of the TCRIT1, TCRIT2 and TCRIT3 pins can be read back from the status registers via the SMBus interface. The remote channels have two separate limits each that control the TCRIT1 and TCRIT2 pins. The TCRIT3 pin shares the limits of the TCRIT2 pin but allows for different masking options. All limits have a shared programmable hysteresis register. Remote Diode temperature channels have programmable digital filters in order to avoid false triggering the TCRIT pins. LM95233 has a three-level address pin to connect up to 3 devices to the same SMBus master. LM95233 also has programmable conversion rate register as well as a shutdown mode for power savings. One round of conversions can be triggered in shutdown mode by writing to the one-shot register through the SMBus interface. LM95233 can be programmed to turn off unused channels for more power savings. The LM95233 register set has an 8-bit data structure and includes: 1. Temperature Value Registers with signed format — Most-Significant-Byte (MSB) and Least-SignificantByte (LSB) Local Temperature — MSB and LSB Remote Temperature 1 — MSB and LSB Remote Temperature 2 2. Temperature Value Registers with unsigned format — MSB and LSB Remote Temperature 1 — MSB and LSB Remote Temperature 2 3. Diode Configuration Registers — Diode Model Select — Remote 1 Offset — Remote 2 Offset 4. General Configuration Registers www.national.com 5. 6. — Configuration (Standby, Conversion Rate) — Channel Conversion Enable — Filter Setting for Remote 1 and 2 — 1-Shot Status Registers — Main Status Register (Busy bit, Not Ready, Status Register 1 to 4 Flags) — Status 1 (diode fault) — Status 2 (TCRIT1) — Status 3 (TCRIT2) — Status 4 (TCRIT3) — Diode Model Status Mask Registers — TCRIT1 Mask — TCRIT2 Mask — TCRIT3 Mask 7. Limit Registers — Local Tcrit Limit — Remote 1 Tcrit-1 Limit — Remote 2 Tcrit-1 Limit — Remote 1 Tcrit-2 and Tcrit-3 Limit — Remote 2 Tcrit-2 and Tcrit-3 Limit — Common Tcrit Hysteresis 8. 9. Manufacturer ID Register Revision ID Register 1.1 CONVERSION SEQUENCE The LM95233 takes approximately 95 ms to convert the Local Temperature, Remote Temperatures 1 and 2, and to update all of its registers. These conversions for each thermal diode are addressed in a round robin sequence. Only during the conversion process the busy bit (D7) in Status register (02h) is high. The conversion rate may be modified by the Conversion Rate bits found in the Configuration Register (03h). When the conversion rate is modified a delay is inserted between each round of conversions, the actual time for each round remains at 95 ms (typical all channels enabled). The time a round takes depends on the number of channels that are on. Different conversion rates will cause the LM95233 to draw different amounts of average supply current as shown in Figure 1. This curve assumes all the channels are on. If channels are turned off the average current will drop since the round robin time will decrease and the shutdown time will increase during each conversion interval. 10 1.3 SMBus INTERFACE The LM95233 operates as a slave on the SMBus, so the SMBCLK line is an input and the SMBDAT line is bidirectional. The LM95233 never drives the SMBCLK line and it does not support clock stretching. According to SMBus specifications, the LM95233 has a 7-bit slave address. Three SMBus device address can be selected by connecting A0 (pin 6) to either Low, Mid-Supply or High voltages. The LM95233 has the following SMBus slave address: A0 Pin State 20206306 1.2 POWER-ON-DEFAULT STATES LM95233 always powers up to these known default states. The LM95233 remains in these states until after the first conversion. 1. All Temperature readings set to 0°C until the end of the first conversion 2. Diode Model Select: Remote 1 set to 65 nm Intel processor, Remote 2 set to MMBT3904 3. Remote offset for all channels 0°C 4. Configuration: Active converting 5. Continuous conversion with all channels enabled, time = 1s 6. Enhanced digital filter enabled for Remote 1 and 2 7. Status Registers depends on state of thermal diode inputs 8. Local and Remote Temperature Limits for TCRIT1, TCRIT2 and TCRIT3 outputs: Output Pin Temperature Channel Limit Remote 1 (°C) Local (°C) TCRIT1 110 110 Masked, 85 TCRIT2 85 85 85 TCRIT3 Masked, 85 Masked, 85 Masked, 85 Hex Binary Low 18h 001 1000 Mid-Supply 2Ah 010 1010 High 2Bh 010 1011 1.4 TEMPERATURE CONVERSION SEQUENCE Each of the3 temperature channels of LM95233 can be turned OFF independent from each other via the Channel Enable Register. Turning off unused channels will increase the conversion speed in the fastest conversion speed mode. If the slower conversion speed settings are used, disabling unused channels will reduce the average power consumption of LM95233. FIGURE 1. Conversion Rate Effect on Power Supply Current Remote 2 (°C) SMBus Device Address A[6:0] 1.5 DIGITAL FILTER In order to suppress erroneous remote temperature readings due to noise as well as increase the resolution of the temperature, the LM95233 incorporates a digital filter for Remote 1 and 2 Temperature Channels. When a filter is enabled the filtered readings are used for the TCRIT comparisons. There are two possible digital filter settings that are enabled through the Filter Setting Register at register address 0Fh. The filter for each channel can be set according to the following table: R1F[1:0] or R2F[1:0] Filter Setting 0 0 No Filter 0 1 Filter (equivalent to Level 2 filter of the LM86/LM89) 1 0 Reserved 1 1 Enhanced Filter (Filter with transient noise clipping) Figure 2 describes the filter output in response to a step input and an impulse input. 11 www.national.com LM95233 9. Manufacturers ID set to 01h 10. Revision ID set to 79h LM95233 20206325 a) Seventeen and fifty degree step response 20206326 b) Impulse response with input transients less than 4°C 20206327 c) Impulse response with input transients great than 4°C FIGURE 2. Filter Impulse and Step Response Curves Temperature Digital Output Binary Hex +1°C 0000 0001 0000 0000 0100h +0.125°C 0000 0000 0010 0000 0020h 0°C 0000 0000 0000 0000 0000h −0.125°C 1111 1111 1110 0000 FFE0h −1°C 1111 1111 0000 0000 FF00h −25°C 1110 0111 0000 0000 E700h −55°C 1100 1001 0000 0000 C900h 11-bit, Unsigned Binary Temperature 20206328 FIGURE 3. Digital Filter Response in a typical Intel processor on a 65 nm or 90 nm process. The filter curves were purposely offset for clarity. Figure 3 shows the filter in use in a typical Intel processor on a 65/90 nm process system. Note that the two curves have been purposely offset for clarity. Inserting the filter does not induce an offset as shown. 1.6 TEMPERATURE DATA FORMAT Temperature data can only be read from the Local and Remote Temperature value registers. The data format for all temperature values is left justified 16-bit word available in two 8-bit registers. Unused bits will always report "0". All temperature data is clamped and will not roll over when a temperature exceeds full-scale value. Remote temperature data for all channels can be represented by an 11-bit, two's complement word or unsigned binary word with an LSb (Least Significant Bit) equal to 0.125°C. Hex +255.875°C 1111 1111 1110 0000 FFE0h +255°C 1111 1111 0000 0000 FF00h +201°C 1100 1001 0000 0000 C900h +125°C 0111 1101 0000 0000 7D00h +25°C 0001 1001 0000 0000 1900h +1°C 0000 0001 0000 0000 0100h +0.125°C 0000 0000 0010 0000 0020h 0°C 0000 0000 0000 0000 0000h When the digital filter is enabled on Remote 1 and 2 channels temperature data is represented by a 13-bit unsigned binary or 12-bit plus sign (two's complement) word with an LSb equal to 0.03125°C. 13-bit, 2's Complement (12-bit plus sign) Temperature 11-bit, 2's Complement (10-bit plus sign) Temperature Digital Output Binary Digital Output Digital Output Binary Hex +125°C 0111 1101 0000 0000 7D00h +25°C 0001 1001 0000 0000 1900h +1°C 0000 0001 0000 0000 0100h 0008h +0.03125°C 0000 0000 0000 1000 Binary Hex 0°C 0000 0000 0000 0000 0000h +125°C 0111 1101 0000 0000 7D00h −0.03125°C 1111 1111 1111 1000 FFF8h +25°C 0001 1001 0000 0000 1900h −1°C 1111 1111 0000 0000 FF00h www.national.com 12 this pin until pull-up current is provided by some external source, typically a pull-up resistor. Choice of resistor value depends on many system factors but, in general, the pull-up resistor should be as large as possible without effecting the SMBus desired data rate. This will minimize any internal temperature reading errors due to internal heating of the LM95233. The maximum resistance of the pull-up to provide a 2.1V high level, based on LM95233 specification for High Level Output Current with the supply voltage at 3.0V, is 82 kΩ (5%) or 88.7 kΩ (1%). Digital Output Binary Hex −25°C 1110 0111 0000 0000 E700h −55°C 1100 1001 0000 0000 C900h 13-bit, Unsigned Binary Temperature Digital Output Binary Hex +255.875°C 1111 1111 1110 0000 FFE0h +255°C 1111 1111 0000 0000 FF00h +201°C 1100 1001 0000 0000 C900h +125°C 0111 1101 0000 0000 7D00h +25°C 0001 1001 0000 0000 1900h +1°C 0000 0001 0000 0000 0100h +0.03125°C 0000 0000 0000 1000 0008h 0°C 0000 0000 0000 0000 0000h 1.8 TCRIT1, TCRIT2, AND TCRIT3 OUTPUTS The LM95233's TCRIT pins are active-low open-drain outputs and do not include internal pull-up resistors. A “high” level will not be observed on these pins until pull-up current is provided by some external source, typically a pull-up resistor. Choice of resistor value depends on many system factors but, in general, the pull-up resistor should be as large as possible without effecting the performance of the device receiving the signal. This will minimize any internal temperature reading errors due to internal heating of the LM95233. The maximum resistance of the pull-up to provide a 2.1V high level, based on LM95233 specification for High Level Output Current with the supply voltage at 3.0V, is 82 kΩ (5%) or 88.7 kΩ (1%). The three TCRIT pins can each sink 6 mA of current and still guarantee a "Logic Low" output voltage of 0.4V. If all three pins are set at maximum current this will cause a power dissipation of 7.2 mW. This power dissipation combined with a thermal resistance of 77.8°C/W will cause the LM95233's junction temperature to rise approximately 0.6°C and thus cause the Local temperature reading to shift. This can only be cancelled out if the environment that the LM95233 is enclosed in has stable and controlled air flow over the LM95233, as airflow can cause the thermal resistance to change dramatically. Local Temperature data is only represented by an 11-bit, two's complement, word with an LSb equal to 0.125°C. 11-bit, 2's Complement (10-bit plus sign) Temperature Digital Output Binary Hex +125°C 0111 1101 0000 0000 7D00h +25°C 0001 1001 0000 0000 1900h +1°C 0000 0001 0000 0000 0100h +0.125°C 0000 0000 0010 0000 0020h 0°C 0000 0000 0000 0000 0000h −0.125°C 1111 1111 1110 0000 FFE0h −1°C 1111 1111 0000 0000 FF00h −25°C 1110 0111 0000 0000 E700h −55°C 1100 1001 0000 0000 C900h 1.9 TCRIT LIMITS AND TCRIT OUTPUTS Figure 4 describes a simplified diagram of the temperature comparison and status register logic. Figure 5 describes a simplified logic diagram of the circuitry associated with the status registers, mask registers and the TCRIT output pins. 1.7 SMBDAT OPEN-DRAIN OUTPUT The SMBDAT output is an open-drain output and does not have internal pull-ups. A “high” level will not be observed on 13 www.national.com LM95233 Temperature LM95233 20206350 FIGURE 4. Temperature Comparison Logic and Status Register Simplified Diagram www.national.com 14 LM95233 20206353 c) TCRIT3 Mask Register, Status Register 1 and 4, and TCRIT3 output logic diagram. 20206351 a) TCRIT1 Mask Register, Status Register 1 and 2, and TCRIT1 output logic diagram. FIGURE 5. Logic diagrams for the TCRIT1, TCRIT2, and TCRIT3 outputs. If enabled, local temperature is compared to the user programmable Local Tcrit Limit Register (Default Value = 85°C). The result of this comparison is stored in Status Register 2, Status Register 3 and Status Register 4 (see Figure 4).The comparison result can trigger TCRIT1 pin, TCRIT2 pin or TCRIT3 pin depending on the settings in the TCRIT1 Mask, TCRIT2 Mask and TCRIT3 Mask Registers (see Figure 5). The comparison result can also be read back from the Status Register 2, Status Register 3 and Status Register 4. If enabled, remote temperature 1 is compared to the user programmable Remote 1 Tcrit-1 Limit Register (Default Value 110°C) and Remote 1 Tcrit-2 Limit Register (Default Value = 85°C). The result of this comparison is stored in Status Register 2, Status Register 3 and Status Register 4 (see Figure 4). The comparison result can trigger TCRIT1 pin, TCRIT2 pin or TCRIT3 pin depending on the settings in the TCRIT1 Mask, TCRIT2 Mask and TRCIT3 Mask Registers (see Figure 5). The comparison result can also be read back from the Status Register 2, Status Register 3 and Status Register 4. The remote temperature 2 operates in a similar manner to remote temperature 1 using its associated user programmable limit registers: Remote 2 Tcrit-1 Limit Register (Default Value 110° C) and Remote 2 Tcrit-2 Limit Register (Default Value = 85° C). Limit assignments for each TCRIT output pin: TCRIT1 TCRIT2 TCRIT3 20206352 b) TCRIT2 Mask Register, Status Register 1 and 3, and TCRIT2 output logic diagram. 15 Remote 2 Remote 2 Tcrit-1 Limit Remote 2 Tcrit-2 Limit Remote 2 Tcrit-2 Limit Remote 1 Remote 1 Tcrit-1 Limit Remote 1 Tcrit-2 Limit Remote 1 Tcrit-2 Limit Local Local Tcrit Limit Local Tcrit Limit Local Tcrit Limit www.national.com LM95233 20206330 FIGURE 6. TCRIT response diagram (masking options not included) The TCRIT response diagram of Figure 6 shows the local temperature interaction with the Tcrit limit and hysteresis value. As can be seen in the diagram when the local temperature exceeds the Tcrit limit register value the LTn Status bit is set and the T_CRITn output(s) is/are activated. The Status bit(s) and outputs are not deactivated until the temperature goes below the value calculated by subtracting the Common Hysteresis value programmed from the limit. This diagram mainly shows an example function of the hysteresis and is not meant to show complete function of the possible settings and options of all the TCRIT outputs and limit values. A Write to the LM95233 will always include the address byte and the command byte. A write to any register requires one data byte. Reading the LM95233 can take place either of two ways: 1. If the location latched in the Command Register is correct (most of the time it is expected that the Command Register will point to one of the Read Temperature Registers because that will be the data most frequently read from the LM95233), then the read can simply consist of an address byte, followed by retrieving the data byte. 2. If the Command Register needs to be set, then an address byte, command byte, repeat start, and another address byte will accomplish a read. The data byte has the most significant bit first. At the end of a read, the LM95233 can accept either acknowledge or No Acknowledge from the Master (No Acknowledge is typically used as a signal for the slave that the Master has read its last byte). It takes the LM95233 95 ms (typical, all channels enabled) to measure the temperature of the remote diodes and internal diode. When retrieving all 11 bits from a previous remote diode temperature measurement, the master must insure that all 11 bits are from the same temperature conversion. This may be achieved by reading the MSB register first. The LSB will be locked after the MSB is read. The LSB will be unlocked after being read. If the user reads MSBs consecutively, each time the MSB is read, the LSB associated with that temperature will be locked in and override the previous LSB value locked-in. 1.10 DIODE FAULT DETECTION The LM95233 is equipped with operational circuitry designed to detect fault conditions concerning the remote diodes. In the event that the D+ pin is detected as shorted to GND, D−, VDD or D+ is floating, the Remote Temperature reading is –128.000 °C if signed format is selected and 0 °C if unsigned format is selected. In addition, the appropriate status register bits RD1M or RD2M (D1 or D0) are set. 1.11 COMMUNICATING WITH THE LM95233 The data registers in the LM95233 are selected by the Command Register. At power-up the Command Register is set to “00”, the location for the Read Local Temperature Register. The Command Register latches the last location it was set to. Each data register in the LM95233 falls into one of three types of user accessibility: 1. Read only 2. Write only 3. Write/Read same address www.national.com 16 LM95233 20206310 (a) Serial Bus Write to the internal Command Register followed by a the Data Byte 20206311 (b) Serial Bus Write to the Internal Command Register 20206312 (c) Serial Bus Read from a Register with the Internal Command Register preset to desired value. 20206314 (d) Serial Bus Write followed by a Repeat Start and Immediate Read FIGURE 7. SMBus Timing Diagrams 1. 1.12 SERIAL INTERFACE RESET In the event that the SMBus Master is RESET while the LM95233 is transmitting on the SMBDAT line, the LM95233 must be returned to a known state in the communication protocol. This may be done in one of two ways: 17 When SMBDAT is LOW, the LM95233 SMBus state machine resets to the SMBus idle state if either SMBDAT or SMBCLK are held low for more than 35ms (tTIMEOUT). Note that according to SMBus specification 2.0 all devices are to timeout when either the SMBCLK or SMBDAT lines are held low for 25-35ms. Therefore, to www.national.com LM95233 2. insure a timeout of all devices on the bus the SMBCLK or SMBDAT lines must be held low for at least 35ms. When SMBDAT is HIGH, have the master initiate an SMBus start. The LM95233 will respond properly to an SMBus start condition at any point during the communication. After the start the LM95233 will expect an SMBus Address address byte. after which the device returns to standby. This is not a data register and it is the write operation that causes the one-shot conversion. The data written to this address is irrelevant and is not stored. A zero will always be read from this register. All the channels that are enabled in the Channel Enable Register will be converted once and the TCRIT1, TCRIT2 and TCRIT3 pins will reflect the comparison results based on this round of conversion results of the channels that are not masked. 1.13 ONE-SHOT CONVERSION The One-Shot register is used to initiate a round of conversions and comparisons when the device is in standby mode, 2.0 LM95233 Registers Command register selects which registers will be read from or written to. Data for this register should be transmitted during the Command Byte of the SMBus write communication. P7 P6 P5 P4 P3 P2 P1 P0 Command Byte P0-P7: Command Register Summary Register Name Command Read/ Byte Write (Hex) D7 D6 D5 D4 D3 D2 D1 D0 POR Default (Hex) SIGN 64 32 16 8 4 2 1 – Local Temp MSB 0x10 RO Local Temp LSB 0x20 RO 1/2 1/4 1/8 0 0 0 0 0 – Remote Temp 1 MSB – Signed 0x11 RO SIGN 64 32 16 8 4 2 1 – 0 0 0x21 RO 1/2 1/4 1/8 0 0 0 – 1/16 1/32 16 8 4 2 1 – 0 0 0 0 0 – 1/16 1/32 16 8 4 2 1 – 0 0 0 0 0 – 1/16 1/32 16 8 4 2 1 – 0 0 0 0 0 – 1/16 1/32 Remote Temp 1 LSB – Signed, Digital Filter Off Remote Temp 1 LSB – Signed, Digital Filter On Remote Temp 2 MSB – Signed Remote Temp 2 LSB – Signed, Digital Filter Off Remote Temp 2 LSB – Signed, Digital Filter On Remote Temp 1 MSB – Unsigned Remote Temp 1 LSB – Unsigned, Digital Filter Off Remote Temp 1 LSB – Unsigned, Digital Filter On Remote Temp 2 MSB – Unsigned Remote Temp 2 LSB – Unsigned, Digital Filter Off Remote Temp 2 LSB – Unsigned, Digital Filter On 0x12 RO SIGN 64 32 0x22 RO 1/2 1/4 1/8 0x19 RO 128 64 32 0x29 RO 1/2 1/4 1/8 0x1A RO 128 64 32 0x2A RO 1/2 1/4 1/8 Diode Model Select 0x30 R/W 0 0 0 0 0 R2TE R1TE 0 0x02 Remote 1 Offset 0x31 R/W SIGN 32 16 8 4 2 1 1/2 0x00 Remote 2 Offset 0x32 R/W SIGN 32 16 8 4 2 1 1/2 0x00 Configuration 0x03 R/W – STBY – – – – – – 0x00 Conversion Rate 0x04 R/W – – – – – – CR1 CR0 0x02 Channel Conversion Enable 0x05 R/W – – – – – R2CE R1CE LCE 0x1F Filter Setting 0x06 R/W – – – – R2F1 R2F0 R1F1 R1F0 0x0F www.national.com 18 Command Read/ Byte Write (Hex) D7 D6 D5 D4 D3 D2 D1 D0 POR Default (Hex) 1-shot 0x0F WO – – – – – – – – – Common Status Register 0x02 RO BUSY NR – – SR4F SR3F SR2F SR1F 0x00 Status 1 (Diode Fault) 0x07 RO – – – – R2DO R2DS R1DO R1DS – Status 2 (TCRIT1) 0x08 RO – – – – – R2T1 R1T1 LT1 – Status 3 (TCRIT2) 0x09 RO – – – – – R2T2 R1T2 LT2 – Status 4 (TCRIT3) 0x0A RO – – – – – R2T3 R1T3 LT3 – Diode Model Status (TruTherm on and 3904 connected) 0x38 RO – – – – – R2TD R1TD – – TCRIT1 Mask 0x0C R/W – – – – – R2T1M R1T1M LTM 0x01 TCRIT2 Mask 0x0D R/W – – – – – R2T2M R1T2M LTM 0x00 TCRIT3 Mask 0x0E R/W – – – – – R2T2M R1T2M LTM 0x07 Local Tcrit Limit 0x40 R/W 0 64 32 16 8 4 2 1 0x55 Remote 1 Tcrit-1 Limit 0x41 R/W 128 64 32 16 8 4 2 1 0x6E Remote 2 Tcrit-1 Limit 0x42 R/W 128 64 32 16 8 4 2 1 0x6E Remote 1 Tcrit-2 and Tcrit-3 Limit 0x49 R/W 128 64 32 16 8 4 2 1 0x55 Remote 2 Tcrit-2 and Tcrit-3 Limit 0x4A R/W 128 64 32 16 8 4 2 1 0x55 Common Tcrit Hysteresis 0x5A R/W 0 0 0 16 8 4 2 1 0x0A Manufacturer ID 0xFE RO 0 0 0 0 0 0 0 1 0x01 Revision ID 0xFF RO 1 0 0 0 1 0 0 1 0x89 2.1 VALUE REGISTERS For data synchronization purposes, the MSB register should be read first if the user wants to read both MSB and LSB registers. The LSB will be locked after the MSB is read. The LSB will be unlocked after being read. If the user reads MSBs consecutively, each time the MSB is read, the LSB associated with that temperature will be locked in and override the previous LSB value lockedin 2.1.1 Local Value Registers Register Name Command Read/ Byte Write (Hex) D7 D6 D5 D4 D3 D2 D1 D0 POR Default (Hex) Local Temp MSB 0x10 RO SIGN 64 32 16 8 4 2 1 – Local Temp LSB 0x20 RO 1/2 1/4 1/8 0 0 0 0 0 – Bit(s) Bit Name Read/ Write Description 7 SIGN RO Sign bit 6 64 RO bit weight 64°C 5 32 RO bit weight 32°C 4 16 RO bit weight 16°C 3 8 RO bit weight 8°C 2 4 RO bit weight 4°C 1 2 RO bit weight 2°C 0 1 RO bit weight 1°C The Local temperature MSB value register range is +127°C to −128°C. The value programmed in this register is used to determine a local temperature error event. 19 www.national.com LM95233 Register Name LM95233 Bit(s) Bit Name Read/ Write Description 7 1/2 RO bit weight 1/2°C (0.5°C) 6 1/4 RO bit weight 1/4°C (0.25°C) 5 1/8 RO bit weight 1/8°C (0.125°C) 4-0 0 RO Reserved – will report "0" when read. The Local Limit register range is 0°C to 127°C. The value programmed in this register is used to determine a local temperature error event. 2.1.2 Remote Temperature Value Registers with Signed Format Register Name Command Read/ Byte Write (Hex) Remote Temp 1 MSB – Signed 0x11 Remote Temp 1 LSB – Signed, Digital Filter Off Remote Temp 1 LSB – Signed, Digital Filter On Remote Temp 2 MSB – Signed Remote Temp 2 LSB – Signed, Digital Filter Off Remote Temp 2 LSB – Signed, Digital Filter On 0x21 RO D7 D6 D5 D4 D3 D2 D1 D0 POR Default (Hex) SIGN 64 32 16 8 4 2 1 – 0 0 0 0 0 0 – 1/16 1/32 32 16 8 4 2 1 – 0 0 0 0 0 0 – RO 1/2 1/8 0x12 RO SIGN 64 0x22 RO 1/2 1/8 1/16 1/32 The Local temperature MSB value register range is +127°C to −128°C. The value programmed in this register is used to determine a local temperature error event. Bit(s) Bit Name Read/ Write Description 7 SIGN RO Sign bit 6 64 RO bit weight 64°C 5 32 RO bit weight 32°C 4 16 RO bit weight 16°C 3 8 RO bit weight 8°C 2 4 RO bit weight 4°C 1 2 RO bit weight 2°C 0 1 RO bit weight 1°C Bit(s) Bit Name Read/ Write Description 7 1/2 RO bit weight 1/2°C (0.5°C) 6 1/4 RO bit weight 1/4°C (0.25°C) 5 1/8 RO bit weight 1/8°C (0.125°C) 4 0 or 1/16 RO When the digital filter is disabled this bit will always read "0". When the digital filter is enabled this bit will report 1/16°C (0.0625°C) bit state. 3 0 or 1/32 RO When the digital filter is disabled this bit will always read "0". When the digital filter is enabled this bit will report 1/32°C (0.03125°C) bit state. 2-0 0 RO Reserved – will report "0" when read. www.national.com 20 Register Name Command Read/ Byte Write (Hex) Remote Temp 1 MSB – Unsigned Remote Temp 1 LSB – Unsigned, Digital Filter Off Remote Temp 1 LSB – Unsigned, Digital Filter On Remote Temp 2 MSB – Unsigned Remote Temp 2 LSB – Unsigned, Digital Filter Off Remote Temp 2 LSB – Unsigned, Digital Filter On D7 D6 D5 D4 D3 D2 D1 D0 POR Default (Hex) 32 16 8 4 2 1 – 0 0 0 0 0 0 – 1/16 1/32 32 16 8 4 2 1 – 0 0 0 0 0 0 – 1/16 1/32 0x19 RO 128 64 0x29 RO 1/2 1/8 0x1A RO 128 64 0x2A RO 1/2 1/8 Bit(s) Bit Name Read/ Write Description 7 SIGN RO bit weight 128°C 6 64 RO bit weight 64°C 5 32 RO bit weight 32°C 4 16 RO bit weight 16°C 3 8 RO bit weight 8°C 2 4 RO bit weight 4°C 1 2 RO bit weight 2°C 0 1 RO bit weight 1°C Bit(s) Bit Name Read/ Write Description 7 1/2 RO bit weight 1/2°C (0.5°C) 6 1/4 RO bit weight 1/4°C (0.25°C) 5 1/8 RO bit weight 1/8°C (0.125°C) 4 0 or 1/16 RO When the digital filter is disabled this bit will always read "0". When the digital filter is enabled this bit will report 1/16°C (0.0625°C) bit state. 3 0 or 1/32 RO When the digital filter is disabled this bit will always read "0". When the digital filter is enabled this bit will report 1/32°C (0.03125°C) bit state. 2-0 0 RO Reserved – will report "0" when read. 2.2 DIODE CONFIGURATION REGISTERS 2.2.1 Diode Model Select Register Name Command Read/ Byte Write (Hex) Diode Model Select 0x30 R/W D7 D6 D5 D4 D3 D2 D1 D0 POR Default (Hex) 0 0 0 0 0 R2TE R1TE 0 0x02 Bit(s) Bit Name Read/ Write Description 7-3 0 RO Reserved – will report "0" when read. 2 R2TE R/W Remote 2 TruTherm Enable 1 R1TE R/W Remote 1 TruTherm Enable 0 0 RO Reserved - will report "0" when read. 21 logic 1 selects diode model 1 TruTherm™ BJT beta compensation technology enabled (Ex: Intel 65 nm technology) logic 0 selects diode model 2 MMBT3904 www.national.com LM95233 2.1.3 Remote Temperature Value Registers with Unsigned Format LM95233 2.2.2 Remote 1-2 Offset Register Name Command Read/ Byte Write (Hex) D7 D6 D5 D4 D3 D2 D1 D0 POR Default (Hex) Remote 1 Offset 0x31 R/W SIGN 32 16 8 4 2 1 1/2 0x00 Remote 2 Offset 0x32 R/W SIGN 32 16 8 4 2 1 1/2 0x00 Bit(s) Bit Name Read/ Write Description 7 SIGN R/W Sign bit 6 32 R/W bit weight 32°C 5 16 R/W bit weight 16°C 4 8 R/W bit weight 8°C 3 4 R/W bit weight 4°C 2 2 R/W bit weight 2°C 1 1 R/W bit weight 1°C 0 1/2 R/W bit weight 1/2°C (0.5°C) All registers have 2’s complement format. The offset range for each remote is +63.5°C/−64°C. The value programmed in this register is directly added to the actual reading of the ADC and the modified number is reported in the remote value registers. 2.3 CONFIGURATION REGISTERS 2.3.1 Main Configuration Register Register Name Command Read/ Byte Write (Hex) Configuration 0x03 R/W D7 D6 D5 D4 D3 D2 D1 D0 POR Default (Hex) – STBY – – – – – – 0x00 Bit(s) Bit Name Read/ Write Description 7 – RO Reserved will report "0" when read. 6 STBY R/W Software Standby 1 – standby (when in this mode one conversion sequence can be initiated by writing to the one-shot register) 0 – active/converting 5–0 – RO Reserved – will report "0" when read. 2.3.2 Conversion Rate Register Register Name Conversion Rate www.national.com Command Read/ Byte Write (Hex) 0x04 R/W D7 D6 D5 D4 D3 D2 D1 D0 POR Default (Hex) – – – – – – CR1 CR0 0x02 22 LM95233 Bit(s) Bit Name Read/ Write Description 7-2 – RO Reserved – will report "0" when read. 1-0 CR[1:0] R/W Conversion rate control bits modify the time interval for conversion of the channels enabled. The channels enabled are converted sequentially then standby mode enabled for the remainder of the time interval. CR[1:0] Conversion Rate 00 continuous (30 ms to 104 ms) 01 0.364 s 10 1s 11 2.5 s 2.3.3 Channel Conversion Enable When a conversion is disabled for a particular channel it is skipped. The continuous conversion rate is effected all other conversion rates are not effected as extra standby time is inserted in order to compensate. See Conversion Rate Register description. Register Name Command Read/ Byte Write (Hex) Channel Conversion Enable 0x05 R/W D7 D6 D5 D4 D3 – – – – – Bit(s) Bit Name Read/ Description Write 7–3 – RO Reserved – will report "0" when read. 2 R2CE R/W Remote 2 Temperature Conversion Enable 1– Remote 2 temp conversion enabled 0– Remote 2 temp conversion disabled 1 R1CE R/W Remote 1 Temperature Conversion Enable 1– Remote 1 temp conversion enabled 0– Remote 1 temp conversion disabled 0 LCE R/W Local Temperature Conversion Enable 1– Local temp conversion enabled 0– Local temp conversion disabled D2 D1 R2CE R1CE D0 POR Default (Hex) LCE 0x1F 2.3.4 Filter Setting Register Name Command Read/ Byte Write (Hex) Filter Setting 0x06 R/W D7 D6 D5 D4 D3 D2 D1 D0 POR Default (Hex) – – – – R2F1 R2F0 R1F1 R1F0 0x0F Bit(s) Bit Name Read/ Write Description 7–4 – RO Reserved – will report "0" when read. 3–2 R2F[1:0] R/W Remote Channel 2 Filter Enable Bits R2F[1:0] Digital Filter State 00 disable all digital filtering 01 enable basic filter 10 reserved (do not use) 11 enable enhanced filter 23 www.national.com LM95233 Bit(s) Bit Name Read/ Write Description 1–0 R1F[1:0] R/W Remote Channel 1 Filter Enable R1F[1:0] Filter State 00 disable all digital filtering 01 enable basic filter 10 reserved (do not use) 11 enable enhanced filter 2.3.5 1-Shot Register Name Command Read/ Byte Write (Hex) 1-Shot 0x0F WO D7 D6 D5 D4 D3 D2 D1 D0 POR Default (Hex) – – – – – – – – – Bit(s) Bit Name Read/ Description Write 7–0 WO - Writing to this register activates one conversion for all the enabled channels if the chip is in standby mode (i.e. standby bit = 1). The actual data written does not matter and is not stored. 2.4 STATUS REGISTERS 2.4.1 Common Status Register Register Name Command Read/ Byte Write (Hex) Common Status Register 0x02 RO D7 D6 D5 D4 D3 D2 D1 D0 POR Default (Hex) BUSY NR – – SR4F SR3F SR2F SR1F 0x00 Bit(s) Bit Name Read/ Write Description 7 BUSY RO Busy bit (device converting) 6 NR RO Not Ready bit (30 ms), indicates power up initialization sequence is in progress 5–4 – RO Reserved – will report "0" when read. 3 SR4F RO Status Register 4 Flag: 1 – indicates that Status Register 4 has at least one bit set 0 – indicates that all of Status Register 4 bits are cleared 2 SR3F RO Status Register 3 Flag: 1 – indicates that Status Register 3 has at least one bit set 0 – indicates that all of Status Register 3 bits are cleared 1 SR2F RO Status Register 2 Flag: 1 – indicates that Status Register 2 has at least one bit set 0 – indicates that all of Status Register 2 bits are cleared 0 SR1F RO Status Register 1 Flag: 1 – indicates that Status Register 1 has at least one bit set 0 – indicates that all of Status Register 1 bits are cleared 2.4.2 Status 1 Register (Diode Fault) Status fault bits for open or shorted diode (i.e. Short Fault: D+ shorted to Ground or D-; Open Fault: D+ shorted to VDD, or floating). During fault conditions the temperature reading is 0 °C if unsigned value registers are read or –128.000 °C if signed value registers are read. www.national.com 24 Command Read/ Byte Write (Hex) Status 1 (Diode Fault) 0x07 RO D7 D6 D5 D4 0 0 0 0 D3 D2 D1 D0 R2DO R2DS R1DO R1DS Bit(s) Bit Name Read/ Description Write 7-4 – RO Reserved – will report "0" when read. 3 R2DO RO Remote 2 diode open fault status: 1 – indicates that remote 2 diode has an "open" fault 0 – indicates that remote 2 diode does not have an "open" fault 2 R2DS RO Remote 2 diode short fault status: 1 – indicates that remote 2 diode has a "short" fault 0 – indicates that remote 2 diode does not have a "short" fault 1 R1DO RO Remote 1 diode open fault status: 1 – indicates that remote 1 diode has an "open" fault 0 – indicates that remote 1 diode does not have an "open" fault 0 R1DS RO Remote 1 diode short fault status: 1 – indicates that remote 1 diode has a "short" fault 0 – indicates that remote 1 diode does not have a "short" fault POR Default (Hex) – 2.4.3 Status 2 (TCRIT1) Status bits for TCRIT1. When one or more of these bits are set and if not masked the TCRIT1 output will activate. TCRIT1 will deactivate when all these bits are cleared. Register Name Command Read/ Byte Write (Hex) Status 2 (TCRIT1) 0x08 RO D7 D6 D5 D4 D3 D2 D1 D0 POR Default (Hex) – – – – – R2T1 R1T1 LT1 – Bit(s) Bit Name Read/ Description Write 7–3 - RO Reserved – will report "0" when read. 2 R2T1 RO Remote 2 Tcrit-1 Status: 1 – indicates that remote 2 reading is greater than or equal to the value set in Remote 2 Tcrit-1 Limit register 0 – indicates that that remote 2 reading is less than the value set in Remote 2 Tcrit-1 Limit register minus the Common Hysteresis value 1 R1T1 RO Remote 1 Tcrit-1 Status: 1 – indicates that remote 1 reading is greater than or equal to the value set in Remote 1 Tcrit-1 Limit register 0 – indicates that that remote 1 reading is less than the value set in Remote 1 Tcrit-1 Limit register minus the Common Hysteresis value 0 LT1 RO Local Tcrit Status: 1 – indicates that local reading is greater than or equal to the value set in Local Tcrit Limit register 0 – indicates that local reading is less than the value set in Local Tcrit Limit register minus the Common Hysteresis value 2.4.4 Status 3 (TCRIT2) Status bits for TCRIT2. When one or more of these bits are set and if not masked the TCRIT2 output will activate. TCRIT2 will deactivate when all these bits are cleared. 25 www.national.com LM95233 Register Name LM95233 Register Name Command Read/ Byte Write (Hex) Status 3 (TCRIT2) 0x09 RO D7 D6 D5 D4 D3 D2 D1 D0 POR Default (Hex) – – – – – R2T2 R1T2 LT2 – Bit(s) Bit Name Read/ Description Write 7–3 - RO Reserved – will report "0" when read. 2 R2T2 RO Remote 2 Tcrit-2 Status: 1 – indicates that remote 2 reading is greater than or equal to the value set in Remote 2 Tcrit-2 Limit register 0 – indicates that that remote 2 reading is less than the value set in Remote 2 Tcrit-2 Limit register minus the Common Hysteresis value 1 R1T2 RO Remote 1 Tcrit-2 Status: 1 – indicates that remote 1 reading is greater than or equal to the value set in Remote 1 Tcrit-2 Limit register 0 – indicates that that remote 1 reading is less than the value set in Remote 1 Tcrit-2 Limit register minus the Common Hysteresis value 0 LT2 RO Local Tcrit Status: 1 – indicates that local reading is greater than or equal to the value set in Local Tcrit Limit register 0 – indicates that local reading is less than the value set in Local Tcrit Limit register minus the Common Hysteresis value 2.4.5 Status 4 (TCRIT3) Status bits for TCRIT3. When one or more of these bits are set and if not masked the TCRIT3 output will activate. TCRIT3 will deactivate when all these bits are cleared. Register Name Command Read/ Byte Write (Hex) Status 4 (TCRIT3) 0x0A RO D7 D6 D5 D4 D3 D2 D1 D0 POR Default (Hex) – – – – – R2T3 R1T3 LT3 – Bit(s) Bit Name Read/ Description Write 7–3 - RO Reserved – will report "0" when read. 2 R2T3 RO Remote 2 Tcrit-2 Status: 1 – indicates that remote 2 reading is greater than or equal to the value set in Remote 2 Tcrit-2 Limit register 0 – indicates that that remote 2 reading is less than the value set in Remote 2 Tcrit-2 Limit register minus the Common Hysteresis value 1 R1T3 RO Remote 1 Tcrit-2 Status: 1 – indicates that remote 1 reading is greater than or equal to the value set in Remote 1 Tcrit-2 Limit register 0 – indicates that that remote 1 reading is less than the value set in Remote 1 Tcrit-2 Limit register minus the Common Hysteresis value 0 LT3 RO Local Tcrit Status: 1 – indicates that local reading is greater than or equal to the value set in Local Tcrit Limit register 0 – indicates that local reading is less than the value set in Local Tcrit Limit register minus the Common Hysteresis value www.national.com 26 Register Name Command Read/ Byte Write (Hex) Diode Model Status (TruTherm on and 3904 connected) 0x38 RO D7 D6 D5 D4 D3 D2 D1 D0 POR Default (Hex) – – – – – R2TD R1TD – – Bit(s) Bit Name Read/ Write Description 7-3 – RO Reserved – will report "0" when read. 2 R2TD RO Remote 2 TruTherm BJT beta compensation on and 3904 detect: 1 – indicates that for channel 2 TruTherm is ON and 3904 connected 0 – indicates proper operation 1 R1TD RO Remote 1 TruTherm BJT beta compensation on and 3904 detect: 1 – indicates that for channel 4 TruTherm is ON and 3904 connected 0 – indicates proper operation 0 – RO Reserved – will report "0" when read. 2.5 MASK REGISTERS 2.5.1 TCRIT1 Mask Register The mask bits in this register allow control over which error events propagate to the TCRIT1 pin. Register Name Command Read/ Byte Write (Hex) TCRIT1 Mask 0x0C R/W D7 D6 D5 D4 D3 D2 D1 D0 POR Default (Hex) – – – – – R2T1 M R1T1 M LTM 0x01 Bit(s) Bit Name Read/ Description Write 7-3 – RO Reserved – will report "0" when read. 2 R2T1M R/W Remote 2 Tcrit-1 Mask: 1 – prevents the remote 2 temperature error event from propagating to the TCRIT1 pin 0 – allows the remote 2 temperature error event to propagate to the TCRIT1 pin 1 R1T1M R/W Remote 1 Tcrit-1 Mask: 1 – prevents the remote 1 temperature error event from propagating to the TCRIT1 pin 0 – allows the remote 1 temperature error event to propagate to the TCRIT1 pin 0 LTM R/W Local Tcrit Mask: 1 – prevents the local temperature error event from propagating to the TCRIT1 pin 0 – allows the local temperature error event to propagate to the TCRIT1 pin 2.5.2 TCRIT2 Mask Registers Register Name TCRIT2 Mask Command Read/ Byte Write (Hex) 0x0D R/W D7 D6 D5 D4 D3 D2 D1 D0 POR Default (Hex) – – – – – R2T2 M R1T2 M LTM 0x00 27 www.national.com LM95233 2.4.6 Diode Model Status LM95233 Bit(s) Bit Name Read/ Description Write 7-3 – RO Reserved – will report "0" when read. 2 R2T2M R/W Remote 2 Tcrit-2 Mask: 1 – prevents the remote 2 temperature error event from propagating to the TCRIT2 pin 0 – allows the remote 2 temperature error event to propagate to the TCRIT2 pin 1 R1T2M R/W Remote 1 Tcrit-2 Mask: 1 – prevents the remote 1 temperature error event from propagating to the TCRIT2 pin 0 – allows the remote 1 temperature error event to propagate to the TCRIT2 pin 0 LTM R/W Local Tcrit Mask: 1 – prevents the local temperature error event from propagating to the TCRIT2 pin 0 – allows the local temperature error event to propagate to the TCRIT2 pin 2.5.3 TCRIT3 Mask Register The mask bits in this register allow control over which error events propagate to the TCRIT3 pin. Register Name Command Read/ Byte Write (Hex) TCRIT3 Mask 0x0E D7 D6 D5 D4 D3 D2 D1 D0 POR Default (Hex) – – – – – R2T2 M R1T2 M LTM 0x07 R/W Bit(s) Bit Name Read/ Description Write 7-3 – RO Reserved – will report "0" when read. 2 R2T2M R/W Remote 2 Tcrit-2 Mask: 1 – prevents the remote 2 temperature error event from propagating to the TCRIT3 pin 0 – allows the remote 2 temperature error event to propagate to the TCRIT3 pin 1 R1T2M R/W Remote 1 Tcrit-2 Mask: 1 – prevents the remote 1 temperature error event from propagating to the TCRIT3 pin 0 – allows the remote 1 temperature error event to propagate to the TCRIT3 pin 0 LTM R/W Local Tcrit Mask: 1 – prevents the local temperature error event from propagating to the TCRIT3 pin 0 – allows the local temperature error event to propagate to the TCRIT3 pin 2.6 LIMIT REGISTERS 2.6.1 Local Limit Register The Local Limit register range is 0°C to 127°C. The value programmed in this register is used to determine a local temperature error event. Register Name Command Read/ Byte Write (Hex) Local Tcrit Limit 0x40 D7 D6 D5 D4 D3 D2 D1 D0 POR Default (Hex) 0 64 32 16 8 4 2 1 0x55 R/W Bit(s) Bit Name Read/ Write Description 7 0 R0 Read only bit will always report "0". 6 64 R/W bit weight 64°C 5 32 R/W bit weight 32°C 4 16 R/W bit weight 16°C 3 8 R/W bit weight 8°C www.national.com 28 Bit Name Read/ Write Description 2 4 R/W bit weight 4°C 1 2 R/W bit weight 2°C 0 1 R/W bit weight 1°C LM95233 Bit(s) 2.6.2 Remote Limit Registers The range for these registers is 0°C to 255°C. Register Name Command Read/ Byte Write (Hex) D7 D6 D5 D4 D3 D2 D1 D0 POR Default (Hex) Remote 1 Tcrit-1 Limit (used by TCRIT1 error events) 0x41 R/W 128 64 32 16 8 4 2 1 0x6E Remote 2 Tcrit-1 Limit (used by TCRIT1 error events) 0x42 R/W 128 64 32 16 8 4 2 1 0x6E Remote 1 Tcrit-2 and Tcrit3 Limit (used by TCRIT2 and TCRIT3 error events) 0x49 R/W 128 64 32 16 8 4 2 1 0x55 Remote 2 Tcrit-2 and Tcrit3 Limit (used by TCRIT2 and TCRIT3 error events) 0x4A R/W 128 64 32 16 8 4 2 1 0x55 Bit(s) Bit Name Read/ Write Description 7 128 R/W bit weight 128°C 6 64 R/W bit weight 64°C 5 32 R/W bit weight 32°C 4 16 R/W bit weight 16°C 3 8 R/W bit weight 8°C 2 4 R/W bit weight 4°C 1 2 R/W bit weight 2°C 0 1 R/W bit weight 1°C Limit assignments for each TCRIT output pin: Output Pin Remote 2 Remote 1 Local TCRIT1 Remote 2 Tcrit-1 Limit Remote 1 Tcrit-1 Limit Local Tcrit Limit TCRIT2 Remote 2 Tcrit-2 Limit Remote 1 Tcrit-2 Limit Local Tcrit Limit TCRIT3 Remote 2 Tcrit-2 Limit Remote 1 Tcrit-2 Limit Local Tcrit Limit 2.6.3 Common Tcrit Hysteresis Register The hysteresis register range is 0°C to 32°C. The value programmed in this register is used to modify all the limit values for decreasing temperature. Register Name Command Read/ Byte Write (Hex) Common Tcrit Hysteresis 0x5A R/W D7 D6 D5 D4 D3 D2 D1 D0 POR Default (Hex) 0 0 0 16 8 4 2 1 0x0A Bit(s) Bit Name Read/ Write Description 7 0 RO Read only bit will always report "0". 6 0 RO Read only bit will always report "0". 5 0 RO Read only bit will always report "0". 29 www.national.com LM95233 Bit(s) Bit Name Read/ Write Description 4 16 R/W bit weight 16°C 3 8 R/W bit weight 8°C 2 4 R/W bit weight 4°C 1 2 R/W bit weight 2°C 0 1 R/W bit weight 1°C 2.7 IDENTIFICATION REGISTERS Register Name Command Read/ Byte Write (Hex) D7 D6 D5 D4 D3 D2 D1 D0 POR Default (Hex) Manufacturer ID 0xFE RO 0 0 0 0 0 0 0 1 0x01 Revision ID 0xFF RO 1 0 0 0 1 0 0 1 0x89 www.national.com 30 q = 1.6×10−19 Coulombs (the electron charge), T = Absolute Temperature in Kelvin k = 1.38×10−23 joules/K (Boltzmann's constant), η is the non-ideality factor of the process the diode is manufactured on, • IS = Saturation Current and is process dependent, • If = Forward Current through the base-emitter junction • VBE = Base-Emitter Voltage drop In the active region, the -1 term is negligible and may be eliminated, yielding the following equation The LM95233 can be applied easily in the same way as other integrated-circuit temperature sensors, and its remote diode sensing capability allows it to be used in new ways as well. It can be soldered to a printed circuit board, and because the path of best thermal conductivity is between the die and the pins, its temperature will effectively be that of the printed circuit board lands and traces soldered to the LM95233's pins. This presumes that the ambient air temperature is almost the same as the surface temperature of the printed circuit board; if the air temperature is much higher or lower than the surface temperature, the actual temperature of the LM95233 die will be at an intermediate temperature between the surface and air temperatures. Again, the primary thermal conduction path is through the leads, so the circuit board temperature will contribute to the die temperature much more strongly than will the air temperature. To measure temperature external to the LM95233's die, incorporates remote diode sensing technology. This diode can be located on the die of a target IC, allowing measurement of the IC's temperature, independent of the LM95233's temperature. A discrete diode can also be used to sense the temperature of external objects or ambient air. Remember that a discrete diode's temperature will be affected, and often dominated, by the temperature of its leads. Most silicon diodes do not lend themselves well to this application. It is recommended that an MMBT3904 transistor base emitter junction be used with the collector tied to the base. The LM95233’s TruTherm BJT beta compensation technology allows accurate sensing of integrated thermal diodes, such as those found on most processors. With TruTherm BJT beta compensation technology turned off, the LM95233 can measure a diode-connected transistor such as the MMBT3904 or the thermal diode found in an AMD processor. The LM95233 has been optimized to measure the remote thermal diode integrated in a typical Intel processor on 65 nm or 90 nm process or an MMBT3904 transistor. Using the Remote Diode Model Select register any of the four remote inputs can be optimized for a typical Intel processor on 65 nm or 90 nm process or an MMBT3904. (2) In Equation 2, η and IS are dependant upon the process that was used in the fabrication of the particular diode. By forcing two currents with a very controlled ratio(IF2 / IF1) and measuring the resulting voltage difference, it is possible to eliminate the IS term. Solving for the forward voltage difference yields the relationship: (3) Solving Equation 3 for temperature yields: (4) Equation 4 holds true when a diode connected transistor such as the MMBT3904 is used. When this “diode” equation is applied to an integrated diode such as a processor transistor with its collector tied to GND as shown in Figure 8 it will yield a wide non-ideality spread. This wide non-ideality spread is not due to true process variation but due to the fact that Equation 4 is an approximation. TruTherm BJT beta compensation technology uses the transistor equation, Equation 5, which is a more accurate representation of the topology of the thermal diode found in an FPGA or processor. 3.1 DIODE NON-IDEALITY 3.1.1 Diode Non-Ideality Factor Effect on Accuracy When a transistor is connected as a diode, the following relationship holds for variables VBE, T and IF: (5) (1) where: 31 www.national.com LM95233 • • • • 3.0 Applications Hints LM95233 20206315 FIGURE 8. Thermal Diode Current Paths TruTherm BJT beta compensation should only be enabled when measuring the temperature of a transistor integrated as shown in the processor of Figure 8, because Equation 5 only applies to this topology. (6) Solving Equation 6 for RPCB equal to ±1.73Ω results in the additional error due to the spread in the series resistance of ±1.07°C. The spread in error cannot be canceled out, as it would require measuring each individual thermal diode device. This is quite difficult and impractical in a large volume production environment. Equation 6 can also be used to calculate the additional error caused by series resistance on the printed circuit board. Since the variation of the PCB series resistance is minimal, the bulk of the error term is always positive and can simply be cancelled out by subtracting it from the output readings of the LM95233. 3.1.2 Calculating Total System Accuracy The voltage seen by the LM95233 also includes the IFRS voltage drop of the series resistance. The non-ideality factor, η, is the only other parameter not accounted for and depends on the diode that is used for measurement. Since ΔVBE is proportional to both η and T, the variations in η cannot be distinguished from variations in temperature. Since the nonideality factor is not controlled by the temperature sensor, it will directly add to the inaccuracy of the sensor. For the for Intel processor on 65 nm process, Intel specifies a +4.06%/ −0.897% variation in η from part to part when the processor diode is measured by a circuit that assumes diode equation, Equation 4, as true. As an example, assume a temperature sensor has an accuracy specification of ±1.0°C at a temperature of 80°C (353 Kelvin) and the processor diode has a nonideality variation of +1.19%/−0.27%. The resulting system accuracy of the processor temperature being sensed will be: TACC = + 1.0°C + (+4.06% of 353 K) = +15.3 °C Processor Family Transistor Equation ηT, non-ideality min typ max Intel Processor on 65 nm process 0.997 1.001 1.005 Processor Family and TACC = - 1.0°C + (−0.89% of 353 K) = −4.1 °C TrueTherm technology uses the transistor equation, Equation 4, resulting in a non-ideality spread that truly reflects the process variation which is very small. The transistor equation non-ideality spread is ±0.39% for the Intel processor on 90 nm process. The resulting accuracy when using TruTherm technology improves to: TACC = ±0.75°C + (±0.39% of 353 K) = ± 2.16 °C www.national.com 32 4.52 Series R,Ω min typ max 1 1.0065 1.0125 Pentium III CPUID 68h/ PGA370Socket/ Celeron 1.0057 1.008 1.0125 Pentium 4, 423 pin 0.9933 1.0045 1.0368 Pentium 4, 478 pin 0.9933 1.0045 1.0368 Pentium 4 on 0.13 micron process, 2 3.06 GHz 1.0011 1.0021 1.0030 3.64 Pentium 4 on 90 nm 1.0083 process 1.011 1.023 3.33 Intel Processor on 65 nm process 1.009 1.050 4.52 Pentium™ III CPUID 67h The next error term to be discussed is that due to the series resistance of the thermal diode and printed circuit board traces. The thermal diode series resistance is specified on most processor data sheets. For Intel processors in 65 nm process, this is specified at 4.52Ω typical. The LM95233 accommodates the typical series resistance of Intel Processor on 65 nm process. The error that is not accounted for is the spread of the processor's series resistance, that is 2.79Ω to 6.24Ω or ±1.73Ω. The equation to calculate the temperature error due to series resistance (TER) for the LM95233 is simply: Diode Equation ηD, nonideality Series R,Ω 1.000 1.00151 MMBT3904 1.00220 1.00289 3.2 PCB LAYOUT FOR MINIMIZING NOISE 3.06 1.003 AMD Athlon MP model 6 1.002 1.008 1.016 AMD Athlon 64 1.008 1.008 1.096 AMD Opteron 1.008 1.008 1.096 AMD Sempron LM95233 Pentium M (Centrino) 1.00261 0.93 3.1.3 Compensating for Different Non-Ideality In order to compensate for the errors introduced by non-ideality, the temperature sensor is calibrated for a particular processor. National Semiconductor temperature sensors are always calibrated to the typical non-ideality and series resistance of a given processor type. The LM95233 is calibrated for two non-ideality factors and series resistance values thus supporting the MMBT3904 transistor and Intel processors on 65 nm process without the requirement for additional trims. For most accurate measurements TruTherm BJT beta compensation mode should be turned on when measuring the Intel processor on 65 nm process to minimize the error introduced by the false non-ideality spread (see 3.1.1 Diode NonIdeality Factor Effect on Accuracy). When a temperature sensor calibrated for a particular processor type is used with a different processor type, additional errors are introduced. Temperature errors associated with non-ideality of different processor types may be reduced in a specific temperature range of concern through use of software calibration. Typical Non-ideality specification differences cause a gain variation of the transfer function, therefore the center of the temperature range of interest should be the target temperature for calibration purposes. The following equation can be used to calculate the temperature correction factor (TCF) required to compensate for a target non-ideality differing from that supported by the LM95233. 20206317 FIGURE 9. Ideal Diode Trace Layout In a noisy environment, such as a processor mother board, layout considerations are very critical. Noise induced on traces running between the remote temperature diode sensor and the LM95233 can cause temperature conversion errors. Keep in mind that the signal level the LM95233 is trying to measure is in microvolts. The following guidelines should be followed: 1. VDD should be bypassed with a 0.1 µF capacitor in parallel with 100 pF. The 100 pF capacitor should be placed as close as possible to the power supply pin. A bulk capacitance of approximately 10 µF needs to be in the near vicinity of the LM95233. 2. A 100 pF diode bypass capacitor is recommended to filter high frequency noise but may not be necessary. Make sure the traces to the 100 pF capacitor are matched. Place the filter capacitors close to the LM95233 pins. 3. Ideally, the LM95233 should be placed within 10 cm of the Processor diode pins with the traces being as straight, short and identical as possible. Trace resistance of 1Ω can cause as much as 0.62°C of error. This error can be compensated by using simple software offset compensation. 4. Diode traces should be surrounded by a GND guard ring to either side, above and below if possible. This GND guard should not be between the D+ and D− lines. In the event that noise does couple to the diode lines it would be ideal if it is coupled common mode. That is equally to the D+ and D− lines. 5. Avoid routing diode traces in close proximity to power supply switching or filtering inductors. 6. Avoid running diode traces close to or parallel to high speed digital and bus lines. Diode traces should be kept at least 2 cm apart from the high speed digital traces. 7. If it is necessary to cross high speed digital traces, the diode traces and the high speed digital traces should cross at a 90 degree angle. 8. The ideal place to connect the LM95233's GND pin is as close as possible to the Processors GND associated with the sense diode. 9. Leakage current between D+ and GND and between D+ and D− should be kept to a minimum. Thirteen nanoamperes of leakage can cause as much as 0.2°C of error in the diode temperature reading. Keeping the printed circuit board as clean as possible will minimize leakage current. Noise coupling into the digital lines greater than 400 mVp-p (typical hysteresis) and undershoot less than 500 mV below GND, may prevent successful SMBus communication with the LM95233. SMBus no acknowledge is the most common symptom, causing unnecessary traffic on the bus. Although (7) where • ηS = LM95233 non-ideality for accuracy specification • ηPROCESSOR = Processor thermal diode typical non-ideality • TCR = center of the temperature range of interest in °C The correction factor should be directly added to the temperature reading produced by the LM95233. For example when using the LM95233, with the 3904 mode selected, to measure a AMD Athlon processor, with a typical non-ideality of 1.008, for a temperature range of 60 °C to 100 °C the correction factor would calculate to: (8) Therefore, 1.75°C should be subtracted from the temperature readings of the LM95233 to compensate for the differing typical non-ideality target. 33 www.national.com LM95233 the SMBus maximum frequency of communication is rather low (100 kHz max), care still needs to be taken to ensure proper termination within a system with multiple parts on the bus and long printed circuit board traces. An RC lowpass filter with a 3 dB corner frequency of about 40 MHz is included on the LM95233's SMBCLK input. Additional resistance can be www.national.com added in series with the SMBDAT and SMBCLK lines to further help filter noise and ringing. Minimize noise coupling by keeping digital traces out of switching power supply areas as well as ensuring that digital lines containing high speed data communications cross at right angles to the SMBDAT and SMBCLK lines. 34 LM95233 Physical Dimensions inches (millimeters) unless otherwise noted 14-Lead Molded Leadless Leadframe Package (LLP), Order Number LM95233CISD or LM95233CISDX NS Package Number SDA14B 35 www.national.com LM95233 Dual Remote Diode and Local Temperature Sensor with SMBus Interface and TruTherm Technology Notes THE CONTENTS OF THIS DOCUMENT ARE PROVIDED IN CONNECTION WITH NATIONAL SEMICONDUCTOR CORPORATION (“NATIONAL”) PRODUCTS. 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