LM40

LM40 NSC | Alldatasheet

Document overview

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Technical content

Features

— 2 hardware programmable addresses n Voltage Monitoring — 9-bit Σ∆ ADC — Internal scaling resistors for all inputs — Monitors +1.2V, +2.5 V, +3.3 V, +5 V and +12 V n Temperature Sensing — 2 remote diode temperature sensor zones — Internal local temperature zone — 0.5 ˚C resolution — Measures temperatures up to 140 ˚C n 14-lead TSSOP package Key Specifications n Voltage Measurement Accuracy ±2 % (max) n Temperature Sensor Accuracy ±3 ˚C (max) n Temperature Range: — LM40 junction 0 ˚C to +85 ˚C — Remote Temp Accuracy 0 ˚C to +100 ˚C n Power Supply Voltage +3.0 V to +3.6 V n Average Power Supply Current 0.5 mA (typ) n Conversion Time (all Channels) 29.6ms to 1456ms

Applications

n Microprocessor based equipment (Motherboards, Video Cards, Base-stations, Routers, ATMs, Point of Sale, …) n Power Supplies Typical Application 20068401 SensorPath™ is a trademark of National Semiconductor Corporation May 2004 LM40 Hardware Monitor with Dual Thermal Diodes and SensorPath™Bus © 2004 National Semiconductor Corporation DS200684 www.national.com

National Package Number MTC14C Order Number Package Marking NS Package Number Transport Media LM40CIMT LM40 CIMT MTC14C 94 units per rail LM40CIMTX LM40 CIMT MTC14C 2500 units in tape and reel Pin Description Pin Number Pin Name Description Typical Connection 1, 14 NC No Connect May be tied to V+, GND or left floating

2 GND Ground System ground

3 V+/+3.3V_SBY Positive power supply pin as well as a +3.3V voltage monitor Connected system 3.3 V standby power and to a 0.1 µF bypass capacitor in parallel with 100 pF. A bulk capacitance of approximately 10 µF needs to be in the near vicinity of the LM40.

4 SWD SensorPath Bus line; Open-drain

Super I/O, Pull-up resistor, 1.6k

5 ADD Digital input - device number select

input for the serial bus device number Pull-up to 3.3 V or pull-down to GND resistor, 10k; must never be left floating 6 +1.2V +1.2V voltage monitoring input with scaling resistors Processor core voltage to be monitored 7 +2.5V +2.5V voltage monitoring input with scaling resistors Power supply voltage to be monitored 8, 10 D1-, D2- Thermal diode analog voltage output and negative monitoring input Remote Thermal Diode cathode (THERM_DC) - Diode 1 should always be connected to the processor thermal diode. Diode 2 may be connected to an MMBT3904 or GPU thermal diode. A 100 pF capacitor should be connected between respective D- and D+ for noise filtering. 9, 11 D1+, D2+ Thermal diode analog current output and positive monitoring input Remote Thermal Diode anode (THERM_DA) - Diode 1 should always be connected to the processor thermal diode. Diode 2 may be connected to an MMBT3904 or GPU thermal diode. A 100 pF capacitor should be connected between respective D- and D+ for noise filtering. 12 +5V +5V voltage monitoring input with scaling resistors Power supply voltage to be monitored 13 +12V +12V voltage monitoring input with scaling resistors Power supply voltage to be monitored LM40 www.national.com 2

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(Notes 2, 1) Supply Voltage (V+) −0.5 V to 6.0 V Voltage at Any Digital Input or Output Pin −0.5 V to 6.0 V Voltage on 12V Analog Input −0.5 V to 16 V Voltage on 5V Analog Input −0.5 V to 6.67 V Voltage on D1+ and D2+ −0.5 V to (V+ + 0.05 V) Voltage on Other Analog Inputs −0.5 V to 6.0 V Current on D1- and D2- ±1m A Input Current per Pin(Note 3) ±5m A Package Input Current (Note 3) ±30 mA Package Power Dissipation (Note 4) Output Sink Current 10 mA ESD Susceptibility (Note 5) Human Body Model 2500 V Machine Model 250 V Storage Temperature −65˚C to +150˚C Soldering process must comply with National’s reflow temperature profile specifications. Refer to www.national.com/packaging/. (Note 6) Operating Ratings (Notes 1, 2) Temperature Range for Electrical Characteristics LM40CIMT (TMIN≤TA≤TMAX) 0˚C ≤ TA ≤ +85˚C Operating Temperature Range 0˚C ≤ TA ≤ +125˚C Remote Diode Temperature (T D) Range -5 ˚C ≤TD ≤+140 ˚C Supply Voltage Range (V+) +3.0 V to +3.6 V Analog Input Voltage Rage: +1.2V and +2.5V −0.05V to (V+ + 0.05V) +3.3V_SBY (V+) +3.0V to +3.6V +5V −0.05V to +6.67V +12V −0.05V to +16V The following specifications apply for V+ = +3.0 V DC to +3.6 VDC, and all analog source impedance R S =5 0 Ω unless other- wise specified in the conditions. Boldface limits apply for LM40CIMT T A =T J =T MIN=0˚C to TMAX=85˚C;all other limits TA = +25˚C. TA is the ambient temperature of the LM40; T J is the junction temperature of the LM40; T D is the junction tem- perature of the remote thermal diode. POWER SUPPLY CHARACTERISTICS Symbol Parameter Conditions Typical (Note 7) Limits (Note 8) Units (Limit) V+ Power Supply Voltage 3.3 3.0 3.6 V (min) V (max) I+Shutdown Shutdown Power Supply Current SensorPath Bus Inactive (Note 9) 260 420 µA (max) I+Average Average Power Supply Current SensorPath Bus Inactive; all sensors enabled; t CONV=182 ms; (Note 9) 900 µA (max) I+Peak Peak Power Supply Current SensorPath Bus Inactive (Note 9) 3.3 mA (max) Power-On Reset Threshold Voltage 1.6 V (min)

2.8 V (max)

TEMPERATURE-TO-DIGITAL CONVERTER CHARACTERISTICS Parameter Conditions Typical (Note 7) Limits (Note 8) Units (Limits) Temperature Accuracy Using the Remote Thermal Diode, see (Note 12) for Thermal Diode Processor Type. T J = 0˚C to +85˚C TD = +25˚C ±1 ±2.5 ˚C (max) TJ = 0˚C to +85˚C TD = 0˚C to +100˚C ±3 ˚C (max) TJ = 0˚C to +85˚C TD = +100˚C to +125˚C ±4 ˚C (max) Temperature Accuracy Using the Local Diode T J = 0˚C to +85˚C (Note 10) ±1 ±3 ˚C (max) Remote Diode and Local Temperature Resolution 10 Bits 0.5 ˚C D− Source Voltage 0.7 V LM40 www.national.com 4

TEMPERATURE-TO-DIGITAL CONVERTER CHARACTERISTICS Parameter Conditions Typical (Note 7) Limits (Note 8) Units (Limits) Diode Source Current (VD+ −V D−) = +0.65 V; High Current 188 280 µA (max) Low Current 11.75 µA Diode Source Current High Current to Low Current Ratio 16 ANALOG TO DIGITAL CONVERTER CHARACTERISTICS Symbol Parameter Conditions Typical (Note 7) Limits (Note 8) Units (Limit) TUE Total Unadjusted Error(Note 11) ±2 %FS (max) Resolution 9 Bits DNL Differential Non-linearity 1 LSB Power Supply Sensitivity ±1 %/V Input Resistance, all analog inputs (total resistance of divider chain) 210 140 kΩ (min) 400 kΩ (max) SWD and ADD DIGITAL INPUT CHARACTERISTICS Symbol Parameter Conditions Typical (Note 7) Limits (Note 8) Units (Limit) VIH SWD Logical High Input Voltage 2.1 V (min) V+ + 0.5 V (max) VIL SWD Logical Low Input Voltage 0.8 V (max) -0.5 V (min) VIH ADD Logical High Input Voltage 9 0 %xV + V (min) VIL ADD Logical Low Input Voltage 1 0 %xV + V (max) VHYST Input Hysteresis 300 mV IL SWD and ADD Input Current GND ≤ VIN ≤ V+ ±0.005 ±10 µA (max) SWD Input Current with V+ Open or Grounded GND ≤ VIN ≤ 3.6V, and V+ Open or GND ±0.005 µA CIN Digital Input Capacitance 10 pF SWD DIGITAL OUTPUT CHARACTERISTICS Symbol Parameter Conditions Typical (Note 7) Limits (Note 8) Units (Limit) VOL Open-drain Output Logic “Low” Voltage I OL = 4mA 0.4 V (max) I OL = 50µA 0.2 V (max) IOH Open-drain Output Off Current ±0.005 ±10 µA (max) COUT Digital Output Capacitance 10 pF The following specification apply for V+ = +3.0 V DC to +3.6 VDC, unless otherwise specified. Boldface limits apply for TA =T J =T MIN=0˚C to TMAX=85˚C; all other limits T A =T J = 25˚C. The SensorPath Characteristics conform to the SensorPath specification revision 0.98. Please refer to that speciation for further details. Symbol Parameter Conditions Typical (Note 7) Limits (Note 8) Units (Limits) HARDWARE MONITOR CHARACTERISTICS tCONV Total Monitoring Cycle Time (Note 13) All Voltage and Temperature readings (Default) 182 163.8 ms (min) 200.2 ms (max) SensorPath Bus CHARACTERISTICS t f SWD fall time (Note 16) R pull-up=1.25 kΩ ±30%, CL=400 pF 300 ns (max) LM40 www.national.com5

The following specification apply for V+ = +3.0 V DC to +3.6 VDC, unless otherwise specified. Boldface limits apply for TA =T J =T MIN=0˚C to TMAX=85˚C; all other limits T A =T J = 25˚C. The SensorPath Characteristics conform to the SensorPath specification revision 0.98. Please refer to that speciation for further details. Symbol Parameter Conditions Typical (Note 7) Limits (Note 8) Units (Limits) tr SWD rise time (Note 16) R pull-up=1.25 kΩ ±30%, CL=400 pF 1000 ns (max) tINACT Minimum inactive time (bus at high level) guaranteed by the slave before an attention request 11 µs (min) t Mtr0 Master drive for Data Bit 0 write and for Data Bit 0-1read 11.8 µs (min) 17.0 µs (max) tMtr1 Master drive for Data Bit 1 write 35.4 µs (min) 48.9 µs (max) tSFEdet Time allowed for LM40 activity detection 9.6 µs (max) tSLout1 LM40 drive for Data Bit 1 read by master 28.3 µs (min) 38.3 µs (max) tMtrS Master drive for Start Bit 80 µs (min) 109 µs (max) tSLoutA LM40 drive for Attention Request 165 µs (min) 228 µs (max) tRST Master or LM40 drive for Reset 354 µs (min) tRST_MAX Maximum drive of SWD by an LM40, after the power supply is raised above 3V 500 ms (max) Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is functional, but do not guarantee performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. The g uaranteed specifications apply only for the test conditions listed. Some performance characteristics may degrade when the device is not operated under the lis ted test conditions. Note 2: All voltages are measured with respect to GND, unless otherwise noted. Note 3: When the input voltage (VIN) at any pin exceeds the power supplies (V IN < GND or VIN > V+), the current at that pin should be limited to 5 mA. Parasitic components and/or ESD protection circuitry are shown below for the LM40’s pins. The nominal breakdown voltage of the zener is 6.5 V. SNP stands for snap-back device. LM40 www.national.com 6

Circuit All Input Structure Circuits 1N C A Circuit A Circuit C Circuit B Circuit D

2 GND B

3 V+/

3.3V SB B

4 SWD A

5 ADD A

6 +1.2V C 7 +2.5V C

8 D1- D

9 D1+ E

10 D2- D

11 D2+ E

14 NC A

Note 4: Thermal resistance junction-to-ambient in still air when attached to a printed circuit board with 1 oz. foil is 148 ˚C/W. Note 5: Human body model, 100 pF discharged through a 1.5 k Ω resistor. Machine model, 200 pF discharged directly into each pin. Note 6: Reflow temperature profiles are different for lead-free and non lead-free packages. Note 7: “Typicals” are at TA = 25˚C and represent most likely parametric norm. They are to be used as general reference values not for critical design calculations. Note 8: Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level). Note 9: The supply current will not increase substantially with a SensorPath transaction. Note 10: 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 po wer dissipation of the LM40 and the thermal resistance. See (Note 4) for the thermal resistance to be used in the self-heating calculation. Note 11: TUE , total unadjusted error, includes ADC gain, offset, linearity and reference errors. TUE is defined as the "actual Vin" to achieve a given code transition minus the "theoretical Vin" for the same code. Therefore, a positive error indicates that the input voltage is greater than the theoretical input voltage for a given code. If the theoretical input voltage was applied to an LM40 that has positive error, the LM40’s reading would be less than the theoretical. Note 12: The accuracy of the LM40CIMT is guaranteed when using the thermal diode of an Intel 90 nm Pentium 4 processor or any thermal diode with a non-ideality Note 13: This specification is provided only to indicate how often temperature and voltage data are updated. Note 14: The output fall time is measured from (V IH min)t o( VIL max). Note 15: The output rise time is measured from (V IL max)t o( VIH min). Note 16: The rise and fall times are not tested but guaranteed by design. LM40 www.national.com7

FIGURE 1. Timing for Data Bits 0, 1 and Start Bit. See Section 1.2"SensorPath BIT SIGNALING" for further details.

FIGURE 2. Timing for Attention Request and Reset. See Section 1.2"SensorPath BIT SIGNALING" for further details.

1.0 Functional Description

is encoded in the pulse width of the signal being transmitted. implementation of the master when using a micro-controller. voltage data has been updated in the readout registers.

1.1 SensorPath BUS SWD

SWD is the Single Wire Data line used for communication.

1.2 SensorPath BIT SIGNALING

FIGURE 3. SensorPath SWD simplified schematic

1.0 Functional Description (Continued)

that begin with the label Mout_ depict a drive by the master. Signal labels that begin with the label Slv_ depict the drive by the LM40. All other signals show what would be seen when probing SWD for a particular function (e.g. "Master Wr 0" is the Master transmitting a Data Bit with the value of 0).

1.2.1 Bus Inactive

The bus is inactive when the SWD signal is high for a period of at least t INACT. The bus is inactive between each "bit signal".

1.2.2 Data Bit 0 and 1

All Data Bit signal transfers are started by the master. A Data Bit 0 is indicated by a "short" pulse; a Data Bit 1 is indicated by a longer pulse. The direction of the bit is relative to the master, as follows:  Data Write - a Data Bit transferred from the master to the LM40.  Data Read - a Data Bit transferred from the LM40 to the master. A master must monitor the bus as inactive before starting a Data Bit (Read or Write). A master initiates a data write by driving the bus active (low level) for the period that matches the data value (tMtr0 or tMtr1 for a write of "0" or "1", respectively). The LM40 will detect that the SWD becomes active within a period of t SFEdet, and will start measuring the duration that the SWD is active in order to detect the data value. A master initiates a data read by driving the bus for a period of t Mtr0. The LM40 will detect that the SWD becomes active within a period of t SFEdet. For a data read of "0", the LM40 will not drive the SWD. For a data read of "1" the LM40 will start within t SFEdet to drive the SWD low for a period of tSLout1. Both master and LM40 must monitor the time at which the bus becomes inactive to identify a data read of "0" or "1". During each Data Bit, both the master and all the LM40s must monitor the bus (the master for Attention Request and Reset; the LM40s for Start Bit, Attention Request and Reset) by measuring the time SWD is active (low). If a Start Bit, Attention Requests or Reset "bit signal" is detected, the current "bit signal" is not treated as a Data Bit. Note that the bit rate of the protocol varies depending on the data transferred. Thus, the LM40 has a value of "0" in reserved or unused register bits for bus bandwidth efficiency.

1.2.3 Start Bit

A master must monitor the bus as inactive before beginning a Start Bit. The master uses a Start Bit to indicate the beginning of a transfer. LM40s will monitor for Start Bits all the time, to allow synchronization of transactions with the master. If a Start Bit occurs in the middle of a transaction, the LM40 being ad- dressed will abort the current transaction. In this case the transaction is not "completed" by the LM40 (see Section 1.3 "SensorPath Bus Transactions"). During each Start Bit, both the master and all the LM40s must monitor the bus for Attention Request and Reset, by measuring the time SWD is active (low). If an Attention Request or Reset condition is detected, the current "bit signal" is not treated as a Start Bit. The master may attempt to send the Start Bit at a later time.

1.2.4 Attention Request

The LM40 may initiate an Attention Request when the Sen- sorPath bus is inactive. Note that a Data Bit, or Start Bit, from the master may start simultaneously with an Attention Request from the LM40. In addition, two LM40s may start an Attention Request simul- taneously. Due to its length, the Attention Request has pri- ority over any other "bit signal", except Reset. Conflict with Data Bits and Start Bits are detected by all the devices, to allow the bits to be ignored and re-issued by their originator. The LM40 will either check to see that the bus is inactive before starting an Attention Request, or start the Attention Request within the t SFEdet time interval after SWD becomes active. The LM40 will drive the signal low for t SLoutA time. After this, both the master and the LM40 must monitor the bus for a Reset Condition. If a Reset condition is detected, the current "bit signal" is not treated as an Attention Request. After Reset, an Attention Request can not be sent before the master has sent 14 Data Bits on the bus. See Section 1.3.5 for further details on Attention Request generation.

1.2.5 Bus Reset

The LM40 issues a Reset at power up. The master must also generate a Bus Reset at power-up for at least the minimum reset time, it must not rely on the LM40. SensorPath puts no limitation on the maximum reset time of the master. Follow- ing a Bus Reset, the LM40 may generate an Attention Re- quest only after the master has sent 14 Data Bits on the bus. See Section 1.3.5 for further details on Attention Request generation.

1.3 SensorPath BUS TRANSACTIONS

SensorPath is designed to work with a single master and up to seven slave devices. Each slave has a unique address. The LM40 supports up to 2 device addresses that are se- lected by the state of the address pin ADD. The Register Set of the LM40 is defined in Section 2.0.

1.3.1 Bus Reset Operation

A Bus Reset Operation is global on the bus and affects only the communication interface of all the devices connected to it. The Bus Reset operation does not affect either the con- tents of the device registers, or device operation, to the extent defined in LM40 Register Set, see Section 2.0. The Bus Reset operation is performed by generating a Reset signal on the bus. The master must apply Reset after power- up, and before it starts operation. The Reset signal end will be monitored by all the LM40s on the bus. After the Reset Signal the SensorPath specification requires that the master send a sequence of 8 Data Bits with a value of "0", without a preceding Start Bit. This is required to enable slaves that "train" their clocks to the bit timing. The LM40 does not require nor does it support clock training. LM40 www.national.com11

1.3.2 Read Transaction

ignores the broadcast address during a read transaction.  Read/Write (R/W) A "1" indicates a read transaction. tion based on the information that needs to be read. scribed in Section 2.0"Register Set". check the received data before using it. considered "complete" only when the ACK bit is received. automates re-execution of the transaction by the master. — 0: An error was detected (no-acknowledge).

1.3.3 Write Transaction

FIGURE 4. Bus Reset Transaction FIGURE 5. Read Transaction, master reads data from LM40

zation based on the information that needs to be written. scribed in Section 2.0"Register Set". allow the LM40 to check the received data before using it. automates re-execution of the transaction by the master. — 0: An error was detected (no-acknowledge).

1.3.4 Read and Write Transaction Exceptions

plete" the current transaction) and begins a new transaction. the LM40 of the incomplete transaction.

1.3.5 Attention Request Transaction

of simultaneous start with a Data Bit or Start Bit transfer. "Bit Signaling" portion of the data sheet.

1. A Function event that sets the Status Flag has occurred
2. The "physical" condition for an Attention Request is met
3. At the first time 2 is met after 1 occurred, there has not

Device Status register, or since a Bus Reset.

1. A bus error event occurred, and
2. the "physical" condition for an Attention Request is met
3. At the first time 2. is met after 1 occurred, there has not

FIGURE 6. Write Transaction, master write data to LM40

All devices (master or slave) must monitor the bus for an Attention Request signal. The following notes clarify the intended system operation that uses the Attention Request Indication.  Masters are expected to use the attention request as a trigger to read results from the LM40. This is done in a sequence that covers all LM40s. This sequence is re- ferred to as "master sensor read sequence".  After an Attention Request is sent by an LM40 until after the next read from the Device Status register the LM40 does not send Attention Requests for a function event since it is guaranteed that the master will read the Status register as part of the master sensor read sequence. Note that the LM40 will send an attention for BER, re- gardless of the Status register read, to help the master with any error recovery operations and prevent dead- locks.  A master must record the Attention Request event. It must then scan all slave devices in the system by reading their Device Status register and must handle any pending event in them before it may assume that there are no more events to handle. Note: there is no indication of which slave has sent the request. The requirement that multiple requests are not sent allows the master to know within one scan of register reads that there are no more pending events.

1.3.6 Fixed Device Number Setting

The LM40 device number is defined by strapping of the ADD pin. The LM40 will wake (after Device Reset) with the Device Number field of the Device Number register set to the ad- dress as designated inSection 2.3"Device Number". It is the responsibility of the system designer to avoid having two devices with the same Device Number on the bus. Devices should be detected by the master by a read opera- tion of the Device Number register. The read returns "000" if there is no device at that address on the bus (the EP bit must be ignored). LM40 www.national.com 14

2.0 Register Set

2.1 REGISTER SET SUMMARY

W P O R Val Bit MSb Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit LSb 000 000 00h Device Number R * Not Available Reserved See Section 2.300000 000 001 01h Manufacturer ID R 100Bh 0001000000001011 000 010 02h Device ID R 22h RevID Device ID 0000000000100010 000 011 03h Capabilities Fixed R 21h Reserved FuncDescriptor 2 (Voltage-Only) FuncDescriptor 1 (Temperature) 0000000000100001 000 100 04h Device Status R 0h Not Available BER Res ERF2 ERF1 Reserved SF2 SF100 0 000 101 05h Device Control W 0h Reserved EnF2 EnF1 Res Low Pwr Shut down Re set0000000000 0 001 000 08h Temperature Capabilities R 0549h Reserved # of Remotes Int Sens Rout Size Sign 10-Bits 0.5˚C Resolution 0000010101001001 001 001 09h Processor/ Remote Temperature Data Readout R MSb Sign 128 LSb 0.5 Res SNUM EF Res 00 0 Local Temperature Data Readout Res Res Res 00 00 001 010 0Ah Temperature Control W 0h Reserved EN2 EN1 EN0 ATE000000000000 001 011 -001 111 0Bh-0Fh Reserved R Undefined 010 000 10h Voltage Capabilities R 0051h Reserved # of Voltage Sensors Rout Size Resolution 9-Bits 0000000001010001 010 001 11h Voltage Readout R Voltage Readout Reserved SNUM Reserved MSb LSb 0 0 00 010 010 12h Voltage Control W 1Fh Reserved EN4 EN3 EN2 EN1 EN0 ATE Low Rate Function (Read Only) 00000 11111 010 011 -011 111 13h-1Fh Reserved R Undefined 100 000 20h Conversion Rate W 2h Not Available Reserved CR1 CR0000000 100 001 -111 111 21h-3Fh Undefined Registers R Undefined LM40 www.national.com15

2.0 Register Set (Continued)

• Depends on state of ADD pins see Section 2.3"Device Number".

2.2 DEVICE RESET OPERATION

 When the Reset bit in the Device Control register is set to 1 (see Section 2.8"Device Control").  Aborts any device operation in progress and restarts device operation.  Sets all device registers to their "Reset" (default) value.

2.3 DEVICE NUMBER (Addr: 000 000; 00h)

This register is used to specify a unique address for each device on the bus. TABLE 1. Device Number Assignment of the address cannot be changed by software.

2.4 MANUFACTURER ID (Addr: 000 001; 01h)

manufacturer of the device in order to perform manufacturer specific operations.

2.5 DEVICE ID (Addr: 000 010; 02h)

W P O R Val Bit MSb Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit LSb 000 010 Device ID R 22h RevID DeviceID 0000000000100010 The device ID is defined by the manufacturer of the device and is unique for each device produced by a manufacturer. Bits 15-11 identify the revision number of the die and will be incremented upon revision of the device. Bit Type Description 10-0 RO DeviceID (Device ID Value) A fixed value that identifies the device. 15-11 RO RevID (Revision ID Value) A fixed value that identifies the device revision.

2.6 CAPABILITIES FIXED (Addr: 000 011; 03h)

W P O R Val Bit MSb Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit LSb 000 011 Capabilities Fixed R 21h Reserved FuncDescriptor2 FuncDescriptor1 0000000000100001 The value of this register defines the capabilities of the LM40. The LM40 supports two functions, that of Temperature Measurement type (Function 1) and Voltage-Only Measurement type (Function 2). Please refer to the SensorPath specification for further details on other FuncDescriptor values.

2.7 DEVICE STATUS (Addr: 000 100; 04h)

This register is set to the reset value by a Device Reset. Reg Add Register Name R/ W P O R Val Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 LSb 000 100 Device Status R 0h BER Res ERF2 ERF1 Res SF2 SF100 0 Bit Type Description 0R O SF1 (Status Function 1) This bit is set by a Function Event within Function 1. Event details are function dependent and are described within the function. SF1 is cleared by Device Reset or by handling the event within the Temperature Measurement Function (see Section 2.9for further details). 0: Status flag for Function 1 is inactive (no event). 1: Status flag for Function 1 is active indicating that a Function Event has occurred. 1R O SF2 (Status Function 2) Same as SF1 for Function 2, Voltage-Only Measurement Function. (see Section 2.10 for further details) 3-2 RO Reserved. Will always read "0". 4R O ERF1 (Error Function 1) This bit is set in response to an error indication within Function 1. ERF1 is cleared by Device Reset or by handling the error condition within the Temperature Measurement Function (see Section 2.9for further details). 0: No error occurred in Function 1. 1: Error occurred in Function 1. 5R O ERF2 (Error Function 2) Same as ERF1 for Function 2, Voltage-Only Measurement Function. (see Section 2.10 for further details) 6R O Reserved. Will always read "0". LM40 www.national.com17

7R O BER (Bus Error) This bit is set when the device either generates, or receives an error indication in the ACK bit of the transaction (i.e., no-acknowledge). BER is cleared by Device Reset or by reading the Device Status register. 0: No transaction error occurred. 1: An ACK bit error (no-acknowledge) occurred during the last transaction.

2.8 DEVICE CONTROL (Addr: 000 101; 05h)

This register responds to a broadcast write command (Device Number 000). Write using broadcast address is ignored by bits 15-2. This register is set to the reset value by a Device Reset. Reg Add Register Name W P O R Val Bit MSb Bit Bit Bit Bit Bit

10 Bit9 Bit

W 0h Reserved EnF2 EnF1 Res Low Pwr Shut down Re set0000000000 Bit Type Description 0 R/W Reset (Device Reset). When set to "1" this bit initiates a Device Reset operation ( See Section 2.2). This bit self-clears after the Device Reset operation is completed. 0: Normal device operation. (default) 1: Device Reset The LM40 does not require a Device Reset command after power. 1 R/W Shutdown (Shutdown Mode). When set to "1" this bit stops the operation of all functions and places the device in the lowest power consumption mode. 0: Device in Active Mode. (default) 1: Device in Shutdown Mode. 2 R/W LowPwr (Low-Power Mode). When set to "1" this bit slows the operation of all functions and places the device in a low power consumption mode. In Low-Power Mode, the conversion rate of the LM40 is effected see Section 2.11for further details. 0: Device in Active Mode. (default) 1: Device in Low-Power Mode. 3R O Not supported. Will always read "0". 4 R/W EnF1 (Enable Function 1). When bit is set to "1" this bit Function 1 is enabled for operation. A function may require setup before this bit is set. The function registers can be accessed even when the function is disabled. 0: Function 1 is disabled. (default) 1: Function is enabled. 5 R/W EnF2 (Enable Function 2). Same as EnF1 for Function 2. 15-6 RO Not supported. Will always read "0".

2.9 TEMPERATURE MEASUREMENT FUNCTION (TYPE - 0001)

This section defines the register structure and operation of a Temperature Measurement function as it applies to the LM40. The FuncDescriptor value of this function is ‘0001’.

2.9.1 Operation

The Temperature Measurement function as implemented in the LM40 supports 3 temperature zones, the LM40’s internal temperature (LM40’s junction temperature) and the remote temperature of 2 thermal diodes (stand alone transistors or integrated in chips). The function measures multiple temperature points and reports the readout to the master. The measurement of all the enabled temperature sensors is cyclic and continuous. Sensor Scan The Control register of the function defines which temperature sensors are included in the scan. A sensor is scanned only if it is enabled by the Sensor Enable bits (EN0, EN1, and EN2). The sensors are scanned in an ascending, round-robin order, based on the sensor number. Disabled sensors are skipped and the next enabled sensor in ascending order is scanned. LM40 www.national.com 18

The minimum scan rate is recommended to be 4Hz (i.e. the measurement data is updated at least once in 250 ms), see Section 2.11 for further details. In Low-Power Mode, the scan rate is four times lower than the scan rate in Active Mode. The scan rate effects the bus bandwidth required to read the results. The sampling rate of the temperature measurements can also be controlled via the Conversion Rate register, see Section 2.11for further details. Data Readout When a new result is stored in the Readout register a Function Event is generated. Reading the Readout register clears the Status Function 1 flag (SF1). The result is available in the Readout register waiting for the master to read it during the master sensor read sequence. If a new result is ready before the previous result has been read, the new result overwrites the previous result and the Error Function 1 flag (ERF1) is set (indicating an overrun event). Reading the Readout register clears also the Error Function 1 flag (ERF1). The Readout register contains the temperature data, and the sensor number. Since the LM40 only supports three temperature zones the sensor number field will be zero to two. Other fields in the Readout register as defined by the SensorPath specification are not supported. Readout Resolution The resolution of the readout is defined in the Temperature Capabilities register. The resolution of the LM40 is fixed and cannot be modified by software. The temperature readout type is common to all the sensors and is signed two’s complement fixed point value. The readout type is specified in the Capabilities register of the function. Sensor 0 in the Temperature Measurement function is reserved for local temperature measurement (i.e., the junction temperature of the LM40). Function Event The Temperature Measurement function generates a Function Event whenever a conversion cycle is completed and new data is stored in the Readout Register. When the new data is stored into the Readout register the SF1 bit in the device Status register is set to "1" and remains set, until it is cleared by reading the Readout register. An Attention Request is generated on the bus, only if it is enabled by the Attention Enable bit (ATE) in the Temperature Control register. Setup Before Enabling No setup is required for the Temperature Measurement function before the function is enabled.

2.9.2 Temperature Capabilities (Addr: 001 000; 08h)

W P O R Val Bit MSb Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit LSb 001 000 Temperature Capabilities R 0549h Reserved # of Remotes Int Sens Rout Size Sign 10-Bits 0.5˚C Resolution 0000010101001001 This register defines the format of the temperature data in the readout register. The LM40 only supports one format for all temperatures as defined by the values of this register. Bit Type Description 2-0 RO Resolution. This field defines the value of 1 LSb of the Temperature Readout field in the Readout Register. The SensorPath specification defines many different weights for the temperature LSb. The LM40 supports a resolution of 0.5 ˚C and thus a value of 001 for this field. For a full definition of this field, please refer to the SensorPath specification. 5-3 RO Number of Bits. This field defines the total number of significant bits of the Temperature Readout field in the Readout register. The total number of significant bits includes the number of bits representing the integer part of the temperature data and the fractional part of it, as defined by the Resolution field. The LM40 supports 10-bits and thus a value of 001 for this field. For a full definition of this field please refer to the SensorPath specification. 6R O Sign (Signed Data). Defines the type of data in the Temperature Readout field of the Readout register. 0: Unsigned, positive fixed point value. 1: Signed, 2’s complement fixed point value. (value for the LM40) 7R O RoutSize (Readout Register size). Defines the total size of the Readout register. 0: 16 bits. (value for the LM40) 8R O IntSens (Internal Sensor Support). Indicates if the device supports internal temperature measurements, as the LM40 does. 0: No internal temperature measurement 1: Internal temperature sensor implemented. (value for the LM40) 11-9 RO # of Remotes (Number of Remote Sensors). Specifies the number of remote Temperature Sensors supported by the function. 2: The number of Remote Temperature Sensors. (value for the LM40) 15-12 RO Reserved. Will always read "0". LM40 www.national.com19

2.9.3 Temperature Data Readout (Addr: 001 001; 09h)

W P O R Val Bit MSb Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit LSb 001 001 Local Temperature Data Readout R MSb Sign 128 Reserved SNUM Reserved 00 00 Processor/ Remote Temperature Data Readout Reserved EF Res 00 0 Bit Type Description 0R O Reserved. Will always read "0". 1R O Reserved for Local Temperature Data Readout. Will always read "0". EF (Error Flag) for Remote Temperature Data Readout. This bit indicates that an error was detected during the measurement of the current remote Temperature sensor such as a diode fault condition. When a diode fault occurs the value of the temperature reading will be 200h or -256˚C. 0: No error detected. 1: Error detected. 3-2 RO SNUM (Sensor Number). This field indicates the number of the current Temperature Sensor, to which the data in the Temperature Readout field belongs. Temperature Sensor 0 is always assigned to the local sensor of the LM40. 0: Local temperature sensor (see Table Thermal Diode Input Mapping) 1-2: Remote sensor 1 and 2 (see Table Thermal Diode Input Mapping) 5-4 RO Reserved. Will always read "0". 15-6 RO Temperature Readout. This field holds the result of the temperature measurement. The active size of this field for the LM40 is 10-bits, left justified. See Table Temperature Data Formatfor examples. Thermal Diode Input Mapping Sensor Number (SNUM) Sensor Input Board Connection

0 Local none

1 Processor, D1+/D1- CPU Thermal Diode

2 Remote, D2+/D2- MMBT3904 Thermal Diode or GPU

All LM40 temperature data has a common format. The LM40’s temperature data format is two’s complement and has 10-bits of resolution with the LSb having a weight of 0.5 ˚C. The LM40 can resolve temperature between +255.5 ˚C and -256 ˚C, inclusive. It can measure local temperatures between +85 ˚C and 0 ˚C and remote temperatures between +125 ˚C and 0 ˚C with an accuracy of ±3.0 ˚C. Temperature Data Format Temperature Binary Hex +140 ˚C 01 0001 1000 118h +100 ˚C 00 1100 1000 0C8h +1 ˚C 00 0000 0010 002h 0 ˚C 00 0000 0000 000h - 0.5 ˚C 11 1111 1111 3FFh -1 ˚C 11 1111 1110 3FEh LM40 www.national.com 20

Temperature Data Format (Continued) Temperature Binary Hex - 40 ˚C 11 1011 0000 2B0h -255.5 ˚C 10 0000 0001 201h -256 ˚C 10 0000 0000 200h

2.9.4 Temperature Control (Addr: 001 010; 0Ah)

This register is set to the reset value by a Device Reset. Reg Add Register Name W P O R Val Bit MSb Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit LSb 001 010 Temperature Control W 0h Reserved EN2 EN1 EN0 ATE000000000000 Bit Type Description 0 R/W ATE (Attention Enable). When set, this bit enables an Attention Request signal to be generated by the LM40, if the EN0, EN1 or EN2 bits of this register are set. 0: Attention Request disabled (from enabled Temperature Sensor- default) 1: Attention Request enabled (from enabled Temperature Sensor) 1 R/W EN0 (Enable Sensor 0). When this bit is set, the Local Temperature Sensor is enabled for temperature measurements. 0: Temperature Sensor disabled (default) 1: Temperature Sensor enabled 2 R/W EN1 (Enable Sensor 1). When this bit is set, the Remote Thermal Diode 1 Temperature Sensor is enabled for temperature measurements. 0: Temperature Sensor disabled (default) 1: Temperature Sensor enabled 3 R/W EN2 (Enable Sensor 2). When this bit is set, the Remote Thermal Diode 2 Temperature Sensor is enabled for temperature measurements. 0: Temperature Sensor disabled (default) 1: Temperature Sensor enabled 15-4 RO Reserved. Will always read "0".

2.10 VOLTAGE-ONLY MEASUREMENT FUNCTION (TYPE 0010)

This section defines the register structure and operation of the Voltage-Only Measurement Function. The FuncDescriptor value of this function is ‘0010’.

2.10.1 Operation

The Voltage-Only measurement function is capable of measuring the voltage of voltage measurement points ("sensors"). These may be general or dedicated inputs (e.g., for backup battery measurement or the supply voltage to the device). The measurement of all the enabled voltage sensors is cyclic and continuous. Sensor Scan The control register of the function defines which voltage sensors (inputs) are included in the scan. A sensor is scanned only if it is enable by the Sensor Enable bit (EN0, EN1, EN2, EN3 and EN4). The sensors are scanned in an ascending, round-robin order, based on the sensor number. Disabled sensors are skipped and the next enabled sensor in ascending order is scanned. The minimum scan rate is recommended to be 4Hz (i.e., the measurement data is updated at least once in 250 ms), seeSection 2.11 for further details. In Low-Power Mode, the scan rate is four times lower than the scan rate in Active Mode. The scan rate effects the bus bandwidth required to read the results. The sampling rate of the voltage measurements can also be controlled via the Conversion Rate register, see Section 2.11for further details. Data Readout When a new result is stored in the readout register a Function Event is generated. Reading the Readout register clears the Status Function 2 flag (SF2) for the Voltage-Only Measurement Function in the Device Status register. The result is available in the Readout register waiting for the master to read it during the master sensor read sequence. The device should delay or buffer additional conversions to allow the master time to read the result (see Sensor Scan Rate Section 2.11). If a new LM40 www.national.com21

result is ready before the previous result has been read, the new results overwrites the previous result and the Error Function 2 flag (ERF2) for the Voltage-Only function in the Device Status register is set (indicating an overrun event). Reading the Voltage-Only Measurement Readout register clears also the ERF2 flag. Readout Resolution The resolution of the readout register is defined in the Voltage Capabilities register. The resolution of the LM40 is fixed and cannot be modified by software. The voltage readout format is common to all voltage sensors and is 9-bits unsigned. For over or under input voltage conditions the data is guaranteed to saturate at all "1"s or "0"s so long as Operating Ratings of the LM40 are adhered to. Function Event The Voltage-Only Measurement function generates a Function Event to the master whenever a conversion cycle is completed and new data is stored in the Readout register. When the new data is stored into the Readout register the SF2 bit in the Device Status register is set to 1 and remains set, until it is cleared by reading the Readout register. An Attention Request is generated on the bus, only if it is enabled by the Attention Enable bit (ATE) in the Control register. Setup Before Enabling No setup is required for the Voltage-Only Measurement function before it is enabled.

2.10.2 Voltage Capabilities (Addr: 010 000; 10h)

W P O R Val Bit MSb Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit LSb 010 000 Voltage Capabilities R 0051h Reserved # of Voltage Sensors Rout Size 9-bit Resolution 0000000001010001 This register defines the format of the voltage data in the voltage readout register. The LM40 only supports one format for all voltage measurements as defined by the values of this register. Bit Type Description 2-0 RO Resolution. This field defines the total number of significant bits in the Voltage Readout field in the Readout register for this function. The voltage data is always aligned to the left in the Voltage Readout filed and is extended with zeros. 001: 9-bit (value for the LM40, for other field values see the SensorPath specification) 3R O RoutSize (Readout Register size). Defines the total size of the Readout register. 0: 16 bits. (value for the LM40 for other field values see the SensorPath specification) 8-4 RO # of Voltage Sensors (Number of Voltage Sensors). Specifies the number of Voltage Sensors supported by this function. 5: The number of Voltage Sensors. (value for the LM40 for other field values see the SensorPath specification) 15-9 RO Reserved. Will always read "0".

2.10.3 Voltage Readout (Addr: 010 001; 11h)

W P O R Val Bit MSb Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit LSb 010 001 Voltage Readout R Voltage Readout Reserved SNUM Reserved MSb LSb 0 0 0 0 Bit Type Description 0-1 RO Reserved. Will always read "0". 4-2 RO SNUM (Sensor Number). This field indicates the number of the current Voltage Sensor, to which the data in the Voltage Readout field belongs. See Table Analog Input Voltage Mappingfor assignments. 6-5 RO Reserved. Will always read "0". 15-7 RO Voltage Readout. This field holds the result of the voltage measurement. The active size of this field for the LM40 is 9-bits, left justified. See Table Analog Input Voltage Mappingfor voltage mapping details. LM40 www.national.com 22

Analog Input Voltage Mapping Sensor Number (SNUM) Voltage Input Input Voltage for Nominal Reading (code 384 or 180h) Maximum Input Voltage (code 510.5) Register Reading at Maximum Voltage Minimum Input Voltage Register Reading at Minimum Voltage Resolution 0 +2.5V 2.5V 3.32V to 6V 1FFh -0.5V to 3.26mV 00h 6.51mV 1 +1.2V 1.2V 1.6V to 6V 1FFh -0.5V to 2.63mV 00h 5.86mV 2 +3.3V_SBY (V+) 3.3V 4.39V to 6V 1FFh 3.0V 15Dh 8.59mV 3 +5V 5V 6.65V 1FFh -0.5V to 6.51mV 00h 13.02mV 4 +12V 12V 15.95V to 16V 1FFh -0.5V to 15.63mV 00h 31.25mV

2.10.4 Voltage Control (Addr: 010 010; 12h)

This register is set to the reset value by a Device Reset. Reg Add Register Name W P O R Val Bit MSb Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit LSb 010 010 Voltage Control W 1Fh Reserved EN4 EN3 EN2 EN1 EN0 ATE Low Rate Function (Read Only) 00000 11111 Bit Type Description 4-0 RO Low Rate Function This function is not supported by the LM40 and therefore this field is read only. 5 R/W ATE (Attention Enable). When set, this bit enables an Attention Request signal to be generated by the LM40, if one or more EN0-EN4 bits of this register are set. 0: Attention Request disabled (from enabled Temperature Sensor- default) 1: Attention Request enabled 6 R/W EN0 (Enable Sensor 0). When this bit is set, the Voltage Sensor 0 is enabled for voltage measurements. 0: Voltage Sensor disabled (default) 1: Voltage Sensor enabled 10-7 R/W EN1-EN4 (Enable Sensor 1-4). Same as EN0 for Voltage sensors 1-4. 0: Voltage Sensor disabled (default) 1: Voltage Sensor enabled 15-11 RO Reserved. Will always read "0".

2.11 CONVERSION RATE (Addr: 100 000; 20h)

W P O R Val Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 LSb 100 000 Conversion Rate R/ W 2h Reserved CR1 CR0000000 Bit Type Description 1-0 RO CR0 and CR1 (Conversion Rate bits 0 and 1) These bits control the conversion rate of the LM40 for more details see Table Conversion Rate Controland desciption below. LM40 www.national.com23

7-2 RO Reserved. Will always read "0".

3.0 Application Hints

sensing capability allows it to be used in new ways as well. circuit board lands and traces soldered to the LM40’s pins. more strongly than will the air temperature. temperature readings when using a 2N3904 transistor. FIGURE 7. 90 nm Pentium 4 Temperature vs LM40

3.0 Application Hints (Continued)

3.1 DIODE NON-IDEALITY

3.1.1 Diode Non-Ideality Factor Effect on Accuracy

calibrated with the remote diode that it will be paired with.

3.2 PCB LAYOUT for MINIMIZING NOISE

sor and the LM40 can cause temperature conversion errors.

1. Place the 100 pF and 0.1 µF power supply bypass

capacitors as close as possible to the LM40’s power pin. as close as possible to the LM40’s D+ and D− pins.

1. The recommended 100 pF diode capacitor actually has

FIGURE 8. Ideal Diode Trace Layout

1. Ideally, the LM40 should be placed within 10cm of the Processor diode pins with the traces being as straight, short and identical as possible. Trace resistance of 0.7Ω can cause as much as 1˚C of error. This error can be compensated for by adding or subtracting an offset to the remote temperature reading(s). 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 2cm 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 LM40’s GND pin is as close as possible to the Processors GND associated with the sense diode. 9. Leakage current between D+ and GND should be kept to a minimum. Seventeen nano-amperes of leakage can cause as much as 0.2˚C of error in the diode tempera- ture reading (see curve in Section Typical Performance Characteristics). Keeping the printed circuit board as clean as possible will minimize leakage current. The SensorPath Bus is less sensitive to noise than its pre- decessor the SMBus due to the inherent filtering present in the pulse-width encoding of the data. Care still needs to be taken such that induced noise is analyzed and minimized. SensorPath Bus corrupt data is the most common symptom for noise coupled in SWD. A no-ACK is the symptom for noise coupled into the Device Number Select pin (ADD). An RC lowpass filter as well as a debouncing circuit are in- cluded in the LM40 that filter noise spikes less than 2.5 µsec in duration on the SWD signal. LM40 www.national.com 26

Physical Dimensions inches (millimeters) unless otherwise noted 14-Lead Molded Thin Shrink Small Outline Package (TSSOP, JEDEC Registration Number MO-153 Variation AB Ref Note 6 dated 7/93, Order Number LM40CIMT, or LM40CIMTX, LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. 2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. BANNED SUBSTANCE COMPLIANCE National Semiconductor certifies that the products and packing materials meet the provisions of the Customer Products Stewardship Specification (CSP-9-111C2) and the Banned Substances and Materials of Interest Specification (CSP-9-111S2) and contain no ‘‘Banned Substances’’ as defined in CSP-9-111S2. National Semiconductor Americas Customer Support Center Email: new.feedback@nsc.com Tel: 1-800-272-9959 National Semiconductor Europe Customer Support Center Fax: +49 (0) 180-530 85 86 Email: europe.support@nsc.com Deutsch Tel: +49 (0) 69 9508 6208 English Tel: +44 (0) 870 24 0 2171 Français Tel: +33 (0) 1 41 91 8790 National Semiconductor Asia Pacific Customer Support Center Email: ap.support@nsc.com National Semiconductor Japan Customer Support Center Fax: 81-3-5639-7507 Email: jpn.feedback@nsc.com Tel: 81-3-5639-7560 www.national.com LM40 Hardware Monitor with Dual Thermal Diodes and SensorPath™Bus National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the righ t at any time without notice to change said circuitry and specifications.