National Semiconductor LM40 Technical data

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LM40
Hardware Monitor with Dual Thermal Diodes and

LM40 Hardware Monitor with Dual Thermal Diodes and SensorPath

May 2004

SensorPath

™

Bus

General Description

The LM40 is a hardware monitor that measures 3 tempera­ture zones, 5 voltages and has a single-wire interface com­patible with National Semiconductor’s SensorPath bus. Sen­sorPath data is pulse width encoded, thereby allowing the
LM40 to be easily connected to many general purpose
micro-controllers. Several National Semiconductor Super I/O
products include a fully integrated SensorPath master, that
when connected to the LM40 can realize a hardware monitor
function that includes limit checking for measured values,
autonomous fan speed control and many other functions.

The LM40 measures the temperature of its own die as well
as two external devices such as a processor thermal diode
or a diode connected transistor. The LM40 can resolve tem­peratures up to 255˚C and down to -256˚C. The operating
temperature range of the LM40 is 0˚C to +125˚C. Using Σ∆
ADC it measures +1.2V, +2.5V, +3.3V, +5V and +12V analog
input voltages with internal scaling resistors.The address
programming pin allows two LM40s to be placed on one
SensorPath bus.

Features

n SensorPath Interface

— 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
n Temperature Sensor Accuracy
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

±

2 % (max)

±

3 ˚C (max)

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

© 2004 National Semiconductor Corporation DS200684 www.national.com

™

Bus

Connection Diagram

LM40

TSSOP-14

Order
Number

LM40CIMT LM40

LM40CIMTX LM40

Package

Marking

CIMT

CIMT

NS

Package

Number

MTC14C 94 units per

MTC14C 2500 units in

Transport
Media

rail

tape and reel

Top View

National Package Number MTC14C

20068402

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

4 SWD SensorPath Bus line; Open-drain

output

5 ADD Digital input - device number select

input for the serial bus device
number

6 +1.2V +1.2V voltage monitoring input with

scaling resistors

7 +2.5V +2.5V voltage monitoring input with

scaling resistors

8, 10 D1-, D2- Thermal diode analog voltage

output and negative monitoring
input

9, 11 D1+, D2+ Thermal diode analog current

output and positive monitoring input

12 +5V +5V voltage monitoring input with

scaling resistors

13 +12V +12V voltage monitoring input with

scaling resistors

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.

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

Pull-up to 3.3 V or pull-down to GND resistor,
10k; must never be left floating

Processor core voltage to be monitored

Power supply voltage to be monitored

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 D­and D+ for noise filtering.

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.

Power supply voltage to be monitored

Power supply voltage to be monitored

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Block Diagram

LM40

20068403

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Absolute Maximum Ratings

LM40

(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-

Input Current per Pin(Note 3)

Package Input Current (Note 3)

Package Power Dissipation (Note 4)

Output Sink Current 10 mA

±

1mA

±

5mA

±

30 mA

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 (T

MIN≤TA≤TMAX

Operating Temperature Range 0˚C ≤ T

Remote Diode Temperature (T
Range -5 ˚C ≤T

Supply Voltage Range (V+) +3.0 V to +3.6 V

Analog Input Voltage Rage:

+1.2V and +2.5V −0.05V to

) 0˚C ≤ TA≤ +85˚C

)

D

ESD Susceptibility (Note 5)

Human Body Model 2500 V

Machine Model 250 V

Storage Temperature −65˚C to +150˚C

+3.3V_SBY (V+) +3.0V to +3.6V

+5V −0.05V to +6.67V

+12V −0.05V to +16V

DC Electrical Characteristics

The following specifications apply for V+ = +3.0 VDCto +3.6 VDC, and all analog source impedance RS=50Ω unless other-
wise specified in the conditions. Boldface limits apply for LM40CIMT T

= +25˚C. TAis the ambient temperature of the LM40; TJis the junction temperature of the LM40; TDis the junction tem-

T

A

A=TJ=TMIN

=0˚C to T

perature of the remote thermal diode.

=85˚C; all other limits

MAX

≤ +125˚C

A

≤+140 ˚C

D

(V+ + 0.05V)

POWER SUPPLY CHARACTERISTICS

Symbol Parameter Conditions

V+ Power Supply Voltage 3.3

I+

Shutdown

Shutdown Power Supply Current

SensorPath Bus Inactive
(Note 9)

Typical

(Note 7)

260 420 µA (max)

Limits

(Note 8)

3.0

3.6

Units

(Limit)

V (min)

V (max)

SensorPath Bus Inactive; all

I+

Average

I+

Peak

Average Power Supply Current

Peak Power Supply Current

Power-On Reset Threshold Voltage

sensors enabled;

=182 ms; (Note 9)

t

CONV

SensorPath Bus Inactive
(Note 9)

900 µA (max)

3.3 mA (max)

1.6 V (min)

2.8 V (max)

TEMPERATURE-TO-DIGITAL CONVERTER CHARACTERISTICS

Parameter Conditions

Temperature Accuracy Using the Remote Thermal
Diode, see (Note 12) for Thermal Diode Processor
Type.

Temperature Accuracy Using the Local Diode T

T

J

= 0˚C to

TD= +25˚C

+85˚C

T

= 0˚C to

J

+85˚C

TJ = 0˚C to
+85˚C

= 0˚C to +85˚C (Note 10)

J

TD= 0˚C to
+100˚C

T
+125˚C

= +100˚C to

D

Typical

(Note 7)

±

1

±

1

Limits

(Note 8)

±

2.5 ˚C (max)

±

3 ˚C (max)

±

4 ˚C (max)

±

3 ˚C (max)

Units

(Limits)

Remote Diode and Local Temperature Resolution 10 Bits

0.5 ˚C

D− Source Voltage 0.7 V

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TEMPERATURE-TO-DIGITAL CONVERTER CHARACTERISTICS

Parameter Conditions

Diode Source Current

Diode Source Current High Current to Low Current
Ratio

Typical

(Note 7)

(V

D+−VD−

) = +0.65 V; High Current 188 280 µA (max)

Low Current 11.75 µA

16

Limits

(Note 8)

Units

(Limits)

ANALOG TO DIGITAL CONVERTER CHARACTERISTICS

Symbol Parameter Conditions Typical

(Note 7)

TUE Total Unadjusted Error(Note 11)

Limits

(Note 8)

±

2 %FS

Units

(Limit)

(max)

Resolution 9 Bits

DNL Differential Non-linearity 1 LSB

Power Supply Sensitivity

Input Resistance, all analog inputs (total resistance
of divider chain)

±

1 %/V

210 140 kΩ (min)

400 kΩ (max)

SWD and ADD DIGITAL INPUT CHARACTERISTICS

Symbol Parameter Conditions

V

IH

SWD Logical High Input Voltage 2.1 V (min)

Typical

(Note 7)

Limits

(Note 8)

Units

(Limit)

V+ + 0.5 V (max)

V

IL

SWD Logical Low Input Voltage 0.8 V (max)

-0.5 V (min)

V

V

IH

V

IL

HYST

I

L

ADD Logical High Input Voltage 90%xV+ V (min)

ADD Logical Low Input Voltage 10%xV+ V (max)

Input Hysteresis 300 mV

SWD and ADD Input Current GND ≤ VIN≤ V+

SWD Input Current with V+ Open or
Grounded

GND ≤ V

≤ 3.6V,

IN

and V+ Open or

±

0.005

±

0.005 µA

±

10 µA (max)

GND

C

IN

Digital Input Capacitance 10 pF

SWD DIGITAL OUTPUT CHARACTERISTICS

Symbol Parameter Conditions

V

OL

Open-drain Output Logic “Low”
Voltage

I

OH

C

OUT

Open-drain Output Off Current

Digital Output Capacitance 10 pF

IOL= 4mA 0.4 V (max)

I

= 50µA 0.2 V (max)

OL

Typical

(Note 7)

±

0.005

Limits

(Note 8)

±

10 µA (max)

Units

(Limit)

LM40

AC Electrical Characteristics

The following specification apply for V+ = +3.0 VDCto +3.6 VDC, unless otherwise specified. Boldface limits apply for
T

A=TJ=TMIN

=0˚C to T

specification revision 0.98. Please refer to that speciation for further details.

Symbol Parameter Conditions

HARDWARE MONITOR CHARACTERISTICS

t

CONV

Total Monitoring Cycle Time (Note 13) All Voltage and

SensorPath Bus CHARACTERISTICS

t

f

SWD fall time (Note 16) R

=85˚C; all other limits TA=TJ= 25˚C. The SensorPath Characteristics conform to the SensorPath

MAX

Typical

(Note 7)

Limits

(Note 8)

182 163.8 ms (min)

Temperature readings
(Default)

=1.25 kΩ±30%,

pull-up

=400 pF

C

L

200.2 ms (max)

300 ns (max)

Units

(Limits)

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AC Electrical Characteristics (Continued)

LM40

The following specification apply for V+ = +3.0 VDCto +3.6 VDC, unless otherwise specified. Boldface limits apply for
T

A=TJ=TMIN

=0˚C to T

=85˚C; all other limits TA=TJ= 25˚C. The SensorPath Characteristics conform to the SensorPath

MAX

specification revision 0.98. Please refer to that speciation for further details.

Typical

Symbol Parameter Conditions

t

INACT

t

r

SWD rise time (Note 16) R

Minimum inactive time (bus at high level)

=1.25 kΩ±30%,

pull-up

=400 pF

C

L

(Note 7)

guaranteed by the slave before an attention
request

t

Mtr0

Master drive for Data Bit 0 write and for Data
Bit 0-1read

t

Mtr1

t

SFEdet

t

SLout1

t

MtrS

t

SLoutA

t

RST

t

RST_MAX

Master drive for Data Bit 1 write 35.4 µs (min)

Time allowed for LM40 activity detection 9.6 µs (max)

LM40 drive for Data Bit 1 read by master 28.3 µs (min)

Master drive for Start Bit 80 µs (min)

LM40 drive for Attention Request 165 µs (min)

Master or LM40 drive for Reset 354 µs (min)

Maximum drive of SWD by an LM40, after the
power supply is raised above 3V

Limits

(Note 8)

Units

(Limits)

1000 ns (max)

11 µs (min)

11.8 µs (min)

17.0 µs (max)

48.9 µs (max)

38.3 µs (max)

109 µs (max)

228 µs (max)

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 guaranteed
specifications apply only for the test conditions listed. Some performance characteristics may degrade when the device is not operated under the listed test
conditions.

Note 2: All voltages are measured with respect to GND, unless otherwise noted.

Note 3: When the input voltage (V

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.

) at any pin exceeds the power supplies (V

IN

IN

<

GND or V

>

V+), the current at that pin should be limited to 5 mA. Parasitic

IN

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LM40

PIN#Pin

Name

Pin

Circuit

1NC A

2 GND B

V+/

3

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

12 +5V C

13 +12V C

Circuit A

Circuit C

All Input Structure Circuits

Circuit B

Circuit D

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 kΩ 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 T

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 power

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, includesADC 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
factor of 1.011 and series resistance of 3.33Ω. When using a MMBT3904 type transistor as a thermal diode the error band will be typically shifted by -4.5 ˚C.

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

Note 15: The output rise time is measured from (V

Note 16: The rise and fall times are not tested but guaranteed by design.

= 25˚C and represent most likely parametric norm. They are to be used as general reference values not for critical design calculations.

A

IH min

IL max

)to(V

)to(V

IL max

IH min

).

).

Circuit E

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Timing Diagrams

LM40

20068404

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

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Timing Diagrams (Continued)

LM40

20068405

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

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