National Semiconductor LM80 Technical data
June 2001
LM80
Serial Interface ACPI-Compatible Microprocessor System
Hardware Monitor
General Description
The LM80 provides 7 positive voltage inputs, temperature
measurement, fan speed measurement, and hardware
monitoring on an I
WATCHDOG comparisons of all measured values and an
open-drain interrupt output becomes active when any values
exceed programmed limits.AChassis Intrusion input is provided to monitor and reset an external circuit designed to
latch a chassis intrusion event.
The LM80 is especially suited to interface to both linear and
digital temperature sensors. The 10 mV LSB and 2.56 volt
input range is ideal for accepting inputs from a linear sensor
such as the LM50. The BTI is used as an input from either
digital or thermostat sensors such as LM75 and LM56.
The LM80’s 2.8V to 5.75V supply voltage range, low supply
current, and I
applications. These includehardwaremonitoringandprotection applications in personal computers, electronic test
equipment, and office electronics.
2
C™interface. The LM80 performs
2
C interface make it ideal for a wide range of
Features
n Temperature sensing
n 7 positive voltage inputs
n 2 programmable fan speed monitoring inputs
n 10 mV LSB and 2.56V input range accepts outputs from
linear temperature sensors such as the LM50
n Chassis Intrusion Detector input
n WATCHDOG comparison of all monitored values
n Separate input to show status in Interrupt Status
Register of additional external temperature sensors such
as the LM56 or LM75
2
n I
C Serial Bus interface compatibility
n Shutdown mode to minimize power consumption
n Programmable RST_OUT/OS pin: RST_OUT provides a
Reset output; OS provides an Interrupt Output activated
by an Overtemperature Shutdown event
Key Specifications
j
Voltage monitoring Error
j
Temperature Error
−25˚C to +125˚C
j
Supply Voltage Range 2.8V to
j
Supply Current Operating: 0.2 mA typ
Shutdown: 15 µA typ
j
ADC Resolution 8 Bits
j
Temperature Resolution 0.5˚C
±
1% (max)
±
3˚C (max)
5.75V
Applications
n System Thermal and Hardware Monitoring for Servers
and PCs
n Office Electronics
n Electronic Test Equipment and Instrumentation
LM80 Serial Interface ACPI-Compatible Microprocessor System Hardware Monitor
Typical Application
DS100040-1
#
Indicates Active Low (“Not”)
I2C®is a registered trademark of the Philips Corporation.
© 2001 National Semiconductor Corporation DS100040 www.national.com
Ordering Information
LM80
Temperature Range
−25˚C ≤ T
≤ +125˚C Specified
A
Order Number Device
LM80CIMT-3
LM80CIMTX-3
LM80CIMT-5
LM80CIMTX-5
Note:1-Rail transport media, 62 parts per rail
2
-Tape and reel transport media, 3400 parts per reel
1
LM80CIMT-3 MTC24B 3.3V
2
1
LM80CIMT-5 MTC24B 5.0V
2
Block Diagram
Marking
NS
Package
Number
Connection Diagram
Power
Supply
Voltage
DS100040-2
Pin Descriptions
Pin
Name(s)
INT_IN
SDA 2 1 Digital I/O Serial Bus bidirectional Data. Open-drain output.
SCL 3 1 Digital Input Serial Bus Clock.
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Pin
Number
Number
of Pins
Type Description
1 1 Digital Input This is an active low input that propagates the INT_IN signal to the
INT output of the LM80 via Interrupt Mask Register 1 Bit 7 and INT
enable Bit 1 of the Configuration Register.
DS100040-3
Pin Descriptions (Continued)
LM80
Pin
Name(s)
FAN1-FAN2 4-5 2 Digital Inputs 0 to V
BTI
CI (Chassis
Intrusion)
GND 8 1 GROUND Internally connected to all of the digital circuitry.
+
V
(+2.8V to
+5.75V)
INT
GPO (Power
Switch Bypass)
NTEST_IN/
RESET_IN
RST_OUT/OS
GNDA 14 1 GROUND Internally connected to all analog circuitry. The ground reference for
IN6-IN0 15-21 7 Analog Inputs 0V to 2.56V full scale range Analog Inputs.
A0/NTEST_OUT 22 1 Digital I/O The lowest order bit of the Serial Bus Address. This pin functions as
A1-A2 23-24 2 Digital Inputs The two highest order bits of the Serial Bus Address.
TOTAL PINS 24
Pin
Number
6 1 Digital Input Board Temperature Interrupt driven by O.S. outputs of additional
7 1 Digital I/O An active high input from an external circuit which latches a Chassis
9 1 POWER +3.3V or +5V V+power. Bypass with the parallel combination of
10 1 Digital Output Non-Maskable Interrupt (open source)/Interrupt Request (open
11 1 Digital Output An active low open drain output intended to drive an external
12 1 Digital Input An active-low input that enables NAND Tree board-level connectivity
13 1 Digital Output Master Reset, 5 mA driver (open drain), active low output with a
Number
of Pins
Type Description
+
fan tachometer inputs.
temperature sensors such as LM75. Provides internal pull-up of
10 kΩ.
Intrusion event. This line can go high without any clamping action
regardless of the powered state of the LM80. The LM80 provides an
internal open drain on this line, controlled by Bit 5 of the
Configuration Register, to provide a minimum 10 ms reset of this
line.
10 µF (electrolytic or tantalum) and 0.1 µF (ceramic) bypass
capacitors.
drain). The mode is selected with Bit 5 of the Configuration Register
and the output is enabled when Bit 1 of the Configuration Register
is set to 1. The default state is disabled.
P-channel power MOSFET for software power control.
testing. Refer to Section 10.0 on NAND Tree testing. Whenever
NAND Tree connectivity is enabled the LM80 is also reset to its
power on state.
10 ms minimum pulse width. Available when enabled via Bit 4 in
Configuration Register and Bit 7 of the Fan Divisor/RST_OUT/OS
Register. Bit 6 of the Fan Divisor/RST_OUT/OS Register enables
this output as an active low Overtemperature Shutdown (OS).
all analog inputs. This pin needs to be taken to a low noise analog
ground plane for optimum performance.
an output when doing a NAND Tree test.
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Absolute Maximum Ratings (Notes 1, 2)
LM80
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Positive Supply Voltage (V
+
) 6.5V
Voltage on Any Input or Output Pin −0.3V to (V
Ground Difference (GND - GNDA)
Input Current at any Pin (Note 3)
Package Input Current (Note 3)
Maximum Junction Temperature
max) 150˚C
(T
J
ESD Susceptibility(Note 5)
Human Body Model 2000V
Machine Model 125V
+
+0.3V)
±
300 mV
±
5mA
±
20 mA
Soldering Information
MTC24B Package (Note 6) :
Vapor Phase (60 seconds) 215˚C
Infrared (15 seconds) 235˚C
Storage Temperature −65˚C to +150˚C
Operating Ratings(Notes 1, 2)
Operating Temperature Range T
LM80CIMT-3, LM80CIMT-5 −25˚C ≤ TA≤ +125˚C
Specified Temperature Range T
LM80CIMT-3, LM80CIMT-5 −25˚C ≤ TA≤ +125˚C
Junction to Ambient Thermal Resistance (θ
NS Package Number: MTC24B 95˚C/W
+
Supply Voltage (V
) +2.8V to +5.75V
≤ TA≤ T
MIN
≤ TA≤ T
MIN
(Note 4) )
JA
Ground Difference
(|GND − GNDA|) ≤ 100 mV
Voltage Range: −0.05V to V++ 0.05V
V
IN
DC Electrical Characteristics
The following specifications apply for +2.8 VDC≤V+≤ +3.8 VDCfor LM80CIMT-3, +4.25 VDC≤V+≤ +5.75 VDCfor LM80CIMT-5,
IN0-IN6 R
25˚C.(Note 7)
Symbol Parameter Conditions Typical Limits Units
POWER SUPPLY CHARACTERISTICS
+
I
TEMPERATURE-to-DIGITAL CONVERTER CHARACTERISTICS
ANALOG-to-DIGITAL CONVERTER CHARACTERISTICS
TUE Total Unadjusted Error (Note 10)
DNL Differential Non-Linearity
PSS Power Supply Sensitivity
t
C
MULTIPLEXER/ADC INPUT CHARACTERISTICS
=25Ω, unless otherwise specified. Boldface limits apply for TA=TJ=T
S
MIN
to T
; all other limits TA=TJ=
MAX
(Note 8) (Note 9) (Limits)
Supply Current Interface Inactive and
+
= 5.75V
V
Interface Inactive and
+
V
= 3.8V
0.2 2.0 mA (max)
0.18 1.5 mA (max)
Shutdown Mode 15 µA
Temperature Error −25˚C ≤ T
≤ +125˚C
A
±
3 ˚C (max)
Resolution 0.5 ˚C (min)
Resolution (8 bits with full-scale at 2.56V) 10 mV
±
1 % (max)
±
1 LSB
±
1 %/V
Total Monitoring Cycle Time (Note 11)
9-bit Temp resolution
12-bit Temp resolution
1.0 1.5
2
On Resistance 0.5 10 kΩ (max)
Input Current (On Channel Leakage Current)
Off Channel Leakage Current
±
1µA
±
1µA
MAX
MAX
(max)
sec (max)
sec (max)
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DC Electrical Characteristics (Continued)
The following specifications apply for +2.8 VDC≤V+≤ +3.8 VDCfor LM80CIMT-3, +4.25 VDC≤V+≤ +5.75 VDCfor LM80CIMT-5,
IN0-IN6 R
25˚C.(Note 7)
Symbol Parameter Conditions Typical Limits Units
FAN RPM-to-DIGITAL CONVERTER
DIGITAL OUTPUTS: A0/NTEST_OUT, INT
V
OUT(1)
V
OUT(0)
OPEN DRAIN OUTPUTS: GPO, RST_OUT/OS, CI
V
OUT(0)
I
OH
OPEN DRAIN SERIAL BUS OUTPUT: SDA
V
OUT(0)
I
OH
DIGITAL INPUTS: A0/NTEST_Out, A1-A2, BTI, CI (Chassis Intrusion), INT_IN, and NTEST_IN/Reset_IN
V
IN(1)
V
IN(0)
SERIAL BUS INPUTS (SCL, SDA) and FAN TACH PULSE INPUTS (FAN1, FAN2)
V
IN(1)
V
IN(0)
ALL DIGITAL INPUTS Except for BTI
I
IN(1)
I
IN(0)
C
IN
=25Ω, unless otherwise specified. Boldface limits apply for TA=TJ=T
S
MIN
to T
; all other limits TA=TJ=
MAX
(Note 8) (Note 9) (Limits)
Fan RPM Error +25˚C ≤ T
−10˚C ≤ T
−25˚C ≤ T
≤ +75˚C
A
≤ +100˚C
A
≤ +125˚C
A
±
10 % (max)
±
15 % (max)
±
20 % (max)
Full-scale Count 255 (max)
FAN1 and FAN2 Nominal Input
RPM (See
Section 6.0
)
Divisor = 1, Fan Count = 153
(Note 12)
Divisor = 2, Fan Count = 153
8800 RPM
4400 RPM
(Note 12)
Divisor = 3, Fan Count = 153
2200 RPM
(Note 12)
Divisor = 4, Fan Count = 153
1100 RPM
(Note 12)
Internal Clock Frequency +25˚C ≤ T
≤ +75˚C 22.5 20.2 kHz (min)
A
24.8 kHz (max)
−10˚C ≤ T
≤ +100˚C 22.5 19.1 kHz (min)
A
25.9 kHz (max)
18 kHz (min)
27 kHz (max)
2.4 V (min)
0.4 V (max)
0.4 V (min)
Logical “1” Output Voltage I
Logical “0” Output Voltage I
Logical “0” Output Voltage I
High Level Output Current V
RST_OUT/OS, CI
−25˚C ≤ T
OUT
+
= +4.25V, I
V
+
at V
OUT
+
= +5.75V, I
V
+
at V
OUT
+
at V
I
OUT
OUT
≤ +125˚C 22.5
A
= +5.0 mA at
= +2.8V
OUT
= −5.0 mA at
= +3.8V
OUT
=− 5.0 mA
= +5.75V,
= −3.0 mA at V+= +3.8V
+
=V
= +3.0 mA
= −3.0 mA
0.1 100 µA (max)
30 10 ms (min)
Pulse Width
Logical “0” Output Voltage I
High Level Output Current V
= −3.0 mA at
OUT
+
= +5.75V, I
V
+
= +3.8V
at V
=V
OUT
0.4 V (min)
= −3.0 mA
OUT
+
0.1 100 µA (max)
Logical “1” Input Voltage 2.0 V (min)
Logical “0” Input Voltage 0.8 V (max)
Logical “1” Input Voltage 0.7xV
Logical “0” Input Voltage 0.3xV
Logical “1” Input Current VIN=V
Logical “0” Input Current VIN=0V
+
DC
−0.005 −1 µA (min)
0.005 1 µA (max)
+
V (min)
+
V (max)
Digital Input Capacitance 20 pF
LM80
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DC Electrical Characteristics (Continued)
LM80
The following specifications apply for +2.8 VDC≤V+≤ +3.8 VDCfor LM80CIMT-3, +4.25 VDC≤V+≤ +5.75 VDCfor LM80CIMT-5,
IN0-IN6 R
=25Ω, unless otherwise specified. Boldface limits apply for TA=TJ=T
S
MIN
to T
; all other limits TA=TJ=
MAX
25˚C.(Note 7)
Symbol Parameter Conditions Typical Limits Units
(Note 8) (Note 9) (Limits)
BTI Digital Input
I
I
C
IN(1)
IN(0)
IN
Logical “1” Input Current VIN=V
Logical “0” Input Current VIN=0V
Digital Input Capacitance 20 pF
+
DC
−1 −10 µA (min)
500 2000 µA (max)
AC Electrical Characteristics
The following specifications apply for +2.8 VDC≤V+≤ +3.8 VDCfor LM80CIMT-3, +4.25 VDC≤V+≤ +5.75 VDCfor LM80CIMT-5,
unless otherwise specified. Boldface limits apply for T
A=TJ=TMIN
Symbol Parameter Conditions Typical Limits Units
SERIAL BUS TIMING CHARACTERISTICS
t
1
t
2
t
3
t
4
t
5
SCL (Clock) Period 2.5 µs (min)
Data In Setup Time to SCL High 100 ns (min)
Data Out Stable After SCL Low 0 ns (min)
SDA Low Setup Time to SCL Low (start) 100 ns (min)
SDA High Hold Time After SCL High (stop) 100 ns (min)
to T
; all other limits TA=TJ= 25˚C. (Note 13)
MAX
(Note 8) (Note 9) (Limits)
FIGURE 1. Serial Bus Timing Diagram
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DS100040-4
AC Electrical Characteristics (Continued)
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 specific 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 specified
Note 3: When the input voltage (V
The 20 mA maximum package input current rating limits the number of pins that can safely exceed the power supplies with an input current of 5 mA to four.
Note 4: The maximum power dissipation must be derated at elevated temperatures and is dictated by T
allowable power dissipation at any temperature is P
Note 5: The human body model is a 100 pF capacitor discharged through a 1.5 kΩ resistor into each pin. The machine model is a 200 pF capacitor discharged
directly into each pin.
Note 6: See the section titled “Surface Mount” found in any post 1986 National Semiconductor Linear Data Book for other methods of soldering surface mount
devices.
Note 7: Each input and output is protected by a nominal 6.5V breakdown voltage zener diode to GND; as shown below, input voltage magnitude up to 0.3V above
+
V
or 0.3V below GND will not damage the LM80. There are parasitic diodes that exist between the inputs and the power supply rails. Errors in the ADC conversion
can occur if these diodes are forward biased by more than 50 mV. As an example, if V
conversions.
) at any pin exceeds the power supplies (V
IN
=(TJmax−TA)/θJA.
D
<
(GND or GNDA) or V
IN
+
is 4.50 VDC, input voltage must be ≤ 4.55 VDC, to ensure accurate
DS100040-5
>
V+), the current at that pin should be limited to 5 mA.
IN
max, θJAand the ambient temperature, TA. The maximum
J
LM80
An x indicates that the diode exists.
Pin Name D1 D2 D3 Pin Name D1 D2 D3
INT_IN
x x x NTEST_IN/
x
Reset_IN
CI x x IN0-IN6 x x x
GPO
FAN1–FAN2 x INT
x x BTI xxx
xxx
SCL x A1-A2 x x x
SDA x x A0/NTEST_Out x x x
RST_OUT/OS
x
FIGURE 2. ESD Protection Input Structure
Note 8: Typicals are at T
Note 9: Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level).
Note 10: TUE (Total Unadjusted Error) includes Offset, Gain and Linearity errors of the ADC.
Note 11: Total Monitoring Cycle Time includes temperature conversion, 7 analog input voltage conversions and 2 tachometer readings. Each input voltage
conversion takes 100 ms typical and 112 ms maximum. 8-plus sign Temperature resolution takes 100 ms typical and 112 ms maximum, while 11-bit plus sign takes
800 ms typical and 900 ms maximum. Fan tachometer readings take 20 ms typical, at 4400 rpm, and 200 ms max.
Note 12: The total fan count is based on 2 pulses per revolution of the fan tachometer output.
Note 13: Timing specifications are tested at the Serial Bus Input logic levels, V
=25˚C and represent most likely parametric norm.
J=TA
=0.3xV+for a falling edge and V
IN(0)
=0.7xV+for a rising edge.
IN(1)
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Test Circuit
LM80
FIGURE 3. Digital Output Load Test Circuitry
Functional Description
1.0 GENERAL DESCRIPTION
The LM80 provides 7 analog inputs, a temperature sensor, a
Delta-Sigma ADC (Analog-to-Digital Converter), 2 fan speed
counters, WATCHDOG registers, and a variety of inputs and
outputs on a single chip. A two wire Serial Bus interface is
provided. The LM80 performs power supply, temperature,
fan control and fan monitoring for personal computers.
The LM80 continuously converts analog inputs to 8-bit digital
words with a 10 mV LSB (Least Significant Bit) weighting,
yielding input ranges of 0 to 2.56V. The Analog inputs are
intended to be connected to the several power supplies
present in a a typical computer. Temperature can be converted to a 9-bit or 12-bit two’s complement word with resolutions of 0.5˚C LSB or 0.0625˚C LSB, respectively.
Fan inputs can be programmed to accept either fan failure
indicator or tachometer signals. Fan failure signals can be
programmed to be either active high or active low.Fan inputs
measure the period of tachometer pulses from the the fans,
providing a higher count for lower fan speeds. The fan inputs
are digital inputs with and acceptable range of 0 to V
and a transition level of approximately V
fan counts are 255 (8-bit counter), which represent a
stopped or very slow fan. Nominal speed based on a count
of 153, are programmable from 1100 to 8800 RPM. Signal
conditioning circuitry is included to accommodate slow rise
and fall times.
The LM80 provides a number of internal registers, as detailed in
Configuration Register: Provides control and configuration.
Interrupt Status Registers: Two registers to provide
status of each WATCHDOG limit or Interrupt event.
Interrupt Mask Registers: Allows masking of individual
Interrupt sources, as well as separate masking for each of
both hardware Interrupt outputs.
Figure 4
. These include:
+
/2 volts. Full scale
+
volts
DS100040-6
Fan Divisor/RST_OUT/OS Registers: Bits 0-5 of this register contain the divisor bits for FAN1 and FAN2 inputs. Bits
6-7 control the function of the RST_OUT/OS output.
OS Configuration/Temperature Resolution Register: The
configuration of the OS (Overtemperature Shutdown) is controlled by the lower 3 bits of this register. Bit 3 enables 12-bit
temperature conversions. Bits 4-7 reflect the lower four bits
of the temperature reading for a 12-bit resolution.
Value RAM: The monitoring results: temperature, voltages,
fan counts, and Fan Divisor/RST_OUT/OS Register limits
are all contained in the Value RAM. The Value RAM consists
of a total of 32 bytes. The first 10 bytes are all of the results,
the next 20 bytes are the Fan Divisor/RST_OUT/OS Register limits, and are located at 20h-3Fh, including two unused
bytes in the upper locations.
When the LM80 is started, it cycles through each measurement in sequence, and it continuously loops through the
sequence approximately once every second. Each measured value is compared to values stored in WATCHDOG, or
Limit registers. When the measured value violates the programmed limit the LM80 will set a corresponding Interrupt in
the Interrupt Status Registers. Two hardware Interrupt lines,
INT and RST_OUT/OS are available. INT is fully programmable with masking of each Interrupt source, and masking of
each output. RST_OUT/OS is dedicated to the temperature
reading WATCHDOG registers. In addition, the Fan Divisor
register has control bits to enable or disable the hardware
Interrupts.
Additional digital inputs are provided for chaining of INT,
outputs of multiple external LM75 temperature sensors via
the BTI (Board Temperature Interrupt) input, and a CI (Chassis Intrusion) input. The Chassis Intrusion input is designed
to accept an active high signal from an external circuit that
latches when the case is removed from the computer.
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Functional Description (Continued)
2.0 INTERFACE
LM80
FIGURE 4. LM80 Register Structure
DS100040-7
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