Rainbow Electronics LM87 User Manual

December 2003

LM87 Serial Interface System Hardware Monitor with Remote Diode Temperature Sensing

General Description

The LM87 is a highly integrated data acquisition system for hardware monitoring of servers, Personal Computers, or virtually any microprocessor-based system. In a PC, the LM87 can be used to monitor power supply voltages, motherboard and processor temperatures, and fan speeds. Actual values for these inputs can be read at any time. Programmable WATCHDOG limits in the LM87 activate a fully programmable and maskable interrupt system with two out-

puts (INT The LM87 has an on-chip digital output temperature sensor

with 8-bit resolution as well as the capability of monitoring 2 external diode temperatures to 8-bit resolution, an 8 channel analog input ADC with 8-bit resolution and an 8-bit DAC. A channel on the ADC measures the supply voltage applied to the LM87, nominally 3.3 V. Two of the ADC inputs can be redirected to a counter that can measure the speed of up to 2 fans. A slow speed Σ∆ ADC architecture allows stable measurement of signals in an extremely noisy environment. The DAC, witha0to2.5Voutput voltage range, can be used for fan speed control. Additional inputs are provided for Chassis Intrusion detection circuits, and VID monitor inputs. The VID monitor inputs can also be used as IRQ inputs if VID monitoring is not required. The LM87 has a Serial Bus interface that is compatible with SMBus

and THERM#).

™

and I2C™.

Features

n Remote diode temperature sensing (2 channels) n 8 positive voltage inputs with scaling resistors for

monitoring +5 V, +12 V, +3.3 V, +2.5 V, Vccp power supplies directly

n 2 inputs selectable for fan speed or voltage monitoring n 8-bit DAC output for controlling fan speed n Chassis Intrusion Detector input n WATCHDOG comparison of all monitored values n SMBus or I n VID0-VID4 or IRQ0-IRQ4 monitoring inputs n On chip temperature sensor

C Serial Bus interface compatibility

Key Specifications

Voltage Monitoring Error

External Temperature Error

Internal Temperature Error

−40 ˚C to +125 ˚C

Supply Voltage Range 2.8 to 3.8 V

Supply Current 0.7 mA (typ)

ADC and DAC Resolution 8 Bits

Temperature Resolution 1.0 ˚C

2 % (max)

4 ˚C (max)

3 ˚C (typ)

Applications

n System Thermal and Hardware Monitoring for Servers,

Workstations and PCs

n Networking and Telecom Equipment n Office Electronics n Electronic Test Equipment and Instrumentation

LM87 Serial Interface System Hardware Monitor with Remote Diode Temperature Sensing

Ordering Information

Temperature Range

−40 ˚C ≤ T

Order Number Device Marking

LM87CIMT

LM87CIMTX

Note:1-Rail transport media, 61 parts per rail

-Tape and reel transport media, 2500 parts per reel

SMBus™is a trademark of the Intel Corporation.

≤ +125 ˚C

LM87CIMT MTC24B

NS Package

Number

Connection Diagram

10099503

Block Diagram

LM87

10099501

Pin Description

Name(s)

ADD/NTEST_OUT 1 1 Digital I/0 This pin normally functions as a three-state input that controls the

THERM

SMBData 3 1 Digital I/O Serial Bus bidirectional Data. Open-drain output.

SMBCLK 4 1 Digital Input Serial Bus Clock.

FAN1/AIN1FAN2/AIN2

CI 7 1 Digital I/O An active high input from an external circuit which latches a

Number

2 1 Digital I/O This pin functions as an open-drain interrupt output for temperature

5-6 2 Analog/Digital

Number

of Pins

Type Description

two LSBs of the Serial Bus Address. When this pin is tied to V the two LSBs are 01. When tied to Ground, the two LSBs are 10. If this pin is not connected, the two LSBs are 00. This pin also functions as an output during NAND Tree tests (board-level connectivity testing). To ensure proper NAND tree function, this pin should not be tied directly to V resistor should be used to allow the test output function to work. Refer to SECTION 11 on NAND Tree testing.

interrupts only, or as an interrupt input for fan control. It has an on-chip 100 kΩ pullup resistor.

Programmable as analog inputs (0 to 2.5V) or digital Schmitt

Inputs

Trigger fan tachometer inputs.

Chassis Intrusion event. This line can go high without any clamping action regardless of the powered state of the LM87. There is also an internal open-drain output on this line, controlled by Bit 7 of the CI Clear Register (46h), to provide a minimum 20 ms pulse.

or Ground. Instead, a series 5 kΩ

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Pin Description (Continued)

LM87

Name(s)

GND 8 1 GROUND The system ground pin. Internally connected to all circuitry. The

(+2.8 V to

V +3.8 V)

INT#/ALERT

DACOut/NTEST_IN 11 1 Analog

RESET# 12 1 Digital I/O Master Reset, 5 mA driver (open-drain), active low output with a 20

D1− 13 1 Analog Input Analog input for monitoring the cathode of the first external

D1+ 14 1 Analog Input Analog input for monitoring the anode of the first external

+12Vin 15 1 Analog Input Analog input for monitoring +12 V.

+5Vin 16 1 Analog Input Analog input for monitoring +5 V.

Vccp2/D2− 17 1 Analog Input Digitally programmable analog input for monitoring Vccp2 (0 to 3.6

+2.5Vin/D2+ 18 1 Analog Input Digitally programmable analog input for monitoring +2.5 V or the

Vccp1 19 1 Analog Input Analog input (0 to 3.6 V input range) for monitoring Vccp1, the core

VID4/IRQ4VID0/IRQ0

TOTAL PINS 24

Number

9 1 POWER +3.3 V V+power. Bypass with the parallel combination of 10 µF

10 1 Digital Output Interrupt active low open-drain output. This output is enabled when

20-24 5 Digital Inputs Digitally programmable dual function digital inputs. Can be

Number

of Pins

Type Description

ground reference for all analog inputs and the DAC output. This pin needs to be connected to a low noise analog ground plane for optimum performance of the DAC output.

(electrolytic or tantalum) and 0.1 µF (ceramic) bypass capacitors.

Bit 1 in the Configuration Register is set to 1. The default state is disabled. It has an on-chip 100 kΩ pullup resistor. Alternately used as an active low output to signal SMBus Alert Response Protocol.

0 V to +2.5 V amplitude 8-bit DAC output. When forced high on Output/Digital Input

power up by an external voltage the NAND Tree Test mode is

enabled which provides board-level connectivity testing.

ms minimum pulse width. Available when enabled via Bit 4 in the

Configuration register. It also acts as an active low power on

RESET input. It has an on-chip 100 kΩ pullup resistor.

temperature sensing diode.

V input range) or the cathode of the second external temperature

sensing diode.

anode of the second external temperature sensing diode.

voltage of processore 1.

programmed to monitor the VID pins of the Pentium/PRO and

Pentium II processors, that indicate the operating voltage of the

processor, or as interrupt inputs. The values are read in the

VID/Fan Divisor Register and the VID4 Register. These inputs have

on-chip 100 kΩ pullup resistors.

Indicates Active Low (“Not”)

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Absolute Maximum Ratings (Notes 1,

LM87

If Military/Aerospace specified devices are required,

Vapor Phase (60 seconds) 215 ˚C

Infrared (15 seconds) 235 ˚C

Storage Temperature −65 ˚C to +150 ˚C

please contact the National Semiconductor Sales Office/ Distributors for availability and specifications.

Positive Supply Voltage (V

) +6.0 V

Voltage on Any Input or Output Pin:

+12Vin −0.3 V to +18 V

ADD/NTESTOUT,

DACOut/NTEST_IN, AIN1, AIN2

−0.3 V to

All other pins −0.3 V to +6 V

Input Current at any Pin (Note 4)

Package Input Current (Note 4)

Maximum Junction Temperature

max) 150 ˚C

ESD Susceptibility (Note 6)

Human Body Model 2500 V

Machine Model 150V

Soldering Information

MTC Package (Note 7) :

+ 0.3 V)

5mA

20 mA

Operating Ratings(Notes 1, 2)

Operating Temperature Range T

LM87 −40 ˚C ≤ TA≤ +125 ˚C

Specified Temperature Range T

LM87 −40 ˚C ≤ TA≤ +125 ˚C

Junction to Ambient Thermal Resistance (θ

NS Package Number: MTC24B 95 ˚C/W

Supply Voltage (V

Voltage Range:

) +2.8 V to +3.8 V

+12Vin −0.05 V to +15 V

+5Vin −0.05 V to +6.8 V

+3.3Vin −0.05 V to +4.6 V

+2.5Vin −0.05 V to +3.6 V

VID0 - VID4, Vccp −0.05 V to +6.0 V

All other inputs −0.05 V to (V

MIN

DC Electrical Characteristics

The following specifications apply for +2.8 VDC≤ V+≤ +3.8 VDC, Analog voltage inputs RS= 510 Ω, unless otherwise specified. Boldface limits apply for T

A=TJ=TMIN

to T

Symbol Parameter Conditions Typical Limits Units

POWER SUPPLY CHARACTERISTICS

Supply Current Normal Mode, Interface

TEMPERATURE-TO-DIGITAL CONVERTER CHARACTERISTICS

Temperature Error using Internal Diode

Temperature Error using Remote Pentium Diode Sensor (Note 11) and (Note 12)

Temperature Error using Remote 2N3904 Sensor (Note 11) and (Note 12)

Resolution 8 bits 1.0 ˚C (min)

LM87 ANALOG-TO-DIGITAL CONVERTER CHARACTERISTICS

Resolution 8 bits

TUE Total Unadjusted Error (Note 13)

DNL Differential Non-Linearity

Total Monitoring Cycle Time (Note 14) 0.28 sec

ADC INPUT CHARACTERISTICS

Input Resistance (All analog inputs except AIN1 and AIN2)

AIN1 and AIN2 DC Input Current 12 µA

DAC CHARACTERISTICS

Resolution 8 Bits

; all other limits TA=TJ= 25 ˚C.(Note 8)

MAX

(Note 9) (Note 10) (Limits)

0.7 2.0 mA (max)

Inactive

Shutdown Mode 0.5 mA

3˚C

0˚C≤ T

≤ +125 ˚C, Vcc

3 ˚C (max)

= 3.3 Vdc

−40 ˚C ≤ T

≤ +125 ˚C,

4 ˚C (max)

Vcc = 3.3 Vdc

2 % (max)

1 LSB (max)

130 90 kΩ (min)

≤ TA≤ T

(Note 5))

+ 0.05 V)

MAX

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DC Electrical Characteristics (Continued)

The following specifications apply for +2.8 VDC≤ V+≤ +3.8 VDC, Analog voltage inputs RS= 510 Ω, unless otherwise specified. Boldface limits apply for T

A=TJ=TMIN

to T

Symbol Parameter Conditions Typical Limits Units

DAC CHARACTERISTICS

DAC Error 0 ˚C ≤ T

Output Load Resistance VO= 2.5 V 1250 Ω (min)

Output Load Capacitance 20 pF (max)

FAN RPM-TO-DIGITAL CONVERTER

Fan RPM Error +25 ˚C ≤ T

Full-scale Count 255 (max)

FAN1 and FAN2 Nominal Input RPM (See Section 6.0)

DIGITAL OUTPUTS (NTEST_OUT)

OUT(1)

OUT(0)

Logical “1” Output Voltage I

Logical “0” Output Voltage I

OPEN- DRAIN DIGITAL OUTPUTS (SMBData, RESET

OUT(0)

Logical “0” Output Voltage (SMBData) I

Logical “0” Output Voltage (Others) I

High Level Output Current V

RESET

and Chassis Intrusion 45 20 ms (min)

Pulse Width

DIGITAL INPUTS: VID0–VID4, NTEST_IN, ADD/NTEST_OUT, Chassis Intrusion (CI)

Logical “1” Input Voltage 2.0 V (min)

IN(1)

Logical “0” Input Voltage 0.8 V (max)

IN(0)

SMBus DIGITAL INPUTS (SMBCLK, SMBData)

Logical “1” Input Voltage 2.1 V (min)

IN(1)

Logical “0” Input Voltage 0.8 V (max)

IN(0)

Input Hysteresis Voltage 243 mV

HYST

Tach Pulse Logic Inputs (FAN1, FAN2)

Logical “1” Input Voltage 0.7xV

IN(1)

Logical “0” Input Voltage 0.3xV

IN(0)

ALL DIGITAL INPUTS

Logical “1” Input Current VIN=V

IN(1)

Logical “0” Input Current VIN=0V

IN(0)

Digital Input Capacitance 20 pF

; all other limits TA=TJ= 25 ˚C.(Note 8)

MAX

(Note 9) (Note 10) (Limits)

≤ +75 ˚C, V+=

3.3 V, Code = 255

= 3.3 V, 3/4 Scale,

V code 192

0˚C≤ TA≤ +75 ˚C, V, V

= 3.3 V, Code = 8(Note

15)

≤ +75 ˚C

−10 ˚C ≤ T

−40 ˚C ≤ T

≤ +100 ˚C

≤ +125 ˚C

Divisor = 1, Fan Count = 153 (Note 16)

Divisor = 2, Fan Count = 153 (Note 16)

Divisor = 3, Fan Count = 153 (Note 16)

Divisor = 4, Fan Count = 153 (Note 16)

=±3.0 mA at

OUT

= +2.8 V

=±3.0 mA at

OUT

= +3.8 V

, CI, INT#, THERM#)

= −755 µA 0.4 V (min)

OUT

=−3mA 0.4 V (min)

OUT

-3.3 % (min)

+3.7 %

3 % (max)

10 % (max)

15 % (max)

20 % (max)

8800 RPM

4400 RPM

2200 RPM

1100 RPM

2.4 V (min)

0.4 V (max)

5 12 µA (max)

V (min)

V (max)

−12 µA (min)

12 µA (max)

LM87

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AC Electrical Characteristics

LM87

The following specifications apply for +2.8 VDC≤V+≤ +3.8 VDCon SMBCLK and SMBData, unless otherwise specified. Boldface limits apply for T

A=TJ=TMIN

to T

; all other limits TA=TJ= 25˚C. (Note 17)

MAX

Symbol Parameter Conditions Typical Limits Units

(Note 9) (Note 10) (Limits)

SERIAL BUS TIMING CHARACTERISTICS

rise

fall

SMBCLK (Clock) Period 2.5 µs (min)

SMBCLK and SMBData Rise Time 1 µs (max)

SMBCLK and SMBData Fall Time 300 ns (max)

Data In Setup Time to SMBCLK High 100 ns (min)

Data Out Stable After SMBCLK Low 100 ns (min)

300 ns (max)

SMBData Low Setup Time to SMBCLK Low

100 ns (min)

(start)

SMBData High Hold Time After SMBCLK

100 ns (min)

High (stop)

TIMEOUT

SMBCLK low time required to reset the Serial Bus Interface to the Idle State

25 35

Capacitive Load on SMBCLK and SMBData 80 pF (max)

ms (min)

ms (max)

10099504

FIGURE 1. Serial Bus Timing Diagram

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: The Absolute maximum input range for :

+2.5Vin -−0.3Vto(1.4xV

+3.3Vin -−0.3Vto(1.8xV

Note 4: When the input voltage (V

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 5: The maximum power dissipation must be derated at elevated temperatures and is dictated by T allowable power dissipation at any temperature is P

Note 6: The human body model is a 100 pF capacitor discharged through a 1.5 kΩ resistor into each pin.

Note 7: 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 8: Parasitics and or ESD protection circuitry are shown in the figure below for the LM87’s pins. The nominal breakdown voltage of the zener D3 is 6.5 V. Care should be taken not to forward bias the parasitic diode, D1, present on pins: A0/NTEST_OUT, A1 and DACOut/NTEST_IN. Doing so by more than 50 mV may corrupt a temperature or voltage measurement.

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+ 0.42 V or 6 V, whichever is smaller

+ 0.55 V or 6 V, whichever is smaller.

) at any pin exceeds the power supplies (V

=(TJmax−TA)/θJA.

GND or V

V+), the current at that pin should be limited to 5 mA. The 20 mA

max, θJAand the ambient temperature, TA. The maximum

Pin Name D1 D2 D3 R1 R2 R3 R4 Pin Name D1 D2 D3 R1 R2 R3 R4

INT

xxx0∞100k 1M +12Vin x x R1+R2

∞

≈130k

CI xxx0

∞∞

1M +5Vin x x R1+R2

∞

≈130k

FAN1–FAN2 x x x 0

SMBCLK x x x 0

SMBData x x x 0

RESET

xxx0∞100k 1M DACOut/NTEST_IN x x x 0

ADD/NTEST_OUT x x x 0

∞∞

1M +3.3Vin, +2.5Vin,

x x x R1+R2

Vccp1, Vccp2

1M THERM x x x 0

1M VID4–VID0 x x x 0

≈130k

∞

100k 1M

∞

100k 1M

∞∞

LM87

An x indicates that the diode exists.

10099505

FIGURE 2. ESD Protection Input Structure

Note 9: Typicals are at TJ=TA= 25 ˚C and represent most likely parametric norm.

Note 10: Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level).

Note 11: The Temperature Error specification does not include an additional error of

Note 12: The Temperature Error will vary less than

Note 13: TUE (Total Unadjusted Error) includes Offset, Gain and Linearity errors of the ADC.

Note 14: Total Monitoring Cycle Time includes all diode checks, temperature conversions and analog input voltage conversions. Fan tachometer readings are

determined separately and do not affect the completion of the monitoring cycle.

Note 15: This is the lowest DAC code guaranteed to give a non-zero DAC output.

Note 16: The total fan count is based on 2 pulses per revolution of the fan tachometer output.

Note 17: Timing specifications are tested at the specified logic levels, V

1˚C over the operating Vcc range of 2.8V to 3.8V.

for a falling edge and VIHfor a rising edge.

1˚C, caused by the quantization error.

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Test Circuit

LM87

FIGURE 3. Digital Output Load Test Circuitry

Typical Performance Characteristics

DAC Power Supply Sensitivity

10099506

Functional Description

1.0 GENERAL DESCRIPTION

The LM87 provides 7 analog inputs, an internal junction type temperature sensor, two remote junction temperature sensing channels, a Delta-Sigma ADC (Analog-to-Digital Converter), a DAC output, 2 fan speed counters, WATCHDOG registers, and a variety of inputs and outputs on a single chip. A two wire SMBus Serial Bus interface is included. The LM87 performs power supply, temperature, fan control and fan monitoring for personal computers.

The analog inputs are useful for monitoring several power supplies present in a typical computer. The LM87 includes internal resistor dividers that scale external Vccp1, Vccp2, +2.5V, +5.0 V, +12 V and internal +3.3V power supply volt-

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10099536

ages to a 3/4 scale nominal ADC output. Two additional inputs, +AIN1 and +AIN2 (2.5V full scale) are input directly with no resistive dividers. The LM87 ADC continuously converts the scaled inputs to 8-bit digital words. Measurement of negative voltages (such as -5 V and -12 V power supplies) can be accommodated with an external resistor divider applied to the +AIN1 or +AIN2 inputs. Internal and external temperature is converted to 8-bit two’s-complement digital words witha1˚CLSB.

Fan inputs measure the period of tachometer pulses from the fans, providing a higher count for lower fan speeds. The fan inputs are Schmitt-Trigger digital inputs with an acceptable range of0VtoV mately V this represents a stopped or very slow fan. Nominal speeds, based on a count of 153, are programmable from 1100 to

/2. Full scale fan counts are 255 (8-bit counter) and

and a transition level of approxi-

Functional Description (Continued)

8800 RPM on FAN1 and FAN2. Schmitt-Trigger input circuitry is included to accommodate slow rise and fall times. An 8 bit DAC with 0 V to 2.5 V output voltage range can be used for control of fan speed.

The LM87 has several internal registers, as shown in Figure

4, Table 1. The internal registers and their corresponding internal LM87 addresses are as follows: and Section 13.0.

These include:

Configuration Registers: Provide control and con-

•

figuration. Channel Mode Register: Controls the functionality of

•

the dual purpose input pins, scaling for internal Vcc measurement, and operation of some IRQ inputs.

Interrupt Status Registers: Two registers to provide

•

status of each WATCHDOG limit or Interrupt event. Reading the Status Registers clears any active bits.

Interrupt Status Mirror Registers: Two registers to

•

provide status of each WATCHDOG limit or Interrupt event. Reading the Mirror Registers does not affect the status bits.

Interrupt Mask Registers: Allows masking of indi-

•

vidual Interrupt sources, as well as separate masking for each of the two hardware Interrupt outputs.

CI Clear Register: Allows transmitting a 20 ms (mini-

•

mum) low pulse on the chassis intrusion pin (CI). VID/Fan Divisor Register: This register contains the

•

state of the VID0-VID3 input lines and the divisor bits for FAN1 and FAN2 inputs.

VID4 Register: Contains the state of the VID4 input.

•

Extended Mode Register: Enable and control the

•

Alert Response operation. Hardware High Limit Registers: Registers at 13h,

•

14h, 17h and 18h where Internal and External ’Hardware’ WATCHDOG temperature high limits are stored. These limits have Power On Default settings but can be adjusted by the user. The values stored at 13h and 14h can be locked down by setting bits 1 and 2 of Configuration Register 2.

Value and Limit RAM: The DAC digital output, moni-

•

toring results (temperature, voltages, fan counts), WATCHDOG limits, and Company/Stepping IDs are all contained in the Value RAM. The Value RAM consists of a total of 33 bytes, addresses 19h - 3Fh, containing:

— byte 1 at address 19h contains the DAC Data Regis-

ter

— locations 1Ah and 1Bh contain the WATCHDOG low

limits for AIN1 and AIN2

— locations 1Ch - 1Fh are unassigned and do not have

associated registers

— the next 10 bytes at addresses 20h -29h contain all of

the results

— location 2Ah is unassigned and does not have an

associated register

— the next 18 bytes at addresses 2Bh-3Ch are the

remaining WATCHDOG limits

— the last 2 bytes at addresses 3Eh and 3Fh contain the

Company ID and Stepping ID numbers, respectively

When the LM87 is started, it cycles through each measurement in sequence, and it continuously loops through the sequence approximately once every 0.4 s. Each measured value is compared to values stored in WATCHDOG, or Hardware High Limit registers. When the measured value violates the programmed limit the LM87 will set a corresponding Interrupt in the Interrupt Status Registers. The hardware

Interrupt line INT masking of each Interrupt source. In addition, the Configuration Register has a control bit to enable or disable the hardware Interrupt. Another hardware Interrupt line available, THERM Having a dedicated interrupt for these conditions allows specific actions to be taken for thermal events. This output is enabled by setting bit 2 of Configuration Register 1.

The Chassis Intrusion input is designed to accept an active high signal from an external circuit that activates and latches when the case is removed from the computer.

is fully programmable with separate

is used to signal temperature specific events.

LM87

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Functional Description (Continued)

LM87

2.0 INTERFACE

FIGURE 4. LM87 Register Structure

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10099507

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