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LM87

www.ti.com

SNAS034J –APRIL 2000–REVISED MARCH 2013

LM87 Serial Interface System Hardware Monitor with Remote Diode Temperature Sensing

Check for Samples: LM87

FEATURES

DESCRIPTION

The LM87 is a highly integrated data acquisition

234

• Remote diode temperature sensing (2

system for hardware monitoring of servers, Personal

channels)

Computers, or virtually any microprocessor-based

• 8 positive voltage inputs with scaling resistors

system. In a PC, the LM87 can be used to monitor

for monitoring +5 V, +12 V, +3.3 V, +2.5 V,

power supply voltages, motherboard and processor

Vccp power supplies directly

temperatures, and fan speeds. Actual values for

these inputs can be read at any time. Programmable

• 2 inputs selectable for fan speed or voltage

WATCHDOG limits in the LM87 activate a fully

monitoring

programmable and maskable interrupt system with

• 8-bit DAC output for controlling fan speed

two outputs (INT# and THERM#).

• Chassis Intrusion Detector input

The LM87 has an on-chip digital output temperature

• WATCHDOG comparison of all monitored

sensor with 8-bit resolution as well as the capability of

values

monitoring 2 external diode temperatures to 8-bit

resolution, an 8 channel analog input ADC with 8-bit

• SMBus™ or I

C Serial Bus interface

resolution and an 8-bit DAC. A channel on the ADC

compatibility

measures the supply voltage applied to the LM87,

• VID0-VID4 or IRQ0-IRQ4 monitoring inputs

nominally 3.3 V. Two of the ADC inputs can be

• On chip temperature sensor

redirected to a counter that can measure the speed of

up to 2 fans. A slow speed ΣΔ ADC architecture

APPLICATIONS

allows stable measurement of signals in an extremely

noisy environment. The DAC, with a 0 to 2.5 V output

• System Thermal and Hardware Monitoring for

voltage range, can be used for fan speed control.

Servers, Workstations and PCs

Additional inputs are provided for Chassis Intrusion

• Networking and Telecom Equipment

detection circuits, and VID monitor inputs. The VID

monitor inputs can also be used as IRQ inputs if VID

• Office Electronics

monitoring is not required. The LM87 has a Serial

• Electronic Test Equipment and

Bus interface that is compatible with SMBus™ and

Instrumentation

C™.

KEY SPECIFICATIONS

Connection Diagram

• Voltage Monitoring Error ±2 % (max)

• External Temperature Error ±4 °C (max)

• Internal Temperature Error

– −40 °C to +125 °C ± 3 °C (typ)

• 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

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

2SMBus is a trademark of Intel Corporation.

C is a trademark of dcl_owner.

4All other trademarks are the property of their respective owners.

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of the Texas

Instruments standard warranty. Production processing does not

necessarily include testing of all parameters.

Summary of content (43 pages)

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LM87 www.ti.com SNAS034J – APRIL 2000 – REVISED MARCH 2013 LM87 Serial Interface System Hardware Monitor with Remote Diode Temperature Sensing Check for Samples: LM87 FEATURES DESCRIPTION • Remote diode temperature sensing (2 channels) • 8 positive voltage inputs with scaling resistors for monitoring +5 V, +12 V, +3.3 V, +2.
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LM87 SNAS034J – APRIL 2000 – REVISED MARCH 2013 www.ti.
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LM87 www.ti.com SNAS034J – APRIL 2000 – REVISED MARCH 2013 PIN DESCRIPTIONS (1) Pin Name(s) Pin Number Number of Pins Type Description ADD/NTEST_OUT 1 1 Digital I/0 This pin normally functions as a three-state input that controls the two LSBs of the Serial Bus Address. When this pin is tied to VCC 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.
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LM87 SNAS034J – APRIL 2000 – REVISED MARCH 2013 www.ti.com These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. Absolute Maximum Ratings (1) (2) (3) (4) Positive Supply Voltage (V+) +6.0 V Voltage on Any Input or Output Pin: −0.3 V to +16 V +12Vin −0.3 V to (V++ 0.3 V) ADD/NTESTOUT, DACOut/NTEST_IN, AIN1, AIN2 −0.
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LM87 www.ti.com SNAS034J – APRIL 2000 – REVISED MARCH 2013 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 TA = T J = TMIN to TMAX; all other limits TA = TJ = 25 °C. (1) Symbol Parameter Conditions Typical Limits (2) (3) Normal Mode, Interface Inactive 0.7 2.0 Shutdown Mode 0.
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LM87 SNAS034J – APRIL 2000 – REVISED MARCH 2013 www.ti.com 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 TA = T J = TMIN to TMAX; all other limits TA = TJ = 25 °C.
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LM87 www.ti.com SNAS034J – APRIL 2000 – REVISED MARCH 2013 AC Electrical Characteristics The following specifications apply for +2.8 VDC ≤V+ ≤ +3.8 VDC on SMBCLK and SMBData, unless otherwise specified. Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits T A = TJ = 25°C. (1) Symbol Parameter Conditions Typical (2) Limits (3) Units (Limits) SERIAL BUS TIMING CHARACTERISTICS t1 SMBCLK (Clock) Period 2.
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LM87 SNAS034J – APRIL 2000 – REVISED MARCH 2013 (1) www.ti.com Pin Name D1 D2 D3 R1 R2 R3 R4 Pin Name D1 D2 INT# x (1) x x 0 ∞ 100 k 1M +12Vin x x D3 R1 R1+R2 ≈130k R2 R3 ∞ CI x x x 0 ∞ ∞ 1M +5Vin x x R1+R2 ≈130k ∞ FAN1–FAN2 x x x 0 ∞ ∞ 1M +3.3Vin, +2.
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LM87 www.ti.com SNAS034J – APRIL 2000 – REVISED MARCH 2013 Typical Performance Characteristics DAC Power Supply Sensitivity Figure 4.
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LM87 SNAS034J – APRIL 2000 – REVISED MARCH 2013 www.ti.com FUNCTIONAL DESCRIPTION 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.
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LM87 www.ti.com SNAS034J – APRIL 2000 – REVISED MARCH 2013 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.
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LM87 SNAS034J – APRIL 2000 – REVISED MARCH 2013 www.ti.com Internal Registers of the LM87 Table 1. The internal registers and their corresponding internal LM87 addresses are as follows: Register LM87 Internal Hex Address Power on Value Internal Temp. Hardware High Limit 13h 0100 0110 70 °C Default - User adjustable. Lockable by setting bit 1 of register 4Ah. External Temp. Hardware High Limit 14h 0101 0101 85 °C Default - User adjustable. Lockable by setting bit 2 of register 4Ah.
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LM87 www.ti.com SNAS034J – APRIL 2000 – REVISED MARCH 2013 Serial Bus Interface Figure 6. (a) Serial Bus Write to the Internal Address Register followed by the Data Byte Figure 7. (b) Serial Bus Write to the Internal Address Register Only Figure 8. (c) Serial Bus Read from a Register with the Internal Address Register Preset to Desired Location The Serial Bus control lines consist of the SMBData (serial data), SMBCLK (serial clock) and ADD (address) pin. The LM87 can operate only as a slave.
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LM87 SNAS034J – APRIL 2000 – REVISED MARCH 2013 www.ti.com All of these communications are depicted in the Serial Bus Interface Timing Diagrams as shown in Figure 8. The example shown corresponds to the ADD pin tied to Vcc, so XY=01 and the resulting LM87 address is 0101101. Serial Bus Timeout can be initiated by holding the SMBCLK line low for greater than tTIMEOUT (35 ms max).
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LM87 www.ti.com SNAS034J – APRIL 2000 – REVISED MARCH 2013 Bit 2 of Configuration Register 1 enables the THERM# Interrupt output when this bit is taken high. Bit 3 of Configuration Register 1 clears the INT# output when set high, without affecting the contents of the Interrupt Status Registers. The LM87 will stop monitoring. It will resume upon clearing of this bit. Bit 4 of Configuration Register 1 provides an active low 20 ms (minimum) pulse at the RESET# output when set high.
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LM87 SNAS034J – APRIL 2000 – REVISED MARCH 2013 www.ti.com Starting Conversions The monitoring function (Analog inputs, temperature, and fan speeds) in the LM87 is started by writing to Configuration Register 1 and setting INT_Clear (Bit 3) low, and Start (bit 0) high. The LM87 then performs a “round-robin” monitoring of all analog inputs, temperature, and fan speed inputs approximately once every 0.3 s. The sequence of items being monitored is: 1. Check D1 connections 2. Check D2 connections 3.
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LM87 www.ti.com SNAS034J – APRIL 2000 – REVISED MARCH 2013 ANALOG INPUTS All analog input voltages are digitized to 8-bits of resolution. For safety purposes, and to provide maximum accuracy, a 510 Ω resistor should be placed in series with all analog voltage inputs. The resistors will limit the possible current drawn from the power supplies in the event that circuit board traces are bridged, or accidentally shorted during test.
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LM87 SNAS034J – APRIL 2000 – REVISED MARCH 2013 www.ti.com Inputs with internal resistor dividers (+2.5Vin, +3.3Vin or +5Vin, +12Vin) can have voltage applied that exceeds the power supply up to: 3.6 V for +2.5Vin, 4.6 V for +3.3Vin, 6.8 V for +5Vin, and 15 V for +12Vin. The AIN inputs have a parasitic diode to the positive supply, so care should be taken not to forward bias this diode.
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LM87 www.ti.com SNAS034J – APRIL 2000 – REVISED MARCH 2013 Note that Fan 1 and Fan 2 Divisors are programmable via the VID/Fan Divisor Register. Fan tachometer outputs that provide one pulse per revolution should use a divisor setting twice that of outputs that provide two pulses per revolution. For example, a 4400 RPM fan that provides one pulse per revolution should have the divisor set to 4 such that the nominal counter output is 153.
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LM87 SNAS034J – APRIL 2000 – REVISED MARCH 2013 www.ti.com Fans do not start reliably at reduced voltages, so operation at a reduced voltage should be preceded by a brief (typically 1 second) excursion to full operating voltage, then reduce the voltage. Most fans do not operate at all below 5 to 7 volts. At those lower voltages the fan will simply consume current, dissipate power, and not operate, and such conditions should be avoided.
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LM87 www.ti.com SNAS034J – APRIL 2000 – REVISED MARCH 2013 Internal Temperature Measurement The LM87 internal temperature is monitored using a junction type temperature sensor. Remote Temperature Measurement The LM87 monitors the temperature of remote semiconductor devices using the p-n junction temperature sensing principal. Up to two remote IC, diode or bipolar transistor temperatures can be monitored.
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LM87 SNAS034J – APRIL 2000 – REVISED MARCH 2013 www.ti.com PCB Layout Recommendations for Minimizing Noise In a noisy environment, such as a processor mother board, layout considerations are very critical. Noise induced on traces running between the remote temperature diode sensor and the LM87 can cause temperature conversion errors. The following guidelines should be followed: 1. Place a 0.1 μF power supply bypass capacitor as close as possible to the VCC pin and the recommended 2.
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LM87 www.ti.com SNAS034J – APRIL 2000 – REVISED MARCH 2013 WATCHDOG LIMIT COMPARISONS AND INTERRUPT STRUCTURE Figure 13. Interrupt Structure Figure 13 depicts the Interrupt Structure of the LM87. The LM87 can generate Interrupts as a result of each of its internal WATCHDOG registers on the analog, temperature, and fan inputs. External Interrupts can come from the following sources.
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LM87 SNAS034J – APRIL 2000 – REVISED MARCH 2013 • www.ti.com IRQ input is active. Similarly, to mask off these inputs as interrupt sources, they must be disabled via the Channel Mode Register (16h). IRQ3-4: These are active high inputs from any type of external interrupt source. If enabled via the Channel Mode Register (16h) and Configuration Register 2 (4Ah), the INT# output will be activated whenever these inputs are driven high.
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LM87 www.ti.com SNAS034J – APRIL 2000 – REVISED MARCH 2013 The third group of signals that will generate INT# outputs are Hardware Temperature errors, caused by temperatures exceeding the hardware limits stored at 13h, 14h, 17h, and 18h.The internal temperature value is compared with the Internal Temperature Hardware High Limits in Registers 13h and 17h. The external temperature values are compared with the External Temperature Hardware High Limits in Registers 14h and 18h.
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LM87 SNAS034J – APRIL 2000 – REVISED MARCH 2013 www.ti.com SMBALERT# The INT# I/O pin can alternatively be configured as an SMBALERT# output in conjunction with the SMBALERT# protocol. In this mode of operation, rather than connecting the INT# /ALERT# pin to the system interrupt inputs, it will be connected to the SMBALERT# input pin on the SMBus host. When an INT#/ALERT# type error condition is detected, this pin will notify the SMBus host that an SMBus device has an SMBALERT# condition.
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LM87 www.ti.com SNAS034J – APRIL 2000 – REVISED MARCH 2013 Figure 14. LM87 Interrupt Structure RESET# I/O RESET# is intended to provide a master reset to devices connected to this line. Setting Bit 4 in Configuration Register 1 high outputs a 20 ms (minimum) low pulse on this line, at the end of which Bit 4 in the Configuration Register automatically clears. Again, the label for this pin is only its suggested use.
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LM87 SNAS034J – APRIL 2000 – REVISED MARCH 2013 www.ti.com Figure 15. NAND Tree Test Structure FAN MANUFACTURERS Manufacturers of cooling fans with tachometer outputs are listed below: NMB Tech 9730 Independence Ave. Chatsworth, California 91311 818 341-3355 818 341-8207 Model Number Frame Size Airflow CFM 2408NL 2.36 in sq. X 0.79 in 9-16 (60 mm sq. X 20 mm) 2410ML 2.36 in sq. X 0.98 in 14-25 (60 mm sq. X 25 mm) 3108NL 3.15 in sq. X 0.79 in 25-42 (80 mm sq. X 20 mm) 3110KL 3.15 in sq. X 0.
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LM87 www.ti.com SNAS034J – APRIL 2000 – REVISED MARCH 2013 Model Number Frame Size Airflow CFM (80 mm sq. X 25 mm) REGISTERS AND RAM 13.1 Address Pointer Register The main register is the Address Pointer Register. The bit designations are as follows: Bit Name Read/Write 7-0 Address Pointer Bit 7 Write Description Address of RAM and Registers. See the tables below for detail.
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LM87 SNAS034J – APRIL 2000 – REVISED MARCH 2013 www.ti.com Test Register—Address 15h Power on default – <7:0> = 00000000 binary Bit Name Read/Write 0 Shutdown Read/Write 1 Reserved Read/Write 2 Reserved Read/Write 3 Reserved Read/Write 4 Reserved Read/Write 5 Reserved Read/Write 6 Reserved Read/Write 7 Reserved Read/Write Description A one places the LM87 in a lower power "Shutdown" mode.
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LM87 www.ti.com SNAS034J – APRIL 2000 – REVISED MARCH 2013 Configuration Register 1—Address 40h Power on default – <7:0> = 00001000 binary Bit 0 Name Read/Write Start Description Read/Write A one enables startup of monitoring operations, a zero puts the part in standby mode. Note: The outputs of Interrupt pins will not be cleared if the user writes a zero to this location after an interrupt has occurred, unlike the “INT_Clear” bit. At start up, limit checking functions and scanning begin.
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LM87 SNAS034J – APRIL 2000 – REVISED MARCH 2013 www.ti.com Interrupt Mask Register 1—Address 43h Power on default – <7:0> = 0000 0000 binary Bit Name Read/Write 0 +2.5Vin/D2+ Read/Write A one disables the corresponding interrupt status bit for INT# interrupt. Description 1 Vccp1 Read/Write A one disables the corresponding interrupt status bit for INT# interrupt. 2 Vcc Read/Write A one disables the corresponding interrupt status bit for INT# interrupt.
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LM87 www.ti.com SNAS034J – APRIL 2000 – REVISED MARCH 2013 VID0-3/Fan Divisor Register—Address 47h Power on default – <7:4> is 0101, and <3:0>is mapped to VID <3:0> Bit Name 0-3 VID <3:0> Read/Write Read Only 4-5 FAN1 RPM Control Read/Write Description The VID <3:0> inputs from the Pentium/PRO power supplies that indicate the operating voltage (e.g. 1.5 V to 2.9 V). FAN1 Speed Control. <5:4> = 00 - divide by 1; <5:4> = 01 - divide by 2; <5:4> = 10 - divide by 4; <5:4> = 11 - divide by 8.
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LM87 SNAS034J – APRIL 2000 – REVISED MARCH 2013 www.ti.com Interrupt Status Register 1 Mirror—Address 4Ch Power on default – <7:0> = 0000 0000 binary Bit Name Read Only Description 0 +2.5Vin Read Only A one indicates a High or Low limit has been exceeded. 1 Vccp1 Read Only A one indicates a High or Low limit has been exceeded. 2 Vcc Read Only A one indicates a High or Low limit has been exceeded. 3 +5Vin Read Only A one indicates a High or Low limit has been exceeded. 4 Int. Temp.
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LM87 www.ti.com SNAS034J – APRIL 2000 – REVISED MARCH 2013 Value RAM—Address 19h–3Fh Address A6–A0 Description 19h DAC data register; power on default <7:0>=1111 1111 binary 1Ah AIN1 Low Limit 1Bh AIN2 Low Limit 20h +2.
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LM87 SNAS034J – APRIL 2000 – REVISED MARCH 2013 www.ti.com Note: Setting all ones to the high limits for voltages and fans (0111 1111 binary for temperature) means interrupts will never be generated except the case when voltages go below the low limits. For voltage input high limits, the device is doing a greater than comparison. For low limits, however, it is doing a less than or equal to comparison.
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LM87 www.ti.com SNAS034J – APRIL 2000 – REVISED MARCH 2013 REVISION HISTORY Changes from Revision I (March 2013) to Revision J • Page Changed layout of National Data Sheet to TI format ..........................................................................................................
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PACKAGE OPTION ADDENDUM www.ti.
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PACKAGE OPTION ADDENDUM www.ti.com 1-Nov-2013 continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
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PACKAGE MATERIALS INFORMATION www.ti.com 8-Apr-2013 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant LM87CIMTX TSSOP PW 24 2500 330.0 16.4 6.95 8.3 1.6 8.0 16.0 Q1 LM87CIMTX/NOPB TSSOP PW 24 2500 330.0 16.4 6.95 8.3 1.6 8.0 16.
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PACKAGE MATERIALS INFORMATION www.ti.com 8-Apr-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM87CIMTX TSSOP PW 24 2500 367.0 367.0 35.0 LM87CIMTX/NOPB TSSOP PW 24 2500 367.0 367.0 35.
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