LM79 NSC [National Semiconductor], LM79 Datasheet
LM79
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LM79 Summary of contents
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... ADC. An input is provided for the overtemperature outputs of additional temperature sensors and this is linked to the interrupt system. The LM79 provides inputs for three fan tachometer outputs. Additional inputs are provided for Chassis Intrusion detection circuits, 5 VID moni- tor inputs, and chainable interrupt ...
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Typical Application www.national.com 2 DS100036-1 ...
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... Internally connected to all digital circuitry. Digital Input Chainable SMI (System Management Interrupt) Input. This is an active low input that propagates the SMI signal to the SMI output of the LM79 via SMI Mask Register Bit 6 and SMI enable Bit 1 of the Configuration Register. ...
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Pin Description (Continued) Pin Pin Number Name(s) Number of Pins Power 16 1 Switch Bypass FAN3–FAN1 17–19 3 SCL 20 1 SDA 21 1 RESET 22 1 VID4/NTEST 23 1 GNDA 24 1 −IN6 25 1 FB6 26 1 FB5 ...
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... Storage Temperature Operating Ratings 6.5V −0. +0.3V) Operating Temperature Range CC ± 300 mV LM79 ± Specified Temperature Range ± LM79 Junction to Ambient Thermal Resistance ( 150˚C NS Package ID: VGZ44A Supply Voltage (V 2000V Ground Difference 175V (IGNDD–GNDAI) V Voltage Range IN V +5. 8.33 MHz, R ...
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DC Electrical Characteristics The following specifications apply for +4.25 V fied. Boldface limits apply for Symbol Parameter FAN RPM-TO-DIGITAL CONVERTER FAN1 and FAN2 Nominal Input RPM (See Section 6.0 ) FAN3 Design Nominal Input RPM Internal ...
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AC Electrical Characteristics +5.75 V unless otherwise specified. Boldface limits apply for T DC 25˚C. Symbol Parameter ISA TIMING CHARACTERISTICS f System Clock (SYSCLK) Input Frequency SYSCLK t (setup) CS Active to IORD/IOWR Active CS t (hold) IORD/IOWR Inactive to ...
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AC Electrical Characteristics +5.75 V unless otherwise specified. Boldface limits apply for T DC 25˚C. (Continued) Symbol ISA READ TIMING t (setup) Data Valid to IORD Inactive SDRD t (hold) IORD Inactive to Data Invalid SDRD t (setup) IORD Active ...
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... 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 LM79. There are parasitic diodes that exist between the inputs and the power supply rails. Errors in the ADC conversion CC can occur if these diodes are forward biased by more than 50 mV ...
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AC Electrical Characteristics +5.75 V unless otherwise specified. Boldface limits apply for T DC 25˚C. (Continued indicates that the diode exists. Pin Name IORD x IOWR x SYSCLK x D0– SMI__IN x ...
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... The state of VID4 is reflected in this register. The identity of the divice being used can be determined by reading the state of the D7 of this register. An LM79 would be identified when D7 is set high. • POST RAM: POST codes. Overflow of the POST RAM will set an Interrupt ...
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... The LM79s Internal Address Register -Port x6h: Data Register IORD is the standard ISA bus signal that indicates to the LM79 that it may drive data on to the ISA data bus. IOWR is the standard ISA command to the LM79 that it may latch data from the ISA bus. ...
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... Functional Description (Continued) FIGURE 6. LM79 Register Structure 13 DS100036-9 www.national.com ...
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... Functional Description 2.1 Internal Registers of the LM79 TABLE 1. The internal registers and their corresponding internal LM79 address is as follows: Register LM79 Internal Hex (This is the data to be written to Port x5h) Configuration Register Interrupt Status Register 1 Interrupt Status Register 2 SMI Mask Register 1 SMI Mask Register 2 ...
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... Register which Auto-Increments with ISA communi- cations, the Register must be manually incremented for Serial Bus communications. The default power on Serial Bus address for the LM79 is: 0101101 binary. This address can be changed by writing any desired value to the Serial Bus address register, which can be done either via the ISA or Serial Bus ...
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... Reset function described in Section 3.2. Bit 0 of the Configuration Register controls the monitoring loop of the LM79. Setting Bit 0 low stops the LM79 monitor- ing loop and puts the LM79 in shutdown mode, reducing power consumption. ISA and Serial Bus communication is www ...
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... V best noise immunity. Alternatively, use a shunt reference or zener diode to clamp the input level. If fans can be powered while the power to the LM79 is off, the LM79 inputs will provide diode clamping. Limit input current to the Input Current at Any Pin specification shown in the ABSOLUTE MAXIMUM RATINGS section ...
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Functional Description Voltage Measurements (V +2.50V +3.30V +5V +12V −12V −5V FIGURE 8. Input Examples. Resistor Values Shown Provide Approximately 3V at the Analog Inputs www.national.com (Continued NONE 0 ...
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Functional Description (a) Fan with Tach Pull-Up to +5V (c) Fan with Tach Pull-Up to +12V and Diode Clamp Counts are based on 2 pulses per revolution tachometer outputs. RPM Time per Revolution 4400 13.64 ms 3080 19.48 ms 2640 ...
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... Temperature Interrupts The normal mode for temperature interrupts in the LM79 is an “Interrupt” mode operating in the following way: Exceed- ing T causes an interrupt that will remain active indefinitely OI until reset by reading Interrupt Status Register 1. Once an ...
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... FIGURE 12. Interrupt Structure ceeds a programmed threshold LM75’s can be connected to a single Serial Bus bus with their O.S. output’s wire or’d to the BTI input of the LM79. If the temperature of any LM75 exceeds its programmed limit, it drives BTI low. This generates an Interrupt to notify the host of a possible overtemperature condition ...
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... BIOS will output Power On Self Test codes. A write to the POST RAM auto-increments the internal pointer of the LM79 bytes may be stored. An excess of 32 bytes will generate an Interrupt and stop incrementing. The POST RAM is read as like any other register at Ports x5h and x6h, with the POST RAM located at the LM79 Internal Address from 00h to 1Fh ...
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Functional Description 12.0 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 Num- Frame Size ber 2408NL 2.36 in sq. X 0.79 in (60 ...
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... Address of RAM and Registers. See the tables below for detail. A one indicates the device is busy because of a Serial Bus transaction or another ISA bus transaction. With checking this bit, multiple ISA drivers can use LM79 without interfering with each other or a Serial Bus driver. ...
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Functional Description 13.2 Data Register (Port x6h) < > Power on default 7:0 = 00h Bit Name Read/ Write 7–0 Data Read/Write Data to be read from written to RAM and Register. 13.3 Configuration Register — Address ...
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Functional Description 13.4 Interrupt Status Register 1 — Address 41h < > Power on default 7:0 = 00h Bit Name Read/Write 0 IN0 Read Only 1 IN1 Read Only 2 IN2 Read Only 3 IN3 Read Only 4 Temperature Read ...
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Functional Description 13.7 SMI Mask Register 2 — Address 44h < > Power on default 7:0 = 00h Bit Name Read/ Write 0 IN4 Read/Write 1 -IN5 Read/Write 2 -IN6 Read/Write 3 FAN3 Read/Write 4 Chassis Intrusion Read/Write 5 FIFO ...
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... Serial Bus address 6:0 < > 7:0 = 1100 000X. VID4 input A one will reset all the registers of the LM79 to the power on default state. LM79 device identification. The LM78 has IN0 reading IN1 reading IN2 reading IN3 reading IN4 reading -IN5 reading -IN6 reading ...
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Functional Description Address A6–A0 with Address A6–A0 Auto-Increment 29h 69h 2Ah 6Ah 2Bh 6Bh 2Ch 6Ch 2Dh 6Dh 2Eh 6Eh 2Fh 6Fh 30h 70h 31h 71h 32h 72h 33h 73h 34h 74h 35h 75h 36h 76h 37h 77h 38h 78h ...
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... Typical Application FIGURE 13. In this PC application the LM79 monitors temperature, fan speed for 3 fans, and 7 power supply voltages. It also monitors the O.S. Output LM75 digital temperature sensors as well www.national.com as an optical chassis intrusion detector. 30 DS100036-22 ...
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... National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications. inches (millimeters) unless otherwise noted Order Number LM79CCVF NS Package Number VGZ44A 2 ...