LM76CNMX-3 National Semiconductor, LM76CNMX-3 Datasheet

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LM76CNMX-3

Manufacturer Part Number
LM76CNMX-3
Description
0.5C/ 1C/ 12-Bit Sign Digital Temperature Sensor and Thermal Window Comparator with Two-Wire Interface
Manufacturer
National Semiconductor
Datasheet

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© 2000 National Semiconductor Corporation
LM76
and Thermal Window Comparator with Two-Wire
Interface
General Description
The LM76 is a digital temperature sensor and thermal win-
dow comparator with an I
accuracy of
fied for a −10˚C to 45˚C temperature range, while for the
LM76CNM the temperature range is 70˚C to 100˚C. The
LM76CHM is specified with an accuracy
window-comparator architecture of the LM76 eases the de-
sign of temperature control systems conforming to the ACPI
(Advanced Configuration and Power Interface) specification
for personal computers. The open-drain Interrupt (INT) out-
put becomes active whenever temperature goes outside a
programmable window, while a separate Critical Tempera-
ture Alarm (T_CRIT_A) output becomes active when the
temperature exceeds a programmable critical limit. The INT
output can operate in either a comparator or event mode,
while the T_CRIT_A output operates in comparator mode
only.
The host can program both the upper and lower limits of the
window as well as the critical temperature limit. Program-
mable hysterisis as well as a fault queue are available to
minimize false tripping. Two pins (A0, A1) are available for
address selection. The sensor powers up with default thresh-
olds of 2˚C T
T_CRIT.
The LM76’s 3.3V and 5.0V supply voltage, Serial Bus inter-
face, 12-bit + sign output, and full-scale range of over 127˚C
make it ideal for a wide range of applications. These include
thermal management and protection applications in personal
computers, electronic test equipment, office electronics and
bio-medical applications.
±
I 2 C
®
0.5˚C,
is a registered trademark of Philips Corporation.
±
1˚C. This accuracy for the LM76CHM is speci-
HYST
±
, 10˚C T
1˚C, 12-Bit + Sign Digital Temperature Sensor
2
C
LOW
Serial Bus interface with an
, 64˚C T
±
DS101015
0.5˚C at 25˚C. The
HIGH
, and 80˚C
Features
n Window comparison simplifies design of ACPI
n Serial Bus interface
n Separate open-drain outputs for Interrupt and Critical
n Shutdown mode to minimize power consumption
n Up to 4 LM76s can be connected to a single bus
n 12-bit + sign output; full-scale reading of over 127˚C
Key Specifications
Applications
n System Thermal Management
n Personal Computers
n Office Electronics
n HVAC
n Supply Voltage
n Supply Current
n Temperature
n Resolution
compatible temperature monitoring and control.
Temperature shutdown
Accuracy
−10˚C to +45˚C
70˚C to 100˚C
shutdown
operating
+25˚C
450 µA (max)
January 2000
www.national.com
3.3V or 5.0V
±
±
±
250 µA (typ)
8 µA (max)
0.5˚C(max)
1.0˚C(max)
1.0˚C(max)
0.0625˚C

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LM76CNMX-3 Summary of contents

Page 1

... ® registered trademark of Philips Corporation. © 2000 National Semiconductor Corporation DS101015 Features n Window comparison simplifies design of ACPI compatible temperature monitoring and control. n Serial Bus interface ...

Page 2

... Simplified Block Diagram Connection Diagram Ordering Information Order Number Supply Voltage LM76CHM-5 LM76CHMX-5 LM76CNM-3 LM76CNMX-3 Pin Description Label Pin # SDA 1 Serial Bi-Directional Data Line, Open Drain Output, CMOS Logic Level SCL 2 Serial Bus Clock Input, CMOS Logic Level T_CRIT_A 3 Critical Temperature Alarm, Open Drain Output ...

Page 3

Pin Description (Continued) FIGURE 1. Typical Application 3 DS101015-3 www.national.com ...

Page 4

Absolute Maximum Ratings Supply Voltage Voltage at any Pin −0.3V to (+V Input Current at any Pin Package Input Current (Note 2) T_CRIT_A and INT Output Sink Current T_CRIT_A and INT Output Voltage Storage Temperature Temperature-to-Digital Converter Characteristics Unless otherwise ...

Page 5

Logic Electrical Characteristics DIGITAL DC CHARACTERISTICS Unless otherwise noted, these specifications apply for for +V ± = +5.0 Vdc LM76CNM-3 and for +V 10% for the LM76CHM-5. . Boldface limits apply for +25˚C, unless otherwise ...

Page 6

Logic Electrical Characteristics Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. DC and AC electrical specifications do not apply when operating the device beyond its rated operating conditions. Note 2: When the input ...

Page 7

Functional Description “True”: Temperature above T_CRIT is “true” for HIGH those respective bits. A “true” for T is temperature below LOW T . LOW “False”: Assuming temperature has previously crossed above T or T_CRIT, then the ...

Page 8

Functional Description Note: Event Interrupt mode is drawn as if the user is reading the part. If the user doesn’t read, the outputs would go low and stay that way until the LM76 is read. 1.4 TEMPERATURE DATA FORMAT ...

Page 9

Functional Description and T_CRIT_A outputs. The fault queue is enabled by set- ting bit 4 of the Configuration Register high (see Section 1.11). 1.8 INTERNAL REGISTER STRUCTURE There are four data registers in the LM76, selected by the Pointer ...

Page 10

Functional Description 1.9 POINTER REGISTER (Selects which registers will be read from or written to P0–P2: Register Select P3–P7: Must be kept zero. 1.10 TEMPERATURE REGISTER (Read Only): D15 D14 ...

Page 11

I C Timing Diagrams Typical 2-Byte Read From Preset Pointer Location Such as Temp or Comparison Registers Typical Pointer Set Followed by Immediate Read for 2-Byte Register such as Temp or Comparison Registers Typical 1-Byte Read from Configuration ...

Page 12

Application Hints The temperature response graph in Figure 7 depicts a typi- cal application designed to meet ACPI requirements. In this type of application, the temperature scale is given an arbi- trary value of granularity , or the window ...

Page 13

Application Hints (Continued) Note: Event Interrupt mode is drawn as if the user is reading the part. If the user doesn’t read, the outputs would go low and stay that way until the LM76 is read. FIGURE 7. Temperature ...

Page 14

Typical Applications FIGURE 9. ACPI Compatible Terminal Alarm Shutdown. By powering the LM76 from auxilary output of the power supply, a non-functioning overheated computer can be powered down to preserve as much of the system as www.national.com (Continued) possible. ...

Page 15

... Physical Dimensions inches (millimeters) unless otherwise noted 8-Lead (0.150" Wide) Molded Small Outline Package (SOP), JEDEC Order Number LM76CNM-3, LM76CNMX-3, LM76CHM-5 or LM76CHM-5X LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION ...

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