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LM77

www.ti.com

SNIS103F –JUNE 1999–REVISED MARCH 2013

LM77 9-Bit + Sign Digital Temperature Sensor and Thermal Window Comparator with

Two-Wire Interface

Check for Samples: LM77

FEATURES

DESCRIPTION

The LM77 is a digital temperature sensor and thermal

• Window Comparison Simplifies Design of

window comparator with an I

C Serial Bus interface.

ACPI Compatible Temperature Monitoring and

The window-comparator architecture of the LM77

Control.

eases the design of temperature control systems

• Serial Bus Interface

conforming to the ACPI (Advanced Configuration and

Power Interface) specification for personal

• Separate Open-Drain Outputs for Interrupt and

computers. The open-drain Interrupt (INT) output

Critical Temperature Shutdown

becomes active whenever temperature goes outside

• Shutdown Mode to Minimize Power

a programmable window, while a separate Critical

Consumption

Temperature Alarm (T_CRIT_A) output becomes

• Up to 4 LM77s Can be Connected to a Single

active when the temperature exceeds a

Bus

programmable critical limit. The INT output can

operate in either a comparator or event mode, while

• 9-bit + Sign Output; Full-Scale Reading of Over

the T_CRIT_A output operates in comparator mode

128°C

only.

• SOIC and VSSOP 8-lead Packages

The host can program both the upper and lower limits

of the window as well as the critical temperature limit.

APPLICATIONS

Programmable hysterisis as well as a fault queue are

• System Thermal Management

available to minimize false tripping. Two pins (A0, A1)

are available for address selection. The sensor

• Personal Computers

powers up with default thresholds of 2°C T

HYST

, 10°C

• Office Electronics

LOW

, 64°C T

HIGH

, and 80°C T_CRIT.

• Electronic Test Equipment

The LM77's 3.0V to 5.5V supply voltage range, Serial

• Automotive

Bus interface, 9-bit + sign output, and full-scale range

• HVAC

of over 128°C make it ideal for a wide range of

applications. These include thermal management and

KEY SPECIFICATIONS

protection applications in personal computers,

electronic test equipment, office electronics,

• Supply Voltage 3.0V to 5.5V

automotive, and HVAC applications.

• Supply Current

– Operating

– 250 μA (typ)

– 500 μA (max)

– Shutdown

– 5 μA (typ)

• Temperature Accuracy

– −10°C to 65°C, ±1.5°C(max)

– −25°C to 100°C, ±2°C(max)

– −55°C to 125°C, ±3°C(max)

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.

2All 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 (23 pages)

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LM77 www.ti.com SNIS103F – JUNE 1999 – REVISED MARCH 2013 LM77 9-Bit + Sign Digital Temperature Sensor and Thermal Window Comparator with Two-Wire Interface Check for Samples: LM77 FEATURES DESCRIPTION • The LM77 is a digital temperature sensor and thermal window comparator with an I2C Serial Bus interface.
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LM77 SNIS103F – JUNE 1999 – REVISED MARCH 2013 www.ti.com Simplified Block Diagram Figure 1. Connection Diagram Figure 2. SOIC-8 or VSSOP Package See Package Number D0008A or DGK0008A PIN DESCRIPTIONS Pin Name Pin No. Description Typical Connection SDA 1 Serial Bi-Directional Data Line.
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LM77 www.ti.com SNIS103F – JUNE 1999 – REVISED MARCH 2013 Typical Application Figure 3. Typical Application 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) −0.3V to 6.5V Supply Voltage −0.3V to (+VS + 0.
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LM77 SNIS103F – JUNE 1999 – REVISED MARCH 2013 www.ti.com Temperature-to-Digital Converter Characteristics Unless otherwise noted, these specifications apply for +VS=+5 Vdc ±10% for LM77CIM-5, LM77CIMM-5 and +VS=+3.3 Vdc ±10% for LM77CIM-3, LM77CIMM-3 (1). Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits TA= TJ=+25°C, unless otherwise noted. Parameter Accuracy Test Conditions Typical (2) Limits (3) TA = −10°C to +65°C ±1.5 TA = −25°C to +100°C ±2.0 TA = −55°C to +125°C ±3.
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LM77 www.ti.com SNIS103F – JUNE 1999 – REVISED MARCH 2013 Logic Electrical Characteristics Digital DC Characteristics (continued) Unless otherwise noted, these specifications apply for +VS=+5 Vdc ±10% for LM77CIM-5, LM77CIMM-5 and +VS=+3.3 Vdc ±10% for LM77CIM-3, LM77CIMM-3. Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits TA= TJ=+25°C, unless otherwise noted. Parameter VOL Low Level Output Voltage T_CRIT_A Output Saturation Voltage Test Conditions Typical (1) IOL = 3 mA IOUT = 4.
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LM77 SNIS103F – JUNE 1999 – REVISED MARCH 2013 www.ti.com Figure 5.
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LM77 www.ti.com SNIS103F – JUNE 1999 – REVISED MARCH 2013 FUNCTIONAL DESCRIPTION The LM77 temperature sensor incorporates a band-gap type temperature sensor, 10-bit ADC, and a digital comparator with user-programmable upper and lower limit values. The comparator activates either the INT line for temperatures outside the TLOW and THIGH window, or the T_CRIT_A line for temperatures which exceed T_CRIT. The lines are programmable for mode and polarity.
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LM77 SNIS103F – JUNE 1999 – REVISED MARCH 2013 www.ti.com Avoid programming setpoints so close that their hysteresis values overlap. An example would be that with a THYST value of 2°C then setting THIGH and TLOW to within 4°C of each other will violate this restriction. To be more specific, with THYST set to 2°C assume THIGH set to 64°C. If TLOW is set equal to, or higher than 60°C this restriction is violated. DEFAULT SETTINGS The LM77 always powers up in a known state.
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LM77 www.ti.com SNIS103F – JUNE 1999 – REVISED MARCH 2013 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 LM77 is read. Figure 7. Temperature Response Diagram TEMPERATURE DATA FORMAT Temperature data can be read from the Temperature and Set Point registers; and written to the Set Point registers.
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LM77 SNIS103F – JUNE 1999 – REVISED MARCH 2013 www.ti.com SHUTDOWN MODE Shutdown mode is enabled by setting the shutdown bit in the Configuration register via the Serial Bus. Shutdown mode reduces power supply current to 5 μA typical. T_CRIT_A is reset if previously set. Since conversions are stoped during shutdown, T_CRIT_A and INT will not be operational. The Serial Bus interface remains active. Activity on the clock and data lines of the Serial Bus may slightly increase shutdown mode quiescent current.
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LM77 www.ti.com SNIS103F – JUNE 1999 – REVISED MARCH 2013 Reading the LM77 can take place either of two ways: If the location latched in the Pointer is correct (most of the time it is expected that the Pointer will point to the Temperature register because it will be the data most frequently read from the LM77), then the read can simply consist of an address byte, followed by retrieving the corresponding number of data bytes.
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LM77 SNIS103F – JUNE 1999 – REVISED MARCH 2013 www.ti.com D0: Shutdown - When set to 1 the LM77 goes to low power shutdown mode. Power up default of “0”. D1: Interrupt mode - 0 is Comparator Interrupt mode, 1 is Event Interrupt mode. Power up default of “0”. D2, D3: T_CRIT_A and INT Polarity - 0 is active low, 1 is active high. Outputs are open-drain. Power up default of “0” D4: Fault Queue - When set to 1 the Fault Queue is enabled, see FAULT QUEUE. Power up default of “0”.
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LM77 www.ti.com SNIS103F – JUNE 1999 – REVISED MARCH 2013 Figure 13. Typical Pointer Set Followed by Immediate Read from Configuration Register Figure 14. Configuration Register Write Comparison Register Write Figure 15. Timing Diagrams Application Hints The temperature response graph in Figure 16 depicts a typical application designed to meet ACPI requirements.
PAGE 14
LM77 SNIS103F – JUNE 1999 – REVISED MARCH 2013 www.ti.com The Critical Alarm Event activates the separate T_CRIT_A output. Typically, this would feed circuitry separate from the processor on the assumption that if the system reached this temperature, the processor might not be responding. 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 LM77 is read. Figure 16.
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LM77 www.ti.com SNIS103F – JUNE 1999 – REVISED MARCH 2013 Figure 18. Remote HVAC temperature sensor communicates via 3 wires including thermostat signals By powering the LM77 from auxilary output of the power supply, a non-functioning overheated computer can be powered down to preserve as much of the system as possible. Figure 19.
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LM77 SNIS103F – JUNE 1999 – REVISED MARCH 2013 www.ti.com REVISION HISTORY Changes from Revision E (March 2013) to Revision F • 16 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 (3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. (4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device. (5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device.
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PACKAGE MATERIALS INFORMATION www.ti.com 23-Sep-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 LM77CIMM-3/NOPB VSSOP DGK 8 1000 178.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 LM77CIMM-5/NOPB VSSOP DGK 8 1000 178.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 LM77CIMMX-3/NOPB VSSOP DGK 8 3500 330.0 12.4 5.3 3.4 1.4 8.0 12.
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PACKAGE MATERIALS INFORMATION www.ti.com 23-Sep-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM77CIMM-3/NOPB VSSOP DGK 8 1000 210.0 185.0 35.0 LM77CIMM-5/NOPB VSSOP DGK 8 1000 210.0 185.0 35.0 LM77CIMMX-3/NOPB VSSOP DGK 8 3500 367.0 367.0 35.0 LM77CIMMX-5/NOPB VSSOP DGK 8 3500 367.0 367.0 35.0 LM77CIMX-3 SOIC D 8 2500 367.0 367.0 35.0 LM77CIMX-3/NOPB SOIC D 8 2500 367.0 367.0 35.
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