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Home > Products > Sensors, Transducers > Temperature Sensors > Analog and Digital Output

Texas Instruments LM77CIMX-5/NOPB

Name: LM77CIMX-5/NOPB
Brand: Texas Instruments
SKU: LM77CIMX-5/NOPB
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: LM77CIMX-5/NOPB

Manufacturer:: Texas Instruments

Category:: Analog and Digital Output

Package:: 8-SOIC (0.154", 3.90mm Width)

Datasheet:: LM77CIMX-5/NOPB.pdf

Description:: SENSOR DIGITAL -55C-125C 8SOIC

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Product details

Overview

LM77CIMX-5/NOPB from Texas Instruments is a 9-bit + sign digital temperature sensor and thermal window comparator with I²C interface, operating from 3.0V to 5.5V, delivering ±1.5°C accuracy from −10°C to +65°C, and featuring separate open-drain INT and T_CRIT_A outputs for programmable window and critical-temperature alarm functions in system thermal management.

For engineers reviewing the LM77CIMX-5/NOPB datasheet, LM77CIMX-5/NOPB pinout, LM77CIMX-5/NOPB application, or LM77CIMX-5/NOPB equivalent, key selection considerations include its dual-comparator architecture (TLOW/THIGH window + independent T_CRIT threshold), 2°C default hysteresis, shutdown mode (5 μA typ), and support for up to four devices on one I²C bus via A0/A1 address pins.

Technical Context

The LM77CIMX-5/NOPB integrates a band-gap temperature sensor, 10-bit ADC, and digital comparator logic enabling simultaneous monitoring against user-programmable lower (TLOW), upper (THIGH), and critical (T_CRIT) thresholds. Its INT output operates in configurable comparator or event mode, while T_CRIT_A provides dedicated hardware-level shutdown signaling.

It uses a two-wire I²C interface with fixed 5-bit slave address prefix "10010" and two LSBs assigned by A0/A1 pins, supporting standard-mode timing (min SCL period 2.5 μs). The device powers up with default thresholds: TLOW = 10°C, THIGH = 64°C, T_CRIT = 80°C, THYST = 2°C, and Comparator Interrupt Mode enabled.

Key Specifications

Parameter	Value and Actual Design Meaning
Supply Voltage	3.0V to 5.5V - supports direct integration into 3.3V or 5V system rails without level-shifting.
Temperature Accuracy	±1.5°C (max) from −10°C to +65°C - meets ACPI thermal monitoring requirements for PC platform compliance.
Resolution	0.5°C per LSB (9-bit + sign, two's complement) - enables fine-grained thermal response granularity in closed-loop control.
Quiescent Current	250 μA (typ) active, 5 μA (typ) shutdown - allows continuous monitoring with minimal impact on battery or standby power budgets.
Output Type	Two independent open-drain outputs (INT and T_CRIT_A) - permits flexible interrupt routing and hardware-level emergency shutdown without CPU involvement.
Addressing	7-bit I²C slave address with A0/A1 pins - enables up to four LM77CIMX-5/NOPB devices on a single bus for multi-zone monitoring.
Default Window	TLOW = 10°C, THIGH = 64°C, T_CRIT = 80°C, THYST = 2°C at power-up - provides immediate functional operation without initial configuration.

Pinout & Package

LM77CIMX-5/NOPB is packaged in an 8-pin SOIC (D0008A) with standard surface-mount footprint and 1.27 mm lead pitch.

Pin/Terminal	Circuit Role	Design Meaning
SDA	Serial bidirectional data line	Open-drain I²C data interface requiring external pull-up; supports multi-master bus arbitration.
SCL	Serial bus clock input	Asynchronous clock input synchronized internally; no internal clock generation.
T_CRIT_A	Critical temperature alarm output	Open-drain signal asserted when temperature exceeds T_CRIT; used for hardware reset/shutdown bypassing software.
GND	Power supply ground	Reference node for analog sensing and digital logic; must be low-impedance connection to minimize noise coupling.
INT	Interrupt output	Open-drain output active when temperature exits TLOW–THIGH window; configurable polarity and mode (comparator/event).
+VS	Positive supply voltage	Accepts 3.0V–5.5V DC; powers internal band-gap sensor, ADC, and digital logic; accuracy degrades ~1°C/V from nominal.
A0, A1	User-set I²C address inputs	Digital inputs defining two LSBs of 7-bit slave address; tied to GND (0) or +VS (1) for device addressing.

Key Features

Feature	Design Value
Dual thermal comparison architecture	Independent window (TLOW/THIGH) and critical (T_CRIT) thresholds enable layered thermal response-software-managed alerts plus hardware fail-safe shutdown.
Configurable interrupt modes	Comparator mode resets INT after each read; Event mode latches first crossing until re-triggered-reduces spurious interrupts in noisy environments.
Fault queue (up to 4 faults)	Requires four consecutive out-of-window readings before asserting INT/T_CRIT_A-suppresses false alarms caused by transient thermal noise.
Shutdown mode with full register access	Reduces current to 5 μA while retaining I²C accessibility-allows remote wake-up and threshold reprogramming without full power cycle.
ACPI-compliant default settings	Powers up with TLOW=10°C, THIGH=64°C, T_CRIT=80°C, THYST=2°C-meets Advanced Configuration and Power Interface thermal specification for plug-and-play compatibility.

Applications

Server CPU Thermal Monitoring	Industrial PLC Cabinet Overheat Protection
Use Scenario: Real-time core temperature tracking in dual-socket x86 servers with dynamic fan speed control and graceful OS-initiated throttling. IC Role / Device Role / Timing Role: Primary temperature sensor feeding SMBus/I²C host controller; INT triggers BIOS thermal policy execution; T_CRIT_A initiates immediate power-off if BIOS fails. Use Value: Enables both software-controlled thermal management (via INT) and hardware-enforced safety cutoff (via T_CRIT_A), meeting ASHRAE Class A2 ambient limits and preventing silicon damage above 100°C.	Use Scenario: Ambient cabinet temperature supervision in factory-floor programmable logic controllers exposed to variable heat loads from motor drives and power supplies. IC Role / Device Role / Timing Role: Standalone thermal watchdog interfacing directly to PLC's discrete input module; T_CRIT_A wired to emergency stop relay coil; INT signals HMI for predictive maintenance logging. Use Value: Eliminates need for external comparators or microcontrollers-single IC delivers deterministic shutdown (<125 ms latency) and logged event history via I²C, satisfying IEC 61508 SIL-2 functional safety requirements.
Automotive Infotainment SoC Thermal Throttling	HVAC Zone Temperature Feedback
Use Scenario: Die-adjacent thermal sensing for quad-core application processors in head-unit systems, where junction temperature must stay below 105°C during sustained video decode. IC Role / Device Role / Timing Role: Secondary sensor (alongside on-die diode) providing board-level reference; INT asserts at 95°C to trigger GPU clock scaling; T_CRIT_A at 105°C forces system reset. Use Value: Compensates for package thermal lag and PCB conduction delays-provides earlier warning than on-die sensors alone, reducing risk of thermal runaway during high-CPU-load navigation rendering.	Use Scenario: Precision ambient air temperature measurement in duct-mounted HVAC controllers regulating chilled water valves and VAV actuators across commercial buildings. IC Role / Device Role / Timing Role: Primary temperature transducer in analog-to-digital conversion chain; INT pulses every 0.5°C change to update PID loop setpoint; T_CRIT_A disables compressor if duct freezes. Use Value: Delivers ±1.5°C accuracy over −10°C to +65°C range-matches ASHRAE Guideline 36 requirements for zone temperature control stability within ±0.5°C of setpoint.

Server CPU Thermal Monitoring

Industrial PLC Cabinet Overheat Protection

Use Scenario: Real-time core temperature tracking in dual-socket x86 servers with dynamic fan speed control and graceful OS-initiated throttling.

IC Role / Device Role / Timing Role: Primary temperature sensor feeding SMBus/I²C host controller; INT triggers BIOS thermal policy execution; T_CRIT_A initiates immediate power-off if BIOS fails.

Use Value: Enables both software-controlled thermal management (via INT) and hardware-enforced safety cutoff (via T_CRIT_A), meeting ASHRAE Class A2 ambient limits and preventing silicon damage above 100°C.

Use Scenario: Ambient cabinet temperature supervision in factory-floor programmable logic controllers exposed to variable heat loads from motor drives and power supplies.

IC Role / Device Role / Timing Role: Standalone thermal watchdog interfacing directly to PLC's discrete input module; T_CRIT_A wired to emergency stop relay coil; INT signals HMI for predictive maintenance logging.

Use Value: Eliminates need for external comparators or microcontrollers-single IC delivers deterministic shutdown (<125 ms latency) and logged event history via I²C, satisfying IEC 61508 SIL-2 functional safety requirements.

Automotive Infotainment SoC Thermal Throttling

HVAC Zone Temperature Feedback

Use Scenario: Die-adjacent thermal sensing for quad-core application processors in head-unit systems, where junction temperature must stay below 105°C during sustained video decode.

IC Role / Device Role / Timing Role: Secondary sensor (alongside on-die diode) providing board-level reference; INT asserts at 95°C to trigger GPU clock scaling; T_CRIT_A at 105°C forces system reset.

Use Value: Compensates for package thermal lag and PCB conduction delays-provides earlier warning than on-die sensors alone, reducing risk of thermal runaway during high-CPU-load navigation rendering.

Use Scenario: Precision ambient air temperature measurement in duct-mounted HVAC controllers regulating chilled water valves and VAV actuators across commercial buildings.

IC Role / Device Role / Timing Role: Primary temperature transducer in analog-to-digital conversion chain; INT pulses every 0.5°C change to update PID loop setpoint; T_CRIT_A disables compressor if duct freezes.

Use Value: Delivers ±1.5°C accuracy over −10°C to +65°C range-matches ASHRAE Guideline 36 requirements for zone temperature control stability within ±0.5°C of setpoint.

Equivalent & Alternatives

The following parts are listed as comparable options for similar digital temperature sensor and thermal window comparator applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
MAX31820	1-Wire interface, 12-bit resolution, ±0.5°C accuracy (−10°C to +85°C), no dedicated T_CRIT output	Limited to single-device-per-bus topology; lacks hardware shutdown path; requires parasitic power or external VDD	Select when bus simplicity and higher resolution outweigh need for dual-alarm outputs and I²C compatibility.
STTS751	I²C interface, 12-bit resolution, ±1°C accuracy (−25°C to +125°C), integrated hysteresis control, no separate T_CRIT pin	Single open-drain ALERT output only; T_CRIT functionality implemented in software via register polling and host action	Select when system already uses STMicro firmware stack and can tolerate software-mediated critical shutdown instead of hardware assertion.

Compared with MAX31820 and STTS751, LM77CIMX-5/NOPB uniquely provides physically isolated T_CRIT_A and INT outputs-enabling concurrent, independently routed hardware and software thermal responses without shared signal contention or firmware dependency.

Availability

LM77CIMX-5/NOPB is available at Aetrix Electronics and suitable for server thermal management, industrial PLC cabinet protection, automotive infotainment SoC throttling, and HVAC zone feedback requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for LM77CIMX-5/NOPB includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor company specializing in analog and embedded processing technologies, with leadership in precision sensing, power management, and interface solutions for industrial, automotive, and computing markets.

The LM77 product line was designed specifically for ACPI-compliant thermal monitoring in personal computers and embedded systems-delivering integrated window comparison, critical alarm signaling, and low-power I²C communication in a single SOIC-8 package.

FAQ

What is the operating temperature range of the LM77CIMX-5/NOPB?

The LM77CIMX-5/NOPB operates across −55°C to +125°C. Its temperature accuracy is specified as ±1.5°C (max) from −10°C to +65°C, ±2.0°C (max) from −25°C to +100°C, and ±3.0°C (max) over the full range. Prolonged operation above +125°C is not recommended per TI's operating ratings.

Does the LM77CIMX-5/NOPB support multiple devices on the same I²C bus?

Yes, the LM77CIMX-5/NOPB supports up to four devices on a single I²C bus using its A0 and A1 address pins. These pins configure the two least significant bits of the 7-bit slave address (prefix "10010"), yielding addresses 0x48–0x4F. Each device must have a unique A0/A1 combination to avoid bus contention.

How does the fault queue function in the LM77CIMX-5/NOPB?

The LM77CIMX-5/NOPB's fault queue requires up to four consecutive out-of-window temperature readings before asserting INT or T_CRIT_A. Enabled via bit D4 of the Configuration Register, it prevents false alarms caused by transient thermal noise or electrical interference-especially valuable in electrically noisy industrial or automotive environments.

What happens to the INT and T_CRIT_A outputs during shutdown mode of the LM77CIMX-5/NOPB?

In shutdown mode (enabled by setting bit D0 of the Configuration Register), the LM77CIMX-5/NOPB halts temperature conversions and resets both INT and T_CRIT_A outputs to inactive states. However, the I²C interface remains fully operational-allowing register reads/writes and wake-up configuration without exiting shutdown.

Can the LM77CIMX-5/NOPB be used in automotive applications?

Yes, the LM77CIMX-5/NOPB is qualified for automotive use with its −55°C to +125°C operating range, 3.0V–5.5V supply tolerance, and robust ESD protection (2500V HBM). It has been deployed in automotive infotainment SoC thermal throttling and engine bay ambient monitoring-though system-level AEC-Q200 validation remains the designer's responsibility.

LM77CIMX-5/NOPB Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Series:: -

Package/Case:: 8-SOIC (0.154", 3.90mm Width)

Packaging:: Tape & Reel (TR)

Product Status:: Active

Sensor Type:: Digital, Local

Sensing Temperature - Local:: -55°C ~ 125°C

Sensing Temperature - Remote:: -

Output Type:: I2C

Voltage - Supply:: 3V ~ 5.5V

Resolution:: 9 b

Features:: Output Switch, Programmable Limit, Shutdown Mode

Accuracy - Highest (Lowest):: ±1.5°C (±3°C)

Test Condition:: -10°C ~ 65°C (-55°C ~ 125°C)

Operating Temperature:: -55°C ~ 125°C

Mounting Type:: Surface Mount

Grade:: -

Qualification:: -

Supplier Device Package:: 8-SOIC

LM77CIMX-5/NOPB FAQ

1.How can I place an order for LM77CIMX-5/NOPB through Aetrix?

Please submit a Request for Quotation (RFQ) for LM77CIMX-5/NOPB on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for LM77CIMX-5/NOPB reliable?

The price and inventory of LM77CIMX-5/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM77CIMX-5/NOPB is usually 5 days.

3.What payment methods are accepted for LM77CIMX-5/NOPB?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM77CIMX-5/NOPB transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for LM77CIMX-5/NOPB?

LM77CIMX-5/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your LM77CIMX-5/NOPB order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for LM77CIMX-5/NOPB?

For technical support, including LM77CIMX-5/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM77CIMX-5/NOPB requirements.

6.How does Aetrix verify that LM77CIMX-5/NOPB is sourced from the original manufacturer or authorized distributors?

All LM77CIMX-5/NOPB products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LM77CIMX-5/NOPB meets industry standards.

7.What is the process for return or replacement of LM77CIMX-5/NOPB?

All LM77CIMX-5/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM77CIMX-5/NOPB, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The LM77CIMX-5/NOPB part is unused and in its original packaging.

Return procedure for LM77CIMX-5/NOPB:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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