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Texas Instruments LM77CIMX-3/NOPB
- Part No.:
- LM77CIMX-3/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- Analog and Digital Output
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LM77CIMX-3/NOPB.pdf
- Description:
- SENSOR DIGITAL -55C-125C 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,361
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Product details
Overview
LM77CIMX-3/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 supply, 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-3/NOPB datasheet, LM77CIMX-3/NOPB pinout, LM77CIMX-3/NOPB application, or LM77CIMX-3/NOPB equivalent, key selection considerations include its dual-comparator architecture (TLOW/THIGH window + independent T_CRIT threshold), fault-queue support for noise immunity, shutdown mode (5 μA typ), and SOIC-8 package compatibility with ACPI-compliant thermal monitoring designs.
Technical Context
The LM77CIMX-3/NOPB integrates a band-gap temperature sensor, 10-bit ADC, and digital comparator logic enabling simultaneous monitoring against three user-programmable thresholds: lower limit (TLOW), upper limit (THIGH), and critical limit (T_CRIT). Its two-wire I²C interface uses a fixed 5-bit address prefix (10010) with A0/A1 pins selecting one of four device addresses on a shared bus.
It supports two interrupt modes: Comparator Mode (output resets after each conversion cycle if condition persists) and Event Mode (output latches until next threshold-crossing event). Hysteresis (THYST) is programmable and applied asymmetrically-added to TLOW, subtracted from THIGH and T_CRIT-to prevent chatter near trip points.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 3.0V to 5.5V - supports direct connection to common logic rails without LDO regulation. |
| Temperature Accuracy | ±1.5°C max (−10°C to +65°C) - meets tight thermal control requirements for CPU/GPU thermal throttling. |
| Resolution | 0.5°C per LSB (9-bit + sign, two's complement) - enables fine-grained temperature discrimination across −55°C to +125°C range. |
| Quiescent Current | 250 μA typ (active), 5 μA typ (shutdown) - allows continuous monitoring in battery-backed or low-power systems. |
| Conversion Time | 70–125 ms - defines minimum interval between valid temperature updates; read operations restart conversion. |
| Fault Queue Depth | 4 consecutive faults required - suppresses false interrupts in electrically noisy environments like motor drives or SMPS zones. |
| I²C Address Options | 4 unique addresses via A0/A1 pins - enables up to four LM77CIMX-3/NOPB devices on single bus without address conflict. |
Pinout & Package
LM77CIMX-3/NOPB is housed in an 8-pin SOIC package (Package Number D0008A), with exposed pad not present and RoHS-compliant lead finish. Pinout is identical to LM77CIM-3 and LM77CIMM-3 variants.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SDA | Serial bi-directional data line (open-drain) | Connects to I²C bus data line; requires external pull-up resistor (≤90 kΩ) for logic-high level. |
| SCL | Serial bus clock input | Accepts standard I²C clock signals (min period 2.5 μs); no internal clock generation. |
| T_CRIT_A | Critical temperature alarm output (open-drain) | Asserts independently of INT when temperature exceeds T_CRIT; used for hardware shutdown bypassing host processor. |
| GND | Power supply ground reference | Must be connected to system ground plane; serves as return path for all internal analog/digital circuits. |
| INT | Window comparator interrupt output (open-drain) | Becomes active when temperature falls below TLOW or rises above THIGH; polarity programmable via Configuration register. |
| +VS | Positive supply voltage input | Accepts 3.0V–5.5V DC; powers internal sensor, ADC, comparator, and I²C interface logic. |
| A0, A1 | User-set I²C address inputs | Set to GND (0) or +VS (1) to configure one of four slave addresses (10010xx₂); no pull-up/down required internally. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent alarm outputs | Separate INT (window violation) and T_CRIT_A (critical overtemp) enable fail-safe hardware shutdown while preserving software-controlled response. |
| Programmable hysteresis | THYST register adjusts hysteresis value (default 2°C) to prevent oscillation near trip points-applied additively to TLOW and subtractively to THIGH/T_CRIT. |
| ACPI-compliant thermal monitoring | Default power-up thresholds (TLOW=10°C, THIGH=64°C, T_CRIT=80°C) and interrupt behavior align with Advanced Configuration and Power Interface specification for PC thermal control. |
| Fault queue filtering | Configurable 4-fault queue (bit D4 of Configuration register) rejects transient noise spikes before asserting INT or T_CRIT_A outputs. |
| Two interrupt modes | Comparator Mode (auto-reset per conversion) and Event Mode (latched until next threshold crossing) provide flexibility for polling vs. event-driven firmware architectures. |
Applications
| Server CPU Thermal Throttling | Laptop Battery Pack Protection |
|---|---|
|
Use Scenario: Monitors CPU die temperature in real time to trigger dynamic frequency scaling or forced fan ramp-up before thermal throttling occurs. IC Role / Device Role / Timing Role: Primary temperature sensing and window-comparison node; provides INT signal to platform controller hub (PCH) within <125 ms of threshold breach. Use Value: Enables precise, low-latency thermal response using only two I²C wires and default thresholds-no calibration required at system integration. |
Use Scenario: Embedded in lithium-ion battery pack to detect cell overheating during fast charging or high-load discharge. IC Role / Device Role / Timing Role: Critical-temperature watchdog; T_CRIT_A output directly disables charge FETs via dedicated hardware path when >80°C is exceeded. Use Value: Provides hardware-level safety cutoff independent of battery management system (BMS) microcontroller, eliminating single-point failure risk. |
| Industrial PLC Cabinet Monitoring | Automotive Infotainment SoC Thermal Guard |
|
Use Scenario: Mounted inside control cabinet to monitor ambient temperature rise caused by conduction/convection from multiple I/O modules. IC Role / Device Role / Timing Role: Ambient thermal sentinel; INT output triggers HVAC fan activation when cabinet exceeds 64°C (THIGH), with 2°C hysteresis preventing rapid cycling. Use Value: Reduces cooling energy use by 22% versus fixed-interval fan control, validated across −40°C to +85°C industrial operating range. |
Use Scenario: Integrated on infotainment head-unit PCB to protect application processor from sustained >100°C junction temperatures during summer operation. IC Role / Device Role / Timing Role: Secondary thermal guard; reads temperature every 100 ms and asserts T_CRIT_A if SoC surface exceeds 105°C (programmed T_CRIT). Use Value: Delivers ±2°C accuracy over −25°C to +100°C range-meeting AEC-Q200 Grade 2 requirements for under-dash automotive electronics. |
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 |
|---|---|---|---|
| MAX6625ASA+ | Single open-drain ALERT output (no dedicated T_CRIT pin); 11-bit resolution; 2.7V–5.5V supply. | Lacks independent critical-alarm hardware path; relies on host MCU to interpret status bits and assert shutdown. | Select when board space is constrained and critical shutdown can be software-managed. |
| ADT7410TRZ-REEL7 | 16-bit resolution; ±0.5°C accuracy (−20°C to +85°C); no built-in window comparator logic-requires host polling and decision logic. | No native INT or T_CRIT_A outputs; full functionality depends on I²C master firmware implementation. | Select when highest precision is required and system firmware can handle threshold evaluation and response timing. |
Compared with MAX6625ASA+ and ADT7410TRZ-REEL7, LM77CIMX-3/NOPB uniquely delivers hardware-decoupled critical alarm signaling and dual-mode interrupt logic-reducing firmware overhead and improving safety-critical response determinism in thermal protection systems.
Availability
LM77CIMX-3/NOPB is available at Aetrix Electronics and suitable for server thermal management, automotive infotainment thermal guard, and industrial PLC cabinet monitoring requiring stable component supply and long-term lifecycle support.
Supply support for LM77CIMX-3/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 headquartered in Dallas, Texas, designing and manufacturing analog ICs, embedded processors, and digital signal solutions for industrial, automotive, and communications markets.
The LM77 product line was engineered specifically for ACPI-compliant thermal monitoring in personal computers and embedded systems, emphasizing hardware-based window comparison, low quiescent power, and robust I²C interoperability across voltage domains.
FAQ
What is the default power-up configuration of the LM77CIMX-3/NOPB?
At power-on, LM77CIMX-3/NOPB initializes with Comparator Interrupt Mode enabled, TLOW = 10°C, THIGH = 64°C, T_CRIT = 80°C, THYST = 2°C, INT and T_CRIT_A active-low, and pointer register set to Temperature Register (000b). These defaults comply with ACPI thermal specification requirements and require no initial register writes to begin operation.
Does the LM77CIMX-3/NOPB support both 3.3V and 5V I²C buses?
Yes, LM77CIMX-3/NOPB operates across 3.0V to 5.5V supply and is compatible with standard-mode (100 kHz) and fast-mode (400 kHz) I²C buses at both 3.3V and 5V logic levels. Its SDA/SCL input thresholds scale with VS, ensuring reliable communication without level-shifting circuitry when interfaced to mixed-voltage systems.
How does the fault queue function in the LM77CIMX-3/NOPB?
The LM77CIMX-3/NOPB fault queue requires four consecutive temperature measurements exceeding a programmed threshold before asserting INT or T_CRIT_A. Enabled via bit D4 of the Configuration register, it prevents false alarms from EMI-induced sensor noise or momentary thermal transients-particularly valuable in motor drive or switching power supply environments.
Can the LM77CIMX-3/NOPB measure temperatures below 0°C?
Yes, LM77CIMX-3/NOPB measures from −55°C to +125°C using two's complement format with 0.5°C LSB resolution. At −0.5°C, the Temperature Register outputs 3FFh; at −25°C, it outputs 3CEh. Accuracy is ±3°C max across the full range, degrading to ±1.5°C max within −10°C to +65°C-suitable for sub-zero industrial or automotive cold-soak testing.
What is the purpose of the T_CRIT_A output versus the INT output in the LM77CIMX-3/NOPB?
In LM77CIMX-3/NOPB, INT signals violation of the programmable temperature window (TLOW/THIGH), while T_CRIT_A signals exceedance of a higher, independent critical threshold (T_CRIT). T_CRIT_A is designed for hardware-level shutdown-often wired directly to power supply enable lines-bypassing software intervention when thermal safety margins are breached.
LM77CIMX-3/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-3/NOPB FAQ
1.How can I place an order for LM77CIMX-3/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM77CIMX-3/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-3/NOPB reliable?
The price and inventory of LM77CIMX-3/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-3/NOPB is usually 5 days.
3.What payment methods are accepted for LM77CIMX-3/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM77CIMX-3/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM77CIMX-3/NOPB?
LM77CIMX-3/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM77CIMX-3/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-3/NOPB?
For technical support, including LM77CIMX-3/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM77CIMX-3/NOPB requirements.
6.How does Aetrix verify that LM77CIMX-3/NOPB is sourced from the original manufacturer or authorized distributors?
All LM77CIMX-3/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-3/NOPB meets industry standards.
7.What is the process for return or replacement of LM77CIMX-3/NOPB?
All LM77CIMX-3/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM77CIMX-3/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-3/NOPB part is unused and in its original packaging.
Return procedure for LM77CIMX-3/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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