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Texas Instruments LM77CIMM-3/NOPB
- Part No.:
- LM77CIMM-3/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- Analog and Digital Output
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
LM77CIMM-3/NOPB.pdf
- Description:
- SENSOR DIGITAL -55C-125C 8VSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,659
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Product details
Overview
LM77CIMM-3/NOPB from Texas Instruments is a 9-bit + sign digital temperature sensor and thermal window comparator with I²C interface, ±2°C accuracy from −25°C to +100°C, 3.0V–5.5V supply range, and dual open-drain outputs (INT and T_CRIT_A) for programmable thermal monitoring in ACPI-compliant PC power management systems.
For engineers reviewing the LM77CIMM-3/NOPB datasheet, LM77CIMM-3/NOPB pinout, LM77CIMM-3/NOPB application, or LM77CIMM-3/NOPB equivalent, key selection criteria include its dual-threshold window comparison architecture, critical shutdown alarm output, 2°C hysteresis programmability, fault queue support, and VSSOP-8 package compatibility with space-constrained thermal sensing nodes.
Technical Context
The LM77CIMM-3/NOPB integrates a band-gap temperature sensor, 10-bit ADC, and digital comparator with independently programmable TLOW (10°C default), THIGH (64°C default), and T_CRIT (80°C default) thresholds. Its two-wire I²C slave interface uses a fixed 5-bit address prefix "10010" with A0/A1 pins defining LSBs for up to four devices on one bus.
It supports two interrupt modes: Comparator mode (output resets after each read and reasserts if condition persists) and Event mode (output latches until next threshold-crossing event). The T_CRIT_A output operates exclusively in comparator mode and drives hardware shutdown circuitry independent of host processor response.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 3.0V to 5.5V - Enables direct interface with 3.3V or 5V system rails without level-shifting. |
| Temperature Accuracy | ±2°C max from −25°C to +100°C - Sufficient for PC thermal throttling and HVAC setpoint control. |
| Resolution | 0.5°C per LSB (9-bit + sign, two's complement) - Provides fine-grained thermal trend detection. |
| Quiescent Current | 250 μA typical operating / 5 μA typical shutdown - Supports low-power embedded monitoring with rapid wake-up. |
| Conversion Time | 70–125 ms - Determines minimum interval between valid temperature updates for real-time response. |
| Output Type | Two open-drain outputs (INT and T_CRIT_A) - Allows flexible pull-up configuration and wire-OR capability. |
| Address Pins | A0 and A1 - Enable up to four LM77CIMM-3/NOPB devices on a single I²C bus without address conflict. |
Pinout & Package
VSSOP-8 package (DGK0008A), 3.0 mm × 3.0 mm body, 0.65 mm pitch, exposed thermal pad (not electrically connected).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SDA | I²C bidirectional data line | Open-drain output requiring external pull-up; shares bus with other I²C slaves. |
| SCL | I²C clock input | Asynchronous master-driven timing signal; no internal clock generation. |
| T_CRIT_A | Critical temperature alarm output | Asserts when temperature exceeds T_CRIT; used for hardware-initiated shutdown, independent of software. |
| GND | Power supply ground reference | Common return path for analog sensor core and digital logic; must be low-impedance. |
| INT | Thermal window interrupt output | Asserts when temperature falls below TLOW or rises above THIGH; configurable polarity and mode. |
| +VS | Positive supply voltage input | Accepts 3.0V–5.5V; powers internal band-gap sensor, ADC, and digital logic. |
| A1, A0 | I²C address select inputs | Set device address LSBs; tied high/low to configure unique 7-bit slave address on shared bus. |
Key Features
| Feature | Design Value |
|---|---|
| ACPI-compatible thermal monitoring | Meets Advanced Configuration and Power Interface specification for OS-directed thermal management in PCs and servers. |
| Programmable hysteresis (THYST) | Configurable 2°C default hysteresis prevents false triggering near trip points; applied asymmetrically to TLOW, THIGH, and T_CRIT. |
| Fault queue (up to 4 faults) | Requires four consecutive out-of-window readings before asserting INT/T_CRIT_A - suppresses noise-induced false alarms in EMI-prone environments. |
| Dual interrupt modes | Comparator mode (auto-reset on read) and Event mode (edge-triggered latching) enable flexible host firmware strategies for thermal event handling. |
| Shutdown mode via I²C | Reduces supply current to 5 μA while retaining register access - ideal for battery-backed or always-on thermal watchdog applications. |
Applications
| Server CPU Thermal Throttling | Industrial PLC Cabinet Monitoring |
|---|---|
|
Use Scenario: Real-time die temperature tracking during high-load compute cycles to prevent thermal runaway in dual-socket x86 servers. IC Role / Device Role / Timing Role: Primary thermal sensor feeding ACPI _TMP object; triggers OS-level frequency scaling and alerts BMC via SMBus. Use Value: ±2°C accuracy over −25°C to +100°C ensures reliable throttling activation before silicon damage; dual INT/T_CRIT_A outputs separate graceful throttling from emergency shutdown. |
Use Scenario: Continuous ambient temperature surveillance inside sealed industrial control cabinets housing motor drives and I/O modules. IC Role / Device Role / Timing Role: Standalone thermal watchdog interfacing directly to PLC microcontroller via I²C; monitors for slow cabinet heat buildup due to fan failure. Use Value: Fault queue rejects transient spikes from switching transients; shutdown mode extends battery life in backup-powered monitoring during AC loss. |
| Automotive Infotainment SoC Protection | HVAC Zone Temperature Sensing |
|
Use Scenario: Protecting quad-core application processors in head-unit systems exposed to cabin temperature extremes from −40°C to +85°C. IC Role / Device Role / Timing Role: Secondary thermal monitor co-located with SoC; asserts T_CRIT_A to cut power to PMIC upon reaching 105°C junction limit. Use Value: T_CRIT_A hardwired output bypasses firmware latency; VSSOP-8 footprint fits tight PCB space near processor BGA; 3.3V nominal operation matches SoC IO rail. |
Use Scenario: Distributed temperature sensing across multiple HVAC zones using low-cost wired thermostats with local microcontrollers. IC Role / Device Role / Timing Role: Local sensor node providing 0.5°C-resolution readings to zone controller; INT output signals deviation >±1°C from setpoint for proportional fan speed adjustment. Use Value: Programmable TLOW/THIGH window enables zone-specific comfort bands; A0/A1 addressing allows daisy-chained wiring with single I²C master. |
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 |
|---|---|---|---|
| LM75BIMM-3/NOPB | Lacks T_CRIT_A output and critical shutdown alarm; only single INT output with fixed hysteresis; no fault queue. | Suitable for basic temperature logging but not for safety-critical thermal shutdown where hardware-level response is required. | Select LM77CIMM-3/NOPB when dual-threshold window comparison and independent critical alarm output are mandatory. |
| MAX31820MUA+ | 1-Wire interface instead of I²C; higher ±0.5°C accuracy; integrated 12-bit ADC; no dedicated T_CRIT output. | Better suited for distributed sensor networks with long cable runs, but requires 1-Wire master and lacks ACPI-compliant dual-interrupt architecture. | Choose LM77CIMM-3/NOPB for I²C-based systems needing ACPI compliance, hardware shutdown, and multi-device bus scalability. |
Compared with LM75BIMM-3/NOPB and MAX31820MUA+, the LM77CIMM-3/NOPB uniquely delivers simultaneous window monitoring and critical alarm signaling via separate open-drain outputs, enabling both software-managed throttling and hardware-initiated shutdown in a single VSSOP-8 device - essential for robust thermal protection in computing and industrial platforms.
Availability
LM77CIMM-3/NOPB is available at Aetrix Electronics and suitable for server thermal management, industrial PLC cabinet monitoring, automotive infotainment SoC protection, and HVAC zone sensing requiring stable component supply and long-term lifecycle support.
Supply support for LM77CIMM-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 specializing in analog and embedded processing technologies, with leadership in precision sensing, power management, and interface solutions.
The LM77 series belongs to TI's precision analog temperature sensor product line, designed specifically for ACPI-compliant thermal monitoring and hardware-safe critical shutdown in computing, industrial, and automotive systems.
FAQ
What is the default power-up behavior of the LM77CIMM-3/NOPB?
At power-up, the LM77CIMM-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 set to the Temperature Register. These defaults ensure immediate functional readiness without host initialization.
How does the fault queue function in the LM77CIMM-3/NOPB?
The LM77CIMM-3/NOPB fault queue requires 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 electrical noise or transient thermal spikes - critical in motor drive or switching power supply environments.
Can the LM77CIMM-3/NOPB operate from a 3.3V supply?
Yes, the LM77CIMM-3/NOPB is specified for 3.0V to 5.5V operation and is tested at +3.3V ±10% for the "-3" suffix variant. Its I²C logic levels scale with supply voltage, ensuring reliable communication with 3.3V microcontrollers without level shifters.
What is the purpose of the T_CRIT_A output on the LM77CIMM-3/NOPB?
The T_CRIT_A output on the LM77CIMM-3/NOPB is a dedicated open-drain alarm that activates only when temperature exceeds the programmable T_CRIT threshold. It is intended for direct connection to hardware shutdown circuitry - bypassing firmware latency to force immediate power-down when critical thermal limits are breached.
How many LM77CIMM-3/NOPB devices can share one I²C bus?
Up to four LM77CIMM-3/NOPB devices can be connected to a single I²C bus using the A0 and A1 address pins. These pins configure the two LSBs of the 7-bit slave address (prefix "10010"), yielding addresses 0x48–0x4F - enabling scalable multi-zone thermal monitoring without bus contention.
LM77CIMM-3/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- 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-VSSOP
LM77CIMM-3/NOPB FAQ
1.How can I place an order for LM77CIMM-3/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM77CIMM-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 LM77CIMM-3/NOPB reliable?
The price and inventory of LM77CIMM-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 LM77CIMM-3/NOPB is usually 5 days.
3.What payment methods are accepted for LM77CIMM-3/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM77CIMM-3/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM77CIMM-3/NOPB?
LM77CIMM-3/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM77CIMM-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 LM77CIMM-3/NOPB?
For technical support, including LM77CIMM-3/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM77CIMM-3/NOPB requirements.
6.How does Aetrix verify that LM77CIMM-3/NOPB is sourced from the original manufacturer or authorized distributors?
All LM77CIMM-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 LM77CIMM-3/NOPB meets industry standards.
7.What is the process for return or replacement of LM77CIMM-3/NOPB?
All LM77CIMM-3/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM77CIMM-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 LM77CIMM-3/NOPB part is unused and in its original packaging.
Return procedure for LM77CIMM-3/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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