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Texas Instruments LM74CIM-3
- Part No.:
- LM74CIM-3
- Manufacturer:
- Texas Instruments
- Category:
- Analog and Digital Output
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LM74CIM-3.pdf
- Description:
- SENSOR DIGITAL -55C-150C 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:503
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Product details
Overview
LM74CIM-3 from Texas Instruments is a 12-bit plus sign digital temperature sensor with SPI/MICROWIRE interface, 0.0625°C resolution, −55°C to +150°C operating range, and SOIC-8 package. It functions as a self-contained delta-sigma ADC-based thermal monitor for PCB-level temperature measurement in high-reliability industrial systems.
For engineers reviewing the LM74CIM-3 datasheet, LM74CIM-3 pinout, LM74CIM-3 application, or LM74CIM-3 equivalent, this page delivers verified electrical specs, SOIC-8 terminal mapping, thermal accuracy bands across temperature zones, shutdown current behavior, and validated alternative options for thermal sensing designs requiring wide-range operation and low-power polling.
Technical Context
The LM74CIM-3 integrates a band-gap temperature sensor with a 12-bit plus sign delta-sigma ADC, delivering 13-bit two's complement output where LSB = 0.0625°C. Its serial interface operates in slave mode, compatible with both SPI and MICROWIRE protocols using CS, SC, and bidirectional SI/O lines.
Power management includes continuous conversion mode (265 μA typical supply current) and shutdown mode (<3 μA at V+ = 3.3V), triggered by writing 0xFF to the configuration register. The device powers up in continuous mode with POR-initiated register state and uses D2 as a conversion-complete flag.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Temperature Range | −55°C to +150°C - supports extended industrial and automotive under-hood thermal monitoring. |
| Resolution | 0.0625°C per LSB - enables precise thermal threshold detection and fine-grained system throttling control. |
| Accuracy | ±1.25°C max (−10°C to +65°C); ±3°C max (−55°C to +125°C); ±5°C max (−55°C to +150°C) - calibrated error bounds define usable precision zones. |
| Supply Voltage | 3.0V to 5.5V - compatible with standard 3.3V and 5V logic rails without level-shifting. |
| Quiescent Current | 265 μA typical (DSBGA), 310 μA max (SOIC) - enables low-duty-cycle polling in battery-sensitive applications. |
| Shutdown Current | 3 μA typical at 3.3V - reduces average power in intermittent-read thermal logging systems. |
| Interface Protocol | SPI/MICROWIRE 3-wire (CS, SC, SI/O) - interoperable with common microcontrollers including COP8SA, MSP430, and ARM Cortex-M series. |
Pinout & Package
LM74CIM-3 is housed in an 8-pin SOIC (Package Number D), with exposed pad not present. Thermal resistance θJA = 160°C/W when mounted on 2 oz. copper PCB.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| 1 (SI/O) | Serial I/O bidirectional data line | Tri-state capable; transmits temperature data on falling SC edge, receives config commands on rising SC edge. |
| 2 (SC) | Serial clock input (Schmitt-triggered) | Accepts 0.16 μs minimum clock period; timing-critical for reliable 32-clock read/write cycles. |
| 3 (NC) | No connection | Internally unconnected; must remain floating or grounded per layout best practice. |
| 4 (GND) | Power supply ground | Primary reference for analog core and digital I/O; requires low-impedance PCB return path. |
| 5 (NC) | No connection | Internally unconnected; no external tie required. |
| 6 (NC) | No connection | Internally unconnected; no external tie required. |
| 7 (CS) | Chip select active-low input | Initiates communication; must be stable before first SC edge; supports partial-frame reads. |
| 8 (V+) | Positive supply voltage input | 3.0V–5.5V range; bypass with 0.1 μF ceramic capacitor placed near pin for noise immunity. |
Key Features
| Feature | Design Value |
|---|---|
| 13-bit two's complement output format | Directly encodes temperature with 0.0625°C granularity and signed range; eliminates host-side scaling math. |
| Programmable shutdown mode | Reduces current to <3 μA while retaining bus responsiveness - ideal for wake-on-temperature architectures. |
| Manufacturer ID register | Read-only 16-bit register (0x8000) confirms TI origin and validates firmware compatibility during initialization. |
| Power-on reset (POR) behavior | Guarantees known startup state (D15–D2 = 0xFF00) and D2 flag indicates first valid conversion completion. |
| Thermal path optimization | Die temperature tracked via PCB copper through pins - enables accurate board-level thermal profiling without external sensors. |
Applications
| Server CPU Thermal Throttling | Industrial Motor Drive Protection |
|---|---|
Use Scenario: Real-time die temperature monitoring of multi-core processors in rack-mounted servers to trigger dynamic frequency scaling before thermal shutdown. IC Role / Device Role / Timing Role: Primary temperature sensor feeding thermal management unit (TMU) via SPI; sampled every 100 ms during load peaks. Use Value: 0.0625°C resolution enables early detection of 1–2°C hot-spot drift, allowing proactive throttling before performance collapse. |
Use Scenario: Monitoring heatsink temperature adjacent to IGBT modules in variable-frequency drives to prevent overtemperature fault tripping. IC Role / Device Role / Timing Role: Standalone thermal guard IC interfaced to drive MCU; polled during idle cycles to avoid interrupt latency. Use Value: −55°C to +150°C range covers full motor operational envelope; shutdown mode cuts background power in standby states. |
| Medical Imaging Power Supply Monitoring | Avionics Environmental Control Unit |
Use Scenario: Tracking temperature rise in high-voltage DC-DC converters powering X-ray detector arrays to ensure stability during long exposure sequences. IC Role / Device Role / Timing Role: Secondary thermal sensor on power stage PCB; communicates via isolated SPI to safety controller. Use Value: ±1.25°C accuracy at 25°C ensures calibration traceability; SOIC-8 package allows conformal coating for humidity resistance. |
Use Scenario: Cabin air temperature feedback in flight deck environmental control systems where extended temperature range and reliability are mandated. IC Role / Device Role / Timing Role: Redundant thermal sensor co-located with thermistor network; read asynchronously via shared SPI bus. Use Value: −55°C to +150°C rating meets DO-160 Section 4 extreme ambient requirements; TI-manufactured ID register supports configuration audit trails. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar digital temperature sensor applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX31850KASA+ | 1-Wire interface; 0.125°C resolution; −40°C to +125°C range; integrated cold-junction compensation for thermocouples. | Designed for thermocouple-based systems; lacks native SPI/MICROWIRE support and extended −55°C lower limit. | Select when thermocouple integration is required and SPI bus loading must be minimized. |
| ADT7410TRZ-REEL7 | I²C interface; 0.0625°C resolution; −55°C to +150°C range; 200 μA typical supply current; 16-bit output. | Requires I²C pull-ups and arbitration handling; no shutdown command - relies on master-controlled clock stretching. | Prefer when existing system uses I²C infrastructure and higher conversion rate (200 ms max) is acceptable. |
Compared with MAX31850KASA+ and ADT7410TRZ-REEL7, LM74CIM-3 offers native SPI/MICROWIRE compatibility, guaranteed −55°C operation, and deterministic sub-10 μA shutdown - making it optimal for legacy microcontroller interfaces and ultra-low-quiescent thermal logging.
Availability
LM74CIM-3 is available at Aetrix Electronics and suitable for server thermal management, industrial motor protection, medical power supply monitoring, and avionics environmental control requiring stable component supply across extended temperature ranges and long product lifecycles.
Supply support for LM74CIM-3 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 founded in 1930, specializing in analog and embedded processing technologies with broad industrial, automotive, and communications product portfolios.
The LM74 family was designed specifically for high-accuracy, wide-range digital temperature sensing in space-constrained systems requiring minimal external components and direct microcontroller integration.
FAQ
What is the absolute maximum supply voltage for LM74CIM-3?
The absolute maximum supply voltage for LM74CIM-3 is 6.0V. Operation above this level risks permanent damage. The recommended operating range remains 3.0V to 5.5V, and exceeding 6.0V voids TI's standard warranty. LM74CIM-3 includes internal protection against transient overvoltage, but sustained overvoltage conditions must be avoided in layout design. Always verify V+ rail stability with oscilloscope during power-up sequencing.
Does LM74CIM-3 support true SPI mode 0 (CPOL=0, CPHA=0)?
Yes, LM74CIM-3 supports SPI mode 0: SC idles low (CPOL=0), data is sampled on the rising edge and shifted out on the falling edge (CPHA=0). This matches MICROWIRE timing and is explicitly confirmed in the functional description. LM74CIM-3 does not support mode 3 or dual-data-rate modes. Host firmware must assert CS before the first SC edge and maintain stable CS during full 32-clock transactions for reliable register access.
How is temperature data formatted in the LM74CIM-3 output register?
LM74CIM-3 outputs temperature as a 13-bit two's complement word (D15–D3), where D15 is the sign bit and LSB = 0.0625°C. Bits D1–D0 are undefined and tri-stated; D2 is the conversion-complete flag. For example, 0x0C87 = +25°C, 0xFFFF = −0.0625°C. The first byte read is MSB-aligned, enabling partial reads for rapid overtemperature detection without full 16-bit transfer.
Can LM74CIM-3 be used in reflow-soldered assemblies?
Yes, LM74CIM-3 in SOIC-8 (D package) is rated for lead-free reflow per MSL Level-1 (260°C peak). TI specifies compliance with JEDEC J-STD-020 moisture sensitivity standards. Boards must follow TI's published reflow profile - ramp rate ≤3°C/s, time above 217°C ≤60 seconds, peak ≤260°C. Avoid repeated reflow cycles; post-reflow cleaning must use non-ionic flux removers to prevent corrosion of SOIC leads.
What is the thermal resistance (θJA) of LM74CIM-3 on a standard PCB?
The published junction-to-ambient thermal resistance (θJA) for LM74CIM-3 is 160°C/W when mounted on a 2 oz. copper PCB with standard SOIC footprint and no thermal vias. This value assumes natural convection only; forced airflow or added copper pour can reduce effective θJA. LM74CIM-3's die temperature tracking relies on conduction through its pins - so thermal vias under GND and V+ pads significantly improve accuracy in high-power-density layouts.
LM74CIM-3 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Last Time Buy
- Sensor Type:
- Digital, Local
- Sensing Temperature - Local:
- -55°C ~ 150°C
- Sensing Temperature - Remote:
- -
- Output Type:
- SPI
- Voltage - Supply:
- 3V ~ 5.5V
- Resolution:
- 12 b
- Features:
- Shutdown Mode
- Accuracy - Highest (Lowest):
- 1.25°C (±5°C)
- Test Condition:
- -10°C ~ 65°C (-55°C ~ 150°C)
- Operating Temperature:
- -55°C ~ 150°C
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
- Supplier Device Package:
- -
LM74CIM-3 FAQ
1.How can I place an order for LM74CIM-3 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM74CIM-3 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 LM74CIM-3 reliable?
The price and inventory of LM74CIM-3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM74CIM-3 is usually 5 days.
3.What payment methods are accepted for LM74CIM-3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM74CIM-3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM74CIM-3?
LM74CIM-3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM74CIM-3 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 LM74CIM-3?
For technical support, including LM74CIM-3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM74CIM-3 requirements.
6.How does Aetrix verify that LM74CIM-3 is sourced from the original manufacturer or authorized distributors?
All LM74CIM-3 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 LM74CIM-3 meets industry standards.
7.What is the process for return or replacement of LM74CIM-3?
All LM74CIM-3 units undergo pre-shipment inspection (PSI). If there is an issue with LM74CIM-3, 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 LM74CIM-3 part is unused and in its original packaging.
Return procedure for LM74CIM-3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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