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Texas Instruments LM74CIMX-3
- Part No.:
- LM74CIMX-3
- Manufacturer:
- Texas Instruments
- Category:
- Analog and Digital Output
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LM74CIMX-3.pdf
- Description:
- SENSOR DIGITAL -55C-150C 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,306
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Product details
Overview
LM74CIMX-3 from Texas Instruments is a 12-bit plus sign delta-sigma temperature sensor IC with SPI/MICROWIRE interface, 0.0625°C resolution, −55°C to +150°C operating range, and SOIC-8 package. It delivers precise die-temperature measurement for thermal management in high-reliability industrial and embedded systems.
For engineers reviewing the LM74CIMX-3 datasheet, LM74CIMX-3 pinout, LM74CIMX-3 application, or LM74CIMX-3 equivalent, this page provides verified functional identity, validated SOIC-8 pin mapping, confirmed temperature accuracy bands (±1.25°C max over −10°C to +65°C), shutdown current (3 μA typ), and real-world thermal sensing use cases - all tied explicitly to the LM74CIMX-3/NOPB.A ordering variant.
Technical Context
The LM74CIMX-3 integrates a band-gap temperature sensor and 12-bit plus sign ΔΣ ADC, delivering digital temperature data via a 3-wire SPI/MICROWIRE-compatible serial interface. Its continuous conversion mode outputs updated readings every 425 ms (SOIC), while shutdown mode reduces quiescent current to 3 μA at 3.3 V.
It operates from 3.0 V to 5.5 V, supports tri-state output on SI/O, and uses a 16-clock transmit phase followed by optional 8–16 clock receive phase for configuration. The device ID register (0x8000) and dedicated shutdown command (0xFF) enable firmware-level identification and power control without external logic.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Temperature Resolution | 0.0625°C per LSB - enables fine-grained thermal monitoring for fan speed control or overtemperature shutdown thresholds. |
| Operating Range | −55°C to +150°C - supports under-hood automotive, industrial motor drives, and high-temp PCB environments. |
| Accuracy | ±1.25°C max (−10°C to +65°C); ±3.0°C max (−55°C to +125°C) - calibrated performance across extended industrial range. |
| Supply Current | 265 μA typical (active), 3 μA typical (shutdown) - enables low-duty-cycle thermal polling in battery-backed systems. |
| Interface | SPI/MICROWIRE 3-wire (CS, SC, SI/O) - interoperable with standard microcontroller SPI peripherals without protocol translation. |
| Conversion Time | 425 ms max (SOIC package) - deterministic update interval for time-triggered thermal logging or alarm evaluation. |
| Package | SOIC-8 (Package Code D) - industry-standard footprint compatible with automated assembly and thermal pad design rules. |
Pinout & Package
LM74CIMX-3 is housed in an 8-pin SOIC (Small Outline Integrated Circuit) package (TI Package Code D), optimized for surface-mount reflow assembly and board-level thermal coupling. Pin functions are electrically and mechanically validated per TI's SNIS107K datasheet Figures 2 and 4.
| 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 commands on rising SC edge. |
| 2 (SC) | Serial clock input (Schmitt trigger) | Accepts up to 10 MHz clock; timing-critical for read/write synchronization per SPI/MICROWIRE spec. |
| 3 (NC) | No connection | Internally unconnected; must remain floating - no routing or grounding permitted. |
| 4 (GND) | Power supply ground | Primary return path for analog/digital currents; requires low-impedance PCB plane connection. |
| 5 (NC) | No connection | Internally unconnected; must remain floating - no routing or grounding permitted. |
| 6 (NC) | No connection | Internally unconnected; must remain floating - no routing or grounding permitted. |
| 7 (CS) | Chip select input | Active-low enable; initiates communication sequence and controls SI/O tri-state behavior. |
| 8 (V+) | Positive supply voltage input | 3.0 V to 5.5 V operation; requires 0.1 μF ceramic bypass capacitor placed adjacent to pin. |
Key Features
| Feature | Design Value |
|---|---|
| 12-bit plus sign temperature output | Two's complement format with 0.0625°C LSB - eliminates software sign-extension and simplifies host-side arithmetic. |
| Shutdown mode with 3 μA typical current | Enables ultra-low-power thermal polling intervals (e.g., once per second) without external power gating circuitry. |
| Manufacturer/Device ID register | Fixed 0x8000 value readable in shutdown - allows firmware to verify presence and authenticity of LM74CIMX-3 at boot. |
| SOIC-8 package with exposed thermal pad | θJA = 160°C/W on 2 oz copper - supports direct PCB heat sinking for improved long-term calibration stability. |
| Robust digital interface | Input hysteresis ≥0.35 V and 20 pF input capacitance - tolerates noisy industrial bus environments without external filtering. |
Applications
| Server CPU Thermal Monitoring | Disk Drive Spindle Control |
|---|---|
|
Use Scenario: Real-time junction temperature tracking of multi-core processors in 1U rack servers. IC Role / Device Role / Timing Role: Die-temperature sensor feeding closed-loop fan control and throttling logic via SPI. Use Value: ±1.25°C accuracy over −10°C to +65°C ensures reliable thermal margining before CPU thermal trip activation. |
Use Scenario: Monitoring spindle motor housing temperature in enterprise SAS/SATA HDDs. IC Role / Device Role / Timing Role: Embedded temperature node reporting to drive controller MCU via MICROWIRE. Use Value: 425 ms conversion time aligns with drive idle-state polling windows, minimizing impact on I/O throughput. |
| Industrial PLC Cabinet Protection | Laser Diode Driver Thermal Feedback |
|
Use Scenario: Ambient cabinet temperature supervision in programmable logic controllers operating from −40°C to +70°C. IC Role / Device Role / Timing Role: Standalone thermal watchdog interfacing directly to PLC main processor GPIO/SPI. Use Value: −55°C to +150°C range covers full storage-to-operating transition; 3 μA shutdown current extends backup battery life. |
Use Scenario: Co-located die temperature feedback for high-power 980 nm pump laser diodes in fiber amplifiers. IC Role / Device Role / Timing Role: Precision analog front-end sensor providing real-time TEC control setpoint correction. Use Value: 0.0625°C resolution enables sub-degree stabilization critical for wavelength drift compensation in DWDM systems. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar temperature sensor applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX31855KASA+ | K-type thermocouple amplifier with cold-junction compensation; no on-chip sensor; 0.25°C accuracy; SPI-only interface. | Requires external thermocouple; suited for high-temp (>300°C) industrial furnaces, not die-temperature monitoring. | Select only when measuring remote metal surfaces - not a functional replacement for LM74CIMX-3's integrated silicon sensor. |
| ADT7410TRZ-REEL7 | 16-bit I²C temperature sensor; ±0.25°C accuracy (−20°C to +85°C); 200 μA active current; MSOP-8 package. | I²C interface requires different MCU peripheral setup; narrower temp range (−55°C to +150°C not fully specified); higher cost. | Prefer for I²C-based designs needing higher resolution; LM74CIMX-3 remains optimal for SPI-constrained or wide-range legacy systems. |
Compared with MAX31855KASA+ and ADT7410TRZ-REEL7, the LM74CIMX-3 uniquely combines SPI/MICROWIRE compatibility, SOIC-8 footprint, −55°C to +150°C guaranteed range, and 3 μA shutdown current - making it the only drop-in solution for space-constrained, wide-temperature, low-power embedded thermal monitoring where pin count and interface reuse matter.
Availability
LM74CIMX-3 is available at Aetrix Electronics and suitable for server thermal management, industrial PLC cabinet protection, disk drive spindle control, and laser diode driver feedback requiring stable component supply across extended temperature and long product lifecycles.
Supply support for LM74CIMX-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 leader specializing in analog, embedded processing, and connectivity technologies, with decades of expertise in precision sensing and industrial-grade reliability.
The LM74 series was designed specifically for high-accuracy, low-power, digitally interfaced temperature sensing in harsh thermal environments - targeting applications where die-temperature fidelity, wide operating range, and interface simplicity are critical.
FAQ
What is the guaranteed temperature accuracy of the LM74CIMX-3 over its full operating range?
The LM74CIMX-3 guarantees ±1.25°C maximum error from −10°C to +65°C, ±2.1°C maximum from −25°C to +110°C, and ±3.0°C maximum from −55°C to +125°C. At the extreme end of its range (−55°C to +150°C), accuracy degrades to ±5.0°C maximum. These values are measured at V+ = 3.0 V to 3.6 V and are documented in TI's SNIS107K datasheet Section 6.3.
Does the LM74CIMX-3 support both SPI and MICROWIRE protocols simultaneously?
Yes - the LM74CIMX-3 implements a single 3-wire serial interface (CS, SC, SI/O) that is electrically and timing-compatible with both SPI Mode 0 (CPOL = 0, CPHA = 0) and MICROWIRE standards. Data is clocked out on the falling edge of SC and sampled on the rising edge, matching both specifications without mode selection or configuration.
What is the correct shutdown command sequence for the LM74CIMX-3?
To enter shutdown mode, the host must write 0xFF (hex) to the LM74CIMX-3 configuration register - transmitted as two bytes: 0x00 followed by 0xFF, or any 16-bit word ending in 0xFF (e.g., 0xXXFF). Upon receipt, the LM74CIMX-3 immediately drops supply current to ≤10 μA and begins outputting its Manufacturer ID (0x8000) on subsequent reads.
Can the LM74CIMX-3 be used in ultraviolet-exposed environments?
No - UV exposure is not a concern for the LM74CIMX-3 because it uses a SOIC-8 plastic package (not DSBGA), which fully encapsulates the die in opaque epoxy. Unlike the DSBGA variants (e.g., LM74CITPX-3), the LM74CIMX-3 has no light-sensitive EEPROM and is immune to UV-induced calibration drift.
What is the thermal resistance (θJA) of the LM74CIMX-3 in its SOIC-8 package?
The LM74CIMX-3 has a junction-to-ambient thermal resistance (θJA) of 160°C/W when mounted on a standard PCB with 2 oz copper foil, per TI's SNIS107K datasheet Section 6.1. This value assumes proper thermal land pattern and solder paste coverage - critical for maintaining long-term accuracy in high-temperature applications.
LM74CIMX-3 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Not For New Designs
- 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:
- 8-SOIC
LM74CIMX-3 FAQ
1.How can I place an order for LM74CIMX-3 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM74CIMX-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 LM74CIMX-3 reliable?
The price and inventory of LM74CIMX-3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM74CIMX-3 is usually 5 days.
3.What payment methods are accepted for LM74CIMX-3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM74CIMX-3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM74CIMX-3?
LM74CIMX-3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM74CIMX-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 LM74CIMX-3?
For technical support, including LM74CIMX-3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM74CIMX-3 requirements.
6.How does Aetrix verify that LM74CIMX-3 is sourced from the original manufacturer or authorized distributors?
All LM74CIMX-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 LM74CIMX-3 meets industry standards.
7.What is the process for return or replacement of LM74CIMX-3?
All LM74CIMX-3 units undergo pre-shipment inspection (PSI). If there is an issue with LM74CIMX-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 LM74CIMX-3 part is unused and in its original packaging.
Return procedure for LM74CIMX-3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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