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Texas Instruments LM71CIMFX/NOPB
- Part No.:
- LM71CIMFX/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- Analog and Digital Output
- Package:
- SC-74A, SOT-753
- Datasheet:
-
LM71CIMFX/NOPB.pdf
- Description:
- SENSOR DIGITAL -40C-150C SOT23-5
- Quantity:
- Payment:
- Shipping:
Inventory:2,925
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Product details
Overview
LM71CIMFX/NOPB from Texas Instruments is a high-accuracy, low-power digital temperature sensor with SPI/MICROWIRE-compatible three-wire serial interface, 14-bit delta-sigma ADC, ±1.5°C max error (−10°C to +65°C), 0.03125°C resolution, and operates from −40°C to +150°C in a 5-pin SOT-23 package - used for real-time thermal monitoring in embedded microcontroller systems.
For engineers reviewing the LM71CIMFX/NOPB datasheet, LM71CIMFX/NOPB pinout, LM71CIMFX/NOPB application, or LM71CIMFX/NOPB equivalent, key selection considerations include its 2.65V–5.5V supply range, 300 µA typical operating current, 270 ms max conversion time, two's complement 14-bit output format, and compatibility with standard SPI/MICROWIRE controllers without level-shifting.
Technical Context
The LM71CIMFX/NOPB integrates a precision silicon diode-based temperature sensing element with a 13-bit plus sign delta-sigma ADC (effectively 14-bit output), delivering 0.03125°C LSB resolution. Its serial interface uses chip-select (CS), slave clock (SC), and bidirectional SI/O lines, with data clocked out on SC falling edges and sampled on rising edges.
It features three internal registers: read-only temperature register (14-bit two's complement), read-only manufacturer/device ID register (accessed in shutdown mode), and write-only configuration register controlling shutdown vs. continuous conversion modes. Power-up defaults to continuous conversion, requiring ≥270 ms before first valid read.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 2.65V to 5.5V - supports direct connection to common logic rails (3.3V, 5V) without regulation. |
| Temperature Range | −40°C to +150°C - suitable for under-hood automotive, industrial motor control, and high-temp PCB environments. |
| Accuracy | ±1.5°C max (−10°C to +65°C); +3/−2°C max (−40°C to +150°C) - enables reliable thermal throttling and fault detection. |
| Resolution | 0.03125°C per LSB (14-bit two's complement) - allows fine-grained temperature trending and differential measurements. |
| Supply Current | 300 µA typical, 550 µA max (serial bus inactive) - extends battery life in portable and IoT edge sensors. |
| Conversion Time | 270 ms maximum - defines minimum polling interval for stable, repeatable readings. |
| Interface | SPI/MICROWIRE-compatible 3-wire (CS, SC, SI/O) - interoperates with standard MCU SPI peripherals using software bit-banging or hardware master. |
Pinout & Package
LM71CIMFX/NOPB is housed in a 5-pin SOT-23 (DBV) package with 1.45 mm max height, JEDEC MO-178 compliant, and RoHS-compliant matte tin (SN) lead finish. Thermal resistance θJA = 250°C/W when mounted on 2 oz copper PCB.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - CS | Chip Select input | Active-low enable for serial communication; must be held low for full 32-clock transaction or asserted before each 16-bit frame. |
| 2 - GND | Power supply ground | Primary reference for analog sensing and digital I/O; all GND pins must connect to system ground plane. |
| 3 - SI/O | Slave Input/Output | Bidirectional data line with Schmitt trigger input; transmits temperature/ID data on falling SC edge, receives config commands on rising SC edge. |
| 4 - SC | Slave Clock input | Schmitt-triggered serial clock; timing-critical path with 100 ns max rise/fall time; master-controlled frequency up to 6.25 MHz (t1 min = 0.16 µs). |
| 5 - V+ | Positive supply voltage | 2.65V–5.5V input; requires local 0.1 µF ceramic bypass capacitor placed near pin to suppress noise and ensure ADC stability. |
Key Features
| Feature | Design Value |
|---|---|
| 14-bit temperature resolution | 0.03125°C LSB enables precise thermal profiling and small ΔT detection in closed-loop control systems. |
| Shutdown mode via SPI command | Reduces current to ~0 µA (quiescent) by writing 0xFF; retains ability to read Manufacturer ID while minimizing power in idle states. |
| Manufacturer ID register | Fixed 16-bit value (0x800F) confirms TI origin and validates device authenticity during firmware initialization. |
| Two's complement output format | Direct signed integer interpretation simplifies host MCU firmware - no post-processing required for negative temperatures. |
| Internal thermal path optimization | Die temperature closely tracks PCB trace temperature via SOT-23 pin conduction - ideal for board-level hotspot monitoring. |
Applications
| Server CPU Thermal Throttling | Automotive Cabin Climate Control |
|---|---|
Use Scenario: Monitors CPU die temperature in real time to trigger dynamic frequency scaling or fan speed adjustment before thermal shutdown. IC Role / Device Role / Timing Role: Primary temperature sensing node interfaced directly to server BMC or SoC via SPI, reporting every 270+ ms. Use Value: Prevents performance collapse by enabling proactive thermal management with ±1.5°C accuracy across 0–70°C ambient range. | Use Scenario: Measures HVAC duct or cabin air temperature near dashboard vents to regulate blower speed and blend door position. IC Role / Device Role / Timing Role: Ambient temperature sensor connected to automotive-grade MCU (e.g., C2000) over SPI, operating continuously at 125°C junction temp. Use Value: Maintains occupant comfort with <±2°C error over full −40°C to +85°C vehicle operating range. |
| Industrial Motor Drive Heat Monitoring | Portable Medical Diagnostic Device |
Use Scenario: Mounted on IGBT gate driver PCB to track power stage temperature rise during duty-cycle modulation. IC Role / Device Role / Timing Role: High-temp sensor (−40°C to +150°C) feeding thermal protection logic in real time; reads every 500 ms. Use Value: Enables safe operation at rated load by detecting localized hotspots before insulation degradation occurs. | Use Scenario: Embedded in handheld ultrasound or glucose meter to monitor internal battery and processor temperature during clinical use. IC Role / Device Role / Timing Role: Low-power (300 µA typ) sensor providing thermal feedback to ARM Cortex-M0+ MCU during 10-hour battery cycle. Use Value: Extends usable runtime and prevents false alarms by distinguishing self-heating from patient-contact temperature changes. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar digital temperature sensor applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM71CISD/NOPB | Same core functionality, but in 6-pin WSON (NGG) package with lower θJA = 57.6°C/W and smaller footprint. | Better thermal response and higher density placement; preferred for space-constrained PCBs where thermal coupling to substrate is critical. | Select LM71CISD/NOPB when board area is limited and improved thermal tracking of PCB copper is needed. |
| MAX31820MUA+ | 1-Wire interface (single-pin), 12-bit resolution (0.0625°C), ±0.5°C accuracy (−10°C to +65°C), 1.7V–5.5V supply. | Reduces wiring complexity in distributed sensor networks; lacks SPI register structure and manufacturer ID verification. | Choose MAX31820MUA+ for multi-drop, low-pin-count systems where absolute accuracy is secondary to cabling simplicity. |
Compared with LM71CIMFX/NOPB, LM71CISD/NOPB offers superior thermal performance in compact layouts, while MAX31820MUA+ trades SPI register control and 14-bit resolution for 1-Wire bus efficiency - making LM71CIMFX/NOPB optimal for deterministic, high-fidelity SPI-based thermal supervision.
Availability
LM71CIMFX/NOPB is available at Aetrix Electronics and suitable for server thermal management, automotive climate control, industrial motor drives, and portable medical diagnostics requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LM71CIMFX/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 high-performance analog components for industrial, automotive, and communications markets.
The LM71 product line delivers highly integrated, low-power digital temperature sensors optimized for direct SPI/MICROWIRE interfacing in thermally demanding embedded systems - emphasizing accuracy, robustness, and ease of firmware integration.
FAQ
What is the absolute maximum supply voltage for LM71CIMFX/NOPB?
The absolute maximum supply voltage for LM71CIMFX/NOPB is 6.0V. Operation above this level risks permanent damage. The recommended operating range remains 2.65V to 5.5V, and the device will not function reliably below ~1.6V due to internal power-on reset threshold behavior. Always use a 0.1 µF ceramic capacitor between V+ and GND to maintain stable operation across this full voltage range.
Does LM71CIMFX/NOPB support true SPI mode with CPOL=0 and CPHA=0?
Yes, LM71CIMFX/NOPB supports standard SPI Mode 0 (CPOL=0, CPHA=0): data is sampled on the rising edge of SC and shifted out on the falling edge. It also complies with MICROWIRE timing, requiring 32 clocks per full transaction (16-bit transmit followed by 16-bit receive). No configuration register access is needed to enable this behavior - it is hardwired into the serial interface logic of LM71CIMFX/NOPB.
How do I read the temperature register from LM71CIMFX/NOPB?
To read the temperature register from LM71CIMFX/NOPB, assert CS low, then clock 16 bits on SC while reading SI/O on each falling edge. The 16-bit result is a two's complement value where LSB = 0.03125°C (e.g., 0x0C83 = +25°C). After power-on, wait ≥270 ms before first read; subsequent reads must be spaced ≥270 ms apart to guarantee valid conversion results in LM71CIMFX/NOPB.
Can LM71CIMFX/NOPB be used in automotive applications?
LM71CIMFX/NOPB is qualified for industrial temperature range (−40°C to +150°C) and meets JEDEC standards for reliability, but it is not AEC-Q200 or AEC-Q100 certified. For production automotive applications, TI recommends LM71QCIMFX/NOPB (AEC-Q100 Grade 0 qualified). LM71CIMFX/NOPB may be used in non-safety-critical automotive prototyping or aftermarket modules where formal qualification is not mandated.
What is the meaning of the Manufacturer ID register value 0x800F in LM71CIMFX/NOPB?
The Manufacturer ID register in LM71CIMFX/NOPB returns a fixed 16-bit value of 0x800F upon reading in shutdown mode. Bits D15–D11 (10000) identify Texas Instruments as the manufacturer, while D10–D0 encode device-specific identification. This register provides firmware-level validation that the connected device is an authentic TI LM71CIMFX/NOPB and not a counterfeit or misprogrammed part.
LM71CIMFX/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- SC-74A, SOT-753
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Sensor Type:
- Digital, Local
- Sensing Temperature - Local:
- -40°C ~ 150°C
- Sensing Temperature - Remote:
- -
- Output Type:
- SPI
- Voltage - Supply:
- 2.65V ~ 5.5V
- Resolution:
- 13 b
- Features:
- Shutdown Mode
- Accuracy - Highest (Lowest):
- 1.5°C (-2°C, 3°C)
- Test Condition:
- -10°C ~ 65°C (-40°C ~ 150°C)
- Operating Temperature:
- -40°C ~ 150°C
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
- Supplier Device Package:
- SOT-23-5
LM71CIMFX/NOPB FAQ
1.How can I place an order for LM71CIMFX/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM71CIMFX/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 LM71CIMFX/NOPB reliable?
The price and inventory of LM71CIMFX/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM71CIMFX/NOPB is usually 5 days.
3.What payment methods are accepted for LM71CIMFX/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM71CIMFX/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM71CIMFX/NOPB?
LM71CIMFX/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM71CIMFX/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 LM71CIMFX/NOPB?
For technical support, including LM71CIMFX/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM71CIMFX/NOPB requirements.
6.How does Aetrix verify that LM71CIMFX/NOPB is sourced from the original manufacturer or authorized distributors?
All LM71CIMFX/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 LM71CIMFX/NOPB meets industry standards.
7.What is the process for return or replacement of LM71CIMFX/NOPB?
All LM71CIMFX/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM71CIMFX/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 LM71CIMFX/NOPB part is unused and in its original packaging.
Return procedure for LM71CIMFX/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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