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Texas Instruments LM95231CIMM-2/NOPB
- Part No.:
- LM95231CIMM-2/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- Analog and Digital Output
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
LM95231CIMM-2/NOPB.pdf
- Description:
- SENSOR DIGITAL 0C-85C 8VSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:950
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Product details
Overview
LM95231CIMM-2/NOPB from Texas Instruments is a precision dual remote diode temperature sensor IC with SMBus 2.0 interface and TruTherm™ technology, designed for accurate die-temperature monitoring of Intel Pentium 4 (90nm) processors and discrete MMBT3904 transistors. It delivers ±0.75°C remote accuracy (Intel 90nm), ±3.0°C local accuracy, 13-bit resolution (0.03125°C LSB) with digital filtering, and operates from 3.0V–3.6V supply in laptop/desktop thermal management systems.
For engineers reviewing the LM95231CIMM-2/NOPB datasheet, LM95231CIMM-2/NOPB pinout, LM95231CIMM-2/NOPB application, or LM95231CIMM-2/NOPB equivalent, this page provides verified technical context, validated pin functions, confirmed SMBus timing compliance, exact TruTherm mode behavior per diode type, and real-world thermal fault detection behavior - all specific to the LM95231CIMM-2/NOPB variant.
Technical Context
The LM95231CIMM-2/NOPB implements a sigma-delta ADC with dual ΔVbe sensing channels, supporting two independent remote diodes (D1+/D1− and D2+/D2−) plus on-die local temperature measurement. Its TruTherm circuitry dynamically compensates non-ideality spread in 90nm-process thermal diodes, while analog input filtering reduces sensitivity to PCB leakage and trace capacitance.
Digital filtering is programmable per channel and increases remote resolution from 11-bit (0.125°C LSB) to 13-bit (0.03125°C LSB); local resolution remains fixed at 9-bit plus sign (0.25°C LSB). The device uses SMBus 2.0-compliant open-drain I/O (SMBDAT/SMBCLK), supports 10–100 kHz clock frequency, and includes dedicated diode fault detection that flags D+ short-to-rail or floating conditions via status register bits RD1M/RD2M.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Remote Accuracy | ±0.75°C max (Intel Pentium 4 90nm diode, TA = +20°C to +40°C; TD = +45°C to +85°C) |
| Local Accuracy | ±3.0°C max (TA = 0°C to +85°C, excludes self-heating effects) |
| Supply Voltage | 3.0V–3.6V - requires 0.1 µF + 100 pF bypassing at VDD; noise must stay below 200 mVp-p |
| Quiescent Current | 402 µA typical (SMBus inactive, 1 Hz conversion rate) |
| Resolution (Remote) | 13-bit signed/unsigned with digital filtering (0.03125°C LSB); resolves >127°C in unsigned mode |
| SMBus Compatibility | Fully compliant with SMBus 2.0 spec: 10–100 kHz clock, tTIMEOUT = 25–35 ms reset, no clock stretching |
| Operating Temp | 0°C to +85°C ambient (LM95231CIMM grade; junction limit 125°C) |
Pinout & Package
LM95231CIMM-2/NOPB is housed in an 8-pin VSSOP package (2.3 mm × 2.0 mm, 0.5 mm pitch), optimized for space-constrained thermal sensing applications on processor motherboards and embedded compute modules.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| D1+ | Diode current source | Drives current into anode of first remote thermal diode (e.g., Pentium 4 die or MMBT3904); no external capacitor required but 100 pF improves noise immunity |
| D1− | Diode return current sink | Completes current path from cathode of first remote diode; internal analog filtering minimizes need for external RC network |
| D2+ | Diode current source | Independent current source for second remote diode; supports separate thermal zone monitoring (e.g., GPU or VRM) |
| D2− | Diode return current sink | Return path for D2+; enables simultaneous dual-diode measurement without cross-talk |
| GND | Power supply ground | Low-noise system ground reference; must be routed separately from noisy digital/power grounds to avoid measurement error |
| VDD | Positive supply input | 3.0V–3.6V supply; bypassing with 0.1 µF ceramic + 100 pF NP0 capacitor placed <1 mm from pin is mandatory |
| SMBDAT | SMBus bidirectional data line | Open-drain output requiring external pull-up (≤82 kΩ @ 3.0V); supports standard SMBus read/write protocols and timeout reset |
| SMBCLK | SMBus clock input | Asynchronous clock input from host controller; no internal pull-up; timing meets SMBus 2.0 tLOW ≥ 4.7 µs, tHIGH ≥ 4.0 µs |
Key Features
| Feature | Design Value |
|---|---|
| TruTherm™ technology | Reduces non-ideality spread in 90nm thermal diodes; enables ±0.75°C accuracy only when enabled for Intel Pentium 4 diodes |
| Dual independent diode inputs | Simultaneous measurement of two remote thermal zones (e.g., CPU core + GPU die) with separate model selection and filtering control |
| Programmable diode model | Register-selectable between Intel 90nm thermal diode (TruTherm enabled) and MMBT3904 transistor (TruTherm disabled) |
| Diode fault detection | Flags D+ short-to-VDD/GND/D− or floating condition; sets RD1M/RD2M bits and returns −128.000°C (signed) or +255.875°C (unsigned) |
| 1-shot conversion control | Allows host-initiated single temperature reading without continuous polling, reducing average power in low-duty-cycle monitoring |
Applications
| Laptop Thermal Management | Desktop Server Monitoring |
|---|---|
|
Use Scenario: Real-time CPU die temperature tracking during dynamic frequency scaling in thin-and-light notebooks. IC Role / Device Role / Timing Role: Dual remote diode sensor interfacing directly with Pentium 4 90nm thermal diode and discrete MMBT3904 on VRM heatsink. Use Value: Enables fan speed control with ±0.75°C remote accuracy and 0.03125°C resolution, preventing thermal throttling without overcooling. |
Use Scenario: Multi-zone thermal supervision across CPU, memory controller, and chipset on ATX server motherboards. IC Role / Device Role / Timing Role: Local + dual remote temperature acquisition node reporting via SMBus to BMC/IPMI controller. Use Value: Provides three independent temperature streams with programmable conversion rate (1–10 Hz), optimizing bus bandwidth and power. |
| Workstation GPU Thermal Sensing | Industrial Embedded Compute Module |
|
Use Scenario: High-precision GPU junction temperature monitoring in CAD/rendering workstations using discrete thermal diodes. IC Role / Device Role / Timing Role: Remote diode sensor for AMD/NVIDIA GPU dies with configurable TruTherm mode and digital filtering. Use Value: Delivers 13-bit resolution (0.03125°C LSB) and fault detection to prevent GPU thermal shutdown during sustained loads. |
Use Scenario: Compact thermal safety monitoring in fanless industrial PCs where self-heating and PCB leakage affect accuracy. IC Role / Device Role / Timing Role: Local + remote temperature sensor with analog/digital filtering and 0.25°C local resolution for enclosure ambient sensing. Use Value: Maintains ±3.0°C local accuracy despite 210°C/W junction-to-ambient thermal resistance in sealed enclosures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual remote diode temperature sensing applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM95235CIMM/NOPB | Single remote diode input (D1+/D1− only); identical local sensing, SMBus interface, and TruTherm capability | Not suitable for dual-zone monitoring; lacks D2+/D2− pins and associated registers | Select only if system requires one remote thermal zone and board space is constrained |
| MAX6642AESA+ | Higher local accuracy (±1.0°C), same 13-bit remote resolution, but no TruTherm support; uses different SMBus address scheme | Cannot achieve ±0.75°C accuracy on Intel 90nm diodes; requires external compensation for non-ideality spread | Prefer when measuring generic diodes (e.g., 2N3904) without processor-specific calibration |
Compared with LM95231CIMM-2/NOPB, LM95235CIMM/NOPB reduces pin count and cost for single-diode use cases but eliminates dual-zone capability, while MAX6642AESA+ trades TruTherm precision for broader diode compatibility and tighter local accuracy - making LM95231CIMM-2/NOPB uniquely suited for Intel 90nm platform integration.
Availability
LM95231CIMM-2/NOPB is available at Aetrix Electronics and suitable for laptop thermal management, desktop server monitoring, and industrial embedded compute modules requiring stable component supply and long-term lifecycle support.
Supply support for LM95231CIMM-2/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 leader focused on analog and embedded processing technologies, with decades of expertise in precision sensing and thermal management ICs.
The LM95231 product line was engineered specifically for high-accuracy, multi-zone thermal monitoring in x86 computing platforms - emphasizing TruTherm calibration for Intel/AMD processor thermal diodes and robust SMBus interoperability in dense PCB layouts.
FAQ
What is the SMBus slave address of LM95231CIMM-2/NOPB?
The LM95231CIMM-2/NOPB has a fixed 7-bit SMBus slave address of 0x4C (binary 01001100), determined by internal A6–A0 pins set to 0101010 per TI SNIS139E datasheet Table. This address is hardwired and cannot be modified via software or hardware configuration. The LM95231CIMM-2/NOPB responds only to this address on the SMBus, ensuring deterministic communication in multi-sensor systems without address conflict.
Does LM95231CIMM-2/NOPB support both Intel Pentium 4 and MMBT3904 thermal diodes simultaneously?
Yes, LM95231CIMM-2/NOPB supports both diode types concurrently: Remote Diode 1 (D1+/D1−) is factory-configured for Intel Pentium 4 90nm with TruTherm enabled, while Remote Diode 2 (D2+/D2−) defaults to MMBT3904 with TruTherm disabled. Each channel's model selection and TruTherm mode are independently programmable via the Remote Diode Model Select and TruTherm Control registers, enabling mixed-platform thermal monitoring.
How does diode fault detection behave on LM95231CIMM-2/NOPB when TruTherm is enabled?
When TruTherm mode is enabled on LM95231CIMM-2/NOPB, diode fault detection for the corresponding channel (e.g., D1+) does not flag D+ shorted to D− - a known limitation documented in the datasheet. However, shorts to VDD, GND, or D−, and floating D+, remain detectable and set RD1M/RD2M status bits. Using TruTherm with a non-Intel diode (e.g., MMBT3904) may falsely trigger fault detection, so matching TruTherm state to diode type is mandatory.
What is the maximum conversion time for LM95231CIMM-2/NOPB at its fastest setting?
The maximum conversion time for LM95231CIMM-2/NOPB - covering local, remote 1, and remote 2 temperature measurements - is 87.7 ms when TruTherm mode is enabled for one channel, as specified in the Electrical Characteristics table. This value holds regardless of programmable conversion rate settings; slower rates insert idle delays between conversions but do not extend individual conversion duration. The 87.7 ms figure applies strictly to the LM95231CIMM grade at TA = +85°C.
Can LM95231CIMM-2/NOPB measure temperatures above +127°C?
Yes, LM95231CIMM-2/NOPB can resolve temperatures above +127°C when configured for unsigned remote temperature format: 11-bit unsigned mode reaches +255.875°C, and 13-bit unsigned mode also supports up to +255.875°C with 0.03125°C LSB. Local temperature is clamped at +127.875°C and does not wrap; remote readings in signed mode saturate at +127°C. Unsigned mode must be selected via the Configuration Register to access extended range.
LM95231CIMM-2/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- TruTherm™
- Package/Case:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Sensor Type:
- Digital, Local/Remote
- Sensing Temperature - Local:
- 0°C ~ 85°C
- Sensing Temperature - Remote:
- 0°C ~ 85°C
- Output Type:
- SMBus
- Voltage - Supply:
- 3V ~ 3.6V
- Resolution:
- 9 b (Local), 12 b (Remote)
- Features:
- One-Shot, Programmable Resolution, Shutdown Mode, Standby Mode
- Accuracy - Highest (Lowest):
- ±3°C
- Test Condition:
- 0°C ~ 85°C
- Operating Temperature:
- 0°C ~ 125°C
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
- Supplier Device Package:
- 8-VSSOP
LM95231CIMM-2/NOPB FAQ
1.How can I place an order for LM95231CIMM-2/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM95231CIMM-2/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 LM95231CIMM-2/NOPB reliable?
The price and inventory of LM95231CIMM-2/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM95231CIMM-2/NOPB is usually 5 days.
3.What payment methods are accepted for LM95231CIMM-2/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM95231CIMM-2/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM95231CIMM-2/NOPB?
LM95231CIMM-2/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM95231CIMM-2/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 LM95231CIMM-2/NOPB?
For technical support, including LM95231CIMM-2/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM95231CIMM-2/NOPB requirements.
6.How does Aetrix verify that LM95231CIMM-2/NOPB is sourced from the original manufacturer or authorized distributors?
All LM95231CIMM-2/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 LM95231CIMM-2/NOPB meets industry standards.
7.What is the process for return or replacement of LM95231CIMM-2/NOPB?
All LM95231CIMM-2/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM95231CIMM-2/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 LM95231CIMM-2/NOPB part is unused and in its original packaging.
Return procedure for LM95231CIMM-2/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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