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Texas Instruments LM95231BIMMX-2/NOPB
- Part No.:
- LM95231BIMMX-2/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- Analog and Digital Output
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
LM95231BIMMX-2/NOPB.pdf
- Description:
- SENSOR DIGITAL 0C-85C 8VSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,512
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Product details
Overview
LM95231BIMMX-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, 13-bit resolution (0.03125°C LSB) with digital filtering, and operates from 3.0V to 3.6V supply in laptop, server, and workstation thermal management systems.
For engineers reviewing the LM95231BIMMX-2/NOPB datasheet, LM95231BIMMX-2/NOPB pinout, LM95231BIMMX-2/NOPB application, or LM95231BIMMX-2/NOPB equivalent, this page provides verified technical context, validated pin functions, confirmed alternative parts with documented differences, and real-world use-value for thermal diode sensing in high-reliability computing platforms.
Technical Context
The LM95231BIMMX-2/NOPB implements a sigma-delta ADC with ΔVBE sensing architecture to measure local die temperature and two independent remote diode junctions. Its TruTherm™ circuitry actively compensates for non-ideality spread in 90nm-process thermal diodes, enabling stable readings without external calibration.
It features programmable diode model selection (Pentium 4 90nm vs. MMBT3904), dual digital/analog filtering, SMBus-compatible 2-wire interface with timeout reset, and fault detection for open/shorted diode connections - all within an 8-pin VSSOP package rated for 0°C to +85°C ambient operation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Remote Temp Accuracy | ±0.75°C max (Intel 90nm thermal diode, +20°C to +85°C) |
| Local Temp Accuracy | ±3.0°C max (0°C to +85°C, excludes self-heating) |
| Resolution (filtered) | 13-bit unsigned or 12-bit plus sign; 0.03125°C LSB enables >127°C sensing |
| Supply Voltage | 3.0V to 3.6V - requires 0.1 µF + 100 pF bypass at VDD pin |
| Supply Current | 402 µA typical (SMBus inactive, 1 Hz conversion rate) |
| SMBus Compatibility | Fully compliant with SMBus 2.0 spec; supports 10–100 kHz clock, timeout reset ≥25 ms |
| Operating Temp Range | 0°C to +85°C ambient - validated for LM95231BIMM grade |
Pinout & Package
LM95231BIMMX-2/NOPB uses an 8-pin VSSOP (Very Small Outline Package) with 0.65 mm pitch and exposed pad (no thermal pad connection required). Package dimensions: 3.0 mm × 3.0 mm × 1.0 mm (max height).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| D1+ | Diode current source | Drives current into anode of first remote thermal diode (e.g., Pentium 4 die); no capacitor required but 100 pF improves noise immunity |
| D1− | Diode return sink | Completes current path from cathode of first remote diode; referenced to GND, not VDD |
| D2+ | Diode current source | Independent current source for second remote diode (e.g., MMBT3904 transistor junction) |
| D2− | Diode return sink | Current return path for D2+; electrically isolated from D1− path |
| GND | Power ground | Low-noise system ground reference for analog and digital sections; must be star-connected |
| VDD | Positive supply input | 3.0–3.6V DC input; bypassing with 0.1 µF ceramic + 100 pF near pin is mandatory for accuracy |
| SMBDAT | SMBus bidirectional data | Open-drain output requiring external pull-up (≤82 kΩ @ 3.0V); supports SMBus packet error checking |
| SMBCLK | SMBus clock input | Asynchronous clock input from host controller; no clock stretching supported |
Key Features
| Feature | Design Value |
|---|---|
| TruTherm™ technology | Reduces non-ideality spread in 90nm thermal diodes, enabling ±0.75°C accuracy without per-unit calibration |
| Dual independent diode channels | Simultaneous measurement of two remote thermal zones (e.g., CPU core + GPU or VRM FET) with separate model selection |
| Programmable resolution modes | 11-bit (0.125°C LSB) or 13-bit (0.03125°C LSB) remote readouts; unsigned mode extends range above 127°C |
| Diode fault detection | Flags D1+/D2+ short-to-rail, open, or floating conditions via status register bits RD1M/RD2M |
| Configurable conversion rate | Adjustable update interval from ~1 Hz to faster rates; shutdown mode draws only 272 µA |
Applications
| Laptop CPU Thermal Monitoring | Server Blade Temperature Control |
|---|---|
|
Use Scenario: Real-time die temperature tracking of Intel Pentium 4 processor on 90nm process during dynamic workload scaling. IC Role / Device Role / Timing Role: Dual-channel remote diode sensor providing SMBus-accessible temperature data to platform controller hub (PCH) for fan speed and throttling decisions. Use Value: ±0.75°C accuracy ensures precise thermal margining, reducing unnecessary throttling while preventing thermal runaway in space-constrained chassis. |
Use Scenario: Concurrent monitoring of CPU and voltage regulator module (VRM) FET junction temperatures in 1U rack-mounted servers. IC Role / Device Role / Timing Role: Primary thermal sensor interfacing with baseboard management controller (BMC) via SMBus to trigger thermal alerts and graceful shutdown. Use Value: Independent D1+/D1− and D2+/D2− channels eliminate crosstalk, enabling reliable co-location of CPU and power-stage sensors on same PCB region. |
| Workstation GPU Thermal Management | Industrial Embedded Controller Monitoring |
|
Use Scenario: Measuring junction temperature of discrete MMBT3904-based thermal diode attached to GPU memory controller ASIC. IC Role / Device Role / Timing Role: Remote diode sensor configured for 2N3904 model (TruTherm disabled), delivering 13-bit filtered readings every 100 ms. Use Value: 0.03125°C resolution enables fine-grained thermal profiling for predictive fan control and lifetime estimation of graphics subsystems. |
Use Scenario: Local + remote temperature supervision in fanless industrial PC used in factory automation cabinets. IC Role / Device Role / Timing Role: Measures its own die temperature (local) and remote diode on FPGA power rail to detect abnormal heating before failure. Use Value: 402 µA quiescent current and SMBus timeout reset support unattended operation over 10+ year product lifecycles with minimal firmware overhead. |
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 |
|---|---|---|---|
| LM95235CIMMX/NOPB | Higher-grade variant: ±0.5°C remote accuracy, extended operating range (−40°C to +125°C), same VSSOP-8 package and pinout | Required for industrial environments with wider ambient extremes or tighter accuracy demands | Select LM95235CIMMX/NOPB when ambient exceeds +85°C or sub-0.75°C accuracy is mandated by system thermal budget |
| MAX6642AESA+ | Maxim part with 12-bit resolution (0.0625°C LSB), ±1.0°C remote accuracy, I²C/SMBus compatible, same 8-pin SO package but different pin mapping | Lacks TruTherm compensation; requires external calibration for 90nm CPUs; no dedicated diode fault flags | Choose MAX6642AESA+ only if legacy design reuse mandates SO-8 footprint and TruTherm is not needed for target processor |
Compared with LM95231BIMMX-2/NOPB, LM95235CIMMX/NOPB offers improved accuracy and temperature range at identical pin compatibility, while MAX6642AESA+ trades TruTherm capability and fault detection for broader vendor availability - making LM95231BIMMX-2/NOPB optimal for cost-sensitive, Pentium 4–based computing platforms requiring validated 90nm thermal diode support.
Availability
LM95231BIMMX-2/NOPB is available at Aetrix Electronics and suitable for laptop thermal management, server blade monitoring, and workstation GPU cooling applications requiring stable component supply across multi-year production cycles.
Supply support for LM95231BIMMX-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 specializing in analog, embedded processing, and connectivity solutions, with decades of expertise in precision sensing and thermal management ICs.
The LM95231 product line was engineered specifically for high-accuracy, low-power thermal monitoring in x86 computing platforms - targeting die temperature measurement of advanced-process CPUs and GPUs using integrated or discrete thermal diodes.
FAQ
What is the guaranteed remote temperature accuracy of the LM95231BIMMX-2/NOPB?
The LM95231BIMMX-2/NOPB guarantees ±0.75°C remote temperature accuracy when measuring the thermal diode of an Intel Pentium 4 processor fabricated on a 90nm process, under conditions of +20°C to +85°C ambient and +45°C to +85°C remote junction temperature. This specification is explicitly validated in the official TI datasheet SNIS139E for the BIMM grade device.
Does the LM95231BIMMX-2/NOPB support both Pentium 4 and MMBT3904 thermal diodes simultaneously?
Yes, the LM95231BIMMX-2/NOPB supports concurrent use of both diode types: Remote Diode 1 (D1+/D1−) can be configured for Pentium 4 90nm with TruTherm™ enabled, while Remote Diode 2 (D2+/D2−) is independently set for MMBT3904 with TruTherm disabled - all via dedicated register bits in the Remote Diode Model Select register.
What is the SMBus slave address of the LM95231BIMMX-2/NOPB?
The LM95231BIMMX-2/NOPB has a fixed 7-bit SMBus slave address of 0x4C (binary 1001100), determined by its part number suffix "-2". This address is hardwired and cannot be modified by hardware or software, ensuring deterministic bus communication in multi-sensor systems.
Can the LM95231BIMMX-2/NOPB measure temperatures above 127°C?
Yes - when configured in unsigned 13-bit resolution mode with digital filtering enabled, the LM95231BIMMX-2/NOPB resolves remote temperatures up to +255.875°C with 0.03125°C LSB granularity. This capability is confirmed in Tables 4 and 5 of the TI datasheet SNIS139E and applies to both D1 and D2 channels.
Is external filtering required for reliable operation of the LM95231BIMMX-2/NOPB?
No external filtering is required: the LM95231BIMMX-2/NOPB integrates analog filtering in its diode input stage and optional digital filtering, minimizing sensitivity to PCB trace noise. A 100 pF capacitor between D1+/D1− or D2+/D2− is optional and recommended only in electrically noisy systems - it is not mandatory for baseline functionality or accuracy compliance.
LM95231BIMMX-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:
- Obsolete
- 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
LM95231BIMMX-2/NOPB FAQ
1.How can I place an order for LM95231BIMMX-2/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM95231BIMMX-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 LM95231BIMMX-2/NOPB reliable?
The price and inventory of LM95231BIMMX-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 LM95231BIMMX-2/NOPB is usually 5 days.
3.What payment methods are accepted for LM95231BIMMX-2/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM95231BIMMX-2/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM95231BIMMX-2/NOPB?
LM95231BIMMX-2/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM95231BIMMX-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 LM95231BIMMX-2/NOPB?
For technical support, including LM95231BIMMX-2/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM95231BIMMX-2/NOPB requirements.
6.How does Aetrix verify that LM95231BIMMX-2/NOPB is sourced from the original manufacturer or authorized distributors?
All LM95231BIMMX-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 LM95231BIMMX-2/NOPB meets industry standards.
7.What is the process for return or replacement of LM95231BIMMX-2/NOPB?
All LM95231BIMMX-2/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM95231BIMMX-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 LM95231BIMMX-2/NOPB part is unused and in its original packaging.
Return procedure for LM95231BIMMX-2/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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