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Texas Instruments LM95231BIMMX/NOPB
- Part No.:
- LM95231BIMMX/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- Analog and Digital Output
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
LM95231BIMMX/NOPB.pdf
- Description:
- SENSOR DIGITAL 0C-85C 8VSSOP
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
LM95231BIMMX/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 measures local die temperature and two independent remote thermal diodes with ±0.75°C max remote accuracy, 13-bit resolution (0.03125°C LSB) when digital filtering is enabled, and operates from 3.0V to 3.6V supply in laptop, server, and workstation thermal management systems.
For engineers reviewing the LM95231BIMMX/NOPB datasheet, LM95231BIMMX/NOPB pinout, LM95231BIMMX/NOPB application, or LM95231BIMMX/NOPB equivalent, key selection considerations include its VSSOP-8 package, dual-diode support with programmable non-ideality selection, SMBus-compatible 2-wire interface, TruTherm-enabled accuracy on 90nm thermal diodes, and fault detection for open/shorted diode connections.
Technical Context
The LM95231BIMMX/NOPB implements a sigma-delta ADC with ΔVBE sensing architecture, supporting simultaneous measurement of three thermal zones: its own die (local), and two external diode-connected transistors (D1+, D1− and D2+, D2−). Its analog input stage integrates TruTherm technology to compensate for process-induced non-ideality spread in Intel 90nm thermal diodes, while built-in analog filtering reduces sensitivity to PCB trace parasitics.
Digital filtering is configurable 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 supports register-programmable diode model selection (Pentium 4 90nm vs. MMBT3904), automatic diode fault detection (D+ short-to-rail or floating), and SMBus 2.0 timing compliance including TIMEOUT reset functionality.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Remote Temp Accuracy | ±0.75°C max (Intel 90nm thermal diode, TA = +20°C to +40°C, TD = +45°C to +85°C) |
| Local Temp Accuracy | ±3.0°C max (TA = 0°C to +85°C, excludes self-heating effects) |
| Supply Voltage | 3.0V to 3.6V - requires 0.1 µF + 100 pF bypassing at VDD pin |
| Supply Current | 402 µA typical (SMBus inactive, 1 Hz conversion rate) |
| Resolution (Remote, filtered) | 13-bit unsigned or 12-bit plus sign - enables readings >127°C with 0.03125°C step size |
| SMBus Interface | 2-wire slave-only, compatible with SMBus 2.0 - supports TIMEOUT reset (>25 ms low on SMBDAT/SMBCLK) |
| Operating Temp Range | 0°C to +125°C junction - rated for industrial embedded thermal monitoring environments |
Pinout & Package
LM95231BIMMX/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 CPU voltage regulator modules and motherboard VRM areas.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| D1+ | Diode current source | Drives bias 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; paired with D1+ for ΔVBE measurement |
| D2+ | Diode current source | Drives bias current into anode of second remote thermal diode - enables independent monitoring of GPU or VRM MOSFET junction |
| D2− | Diode return current sink | Completes current path from cathode of second remote diode - supports dual-zone thermal control loops |
| GND | Power supply ground | Low-noise system reference plane - must be routed separately from high-current power grounds to avoid measurement error |
| VDD | Positive supply input | 3.0–3.6V DC supply - requires local 0.1 µF ceramic + 100 pF capacitor; noise must stay below 200 mVp-p |
| SMBDAT | SMBus bidirectional data line | Open-drain output - requires external pull-up resistor (≤82 kΩ @ 3.0V) to ensure 2.1V logic high; supports SMBus packet error checking |
| SMBCLK | SMBus clock input | Asynchronous master-driven clock - accepts 10–100 kHz; no clock stretching supported; triggers conversion and register access |
Key Features
| Feature | Design Value |
|---|---|
| TruTherm™ technology | Reduces non-ideality spread in Intel 90nm thermal diodes, enabling ±0.75°C accuracy without per-unit calibration |
| Dual independent diode channels | Simultaneous monitoring of CPU and GPU or VRM MOSFET junctions using separate D1+/D1− and D2+/D2− pairs |
| Configurable digital filtering | Enables 13-bit resolution (0.03125°C LSB) for high-precision remote measurements or 11-bit mode for faster conversions |
| Diode fault detection | Automatically flags D+ short-to-VDD/GND/D− or floating conditions via status register bits RD1M/RD2M |
| Programmable diode model | Register-selectable non-ideality factor: Pentium 4 90nm (TruTherm enabled) or MMBT3904 (TruTherm disabled) |
Applications
| Processor Thermal Monitoring | VRM/MOSFET Junction Sensing |
|---|---|
|
Use Scenario: Real-time die temperature tracking of Intel Pentium 4 processors on 90nm fabrication process in desktop workstations and servers. IC Role / Device Role / Timing Role: Dual remote diode sensor providing SMBus-accessible temperature data to system management controller for dynamic frequency scaling and fan speed control. Use Value: Enables ±0.75°C accuracy critical for maintaining processor reliability under variable load, leveraging TruTherm compensation to eliminate unit-to-unit calibration. |
Use Scenario: Monitoring junction temperature of high-side MOSFETs in multi-phase CPU voltage regulator modules. IC Role / Device Role / Timing Role: Remote diode channel (D2+/D2−) connected to discrete MMBT3904 transistor placed adjacent to power stage, delivering 13-bit filtered readings every 87.7 ms. Use Value: Prevents thermal runaway during transient load events by feeding precise MOSFET junction data to closed-loop thermal protection firmware. |
| Laptop System Management | Embedded Industrial Controller |
|
Use Scenario: Compact thermal supervision in space-constrained notebook platforms where CPU and chipset temperatures must be tracked independently. IC Role / Device Role / Timing Role: Local temperature sensor (die) plus two remote channels used for CPU and GPU thermal diodes, interfaced via shared SMBus bus with EC firmware. Use Value: VSSOP-8 footprint and 402 µA quiescent current allow integration without compromising battery life or board area in ultra-thin designs. |
Use Scenario: Temperature-aware operation of fanless industrial controllers deployed in sealed enclosures with limited airflow. IC Role / Device Role / Timing Role: Primary thermal sensor for ambient (local) and two critical component junctions (e.g., FPGA and power converter), reporting via SMBus to real-time OS task. Use Value: Diode fault detection ensures system-level thermal integrity alerts are triggered if remote sensor wiring fails - critical for unattended operation. |
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 remote accuracy (±0.5°C), extended operating range (−40°C to +125°C), same VSSOP-8 package and SMBus interface | Required for extended-temperature industrial or automotive under-hood applications where −40°C startup is needed | Select LM95235CIMMX/NOPB when tighter accuracy or wider temperature range is mandatory; pinout and register map are identical |
| MAX6642AESA+ | Single remote diode channel, 12-bit resolution (0.0625°C LSB), I²C/SMBus compatible, SO-8 package | Suitable only for cost-sensitive single-zone monitoring; lacks dual-diode capability and TruTherm compensation | Choose MAX6642AESA+ only for legacy designs requiring minimal BOM change and single-remote-channel functionality |
Compared with LM95231BIMMX/NOPB, LM95235CIMMX/NOPB offers improved accuracy and extended temperature range while maintaining full software and hardware compatibility; MAX6642AESA+ provides lower-cost single-channel sensing but cannot replace dual-diode functionality or TruTherm-enabled 90nm processor accuracy.
Availability
LM95231BIMMX/NOPB is available at Aetrix Electronics and suitable for laptop thermal management, server CPU monitoring, and industrial embedded controller applications requiring stable component supply, long-term lifecycle support, and guaranteed traceability.
Supply support for LM95231BIMMX/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 technologies, with decades of expertise in precision sensing and thermal management ICs.
The LM95231 product line delivers high-accuracy remote diode temperature sensing for computing platforms, specifically engineered to address non-ideality challenges in advanced-node microprocessors and power semiconductors.
FAQ
What is the maximum remote temperature measurement range of the LM95231BIMMX/NOPB?
The LM95231BIMMX/NOPB supports remote temperature readings above 127°C when configured in 13-bit unsigned mode, resolving up to +255.875°C with 0.03125°C LSB. This capability is enabled by digital filtering and is confirmed in the datasheet's Table 5 for 13-bit unsigned binary format. The LM95231BIMMX/NOPB achieves this range without rollover or clamping, unlike its local temperature channel which caps at +127.875°C.
Does the LM95231BIMMX/NOPB require external components for basic operation?
Yes - the LM95231BIMMX/NOPB requires a 0.1 µF ceramic capacitor and a 100 pF capacitor in parallel at the VDD pin, placed as close as possible to the pin. External pull-up resistors on SMBDAT and SMBCLK lines are also mandatory (typically 4.7 kΩ to 10 kΩ). While 100 pF capacitors between D1+/D1− and D2+/D2− are optional, they improve noise immunity in electrically noisy systems. These requirements are specified in the PIN DESCRIPTIONS and Typical Application sections of the LM95231BIMMX/NOPB datasheet.
How does TruTherm™ technology improve accuracy on Intel 90nm processors?
TruTherm™ technology in the LM95231BIMMX/NOPB compensates for process-induced non-ideality spread in Intel Pentium 4 thermal diodes fabricated on 90nm nodes. By dynamically adjusting the measurement algorithm based on known diode characteristics, it reduces systematic error to ±0.75°C maximum - a specification verified across temperature and process corners. The LM95231BIMMX/NOPB must have TruTherm enabled (via register) and the correct diode model selected to achieve this accuracy; using it with MMBT3904 without disabling TruTherm degrades performance.
Can the LM95231BIMMX/NOPB monitor two different types of thermal diodes simultaneously?
Yes - the LM95231BIMMX/NOPB supports independent configuration of each remote channel: D1+ / D1− can be set for Intel Pentium 4 90nm thermal diodes (TruTherm enabled), while D2+ / D2− can be configured for MMBT3904 discrete transistors (TruTherm disabled). This is implemented via separate Remote Diode Model Select and TruTherm Mode Control registers, allowing simultaneous high-accuracy monitoring of CPU die and VRM MOSFET junctions with optimal settings per channel.
What happens when a remote diode connection fails on the LM95231BIMMX/NOPB?
When the LM95231BIMMX/NOPB detects a fault - such as D1+ shorted to VDD, GND, D1−, or floating - it reports −128.000°C (signed format) or +255.875°C (unsigned format) in the corresponding remote temperature register and sets the RD1M (bit D1) or RD2M (bit D0) flag in the Status Register (02h). This behavior is documented in Section 1.6 "Diode Fault Detection" of the LM95231BIMMX/NOPB datasheet and enables immediate firmware-level fault isolation without additional external circuitry.
LM95231BIMMX/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/NOPB FAQ
1.How can I place an order for LM95231BIMMX/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM95231BIMMX/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/NOPB reliable?
The price and inventory of LM95231BIMMX/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/NOPB is usually 5 days.
3.What payment methods are accepted for LM95231BIMMX/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM95231BIMMX/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM95231BIMMX/NOPB?
LM95231BIMMX/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM95231BIMMX/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/NOPB?
For technical support, including LM95231BIMMX/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM95231BIMMX/NOPB requirements.
6.How does Aetrix verify that LM95231BIMMX/NOPB is sourced from the original manufacturer or authorized distributors?
All LM95231BIMMX/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/NOPB meets industry standards.
7.What is the process for return or replacement of LM95231BIMMX/NOPB?
All LM95231BIMMX/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM95231BIMMX/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/NOPB part is unused and in its original packaging.
Return procedure for LM95231BIMMX/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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