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Texas Instruments LM95231CIMM-1/NOPB
- Part No.:
- LM95231CIMM-1/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- Analog and Digital Output
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
LM95231CIMM-1/NOPB.pdf
- Description:
- SENSOR DIGITAL 0C-85C 8VSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,191
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Product details
Overview
LM95231CIMM-1/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 local ±3.0°C accuracy across 0°C to +85°C ambient - deployed in laptop/desktop thermal management subsystems.
For engineers reviewing the LM95231CIMM-1/NOPB datasheet, LM95231CIMM-1/NOPB pinout, LM95231CIMM-1/NOPB application, or LM95231CIMM-1/NOPB equivalent, this page provides verified technical context, validated pin functions, real-world application mappings, and confirmed alternative parts for thermal sensing in compute platforms requiring stable remote diode measurement under SMBus control.
Technical Context
The LM95231CIMM-1/NOPB implements a sigma-delta ADC with TruTherm™ analog front-end to correct non-ideality spread in 90nm-process thermal diodes. Its dual diode input stage supports independent configuration of D1+–D1− and D2+–D2− channels for simultaneous measurement of two remote junctions plus on-chip die temperature.
It uses programmable digital filtering (13-bit signed/unsigned, 0.03125°C LSB) and analog filtering to suppress noise, enabling reliable measurements over longer PCB traces. The SMBus 2.0 slave interface operates at 10–100 kHz, supports TIMEOUT reset, and features fixed 7-bit address (1010111b for LM95231CIMM variants), with no clock stretching.
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 Range | 3.0 V to 3.6 V - requires 0.1 µF + 100 pF bypassing at VDD pin |
| Quiescent Current | 402 µA typical (SMBus inactive, 1 Hz conversion rate) |
| Resolution (Remote, filtered) | 13-bit unsigned or 12-bit plus sign - resolves >127°C; 0.03125°C LSB |
| Resolution (Local) | 9-bit plus sign - 0.25°C LSB, clamped at +127.875°C |
| SMBus Compatibility | Fully compliant with SMBus 2.0 spec - supports TIMEOUT reset, no clock stretching |
Pinout & Package
LM95231CIMM-1/NOPB is housed in an 8-pin VSSOP package (3.0 mm × 3.0 mm, 0.65 mm pitch), optimized for space-constrained thermal sensing nodes on compute motherboards.
| 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); TruTherm correction applied when enabled |
| D1− | Diode return current sink | Completes bias path for D1+; fault detection triggers if shorted to GND, VDD, or floating |
| D2+ | Diode current source | Independent bias source for second remote diode; configurable for 2N3904 model without TruTherm |
| D2− | Diode return current sink | Return path for D2+; supports separate non-ideality selection vs. D1 channel |
| GND | Power supply ground | Low-noise system ground reference; critical for accuracy - must be routed separately from noisy digital returns |
| VDD | Positive supply input | 3.0–3.6 V DC supply; requires local 0.1 µF ceramic + 100 pF capacitor; noise < 200 mVp-p |
| SMBDAT | SMBus bidirectional data line | Open-drain output - requires external pull-up resistor (≤82 kΩ @ 3.0 V); supports SMBus packet error checking |
| SMBCLK | SMBus clock input | Asynchronous clock input from host controller; 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 Intel thermal diodes - enables ±0.75°C accuracy without per-unit calibration |
| Dual Independent Diode Channels | Simultaneous measurement of two remote junctions (e.g., CPU core + GPU or VRM FET) plus local die temperature |
| Programmable Digital Filtering | Enables 13-bit resolution (0.03125°C LSB) and improved noise immunity - extends usable trace length to remote diodes |
| Remote Diode Fault Detection | Automatically flags D+ short-to-rail or open conditions via status register bits RD1M/RD2M - prevents erroneous thermal shutdown |
| Configurable Non-Ideality Selection | Register-selectable models: Intel 90nm processor (TruTherm enabled) or MMBT3904 transistor (TruTherm disabled) |
Applications
| Laptop CPU Thermal Monitoring | Desktop Motherboard Sensor Hub |
|---|---|
Use Scenario: Real-time die temperature tracking of Intel Pentium 4 (90nm) processor during dynamic load transitions in thin-profile laptops. IC Role / Device Role / Timing Role: Dual-channel remote diode sensor providing SMBus-accessible temperature data to EC or SIO for fan speed control and throttling decisions. Use Value: ±0.75°C remote accuracy ensures precise thermal margining; TruTherm eliminates need for per-platform non-ideality tuning. |
Use Scenario: Consolidated thermal sensing node on ATX motherboard measuring CPU, chipset, and VRM MOSFET junction temperatures. IC Role / Device Role / Timing Role: SMBus slave device delivering three-zone temperature data (local + D1 + D2) to BIOS or BMC at programmable 1–10 Hz rates. Use Value: 13-bit filtered resolution (0.03125°C) enables fine-grained thermal response; dual diode inputs reduce component count vs. two single-channel sensors. |
| Workstation GPU Thermal Interface | Embedded Server Baseboard Management |
Use Scenario: Monitoring discrete graphics processor die temperature using onboard MMBT3904-based thermal diode in high-performance workstations. IC Role / Device Role / Timing Role: Remote diode sensor configured for 2N3904 model (TruTherm disabled), interfacing with GPU's analog thermal sense pad. Use Value: Confirmed ±1.25°C accuracy with MMBT3904 allows reliable GPU thermal protection without custom calibration. |
Use Scenario: Integration into server baseboard management controller (BMC) architecture for multi-point thermal telemetry in 1U/2U rack systems. IC Role / Device Role / Timing Role: SMBus 2.0-compliant sensor providing fault-aware temperature data to IPMI stack via standard register map. Use Value: Built-in diode fault detection (RD1M/RD2M bits) enables BMC to distinguish sensor failure from overtemperature events - improving system reliability diagnostics. |
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 | Higher remote accuracy (±0.5°C), extended remote range (−64°C to +191°C), same VSSOP-8 package and SMBus interface | Targeted at server-class platforms requiring tighter thermal margins and wider operating range | Select when ±0.5°C remote accuracy and −64°C low-end support are required; pin-compatible but firmware register mapping differs slightly |
| MAX6642AESA+ | Single remote + local sensor; I²C/SMBus compatible; ±1.0°C remote accuracy; 8-pin SOIC package | Lower-cost option for simpler thermal monitoring where dual remote channels are unnecessary | Choose for cost-sensitive desktop or embedded designs needing only one remote diode channel - not pin- or register-compatible |
Compared with LM95231CIMM-1/NOPB, LM95235CIMM offers higher accuracy and broader range for premium server use, while MAX6642AESA+ reduces BOM count and cost in single-diode applications - neither is drop-in replaceable due to register or channel count differences.
Availability
LM95231CIMM-1/NOPB is available at Aetrix Electronics and suitable for laptop thermal management, desktop motherboard sensor hubs, and workstation GPU thermal interfaces requiring stable component supply and long-term industrial availability.
Supply support for LM95231CIMM-1/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 and embedded processing technologies, with decades of expertise in precision sensing and power management ICs.
The LM95231CIMM-1/NOPB belongs to TI's TruTherm™ temperature sensor product line, engineered specifically for high-accuracy remote diode thermal monitoring in x86 computing platforms - addressing the non-ideality challenges of sub-100nm process geometries.
FAQ
What is the remote temperature accuracy specification for LM95231CIMM-1/NOPB when used with an Intel Pentium 4 90nm processor?
The LM95231CIMM-1/NOPB achieves ±0.75°C maximum remote temperature accuracy when measuring the thermal diode of an Intel Pentium 4 processor fabricated on a 90nm process, under test conditions of TA = +20°C to +40°C ambient and TD = +45°C to +85°C diode junction temperature. This accuracy is guaranteed only when TruTherm™ mode is enabled and the Remote Diode Model Select register is set to the Intel 90nm option. The LM95231CIMM-1/NOPB datasheet specifies this value in its Electrical Characteristics table under "Accuracy Using Remote Diode".
Does LM95231CIMM-1/NOPB support both Intel and discrete transistor thermal diodes?
Yes, LM95231CIMM-1/NOPB supports two distinct remote diode models via register configuration: Intel Pentium 4 processors on 90nm process (with TruTherm™ enabled) and discrete MMBT3904/2N3904-type transistors (with TruTherm™ disabled). The Remote Diode Model Select register allows independent selection for D1 and D2 channels. Using the wrong model - such as enabling TruTherm™ with a 2N3904 - may produce erroneous readings or trigger false diode fault flags in the status register.
What is the SMBus address of LM95231CIMM-1/NOPB and how is it determined?
The LM95231CIMM-1/NOPB has a fixed 7-bit SMBus slave address of 1010111b (0x57 in hexadecimal), as defined by TI's internal programming of address bits A6–A0. This address is shared across all LM95231CIMM variants (including -1/NOPB and -2/NOPB), distinguishing them from LM95231BIMM variants which use 0011001b (0x39). No external address pins exist - the address is hardwired and cannot be modified by software or hardware configuration.
How does the digital filtering feature affect resolution and measurement range in LM95231CIMM-1/NOPB?
When digital filtering is enabled in LM95231CIMM-1/NOPB, remote temperature resolution improves from 11-bit (0.125°C LSB) to 13-bit (0.03125°C LSB), supporting finer thermal granularity. Crucially, the 13-bit unsigned format extends the measurable upper temperature limit beyond +127°C - up to +255.875°C - whereas the unfiltered 11-bit unsigned mode caps at +255.875°C but with coarser step size. Local temperature resolution remains fixed at 9-bit plus sign (0.25°C LSB) regardless of filtering state.
What fault conditions does LM95231CIMM-1/NOPB detect on its remote diode inputs?
LM95231CIMM-1/NOPB detects four fault conditions per diode channel: D+ shorted to GND, D+ shorted to VDD, D+ shorted to D−, or D+ floating (open). When detected, the corresponding remote temperature register reports −128.000°C (signed) or +255.875°C (unsigned), and the status register sets bit RD1M (for D1) or RD2M (for D2). Note that D+–D− short detection is disabled when TruTherm™ mode is active - a known limitation documented in the functional description.
LM95231CIMM-1/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-1/NOPB FAQ
1.How can I place an order for LM95231CIMM-1/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM95231CIMM-1/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-1/NOPB reliable?
The price and inventory of LM95231CIMM-1/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-1/NOPB is usually 5 days.
3.What payment methods are accepted for LM95231CIMM-1/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM95231CIMM-1/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM95231CIMM-1/NOPB?
LM95231CIMM-1/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM95231CIMM-1/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-1/NOPB?
For technical support, including LM95231CIMM-1/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM95231CIMM-1/NOPB requirements.
6.How does Aetrix verify that LM95231CIMM-1/NOPB is sourced from the original manufacturer or authorized distributors?
All LM95231CIMM-1/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-1/NOPB meets industry standards.
7.What is the process for return or replacement of LM95231CIMM-1/NOPB?
All LM95231CIMM-1/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM95231CIMM-1/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-1/NOPB part is unused and in its original packaging.
Return procedure for LM95231CIMM-1/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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