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Texas Instruments LM95231BIMM-1/NOPB
- Part No.:
- LM95231BIMM-1/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- Analog and Digital Output
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
LM95231BIMM-1/NOPB.pdf
- Description:
- SENSOR DIGITAL 0C-85C 8VSSOP
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
LM95231BIMM-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 measures local die temperature plus two independent remote junctions, delivers ±0.75°C max remote accuracy (Intel 90nm), operates from 3.0V–3.6V, and features programmable 11-/13-bit resolution with digital filtering - deployed in laptop/desktop thermal management systems.
For engineers reviewing the LM95231BIMM-1/NOPB datasheet, LM95231BIMM-1/NOPB pinout, LM95231BIMM-1/NOPB application, or LM95231BIMM-1/NOPB equivalent, key selection criteria include remote diode non-ideality support (Pentium 4 90nm vs. 2N3904), SMBus timing compliance (100 kHz max), VSSOP-8 package thermal resistance (210°C/W), and TruTherm mode enable/disable control per channel.
Technical Context
The LM95231BIMM-1/NOPB implements a sigma-delta ADC with ΔVBE sensing architecture to measure three thermal zones: its own die (local) and two external diode-connected transistor junctions. Its analog input stage integrates TruTherm technology to correct non-ideality spread in 90nm+ processor thermal diodes and includes on-chip analog filtering to reduce external capacitor dependency.
Digital filtering is configurable per remote channel and increases resolution from 11-bit (0.125°C LSB) to 13-bit (0.03125°C LSB); local sensing is fixed at 9-bit + sign (0.25°C LSB). The device supports register-programmable diode model selection (Intel 90nm or MMBT3904) and automatic fault detection for open/shorted D+/D− connections.
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) |
| Local Accuracy | ±3.0°C max (TA = 0°C to +85°C, excludes self-heating) |
| Supply Voltage | 3.0V–3.6V - requires 0.1 µF + 100 pF bypassing at VDD |
| Supply Current | 402 µA typ (SMBus inactive, 1 Hz conversion rate) |
| Resolution (Remote) | 13-bit + sign with digital filtering (0.03125°C LSB); resolves >127°C in unsigned mode |
| SMBus Interface | 2-wire slave-compatible with SMBus 2.0; 100 kHz max clock; no clock stretching |
| Operating Temp | 0°C to +85°C (LM95231BIMM grade); junction limit 125°C |
Pinout & Package
LM95231BIMM-1/NOPB is housed in an 8-pin VSSOP package (2.3 mm × 2.0 mm, 0.65 mm pitch), optimized for low thermal resistance (210°C/W junction-to-ambient on 1 oz copper PCB).
| 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 sink | Completes current path from cathode of first remote diode; paired with D1+ for ΔVBE measurement |
| D2+ | Diode current source | Drives second remote diode (independent channel); supports separate non-ideality setting vs. D1 |
| D2− | Diode return sink | Completes current path for second remote diode; enables simultaneous dual-processor or multi-core monitoring |
| GND | Power ground | Low-noise system reference; must be routed separately from noisy digital/power grounds |
| VDD | Positive supply | 3.0V–3.6V input; requires tight decoupling (0.1 µF || 100 pF) placed adjacent to pin |
| SMBDAT | SMBus bidirectional data | Open-drain output; requires external pull-up (≤82 kΩ @ 3.0V) to ensure 2.1V logic high |
| SMBCLK | SMBus clock input | Asynchronous master-driven clock; no internal pull-up; timing compliant with SMBus 2.0 tLOW ≥ 4.7 µs |
Key Features
| Feature | Design Value |
|---|---|
| TruTherm™ technology | Compensates for non-ideality spread in Intel 90nm+ processor thermal diodes, enabling ±0.75°C accuracy without calibration |
| Dual independent remote channels | Supports concurrent monitoring of two CPUs, GPUs, or FPGAs - each with selectable diode model (Pentium 4 or MMBT3904) |
| Configurable digital filtering | Enables 13-bit resolution (0.03125°C LSB) and improved noise rejection for long PCB traces or noisy environments |
| Remote diode fault detection | Flags D1+/D2+ short-to-rail, open, or floating conditions via status register bits RD1M/RD2M - prevents false thermal shutdown |
| Programmable conversion rate | Adjusts update frequency (and quiescent current) from 1 Hz to faster rates; shutdown mode draws only 272 µA |
Applications
| Laptop CPU Thermal Management | Desktop Workstation Monitoring |
|---|---|
|
Use Scenario: Real-time die temperature tracking of Intel Pentium 4 (90nm) CPU in thin-profile laptops with limited airflow. IC Role / Device Role / Timing Role: Dual-channel remote sensor reading CPU thermal diode and VRM MOSFET junction, updating every 100 ms via SMBus. Use Value: Enables dynamic fan speed control and thermal throttling with ±0.75°C accuracy - avoids premature throttling while preventing thermal runaway. |
Use Scenario: Simultaneous monitoring of dual-socket Xeon processors and chipset in high-performance desktop workstations. IC Role / Device Role / Timing Role: LM95231BIMM-1/NOPB acts as centralized thermal hub, reading both CPU diodes and local board temperature for BIOS thermal policy engine. Use Value: Eliminates need for two separate sensors; 13-bit filtered resolution detects sub-degree thermal gradients critical for stability under sustained load. |
| Office All-in-One PC Cooling | Embedded Industrial Controller |
|
Use Scenario: Fanless or low-noise cooling in compact all-in-one PCs where thermal margin is constrained by enclosure design. IC Role / Device Role / Timing Role: Measures local ambient (via on-die sensor) and remote CPU/GPU junctions using MMBT3904 discrete diodes mounted near hotspots. Use Value: Local ±3.0°C accuracy and remote ±1.25°C (MMBT3904) provide sufficient margin for passive/active hybrid cooling decisions without over-engineering. |
Use Scenario: Temperature supervision in DIN-rail mounted PLC controllers operating continuously in 0°C–70°C industrial cabinets. IC Role / Device Role / Timing Role: LM95231BIMM-1/NOPB interfaces with microcontroller over SMBus to log thermal history and trigger alerts at 85°C junction threshold. Use Value: 0°C to +85°C operating range, SMBus TIMEOUT reset (25–35 ms), and robust fault detection ensure reliable operation in electrically noisy factory environments. |
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 channel + local; no D2+/D2− pins; identical accuracy and SMBus interface | Reduced channel count - suitable only when monitoring one CPU or GPU, not dual-processor systems | Select LM95231BIMM-1/NOPB when dual independent remote diode inputs are required; LM95235CIMM/NOPB saves cost and board space for single-sensor use cases. |
| MAX6642AESA+ | Maxim part; 2-wire SMBus/I²C; ±1.0°C remote accuracy (wider tolerance); no TruTherm correction | Lacks processor-specific non-ideality compensation - less accurate on 90nm+ Intel CPUs without host-side calibration | Choose LM95231BIMM-1/NOPB for guaranteed ±0.75°C on Pentium 4 90nm; MAX6642AESA+ may suffice for general-purpose discrete diode monitoring where tighter accuracy isn't critical. |
Compared with LM95235CIMM/NOPB and MAX6642AESA+, the LM95231BIMM-1/NOPB uniquely delivers dual-channel remote sensing with TruTherm-optimized accuracy for modern processor thermal diodes - making it irreplaceable in multi-CPU thermal architectures requiring uncalibrated precision.
Availability
LM95231BIMM-1/NOPB is available at Aetrix Electronics and suitable for laptop thermal management, desktop workstation monitoring, and embedded industrial controller designs requiring stable component supply and long-term lifecycle support.
Supply support for LM95231BIMM-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, embedded processing, and connectivity solutions, with decades of expertise in precision sensing and power management ICs.
The LM95231BIMM-1/NOPB belongs to TI's TruTherm™ temperature sensor product line, engineered specifically for high-accuracy, low-overhead thermal monitoring of advanced-process CPUs, GPUs, and FPGAs in space- and power-constrained computing platforms.
FAQ
What is the remote temperature accuracy of the LM95231BIMM-1/NOPB when measuring an Intel Pentium 4 processor on 90nm process?
The LM95231BIMM-1/NOPB achieves ±0.75°C maximum remote temperature accuracy when configured for Intel Pentium 4 90nm thermal diode operation with TruTherm™ mode enabled and tested over +20°C to +40°C ambient and +45°C to +85°C diode junction temperature. This specification is validated per TI's SNIS139E datasheet Section 6.5 and applies only when the Remote Diode Model Select register is set correctly.
Does the LM95231BIMM-1/NOPB support both Pentium 4 and MMBT3904 thermal diodes simultaneously?
Yes - the LM95231BIMM-1/NOPB supports independent configuration of each remote channel: D1+ and D1− can be set for Intel Pentium 4 90nm (TruTherm enabled), while D2+ and D2− can be set for MMBT3904 (TruTherm disabled). This dual-model capability is implemented via separate Remote Diode Model Select bits in the configuration registers and is confirmed in the Functional Description section of the datasheet.
What is the SMBus address of the LM95231BIMM-1/NOPB, and how is it determined?
The LM95231BIMM-1/NOPB has a fixed 7-bit SMBus slave address of 0x19 (binary 0011001), as defined by its part number suffix "-1". Per the datasheet Table on page 10, the A6–A0 bits for LM95231BIMM-1 are 0011001 - resulting in read address 0x32 and write address 0x33. This address is hardwired and cannot be modified by hardware or software.
Can the LM95231BIMM-1/NOPB measure temperatures above 127°C, and if so, how?
Yes - the LM95231BIMM-1/NOPB supports temperatures above 127°C in remote channels when configured for unsigned 13-bit resolution (digital filtering enabled). In this mode, the 13-bit unsigned format resolves up to +255.875°C with 0.03125°C LSB step size. Local temperature remains limited to +127.875°C due to its fixed 9-bit + sign format and clamping behavior.
How does the LM95231BIMM-1/NOPB handle remote diode faults, and what status indicators are provided?
The LM95231BIMM-1/NOPB detects D1+ or D2+ short-to-rail (VDD/GND/D−), open, or floating conditions and reports them via dedicated bits RD1M (bit D1) and RD2M (bit D0) in the Status Register (address 02h). Upon fault detection, the corresponding remote temperature register returns –128.000°C (signed) or +255.875°C (unsigned), enabling immediate firmware-level thermal policy override without requiring external diagnostics.
LM95231BIMM-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
LM95231BIMM-1/NOPB FAQ
1.How can I place an order for LM95231BIMM-1/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM95231BIMM-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 LM95231BIMM-1/NOPB reliable?
The price and inventory of LM95231BIMM-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 LM95231BIMM-1/NOPB is usually 5 days.
3.What payment methods are accepted for LM95231BIMM-1/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM95231BIMM-1/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM95231BIMM-1/NOPB?
LM95231BIMM-1/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM95231BIMM-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 LM95231BIMM-1/NOPB?
For technical support, including LM95231BIMM-1/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM95231BIMM-1/NOPB requirements.
6.How does Aetrix verify that LM95231BIMM-1/NOPB is sourced from the original manufacturer or authorized distributors?
All LM95231BIMM-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 LM95231BIMM-1/NOPB meets industry standards.
7.What is the process for return or replacement of LM95231BIMM-1/NOPB?
All LM95231BIMM-1/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM95231BIMM-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 LM95231BIMM-1/NOPB part is unused and in its original packaging.
Return procedure for LM95231BIMM-1/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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