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Texas Instruments LM94CIMT
- Part No.:
- LM94CIMT
- Manufacturer:
- Texas Instruments
- Category:
- Thermal Management
- Package:
- 56-TFSOP (0.240", 6.10mm Width)
- Datasheet:
-
LM94CIMT.pdf
- Description:
- IC HARDWARE MONITOR 56-TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,243
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Product details
Overview
LM94CIMT from Texas Instruments is a hardware monitor IC for dual-processor server management, featuring an 8-bit ΣΔ ADC, monitoring of 16 power supplies and 4 remote thermal diodes, 2.5V reference output, SMBus 2.0 interface, and dual PWM fan control with PI loop support. It operates from +3.0V to +3.6V and delivers 0.0625°C filtered temperature resolution for precision thermal regulation in Xeon-class motherboards.
For engineers reviewing the LM94CIMT datasheet, LM94CIMT pinout, LM94CIMT application, or LM94CIMT equivalent, this page provides verified technical context, real-world fan control architecture details, confirmed voltage/temperature measurement accuracy, and validated alternative options for server thermal management ASIC replacement or upgrade paths.
Technical Context
The LM94CIMT implements TruTherm™ technology for precision thermal diode measurements on sub-micron processors, supporting both 90 nm and 65 nm Pentium/Xeon dies. Its dual PI control loops operate with Tcontrol feedback and integrate digital filters to smooth temperature readings before fan speed calculation.
It features a 56-pin TSSOP package with four tachometer inputs, two open-drain PWM outputs, dual PROCHOT monitoring, VRD10.2/11-compliant dynamic VID tracking (6–7 VIDs per CPU), and 8 configurable GPIOs-four usable as tach inputs, two for THERMTRIP, and two for IERR monitoring.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | +3.0V to +3.6V - ensures compatibility with 3.3V standby rails and stable operation during low-power server states |
| Temperature Resolution | 0.0625°C (filtered) - enables fine-grained fan speed adjustments to minimize acoustic noise in data centers |
| Voltage Accuracy | ±2% FS max - supports reliable rail health monitoring across 16 supplies including ±12V, +5V, +3.3V, and processor Vccp |
| Remote Temp Accuracy | ±2.5°C max (0°C–125°C range) - validated for Intel Pentium/Xeon thermal diodes on 90/65 nm processes |
| ADC Architecture | 8-bit ΣΔ - provides high noise immunity for simultaneous multi-rail and multi-diode measurements in electrically noisy server environments |
| Fan Control Outputs | 2 PWM (open-drain) - drives external MOSFETs or fan drivers with up to 8 mA sink capability per channel |
| Interface | SMBus 2.0 compliant - enables plug-and-play integration with BMCs and host controllers without protocol translation |
Pinout & Package
LM94CIMT is housed in a 56-pin TSSOP (Package Code DGG0056A), optimized for high-density server motherboard layouts with exposed thermal pad for enhanced heat dissipation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GPIO_0/TACH1 – GPIO_3/TACH4 | Fan tachometer input / GPIO | Four configurable open-drain inputs accepting TTL/AGTL logic; each measures RPM via pulse counting for closed-loop speed verification |
| PWM1 / PWM2 | Fan speed control output | Open-drain PWM signals with 8 mA sink capability; directly drive external gate drivers or optocouplers for variable-speed fan control |
| REMOTE1a+/REMOTE1−, REMOTE2a+/REMOTE2− | Thermal diode interface | Dedicated current-source (+) and current-sink (−) pairs for precise forward-voltage measurement of CPU1/CPU2 thermal diodes |
| P1_PROCHOT / P2_PROCHOT | Processor hot signal interface | Bidirectional open-drain I/O with level-shifting; monitors and asserts PROCHOT to throttle CPUs during thermal emergencies |
| SMBDAT / SMBCLK | SMBus 2.0 interface | 5V-tolerant, open-drain data/clock lines supporting byte/block reads/writes and interrupt-driven ALERT signaling |
| VREF | Analog reference output | Stable 2.5V ±1% output used externally for ADC calibration or as reference for auxiliary sensors |
Key Features
| Feature | Design Value |
|---|---|
| TruTherm™ thermal diode measurement | Enables ±2.5°C accuracy on 90/65 nm Xeon processors by compensating for beta variation and series resistance errors |
| PI loop + lookup table fan control | Combines adaptive proportional-integral response with static LUT-based thresholds to balance responsiveness and stability across thermal transients |
| Dual dynamic VID monitoring | Tracks 6–7 VID bits per CPU per VRD10.2/11 spec, enabling real-time Vccp correlation with processor load and temperature |
| Autonomous fan boost on tach error | Immediately increases PWM duty cycle when tachometer input fails or stalls, preventing thermal runaway during fan failure |
| Programmable ALERT output | Configurable as interrupt or comparator mode; masks non-critical events while asserting only on unmasked limit violations or PROCHOT triggers |
Applications
| Server Thermal Management | Dual-CPU Workstation Monitoring |
|---|---|
Use Scenario: Real-time thermal supervision of dual Xeon processors, memory banks, and VRMs in 1U/2U rack servers. IC Role / Device Role / Timing Role: Central hardware monitor coordinating temperature, voltage, and fan control via SMBus with BMC. Use Value: Enables autonomous fan speed adjustment using PI control and TruTherm™-calibrated diode readings, reducing acoustic noise by >3 dB(A) versus fixed-speed schemes. | Use Scenario: High-reliability thermal oversight in engineering workstations running sustained compute loads. IC Role / Device Role / Timing Role: Primary sensor hub aggregating 16 rail voltages, 4 remote diodes, and dual PROCHOT signals for system-level throttling decisions. Use Value: Delivers ±2.5°C remote temp accuracy and 0.0625°C filtered resolution to prevent premature throttling during burst workloads. |
| VRD10.2/11 Compliant Platform | Multi-Processor Server BMC Interface |
Use Scenario: Motherboard implementation meeting Intel VRD10.2/11 specifications for dynamic Vccp and VID tracking. IC Role / Device Role / Timing Role: Dedicated dynamic VID decoder and Vccp monitor interfacing directly with CPU VID pins and analog Vccp sense points. Use Value: Supports full 6–7 bit VID decoding per CPU and correlates Vccp shifts with thermal events to optimize power-performance tradeoffs. | Use Scenario: Baseboard Management Controller communication hub in OCP-compliant servers. IC Role / Device Role / Timing Role: SMBus 2.0 slave device providing register-mapped telemetry (voltage, temp, fan, status) to BMC firmware. Use Value: Provides block-read capability and ALERT interrupt signaling to reduce BMC polling overhead and improve fault response latency by ≥40 ms. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar hardware monitor applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM93CIMT | Lacks TruTherm™, no PI loop, supports only 3 remote diodes and single CPU PROCHOT/VID | Targeted at single-processor or legacy VRD9 platforms; lower thermal accuracy (±3°C) | Select when cost sensitivity outweighs need for dual-CPU precision thermal control and VRD10.2/11 compliance |
| ADM1027ASTZ | Supports only 2 remote diodes, no dynamic VID decoding, uses 10-bit SAR ADC instead of ΣΔ | Designed for AMD Opteron platforms; lacks VRD_HOT detection and THERMTRIP GPIO configuration | Choose for AMD-based systems requiring SMBus-compatible monitoring but not Intel-specific VRD10.2/11 or PROCHOT features |
Compared with LM94CIMT, LM93CIMT offers reduced feature set and thermal fidelity for simpler platforms, while ADM1027ASTZ provides alternate architecture for AMD ecosystems-neither matches LM94CIMT's dual-processor TruTherm™ precision, PI loop fan control, or VRD10.2/11 VID decoding capability.
Availability
LM94CIMT is available at Aetrix Electronics and suitable for server thermal management, dual-CPU workstation monitoring, and VRD10.2/11-compliant motherboard designs requiring stable component supply and long-term lifecycle support.
Supply support for LM94CIMT 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 company specializing in analog and embedded processing technologies, with leadership in power management, signal chain, and interface solutions.
The LM94CIMT belongs to TI's TruTherm™ hardware monitor product line, engineered specifically for intelligent thermal and power supervision in high-density, multi-processor server and workstation platforms.
FAQ
What is the operating temperature range for the LM94CIMT?
The LM94CIMT has an operational ambient temperature range of 0°C to +85°C. Its remote thermal diode measurement accuracy is specified over 0°C to +125°C for CPU die temperatures. This makes LM94CIMT suitable for use inside server chassis where ambient PCB temperatures remain within industrial limits while accurately reading high-temperature processor junctions.
Does the LM94CIMT support both Intel and AMD processor thermal diodes?
The LM94CIMT is explicitly validated for Intel Pentium and Xeon processors on 90 nm and 65 nm processes using TruTherm™ technology. While it can interface with generic NPN diode-connected transistors (e.g., MMBT3904), its remote diode accuracy specifications and beta compensation are tuned for Intel thermal diodes. AMD platform support is not documented for LM94CIMT.
How many power supply rails can the LM94CIMT monitor simultaneously?
The LM94CIMT monitors up to 16 power supply rails using its integrated 8-bit ΣΔ ADC with programmable input attenuators. Supported rails include +12V (three channels), +5V, +3.3V, +2.5V, +1.969V, +1.5V, +1.312V, +0.984V, −12V, FSB_Vtt, and processor-specific Vccp for both CPU1 and CPU2 - all with ±2% full-scale accuracy.
Can the LM94CIMT perform autonomous fan control without host intervention?
Yes, the LM94CIMT supports fully autonomous fan control using either a 13-step lookup table, a PI control loop, or a hybrid mode combining both. It uses internal digital filters on temperature readings and responds to tachometer limit errors with immediate fan boost - all without SMBus host commands once configured.
What SMBus address options does the LM94CIMT support?
The LM94CIMT supports three SMBus slave addresses selected via the Address Select pin (Pin 38), which accepts tri-level analog voltage (low/mid/high) to configure bits A1–A0. Valid addresses are 0x2C, 0x2D, and 0x2E - enabling multiple LM94CIMT devices on the same bus without address conflict in complex server topologies.
LM94CIMT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- TruTherm™
- Package/Case:
- 56-TFSOP (0.240", 6.10mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Function:
- Hardware Monitor
- Sensor Type:
- Internal and External
- Sensing Temperature:
- 0°C ~ 125°C
- Accuracy:
- ±2.5°C(Max)
- Topology:
- ADC (Sigma Delta), Comparator, Fan Control, Multiplexer, Register Bank
- Output Type:
- 2-Wire Serial, I2C/SMBUS
- Output Alarm:
- No
- Output Fan:
- Yes
- Voltage - Supply:
- 3V ~ 3.6V
- Operating Temperature:
- 0°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 56-TSSOP
LM94CIMT FAQ
1.How can I place an order for LM94CIMT through Aetrix?
Please submit a Request for Quotation (RFQ) for LM94CIMT 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 LM94CIMT reliable?
The price and inventory of LM94CIMT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM94CIMT is usually 5 days.
3.What payment methods are accepted for LM94CIMT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM94CIMT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM94CIMT?
LM94CIMT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM94CIMT 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 LM94CIMT?
For technical support, including LM94CIMT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM94CIMT requirements.
6.How does Aetrix verify that LM94CIMT is sourced from the original manufacturer or authorized distributors?
All LM94CIMT 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 LM94CIMT meets industry standards.
7.What is the process for return or replacement of LM94CIMT?
All LM94CIMT units undergo pre-shipment inspection (PSI). If there is an issue with LM94CIMT, 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 LM94CIMT part is unused and in its original packaging.
Return procedure for LM94CIMT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM94CIMT Tags
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EMC2101-ACZL-TR
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