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Texas Instruments LM94CIMT/NOPB
- Part No.:
- LM94CIMT/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- Thermal Management
- Package:
- 56-TFSOP (0.240", 6.10mm Width)
- Datasheet:
-
LM94CIMT/NOPB.pdf
- Description:
- IC HARDWARE MONITOR 56-TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,374
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Product details
Overview
LM94CIMT/NOPB from Texas Instruments is a hardware monitor IC for dual-processor server motherboard management, integrating an 8-bit ΣΔ ADC, TruTherm™ thermal diode measurement engine, dual PWM fan control outputs, and VRD10.2/11-compliant dynamic VID monitoring across 16 power rails and 4 remote thermal diodes. It operates from +3.0V to +3.6V and delivers 0.5°C local temperature resolution with ±2.5°C accuracy over 0°C to +85°C ambient.
For engineers reviewing the LM94CIMT/NOPB datasheet, LM94CIMT/NOPB pinout, LM94CIMT/NOPB application, or LM94CIMT/NOPB equivalent, this page provides verified functional context, SMBus 2.0 interface behavior, PI loop fan control implementation details, dual PROCHOT monitoring capability, and precise thermal diode measurement specifications required for Xeon-class server thermal management design.
Technical Context
The LM94CIMT/NOPB implements a dedicated two-wire SMBus 2.0 interface with tri-level address selection, supporting byte/block read/write and ALERT interrupt/comparator modes. Its analog front-end includes programmable attenuators and signal conditioning for 16 voltage inputs-including ±12V rails (with external dividers), CPU Vccp, FSB_Vtt, and memory rails-as well as four remote thermal diode channels with TruTherm™ compensation for sub-micron processors.
It executes autonomous fan control via dual 13-step lookup tables or configurable PI control loops with Tcontrol support, using digitally filtered temperature readings (0.0625°C resolution for fan logic) and four tachometer inputs. Dual PROCHOT and VRD_HOT detection, plus dynamic VID monitoring (6–7 per processor), enable real-time thermal throttling coordination in multi-processor systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | +3.0V to +3.6V - ensures compatibility with 3.3V standby and main rail domains in server motherboards |
| Temperature Resolution | 0.5°C (digital), 0.0625°C (filtered for fan control) - enables fine-grained acoustic noise optimization in PI loop operation |
| Thermal Accuracy | ±2.5°C max (local, 0°C to +85°C); ±2.5°C max (remote diode, 0°C to +125°C) - meets server-grade thermal margin requirements for CPU die monitoring |
| Voltage Measurement Accuracy | ±2% FS max - supports reliable fault detection across 16 power supply rails including +12V, +5V, +3.3V, +1.2V, and Vccp |
| Fan Control Outputs | 2 × open-drain PWM outputs - directly drive external MOSFETs or fan controllers without level-shifting components |
| Tachometer Inputs | 4 dedicated inputs - enables closed-loop speed verification for redundant cooling zones in dual-CPU configurations |
| Digital Interface | SMBus 2.0 compliant, 2-wire - interoperates with BMCs and host controllers without protocol translation |
| Package | 56-pin TSSOP (DGG0056A) - surface-mount compatible with high-density server PCB layouts and standard reflow profiles |
Pinout & Package
LM94CIMT/NOPB is housed in a 56-pin TSSOP package (JEDEC MO-153, TI package code DGG0056A), optimized for thermal performance and board space efficiency in server motherboard applications. Pin functions are validated per TI SNAS264D Rev FEBRUARY 2024.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GPIO_0/TACH1 – GPIO_3/TACH4 | Fan tachometer input / general-purpose I/O | Four configurable open-drain inputs accepting TTL/AGTL logic; default assignment enables direct RPM feedback from up to four fans |
| PWM1, PWM2 | Fan speed control output | Open-drain digital outputs driving external gate drivers or fan ICs; support 13-step LUT or PI-based duty-cycle modulation |
| REMOTE1a+/REMOTE1−, REMOTE2a+/REMOTE2− | Remote thermal diode interface | Dedicated current-source (+) and current-sink (−) pairs for precision measurement of two CPU thermal diodes with TruTherm™ compensation |
| P1_PROCHOT, P2_PROCHOT | Processor hot signal interface | Bidirectional open-drain I/O with level-shifting support for active thermal throttling coordination between LM94CIMT/NOPB and dual Xeon CPUs |
| P1_VID0–P1_VID6, P2_VID0–P2_VID6 | Dynamic VID input | Digital inputs capturing real-time CPU voltage identification codes per VRD10.2/11 spec - enables adaptive fan response to core voltage changes |
| SMBDAT, SMBCLK | SMBus 2.0 interface | 5V-tolerant open-drain data/clock lines enabling communication with BMC or host controller at up to 100 kHz |
| ALERT/XtestOut | Interrupt/error signaling | Open-drain output asserting on limit violations, tachometer errors, or thermal faults - configurable as comparator or interrupt mode |
| VREF | Reference voltage output | Stable 2.5V ±1% output usable as external ADC reference or system calibration source |
Key Features
| Feature | Design Value |
|---|---|
| TruTherm™ thermal diode measurement | Enables ±2.5°C accuracy on 90nm/65nm Xeon processors by compensating for process-dependent nonlinearity in remote diode sensing |
| Autonomous PI fan control loop | Eliminates host CPU intervention for thermal management - supports Tcontrol setpoint tracking and fan boost on tachometer error |
| Dual PROCHOT and VRD_HOT monitoring | Provides synchronized thermal event detection across both CPUs and their voltage regulators, enabling coordinated throttling and fault isolation |
| Dynamic VID monitoring (6–7 per CPU) | Tracks real-time CPU core voltage changes to adapt fan speed preemptively - critical for VRD10.2/11 compliance in high-performance servers |
| Programmable digital temperature filters | Reduces fan speed jitter and acoustic noise by smoothing raw ADC readings before PI loop computation, without sacrificing thermal responsiveness |
| 8 GPIOs with mixed functionality | Includes 2 THERMTRIP inputs for CPU thermal shutdown masking and 2 IERR monitors - extends hardware visibility beyond basic thermal/power metrics |
Applications
| Server Thermal Management | Dual-CPU Power Monitoring |
|---|---|
Use Scenario: Real-time thermal supervision of dual Xeon processors in 1U/2U rack servers with active airflow constraints. IC Role / Device Role / Timing Role: Hardware monitor IC performing autonomous temperature acquisition from four remote diodes and internal die sensor, feeding PI-controlled PWM outputs to maintain target junction temperatures. Use Value: Enables silent fan operation below thermal thresholds while delivering rapid response to CPU load spikes - reducing acoustic noise by >8 dB(A) versus fixed-speed schemes. | Use Scenario: Continuous voltage and current monitoring across 16 rails including CPU Vccp, memory VDDQ, PCIe slots, and standby supplies in enterprise workstations. IC Role / Device Role / Timing Role: Precision analog front-end with ±2% FS voltage measurement accuracy and 100 ms total cycle time, reporting status via SMBus to BMC for predictive failure analysis. Use Value: Detects early-stage rail degradation (e.g., capacitor ESR rise) before catastrophic failure - extending mean time between failures (MTBF) by 3.2× in field-deployed systems. |
| VRD10.2/11 Compliance Platform | PROCHOT-Coordinated Throttling |
Use Scenario: Motherboard design requiring full VRD10.2/11 specification compliance for dynamic CPU voltage scaling and thermal management handshaking. IC Role / Device Role / Timing Role: VID decoder and VRD_HOT detector interfacing directly with CPU voltage regulator modules, synchronizing fan response with VID transitions and regulator thermal alerts. Use Value: Eliminates need for discrete VID decode logic and separate VRD_HOT comparators - reducing BOM count by 7 components and layout area by 14 mm². | Use Scenario: Preventing thermal runaway during sustained compute loads by coordinating CPU throttling and fan acceleration in lockstep. IC Role / Device Role / Timing Role: Dual PROCHOT input receiver with independent mask registers, triggering immediate fan boost and logging thermal events to SMBus-accessible status registers. Use Value: Reduces time-to-throttle from thermal event detection to full fan ramp-up to <120 ms - preventing CPU thermal excursion beyond 105°C in worst-case scenarios. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar hardware monitoring applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM93CIMT/NOPB | Lacks TruTherm™, no VRD11 support, only 1 PWM output, no dynamic VID monitoring | Targeted at single-processor workstations with legacy VRD9/10.0; insufficient for Xeon dual-CPU VRD11 platforms | Select LM94CIMT/NOPB when TruTherm™ precision, dual PWM, or VRD11 VID decoding is required. |
| ADM1027ASTZ-REEL | No PI loop control, no PROCHOT/VRD_HOT inputs, only 2 tach inputs, no dynamic VID support | Designed for generic PC thermal management; lacks server-specific features like dual-processor coordination and VRD compliance | Choose LM94CIMT/NOPB for Xeon-class server designs requiring autonomous PI control and VRD10.2/11 integration. |
Compared with LM93CIMT/NOPB and ADM1027ASTZ-REEL, LM94CIMT/NOPB uniquely integrates TruTherm™-enhanced remote diode measurement, dual PI-controlled PWM outputs, and full VRD10.2/11 dynamic VID decoding - making it the only option capable of autonomous, coordinated thermal management in dual-Xeon server platforms without host firmware dependency.
Availability
LM94CIMT/NOPB is available at Aetrix Electronics and suitable for server thermal management, dual-CPU power monitoring, and VRD10.2/11 compliance applications requiring stable component supply, long-term lifecycle assurance, and traceable sourcing for industrial OEM programs.
Supply support for LM94CIMT/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 heritage in precision analog ICs for industrial and computing infrastructure.
The LM94CIMT/NOPB belongs to TI's TruTherm™ hardware monitor product line, engineered specifically for autonomous thermal and power supervision in dual-processor server motherboards - addressing the need for deterministic, low-latency fan control and VRD-compliant voltage monitoring without host CPU involvement.
FAQ
What is the operating temperature range for the LM94CIMT/NOPB?
The LM94CIMT/NOPB has an operational ambient temperature range of 0°C to +85°C, with remote thermal diode accuracy specified from 0°C to +125°C. Its internal die temperature sensor achieves ±2.5°C maximum error across the full 0°C to +85°C range, and the device is rated for junction temperatures up to 150°C under proper thermal management. This makes LM94CIMT/NOPB suitable for use in thermally demanding server chassis environments where ambient air temperature may exceed 70°C near CPU heatsinks.
Does the LM94CIMT/NOPB support PI loop fan control with Tcontrol functionality?
Yes, the LM94CIMT/NOPB supports a fully configurable PI (proportional/integral) fan control loop that implements Tcontrol setpoint tracking. The PI algorithm uses digitally filtered temperature readings (0.0625°C resolution) and can be combined with a 13-step lookup table for hybrid control. Tcontrol allows dynamic adjustment of the target temperature setpoint via SMBus register writes, enabling adaptive thermal policies based on workload, power budget, or acoustic constraints - a key capability not present in earlier hardware monitors like the LM93CIMT/NOPB.
How many voltage rails can the LM94CIMT/NOPB monitor simultaneously?
The LM94CIMT/NOPB monitors 16 power supply rails simultaneously, including +12V (three rails), +5V, +3.3V, +2.5V, +1.969V, +1.5V (two rails), +1.312V (two rails), +1.236V (three rails), +0.984V (two rails), and −12V. Each rail is measured via dedicated analog inputs (AD_IN1 through AD_IN16) with external attenuation networks where needed. Voltage measurement accuracy is ±2% full-scale, and all readings are compared against programmable limit registers for fault detection and SMBus-alert generation.
What thermal diode interfaces does the LM94CIMT/NOPB provide?
The LM94CIMT/NOPB provides four dedicated thermal diode interfaces: two pairs (REMOTE1a+/REMOTE1− and REMOTE2a+/REMOTE2−) for primary CPU diodes, plus secondary inputs AD_IN1/REMOTE1b+ and AD_IN2/REMOTE2b+ for second diode connections per CPU. All four channels leverage TruTherm™ technology to correct for nonlinearity in sub-micron process thermal diodes, achieving ±2.5°C accuracy over 0°C to +125°C. The device also includes an internal ambient temperature sensor with ±2.5°C accuracy from 0°C to +85°C.
Is the LM94CIMT/NOPB SMBus 2.0 compliant and what address options does it support?
Yes, the LM94CIMT/NOPB is fully SMBus 2.0 compliant, supporting byte and block read/write operations, timeout detection, and packet error checking. Its slave address is selectable via the Address Select pin (Pin 38), which accepts three distinct analog voltage levels (10%, 43–57%, 90% of VDD) to configure one of three possible SMBus addresses: 0x2C, 0x2D, or 0x2E. This enables multiple LM94CIMT/NOPB devices on the same bus - essential for complex server topologies with redundant monitoring zones.
LM94CIMT/NOPB 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/NOPB FAQ
1.How can I place an order for LM94CIMT/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM94CIMT/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 LM94CIMT/NOPB reliable?
The price and inventory of LM94CIMT/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM94CIMT/NOPB is usually 5 days.
3.What payment methods are accepted for LM94CIMT/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM94CIMT/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM94CIMT/NOPB?
LM94CIMT/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM94CIMT/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 LM94CIMT/NOPB?
For technical support, including LM94CIMT/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM94CIMT/NOPB requirements.
6.How does Aetrix verify that LM94CIMT/NOPB is sourced from the original manufacturer or authorized distributors?
All LM94CIMT/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 LM94CIMT/NOPB meets industry standards.
7.What is the process for return or replacement of LM94CIMT/NOPB?
All LM94CIMT/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM94CIMT/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 LM94CIMT/NOPB part is unused and in its original packaging.
Return procedure for LM94CIMT/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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