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Texas Instruments LM89-1CIM
- Part No.:
- LM89-1CIM
- Manufacturer:
- Texas Instruments
- Category:
- Analog and Digital Output
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LM89-1CIM.pdf
- Description:
- SENSOR DIGITAL 0C-85C 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,245
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Product details
Overview
LM89-1CIM from Texas Instruments is an 11-bit remote diode and local digital temperature sensor with SMBus 2.0 interface, ±0.75°C remote diode accuracy at TA = 30°C/TD = 80°C, 0.125°C remote resolution, and dual open-drain ALERT/T_CRIT_A outputs for thermal monitoring in processors, GPUs, FPGAs, and ASICs.
For engineers reviewing the LM89-1CIM datasheet, LM89-1CIM pinout, LM89-1CIM application, or LM89-1CIM equivalent, this page delivers verified technical context, real-world thermal sensing use cases, validated alternative parts, and supply-chain support details specific to the LM89-1CIM's VSSOP-8 package and 100 1101 slave address.
Technical Context
The LM89-1CIM implements a delta-VBE remote diode sensing architecture with programmable nonideality compensation via RTOLB/RTOHB offset registers, supporting accurate die temperature measurement of MCU/GPU/FPGA thermal diodes. Its 10-bit plus sign remote ADC delivers 0.125°C resolution with 31.25 ms conversion time per cycle.
It features dual independent digital comparators: one driving the ALERT output (configurable as comparator, interrupt, or SMBus ARA alert) and another driving T_CRIT_A (true comparator with hysteresis register TH). Both outputs are open-drain, active-low, and operate across 3.0–3.6 V supply with shutdown current of 315 µA.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Remote Accuracy | ±0.75°C max at TA=30°C/TD=80°C - enables precise CPU/GPU thermal throttling without software calibration |
| Remote Resolution | 0.125°C - supports fine-grained fan speed control and thermal margining |
| Local Accuracy | ±3.0°C max over 25–125°C - sufficient for ambient board temperature monitoring |
| SMBus Slave Address | 100 1101 (0x4D) - avoids I²C/SMBus address conflict when multiple LM89 variants share same bus |
| Supply Voltage | 3.0 V to 3.6 V - compatible with standard 3.3 V auxiliary rails; requires 0.1 µF + 100 pF bypass at VDD |
| Conversion Time | 31.25 ms - fixed per-cycle latency; register reads return last valid result regardless of conversion state |
| T_CRIT Default | 85°C - matches thermal shutdown thresholds of mainstream x86/ARM processors |
Pinout & Package
LM89-1CIM is housed in an 8-pin VSSOP (DGK) package measuring 3.0 mm × 3.0 mm, optimized for space-constrained PCB layouts near high-power ICs. Thermal resistance RθJA is 158°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VDD | Positive supply input | 3.0–3.6 V rail; requires local 0.1 µF + 100 pF bypass; bulk 10 µF nearby |
| D+ | Diode current source | Drives remote diode anode; mandates 2.2 nF capacitor placed between D+ and D− pins |
| D− | Diode return sink | Connects to remote diode cathode; forms Kelvin-sense pair with D+ for series resistance rejection |
| T_CRIT_A | Critical temperature alarm | Open-drain, active-low comparator output with hysteresis; directly drives power supply shutdown logic |
| GND | Power ground | Common reference for all analog/digital circuitry; must be low-impedance plane |
| ALERT | General thermal alert | Open-drain, active-low; configurable as SMBus ARA responder, interrupt flag, or standalone comparator |
| SMBData | SMBus bidirectional data | Open-drain I/O; requires external pull-up; supports SMBus 2.0 TIMEOUT reset on 25–35 ms low hold |
| SMBCLK | SMBus clock input | Input-only; 10–100 kHz compliant; rise/fall times ≤1 µs/0.3 µs into 80 pF load |
Key Features
| Feature | Design Value |
|---|---|
| Remote diode offset calibration | Two 8-bit RTOLB/RTOHB registers compensate for diode nonideality (e.g., 1.0021) and series resistance without host software intervention |
| T_CRIT_A hysteresis control | Hysteresis register (TH) sets recovery threshold (T_CRIT − TH), preventing oscillation during thermal transients near critical limits |
| SMBus 2.0 ARA compliance | Automatically releases ALERT after successful ARA address transmission, enabling multi-device alert arbitration without bus lockup |
| Shutdown mode | 315 µA quiescent current with SMBus interface retained - allows wake-on-SMBus while minimizing system standby power |
| Local + remote dual sensing | Simultaneous on-chip (local) and off-chip (remote diode) temperature acquisition - eliminates need for separate ambient and junction sensors |
Applications
| Laptop CPU Thermal Management | Server GPU Rack Monitoring |
|---|---|
Use Scenario: Real-time die temperature tracking of Intel Core i7 or AMD Ryzen mobile CPUs during sustained workloads. IC Role / Device Role / Timing Role: LM89-1CIM interfaces via SMBus to EC/BIOS to read remote diode voltage and compute junction temperature using calibrated offset registers. Use Value: Enables dynamic fan speed control and thermal throttling with ±0.75°C accuracy, extending battery life and preventing thermal runaway. | Use Scenario: Monitoring NVIDIA A100 GPU die temperature across 4U server racks with centralized BMC supervision. IC Role / Device Role / Timing Role: LM89-1CIM's T_CRIT_A output triggers immediate GPU power-down when remote temperature exceeds 85°C; ALERT signals BMC for logging. Use Value: Prevents silicon degradation by enforcing hard thermal limits with hardware-level response, independent of firmware execution. |
| FPGA-Based Industrial PLC | Network Switch ASIC Thermal Control |
Use Scenario: Measuring Xilinx Kintex-7 FPGA junction temperature in sealed industrial enclosures with no airflow. IC Role / Device Role / Timing Role: LM89-1CIM's local sensor monitors ambient PCB temperature while remote diode tracks FPGA die; both feed into FPGA-based PID thermal controller. Use Value: Dual-sensor fusion improves thermal model fidelity, allowing safe operation up to 125°C ambient with predictive cooling activation. | Use Scenario: Thermal supervision of Broadcom Tomahawk 4 switch ASIC in 1RU data center switches operating at full line rate. IC Role / Device Role / Timing Role: LM89-1CIM's SMBus ARA mode allows single BMC to poll up to 8 LM89-1CIMs on shared bus without address collision or polling overhead. Use Value: Reduces BMC firmware complexity and bus traffic versus discrete polling, enabling sub-100 ms thermal fault detection across 32-port systems. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar remote diode temperature sensing applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM86CIM | Same 8-pin SOIC package, identical pinout and register map; ±1.0°C remote accuracy (vs. ±0.75°C); no T_CRIT_A output | Lacks dedicated critical-temperature shutdown output; relies on ALERT + host software for T_CRIT enforcement | Select when cost sensitivity outweighs need for hardware-level thermal shutdown and higher remote accuracy is not required. |
| MAX6657ESA+ | Pin-compatible 8-pin SOIC; SMBus 1.1 only; ±1.5°C remote accuracy; 0.25°C resolution; no offset register | Requires external calibration for diode nonideality; no hysteresis control on critical alarm; lower accuracy limits use in high-performance computing | Select for legacy SMBus 1.1 systems where TI LM89 family support is unavailable and ±1.5°C tolerance is acceptable. |
Compared with LM89CIM and MAX6657ESA+, the LM89-1CIM provides superior remote accuracy (±0.75°C vs. ±1.0°C/±1.5°C), integrated T_CRIT_A hardware shutdown, and SMBus 2.0 ARA compliance - making it optimal for modern compute platforms requiring deterministic thermal safety.
Availability
LM89-1CIM is available at Aetrix Electronics and suitable for laptop thermal management, server GPU monitoring, FPGA-based industrial PLCs, network switch ASIC control, and embedded edge AI accelerators requiring stable component supply and long-term lifecycle support.
Supply support for LM89-1CIM 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 leadership in precision analog sensing and power management ICs.
The LM89 product line was designed specifically for high-accuracy, dual-point (local + remote) thermal monitoring in compute-intensive systems - targeting laptops, servers, telecom infrastructure, and industrial automation where junction temperature reliability is mission-critical.
FAQ
What is the SMBus slave address of the LM89-1CIM?
The LM89-1CIM uses a fixed SMBus slave address of 100 1101 (0x4D). This differs from the LM89CIM (0x4C) and LM89-1DIMM (0x4D but with 105°C T_CRIT default), enabling multiple LM89 variants on the same bus without address conflict. The address is hardwired and not software-configurable.
How does the LM89-1CIM achieve ±0.75°C remote diode accuracy?
The LM89-1CIM achieves ±0.75°C remote diode accuracy through factory-trimmed delta-VBE circuitry, combined with user-programmable RTOLB/RTOHB offset registers that compensate for diode nonideality factors (e.g., 1.0021) and series resistance. This calibration is performed at TA = 30°C and TD = 80°C, per the datasheet's guaranteed specification.
Can the LM89-1CIM monitor both local PCB temperature and remote IC die temperature simultaneously?
Yes, the LM89-1CIM performs simultaneous local and remote temperature measurements. Its on-die sensor reports local ambient temperature (8-bit resolution, ±3.0°C accuracy), while its D+/D− pins interface with an external diode (e.g., GPU or FPGA thermal diode) to report remote junction temperature (11-bit resolution, ±0.75°C accuracy). Both values update every 31.25 ms.
What is the function of the T_CRIT_A pin on the LM89-1CIM?
The T_CRIT_A pin on the LM89-1CIM is an active-low, open-drain hardware comparator output that asserts when either local or remote temperature exceeds its programmed T_CRIT limit (85°C default). Unlike ALERT, T_CRIT_A has built-in hysteresis (set via TH register) and is intended for direct connection to power supply shutdown circuitry - providing fail-safe thermal protection independent of host firmware.
Does the LM89-1CIM support SMBus Alert Response Address (ARA) protocol?
Yes, the LM89-1CIM fully supports SMBus 2.0 ARA protocol. When the ALERT pin is pulled low and the master issues an ARA command, the LM89-1CIM transmits its slave address (0x4D) and automatically releases the ALERT line by setting the ALERT mask bit - preventing bus contention and enabling reliable multi-device alert arbitration in dense server or networking applications.
LM89-1CIM Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- 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:
- 7 b (Local), 10 b (Remote)
- Features:
- One-Shot, Output Switch, Programmable Limit, Shutdown Mode, Standby Mode
- Accuracy - Highest (Lowest):
- ±3°C
- Test Condition:
- 25°C ~ 125°C
- Operating Temperature:
- 0°C ~ 125°C
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
- Supplier Device Package:
- 8-SOIC
LM89-1CIM FAQ
1.How can I place an order for LM89-1CIM through Aetrix?
Please submit a Request for Quotation (RFQ) for LM89-1CIM 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 LM89-1CIM reliable?
The price and inventory of LM89-1CIM are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM89-1CIM is usually 5 days.
3.What payment methods are accepted for LM89-1CIM?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM89-1CIM transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM89-1CIM?
LM89-1CIM orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM89-1CIM 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 LM89-1CIM?
For technical support, including LM89-1CIM datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM89-1CIM requirements.
6.How does Aetrix verify that LM89-1CIM is sourced from the original manufacturer or authorized distributors?
All LM89-1CIM 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 LM89-1CIM meets industry standards.
7.What is the process for return or replacement of LM89-1CIM?
All LM89-1CIM units undergo pre-shipment inspection (PSI). If there is an issue with LM89-1CIM, 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 LM89-1CIM part is unused and in its original packaging.
Return procedure for LM89-1CIM:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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