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Texas Instruments LM83CIMQA/NOPB
- Part No.:
- LM83CIMQA/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- Analog and Digital Output
- Package:
- 16-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
LM83CIMQA/NOPB.pdf
- Description:
- SENSOR DIGITAL -40C-125C 16SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,518
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Product details
Overview
LM83CIMQA/NOPB from Texas Instruments (formerly National Semiconductor) is a triple-diode input and local digital temperature sensor with SMBus/I²C interface, designed for system-level thermal monitoring in multi-processor or multi-die environments. It measures its own die temperature (±3.0°C accuracy from 0°C to +85°C) plus three remote diode junctions (e.g., Pentium II® CPU, ASICs, or discrete 2N3904-based sensors), supports programmable T_CRIT and T_HIGH thresholds, and delivers 1°C resolution via 7-bit+sign output format.
For engineers reviewing the LM83CIMQA/NOPB datasheet, LM83CIMQA/NOPB pinout, LM83CIMQA/NOPB application, or LM83CIMQA/NOPB equivalent, key selection considerations include remote diode channel count (3), dual open-drain interrupt outputs (INT and T_CRIT_A), QSOP-16 package compatibility, SMBus 1.1 TIMEOUT support, and register-level compatibility with LM84/MAX1617/ADM1021 for legacy thermal management designs.
Technical Context
The LM83CIMQA/NOPB implements a Delta-Sigma ADC architecture to digitize local and three remote diode voltages, with sequential conversion (Local → D2 → D1 → D3) completing every ~480 ms. Its digital comparator logic independently evaluates each temperature against user-programmable HIGH limits and a shared critical limit (T_CRIT), driving dedicated open-drain outputs: INT for per-channel over-temperature alerts and T_CRIT_A for any-channel critical violation.
Addressing uses two tri-state pins (ADD0/ADD1) enabling up to nine devices on one SMBus segment, while power-on defaults set T_CRIT and all T_HIGH registers to +127°C. The device supports SMBus 1.1 timing-including TIMEOUT recovery-and operates across −40°C to +125°C ambient with 3.0V–3.6V supply.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 3.0 V to 3.6 V - compatible with standard 3.3 V logic rails; power-on reset triggers below 1.8 V |
| Supply Current | 0.8 mA max - enables low-power thermal monitoring without significant system load |
| Local Temp Accuracy | ±3.0°C max (0°C to +85°C) - sufficient for PCB-level thermal profiling near processors or power stages |
| Remote Diode Accuracy | ±3°C max (+25°C to +100°C); ±4°C max (0°C to +125°C) - calibrated for silicon junctions like Pentium II or 2N3904 BE junctions |
| Temperature Resolution | 1°C - 7-bit two's complement output format simplifies host firmware parsing |
| Conversion Time | 600 ms max for full cycle (Local + D1/D2/D3) - ensures deterministic update intervals for thermal control loops |
| SMBus Clock Frequency | 10 kHz to 100 kHz - interoperable with standard I²C/SMBus controllers without custom timing |
Pinout & Package
LM83CIMQA/NOPB is housed in a 16-pin QSOP (MQA16A) package with 0.635 mm pitch, optimized for compact thermal sensor placement on high-density PCBs. Thermal resistance (junction-to-ambient) is specified with 2 oz copper PCB layout per Figure 3 in DS101058.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| D1+, D2+, D3+ | Diode current source outputs | Drive remote diode anodes; floating when unused - no external bias required |
| D− | Diode return current sink | Star-connected cathode return for all three remote diodes; must float if unused |
| VCC | Positive supply input | 3.0–3.6 V rail; powers internal bandgap reference, ADC, and SMBus interface |
| GND (Pins 7, 8) | Power ground | Dual ground pins reduce impedance and improve noise immunity for analog measurements |
| ADD0, ADD1 | SMBus address select inputs | Tri-state capable (GND/VCC/floating) - selects one of nine unique 7-bit slave addresses |
| SMBData | Bi-directional SMBus data line | Open-drain; requires external pull-up; supports SMBus 1.1 TIMEOUT recovery |
| SMBCLK | SMBus clock input | Asynchronous master-driven clock; defines communication timing and data sampling |
| INT | Programmable interrupt output | Open-drain; asserts when any temperature exceeds its T_HIGH limit; maskable per channel |
| T_CRIT_A | Critical temperature alarm output | Open-drain; asserts when any temperature exceeds T_CRIT; individually maskable per channel |
Key Features
| Feature | Design Value |
|---|---|
| Triple remote diode sensing | Simultaneous monitoring of three independent IC dies or discrete junctions - eliminates need for multiple single-channel sensors |
| Local + remote temperature accuracy | ±3°C over 0°C–100°C range - validated for Pentium II and 2N3904 BE junctions, enabling reliable CPU/ASIC thermal throttling |
| Dual independent interrupt outputs | INT for per-channel warnings, T_CRIT_A for system-critical shutdown - supports hierarchical thermal response without host polling |
| 9-device SMBus addressing | ADD0/ADD1 tri-state logic enables scalable thermal monitoring across multi-slot servers or blade chassis without address conflicts |
| Register compatibility | PIN- and REGISTER-compatible with LM84, MAX1617, ADM1021 - allows drop-in replacement in existing SMBus thermal firmware |
Applications
| Server CPU Thermal Monitoring | Multi-Core Processor Thermal Management |
|---|---|
Use Scenario: Real-time die temperature tracking of dual-CPU workstations or rack-mounted servers with Intel Pentium II Pro processors and companion chipsets. IC Role / Device Role / Timing Role: LM83CIMQA/NOPB acts as primary thermal supervisor, reading local sensor and three remote diodes embedded in CPU packages to feed thermal control logic. Use Value: Enables dynamic frequency scaling and fan speed control based on actual silicon junction temperatures-not board or ambient readings-improving reliability and energy efficiency. |
Use Scenario: Thermal supervision of multi-die ASICs where each functional block includes a dedicated diode junction for localized temperature feedback. IC Role / Device Role / Timing Role: LM83CIMQA/NOPB interfaces via SMBus to host controller, sequentially scanning four temperature sources (local + 3 remote) every ~480 ms. Use Value: Provides granular thermal visibility across heterogeneous die regions, supporting targeted thermal mitigation before hotspots trigger system-level throttling. |
| Industrial PLC Cabinet Monitoring | Test Equipment Thermal Calibration |
Use Scenario: Ambient and component-level thermal monitoring inside sealed industrial PLC enclosures exposed to wide ambient swings (−40°C to +85°C). IC Role / Device Role / Timing Role: LM83CIMQA/NOPB serves as local temperature reference while monitoring remote diodes on power MOSFETs and FPGA voltage regulators. Use Value: Delivers ±3°C accuracy over full industrial temperature range, enabling predictive maintenance alerts and safe operating area enforcement. |
Use Scenario: Reference-grade thermal validation in benchtop electronic test equipment requiring traceable junction temperature measurement during burn-in or stress testing. IC Role / Device Role / Timing Role: LM83CIMQA/NOPB reads calibrated 2N3904-based remote diodes placed on DUT heatsinks and PCB hotspots. Use Value: Achieves 1°C resolution and SMBus-readback capability, allowing automated logging of thermal transients without manual probe repositioning. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar digital temperature sensor applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM84CIMQA/NOPB | Pin-for-pin and register-compatible; adds remote diode fault detection and improved remote accuracy (±2°C over +25°C to +100°C) | Preferred where diode disconnection detection is required for safety-critical thermal monitoring | Select LM84CIMQA/NOPB if enhanced fault diagnostics and tighter remote accuracy are needed; otherwise LM83CIMQA/NOPB remains optimal for cost-sensitive SMBus thermal nodes |
| MAX1617AEEE+ | Same SMBus interface and 3-remote-diode capability; differs in default T_CRIT value (+125°C vs. +127°C) and lacks T_CRIT_A masking bits | Better suited for legacy Maxim-based platforms where register mapping matches existing firmware | Choose MAX1617AEEE+ only when migrating from existing MAX1617 designs; LM83CIMQA/NOPB offers broader address flexibility and more granular T_CRIT_A control |
Compared with LM84CIMQA/NOPB and MAX1617AEEE+, the LM83CIMQA/NOPB provides the broadest SMBus address range (9 options), full T_CRIT_A masking per channel, and identical register structure to both alternatives-making it the most flexible choice for new designs requiring proven thermal sensing with minimal firmware adaptation.
Availability
LM83CIMQA/NOPB is available at Aetrix Electronics and suitable for server thermal management, industrial PLC cabinet monitoring, and test equipment calibration requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LM83CIMQA/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 acquired National Semiconductor in 2011 and maintains full technical and supply chain support for legacy analog and interface products including the LM83 family.
The LM83CIMQA/NOPB belongs to TI's precision analog temperature sensor product line, engineered specifically for SMBus-based thermal monitoring in computing, industrial, and test equipment systems where multi-junction visibility and deterministic interrupt behavior are essential.
FAQ
What is the operating temperature range of the LM83CIMQA/NOPB?
The LM83CIMQA/NOPB operates across −40°C to +125°C ambient temperature. Its local temperature sensing accuracy is specified as ±3.0°C maximum from 0°C to +85°C, and ±4°C maximum from −40°C to +125°C. Remote diode accuracy is ±3°C from +25°C to +100°C and ±4°C from 0°C to +125°C. These ranges ensure robust performance in industrial and computing environments where thermal extremes are common. The LM83CIMQA/NOPB maintains full SMBus functionality throughout this range.
How many remote temperature sources can the LM83CIMQA/NOPB monitor simultaneously?
The LM83CIMQA/NOPB monitors one local temperature (its own die) and three independent remote diode junctions (D1, D2, D3), for a total of four distinct temperature sources. Each remote channel uses dedicated D+ and shared D− terminals, with sequential conversion completing every ~480 ms. This architecture enables comprehensive thermal coverage of multi-die systems such as dual-CPU servers or complex ASICs without requiring additional sensors. The LM83CIMQA/NOPB does not support more than three remote diodes.
Does the LM83CIMQA/NOPB support I²C bus protocol?
Yes, the LM83CIMQA/NOPB is fully compatible with standard I²C bus protocol in addition to SMBus 1.1. It uses open-drain SMBData and SMBCLK pins, supports 10 kHz to 100 kHz clock frequencies, and implements SMBus TIMEOUT recovery (tTIMEOUT = 25–40 ms). Its register map, command structure, and electrical characteristics meet both I²C and SMBus specifications, allowing seamless integration into either bus architecture. The LM83CIMQA/NOPB requires no protocol-specific configuration to operate on I²C.
What are the default temperature thresholds at power-up for the LM83CIMQA/NOPB?
At power-up, the LM83CIMQA/NOPB initializes all T_HIGH registers (LHS, D1RHS, D2RHS, D3RHS) and the T_CRIT register to +127°C. The Command Register defaults to 00h (Read Local Temperature), Status Registers to 00h, and Configuration Register to 00h (INT enabled, all T_CRIT_A masks disabled). These defaults ensure safe startup behavior-no interrupts assert until thresholds are explicitly programmed lower. The LM83CIMQA/NOPB retains these values until overwritten via SMBus write commands.
Can the LM83CIMQA/NOPB be used with discrete diodes like the 2N3904?
Yes, the LM83CIMQA/NOPB is explicitly validated for use with discrete 2N3904 transistors configured as diode-connected devices (base-emitter junction with collector tied to base). This configuration closely matches the non-ideality factor of integrated processor diodes, enabling accurate remote junction temperature measurement. The LM83CIMQA/NOPB's diode bias current (5–125 µA) and fault detection logic are optimized for such discrete implementations, making it suitable for thermal monitoring of heatsinks, power components, or ambient air where integrated diodes are unavailable.
LM83CIMQA/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 16-SSOP (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Sensor Type:
- Digital, Local/Remote
- Sensing Temperature - Local:
- -40°C ~ 125°C
- Sensing Temperature - Remote:
- -40°C ~ 125°C
- Output Type:
- I2C/SMBus
- Voltage - Supply:
- 3V ~ 3.6V
- Resolution:
- 7 b
- Features:
- Output Switch, Programmable Limit
- Accuracy - Highest (Lowest):
- ±3°C (±4°C)
- Test Condition:
- 0°C ~ 85°C (-40°C ~ 125°C)
- Operating Temperature:
- -40°C ~ 125°C
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
- Supplier Device Package:
- 16-QSOP
LM83CIMQA/NOPB FAQ
1.How can I place an order for LM83CIMQA/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM83CIMQA/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 LM83CIMQA/NOPB reliable?
The price and inventory of LM83CIMQA/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM83CIMQA/NOPB is usually 5 days.
3.What payment methods are accepted for LM83CIMQA/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM83CIMQA/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM83CIMQA/NOPB?
LM83CIMQA/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM83CIMQA/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 LM83CIMQA/NOPB?
For technical support, including LM83CIMQA/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM83CIMQA/NOPB requirements.
6.How does Aetrix verify that LM83CIMQA/NOPB is sourced from the original manufacturer or authorized distributors?
All LM83CIMQA/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 LM83CIMQA/NOPB meets industry standards.
7.What is the process for return or replacement of LM83CIMQA/NOPB?
All LM83CIMQA/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM83CIMQA/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 LM83CIMQA/NOPB part is unused and in its original packaging.
Return procedure for LM83CIMQA/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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