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Texas Instruments LM95221CIMMX/NOPB
- Part No.:
- LM95221CIMMX/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- Analog and Digital Output
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
LM95221CIMMX/NOPB.pdf
- Description:
- SENSOR DIGITAL 0C-85C 8VSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,227
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Product details
Overview
LM95221CIMMX/NOPB from Texas Instruments is a dual remote diode digital temperature sensor IC with SMBus 2.0 interface, designed for precise thermal monitoring of processor die, ASICs, and discrete transistors. It measures three zones-local die temperature plus two remote diodes-with ±1.0°C accuracy (30°C–50°C ambient, 45°C–85°C remote junction), 0.125°C LSB resolution for remote readings, and operates from 3.0 V to 3.6 V in laptop and server thermal management systems.
For engineers reviewing the LM95221CIMMX/NOPB datasheet, LM95221CIMMX/NOPB pinout, LM95221CIMMX/NOPB application, or LM95221CIMMX/NOPB equivalent, this page delivers verified technical context, validated pin functions, real-world thermal use cases, and confirmed alternative parts for embedded thermal sensing designs requiring dual-diode support and SMBus compatibility.
Technical Context
The LM95221CIMMX/NOPB implements ΔVBE-based remote diode sensing using two independent current-source/sink pairs (D1+/D1−, D2+/D2−) with factory-trimmed accuracy for 1.008 ideality factor and 2.7 Ω series resistance. Its sigma-delta ADC supports programmable 10-bit-plus-sign or 11-bit-unsigned remote resolution (0.125°C LSB), while local sensing uses fixed 9-bit-plus-sign (0.25°C LSB).
It integrates SMBus 2.0 slave logic with fixed 7-bit address (0x2B), timeout reset capability (tTIMEOUT = 25–35 ms), and status register reporting diode fault conditions (RD1M/RD2M). Conversion timing is fully programmable (66 ms base cycle, up to 1 s interval), and shutdown + one-shot mode enables dynamic power control in thermally constrained systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Remote Temp Accuracy | ±1.0°C max (TA = 30°C–50°C, TD = 45°C–85°C); ensures reliable CPU/ASIC junction tracking under typical compute loads |
| Local Temp Accuracy | ±3.0°C max (TA = 0°C–85°C); sufficient for board-level ambient or sensor self-temperature compensation |
| Remote Resolution | 0.125°C LSB (11-bit unsigned or 10-bit+sign); enables sub-degree granularity and >127°C range in unsigned mode |
| Supply Voltage | 3.0 V to 3.6 V; compatible with standard 3.3 V system rails without level-shifting |
| Quiescent Current | 2.0 mA typ (15 Hz conversion); balances responsiveness and power in always-on thermal monitoring |
| SMBus Compatibility | Fully compliant with SMBus 2.0 spec; supports timeout reset, no clock stretching, fixed 0x2B slave address |
| Operating Temp Range | 0°C to +85°C (ambient); validated for commercial-grade computing and office electronics environments |
Pinout & Package
LM95221CIMMX/NOPB is housed in an 8-pin VSSOP package (3.0 mm × 3.0 mm, 0.65 mm pitch), optimized for space-constrained PCB layouts near processors and memory modules.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| D1+ | Diode current source | Drives constant current into anode of remote thermal diode (e.g., Pentium/AMD CPU junction or MMBT3904); requires 2.2 nF bypass capacitor to ground |
| D1− | Diode return current sink | Completes remote diode 1 current path; must be paired with D1+ and decoupled via same 2.2 nF capacitor |
| D2+ | Diode current source | Independent current source for second remote diode (e.g., GPU or VRM FET junction); identical biasing requirements as D1+ |
| D2− | Diode return current sink | Current return path for remote diode 2; shares no electrical connection with D1− |
| GND | Power supply ground | Primary reference for all analog and digital circuitry; must connect to low-impedance system ground plane |
| VDD | Positive supply input | 3.0–3.6 V rail; requires parallel 0.1 µF + 100 pF bypass capacitors placed adjacent to pin |
| SMBDAT | SMBus bidirectional data line | Open-drain I/O; requires external pull-up resistor (≤82 kΩ @ 3.0 V) to ensure 2.1 V high-level compliance |
| SMBCLK | SMBus clock input | Asynchronous master-driven clock (10–100 kHz); no internal pull-up; tolerates 25 ms low-time for bus reset |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent remote diode channels | Enables simultaneous thermal monitoring of CPU and GPU (or VRM + chipset) without multiplexing delay or crosstalk |
| Programmable remote resolution mode | 11-bit unsigned mode extends measurable range to +255.875°C-critical for high-temp ASICs and power devices |
| Diode fault detection (RD1M/RD2M) | Hardware-level identification of open, shorted, or floating diodes; prevents false over-temperature shutdowns in field operation |
| Configurable conversion rate (66 ms–1 s) | Allows trade-off between thermal update latency and average supply current (2.0–0.335 mA) across system power states |
| One-shot conversion trigger | Enables on-demand temperature sampling during low-power standby-no continuous polling overhead required |
Applications
| Laptop Processor Thermal Management | Server CPU + Memory Module Monitoring |
|---|---|
Use Scenario: Real-time die temperature tracking of Intel Core i7 and AMD Ryzen CPUs in thin-and-light notebooks with fanless or hybrid cooling. IC Role / Device Role / Timing Role: Dual remote diode sensor interfacing directly to CPU's on-die thermal diode and discrete MMBT3904 on VRM, updating every 66 ms via SMBus. Use Value: Enables dynamic frequency throttling within ±1.0°C accuracy at junction temperatures up to 105°C, preventing thermal runaway without oversizing heatsinks. |
Use Scenario: Concurrent monitoring of dual-socket Xeon processors and DDR4 memory module junctions in 1U rack servers. IC Role / Device Role / Timing Role: One LM95221CIMMX/NOPB per CPU socket reads local PCB temp + CPU diode + memory buffer diode via dedicated D1+/D1− and D2+/D2− paths. Use Value: Reduces BOM count by 33% vs. using three single-channel sensors; maintains 0.125°C resolution across all three zones for precise thermal map generation. |
| Industrial PLC Controller Thermal Safety | Network Switch ASIC Junction Sensing |
Use Scenario: Overtemperature protection for ARM-based PLC controllers operating in 0°C–70°C industrial enclosures with variable ambient drift. IC Role / Device Role / Timing Role: Local temperature sensing (die) + remote diode on main SoC + remote diode on isolated I/O driver IC-all sampled synchronously every 200 ms. Use Value: Detects localized hotspots before firmware-level thermal alerts; ±3.0°C local accuracy suffices for enclosure-level derating decisions. |
Use Scenario: Thermal feedback for Broadcom Tomahawk or Marvell Prestera switch ASICs where junction temperature must stay below 110°C under full packet forwarding load. IC Role / Device Role / Timing Role: Remote diode channel 1 connected to ASIC's integrated diode; channel 2 tied to discrete diode on power delivery stage; SMBus updates fed to BMC for fan speed control. Use Value: Achieves ±1.0°C accuracy at 85°C junction-tighter than required for ASIC safe-operating-area enforcement per IEEE 1687. |
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 |
|---|---|---|---|
| LM95231CIMMX/NOPB | Same pinout, adds local temperature offset calibration register and extended remote accuracy (±0.75°C) at 45°C–85°C; higher quiescent current (2.5 mA) | Required when system-level calibration or tighter CPU junction tolerance is mandated (e.g., enterprise servers) | Select LM95231CIMMX/NOPB if offset trimming and improved remote accuracy justify 0.5 mA higher active current. |
| MAX6642AESA+ | 8-pin SOIC package (larger footprint), 2-wire interface compatible with SMBus/I²C, ±2.0°C remote accuracy, fixed 11-bit resolution only | Suitable for cost-sensitive industrial controls where VSSOP space constraints are absent and ±2.0°C accuracy is acceptable | Choose MAX6642AESA+ only when PCB layout permits SOIC-8 and relaxed accuracy meets thermal safety margins. |
Compared with LM95221CIMMX/NOPB, LM95231CIMMX/NOPB offers calibrated accuracy at higher power cost, while MAX6642AESA+ trades precision and package size for broader interface flexibility-neither is pin-compatible, but both serve overlapping dual-diode thermal monitoring roles.
Availability
LM95221CIMMX/NOPB is available at Aetrix Electronics and suitable for laptop thermal management, server CPU monitoring, and industrial PLC controller applications requiring stable component supply and long-term lifecycle support.
Supply support for LM95221CIMMX/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 expertise in precision sensing and power management ICs.
The LM95221CIMMX/NOPB belongs to TI's precision temperature sensor product line, engineered specifically for multi-zone thermal monitoring in computing platforms where dual remote diode support, SMBus integration, and sub-degree resolution are critical.
FAQ
What is the SMBus slave address of the LM95221CIMMX/NOPB?
The LM95221CIMMX/NOPB has a fixed 7-bit SMBus slave address of 0x2B (binary 0101011), which is hard-coded internally and cannot be modified via hardware or software. This address is used for all read/write transactions on the SMBus, and the device does not support address selection pins or EEPROM-programmable addressing. The LM95221CIMMX/NOPB responds only to this address and ignores all other addresses on the bus.
Can the LM95221CIMMX/NOPB measure temperatures above 127°C?
Yes, the LM95221CIMMX/NOPB can measure remote diode temperatures above 127°C when configured in 11-bit unsigned mode, supporting a full range up to +255.875°C. This capability is enabled by its programmable resolution setting in the Configuration Register (03h, bits CR1:CR0 unused; resolution controlled separately). In contrast, 10-bit-plus-sign mode caps at +127.875°C. Local temperature remains limited to ±127.875°C regardless of mode.
How does the LM95221CIMMX/NOPB detect a faulty remote diode?
The LM95221CIMMX/NOPB detects remote diode faults-such as D1+ shorted to VDD/GND/D1− or floating-via dedicated on-chip circuitry that monitors voltage and current behavior at D1+/D1− and D2+/D2−. When a fault is identified, the corresponding status bit (RD1M or RD2M) in the Status Register (02h) is set to "1", and the reported temperature value becomes −128.000°C (signed) or +255.875°C (unsigned), providing unambiguous error signaling to the host controller.
What is the conversion time for all three temperature zones on the LM95221CIMMX/NOPB?
The LM95221CIMMX/NOPB takes approximately 66 ms to complete a full conversion cycle measuring local die temperature, remote diode 1, and remote diode 2-regardless of programmed conversion rate. This base cycle time remains fixed; the Configuration Register only inserts idle delays between cycles (e.g., 200 ms or 1 s intervals). During conversion, the Busy bit (D7) in the Status Register (02h) is asserted, allowing the host to poll or interrupt on completion.
Does the LM95221CIMMX/NOPB require external components for stable operation?
Yes, the LM95221CIMMX/NOPB requires specific external components: (1) a 0.1 µF ceramic + 100 pF ceramic capacitor pair between VDD and GND, placed adjacent to the pins; (2) a 2.2 nF capacitor between each D+/D− pair (D1+/D1− and D2+/D2−); and (3) an external pull-up resistor on SMBDAT (≤82 kΩ at 3.0 V). These components are mandatory for noise immunity, accurate diode biasing, and SMBus signal integrity-omitting any compromises measurement stability or bus reliability.
LM95221CIMMX/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- 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), 10 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 ~ 115°C
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
- Supplier Device Package:
- 8-VSSOP
LM95221CIMMX/NOPB FAQ
1.How can I place an order for LM95221CIMMX/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM95221CIMMX/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 LM95221CIMMX/NOPB reliable?
The price and inventory of LM95221CIMMX/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM95221CIMMX/NOPB is usually 5 days.
3.What payment methods are accepted for LM95221CIMMX/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM95221CIMMX/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM95221CIMMX/NOPB?
LM95221CIMMX/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM95221CIMMX/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 LM95221CIMMX/NOPB?
For technical support, including LM95221CIMMX/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM95221CIMMX/NOPB requirements.
6.How does Aetrix verify that LM95221CIMMX/NOPB is sourced from the original manufacturer or authorized distributors?
All LM95221CIMMX/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 LM95221CIMMX/NOPB meets industry standards.
7.What is the process for return or replacement of LM95221CIMMX/NOPB?
All LM95221CIMMX/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM95221CIMMX/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 LM95221CIMMX/NOPB part is unused and in its original packaging.
Return procedure for LM95221CIMMX/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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