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NXP Semiconductors LM75AD,118
- Part No.:
- LM75AD,118
- Manufacturer:
- NXP Semiconductors
- Category:
- Analog and Digital Output
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LM75AD,118.pdf
- Description:
- SENSOR DIGITAL -55C-125C 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:88,080
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Product details
Overview
LM75AD,118 from NXP Semiconductors is a digital temperature sensor and thermal watchdog IC featuring an on-chip band gap sensor, 11-bit sigma-delta ADC, I²C-bus interface, open-drain OS output, and programmable overtemperature shutdown (80 °C default) and hysteresis (75 °C default). It operates from −55 °C to +125 °C with ±2 °C accuracy (−25 °C to +100 °C) and 0.125 °C resolution, used in system thermal management for PCs and industrial controllers.
For engineers reviewing the LM75AD,118 datasheet, LM75AD,118 pinout, LM75AD,118 application, or LM75AD,118 equivalent, this page delivers verified technical context, real-world design meaning of key specs, validated SO8 package mapping, confirmed I²C register behavior, and two rigorously cross-checked alternative parts - all grounded in NXP's official Rev. 04 product data sheet.
Technical Context
The LM75AD,118 implements a sigma-delta A-to-D converter with 11-bit 2's complement output for temperature measurement, delivering 0.125 °C resolution. Its thermal watchdog logic compares Temp register data (9 MSB bits) against programmable Tos and Thyst registers to drive the open-drain OS output in either comparator or interrupt mode.
Configuration is managed via an 8-bit Conf register controlling shutdown mode (bit B0), OS operation mode (comparator/interrupt, bit B1), OS polarity (HIGH/LOW, bit B2), and fault queue (1/2/4/6 consecutive faults, bits B3–B4). The device powers up in normal mode with Tos = 80 °C, Thyst = 75 °C, OS active LOW, and fault queue = 1.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Temp Resolution | 0.125 °C - enables precise detection of thermal drift or runaway in closed-loop thermal control. |
| Accuracy | ±2 °C (−25 °C to +100 °C) - sufficient for PC motherboard thermal monitoring without calibration. |
| Operating Range | −55 °C to +125 °C - supports industrial ambient conditions and extended junction reliability. |
| Supply Voltage | 2.8 V to 5.5 V - compatible with 3.3 V and 5 V logic domains without level-shifting. |
| Shutdown Current | 3.5 µA - allows battery-backed thermal supervision with negligible quiescent drain. |
| I²C Address Pins | A0–A2 - enable up to eight devices on one bus, simplifying multi-zone thermal sensing in server backplanes. |
| Conversion Time | 100 ms - sets minimum polling interval for real-time thermal response in fan control loops. |
Pinout & Package
LM75AD,118 is supplied in SO8 (SOT96-1) package: plastic small outline, 8 leads, 3.9 mm body width, surface-mount. Pin 1 = SDA, Pin 2 = SCL, Pin 3 = OS, Pin 4 = GND, Pin 5 = A2, Pin 6 = A1, Pin 7 = A0, Pin 8 = VCC.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SDA (Pin 1) | I²C bidirectional data line | Open-drain; requires external pull-up; carries register read/write commands and temperature data (2-byte). |
| SCL (Pin 2) | I²C clock input | Master-generated clock; timing governs register access and conversion synchronization. |
| OS (Pin 3) | Overtemperature shutdown output | Open-drain; asserts when Temp > Tos (comparator mode) or after fault queue threshold; drives external fan or latch. |
| GND (Pin 4) | Reference ground | Must connect directly to system ground plane to minimize thermal gradient error in sensor readings. |
| A2–A0 (Pins 5–7) | I²C slave address inputs | Set lower 3 bits of 7-bit address (MSB = 1001); allow eight unique addresses on shared bus. |
| VCC (Pin 8) | Power supply | Accepts 2.8–5.5 V; internal regulator ensures stable band gap reference across voltage range. |
Key Features
| Feature | Design Value |
|---|---|
| 11-bit sigma-delta ADC | Delivers 0.125 °C resolution for high-fidelity thermal profiling in precision equipment. |
| Programmable Tos/Thyst registers | Allow dynamic thermal trip points (e.g., 70 °C shutdown, 65 °C recovery) without hardware change. |
| Configurable OS modes | Comparator mode provides autonomous thermostat action; interrupt mode enables host-controlled event logging. |
| Three address pins (A2–A0) | Enable daisy-chained thermal monitoring across CPU, GPU, VRM, and memory modules on one I²C bus. |
| Power-up default configuration | Enters normal mode with Tos = 80 °C, Thyst = 75 °C, OS active LOW - functions as plug-and-play thermostat. |
Applications
| Server CPU Thermal Monitoring | Industrial PLC Cabinet Protection |
|---|---|
Use Scenario: Real-time die temperature tracking of multi-core processors during load transients. IC Role / Device Role / Timing Role: Digital temperature sensor providing 100 ms periodic updates to BMC via I²C for dynamic fan speed control. Use Value: 0.125 °C resolution detects sub-degree thermal gradients, enabling tighter thermal throttling margins and extended processor boost duration. | Use Scenario: Ambient cabinet temperature supervision to prevent overheating of programmable logic controllers. IC Role / Device Role / Timing Role: Stand-alone thermal watchdog asserting OS output at 80 °C to cut power or trigger alarm relay. Use Value: Pre-programmed Tos/Thyst eliminates firmware dependency; ±2 °C accuracy ensures reliable trip within safety-critical industrial temperature bands. |
| PC Motherboard Health Management | Network Switch Power Supply Monitoring |
Use Scenario: System-level thermal health reporting in desktop and workstation motherboards. IC Role / Device Role / Timing Role: I²C-connected sensor feeding temperature data to EC or BIOS for thermal event logging and shutdown coordination. Use Value: 3.5 µA shutdown current enables always-on thermal awareness during S5 sleep state without compromising battery life. | Use Scenario: Monitoring heatsink temperature near DC-DC converters in 1U network switches. IC Role / Device Role / Timing Role: Thermal watchdog driving MOSFET gate via OS output to disable faulty PSU before thermal runaway. Use Value: Programmable fault queue (1–6 conversions) prevents false trips from transient spikes, increasing system uptime in noisy power environments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar digital temperature sensor applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| STLM75DT | Same 0.125 °C resolution and −55 °C to +125 °C range; identical SO8 package; I²C address pins A0–A2; but Tos/Thyst defaults differ (75 °C/65 °C). | Requires reconfiguration of set-point registers for drop-in replacement in legacy LM75A designs. | Select STLM75DT when sourcing from STMicroelectronics preferred supply chain; verify register initialization sequence matches host firmware. |
| MAX6625ASA+ | Higher accuracy (±1 °C over 0 °C to +70 °C); same SO8 footprint; but no OS output - only I²C temperature readout. | Lacks autonomous thermal shutdown capability; requires host MCU intervention for overtemp response. | Choose MAX6625ASA+ where precision measurement dominates over hardware-level thermal protection. |
Compared with STLM75DT and MAX6625ASA+, the LM75AD,118 uniquely combines autonomous OS output with 0.125 °C resolution and factory-default 80 °C/75 °C thresholds - making it optimal for cost-sensitive, self-contained thermal protection in embedded systems without dedicated thermal management firmware.
Availability
LM75AD,118 is available at Aetrix Electronics and suitable for server thermal management, industrial PLC protection, PC motherboard health monitoring, and network switch power supply supervision requiring stable component supply across long-lifecycle deployments.
Supply support for LM75AD,118 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
NXP Semiconductors is a global semiconductor company headquartered in Eindhoven, Netherlands, specializing in secure connectivity solutions for automotive, industrial, and IoT applications.
The LM75A family was designed as a pin-compatible upgrade to the industry-standard LM75, delivering enhanced 0.125 °C resolution and single-supply operation across 2.8–5.5 V for robust thermal sensing in space-constrained embedded systems.
FAQ
What is the default power-up configuration of the LM75AD,118?
The LM75AD,118 powers up in normal operation mode with OS comparator mode enabled, Tos set to 80 °C, Thyst set to 75 °C, OS active LOW, fault queue = 1, and pointer register initialized to 0 (selecting the Temp register). This allows immediate temperature reading without register writes, and autonomous thermal shutdown functionality out-of-box.
How does the LM75AD,118 achieve 0.125 °C temperature resolution?
The LM75AD,118 uses an on-chip band gap temperature sensor coupled with an 11-bit sigma-delta analog-to-digital converter. The resulting 11-bit 2's complement value stored in the Temp register yields 0.125 °C per LSB - confirmed by NXP's Rev. 04 datasheet Table 10 examples and Section 7.4.3 calculation method.
Can the LM75AD,118 operate on a 3.3 V supply?
Yes, the LM75AD,118 is fully specified for 2.8 V to 5.5 V operation. At 3.3 V, it maintains ±2 °C accuracy from −25 °C to +100 °C, draws ≤100 µA in normal mode (I²C inactive), and supports standard-mode I²C communication - making it ideal for 3.3 V embedded control systems.
What is the function of the OS output on the LM75AD,118?
The OS output on the LM75AD,118 is an open-drain thermal alert signal that becomes active when measured temperature exceeds the programmed Tos limit (and meets fault queue criteria). It operates in comparator mode (autonomous hysteresis reset) or interrupt mode (host-resettable), supporting direct connection to microcontroller interrupts or discrete thermal shutdown circuits.
Is the LM75AD,118 pin-compatible with the original LM75?
Yes, the LM75AD,118 is explicitly designed as a pin-for-pin replacement for the industry-standard LM75, sharing identical SO8 pinout, I²C protocol, and register map. However, it improves resolution from 0.5 °C to 0.125 °C and extends supply range to 2.8–5.5 V - requiring no PCB changes but potentially benefiting from updated firmware to leverage higher resolution.
LM75AD,118 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- NXP Semiconductors
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Sensor Type:
- Digital, Local
- Sensing Temperature - Local:
- -55°C ~ 125°C
- Sensing Temperature - Remote:
- -
- Output Type:
- I2C
- Voltage - Supply:
- 2.8V ~ 5.5V
- Resolution:
- 11 b
- Features:
- Output Switch, Programmable Limit, Programmable Resolution, Shutdown Mode
- Accuracy - Highest (Lowest):
- ±2°C (±3°C)
- Test Condition:
- -25°C ~ 100°C (-55°C ~ 125°C)
- Operating Temperature:
- -55°C ~ 125°C
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
- Supplier Device Package:
- 8-SO
LM75AD,118 FAQ
1.How can I place an order for LM75AD,118 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM75AD,118 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 LM75AD,118 reliable?
The price and inventory of LM75AD,118 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM75AD,118 is usually 5 days.
3.What payment methods are accepted for LM75AD,118?
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Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM75AD,118?
LM75AD,118 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM75AD,118 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 LM75AD,118?
For technical support, including LM75AD,118 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM75AD,118 requirements.
6.How does Aetrix verify that LM75AD,118 is sourced from the original manufacturer or authorized distributors?
All LM75AD,118 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 LM75AD,118 meets industry standards.
7.What is the process for return or replacement of LM75AD,118?
All LM75AD,118 units undergo pre-shipment inspection (PSI). If there is an issue with LM75AD,118, 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 LM75AD,118 part is unused and in its original packaging.
Return procedure for LM75AD,118:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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