Texas Instruments LM35CH

Overview

LM35CH from Texas Instruments is a precision centigrade temperature sensor IC with linear analog output, calibrated directly in °C, offering ±1°C accuracy over −55°C to +150°C, 10 mV/°C scale factor, and 60 µA quiescent current. It operates from 4 V to 30 V and delivers low-impedance output (0.1 Ω at 1 mA) for direct interfacing with ADCs or microcontrollers in thermal monitoring circuits.

For engineers reviewing the LM35CH datasheet, LM35CH pinout, LM35CH application, or LM35CH equivalent, key selection criteria include its full-range industrial temperature rating, wafer-trimmed calibration eliminating external adjustment, minimal self-heating (<0.1°C in still air), and compatibility with single-supply systems requiring high linearity and low power consumption.

Technical Context

The LM35CH implements a delta-V_BE temperature-sensing element buffered by a Class-A amplifier, producing a rail-to-rail linear voltage output proportional to junction temperature. Its architecture ensures inherent centigrade scaling without offset subtraction-unlike Kelvin-referenced sensors-and eliminates need for external trimming.

It functions exclusively in analog output mode with no digital interface, configuration registers, or sleep states. Output sourcing capability is limited to ~1 mA; sinking is restricted to 1 µA, and capacitive load drive is rated ≤50 pF without series damping.

Key Specifications

Pinout & Package

LM35CH is supplied in a hermetic TO-46 (TO-CAN) metal can package with 3 leads. The case is internally connected to GND, providing inherent EMI shielding and thermal conduction path.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar analog temperature sensor applications.

Compared with LM35DMX/NOPB, LM35CH offers superior temperature range and hermetic reliability; compared with ADT7320TRZ-REEL7, it provides simpler analog integration but lacks digital configurability and higher absolute accuracy.

Availability

LM35CH is available at Aetrix Electronics and suitable for power supply thermal monitoring, battery pack sensing, and industrial motor protection requiring stable component supply across long-lifecycle programs.

Supply support for LM35CH 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 analog signal conditioning.

The LM35 series was designed specifically for high-fidelity, low-power, centigrade-referenced temperature measurement in industrial, automotive, and instrumentation systems where calibration simplicity and long-term stability are critical.

FAQ

What is the maximum operating temperature of the LM35CH?

The LM35CH is rated for continuous operation from −55°C to +150°C. This full-range specification is validated per TI's SNIS159H datasheet and applies to the hermetic TO-46 package variant. Operation beyond 150°C risks permanent parametric shift or junction failure, and thermal derating is not defined above this limit. Always verify PCB layout thermal resistance to ensure junction temperature remains within spec under worst-case ambient and power dissipation.

Does the LM35CH require external calibration or trimming?

No, the LM35CH does not require external calibration or trimming. It is wafer-level trimmed to achieve ±1°C accuracy at 25°C and ±1.5°C over its full −55°C to +150°C range. The device outputs a precise 10 mV/°C analog voltage referenced directly to 0°C, eliminating the need for offset nulling or gain adjustment in the signal chain. This inherent calibration is guaranteed and tested in production.

Can the LM35CH drive a 100-pF capacitive load directly?

No, the LM35CH is specified to drive ≤50 pF capacitively without external compensation. Driving 100 pF directly may cause instability or overshoot in the output response. To interface with heavier capacitive loads (e.g., long cables or ADC input capacitance), TI recommends adding a 75 Ω series resistor between VOUT and the load, optionally with a 0.2 µF to 1 µF capacitor from that node to GND as an R-C damper - as shown in Figure 13 of the LM35 datasheet.

What is the output impedance of the LM35CH and how does it affect ADC interfacing?

The LM35CH has a typical output impedance of 0.1 Ω at 1 mA load, confirmed in the "Electrical Characteristics" table of the SNIS159H datasheet. This ultra-low impedance allows direct connection to most SAR and delta-sigma ADC inputs without buffer amplification. However, for 16-bit+ resolution, a 1–10 nF ceramic capacitor placed close to the ADC input helps suppress high-frequency noise without loading the LM35CH output.

Is the LM35CH pin-compatible with other LM35 variants like LM35C or LM35D?

No, the LM35CH is not pin-compatible with LM35C (TO-92) or LM35D (SOIC/TO-220). The LM35CH uses a 3-pin TO-46 metal can package with top-view pinout: Pin 1 = +VS, Pin 2 = VOUT, Pin 3 = GND (case-connected). LM35C uses bottom-view TO-92 (Pin 1 = VOUT), and LM35D in SOIC has 8 pins with multiple N.C. terminals. Mechanical and electrical pin mapping differs - PCB layout must be specific to LM35CH.