LM35CZ

LM35CZ Precision Centigrade Temperature Sensor

Overview

The LM35CZ is a precision integrated-circuit temperature sensor that provides an output voltage linearly proportional to the Celsius (Centigrade) temperature. Unlike sensors calibrated in Kelvin, the LM35CZ eliminates the need for subtracting a large constant voltage from its output, simplifying temperature measurement in real-world applications. Designed for accuracy and ease of use, the LM35CZ is ideal for a wide range of temperature sensing applications.

This device operates over a temperature range of -40°C to +110°C (LM35CZ variant) with a typical accuracy of ±¼°C at room temperature and ±¾°C across its full range. Its low power consumption (60 µA) ensures minimal self-heating, making it suitable for precision measurements. The LM35CZ is available in a TO-92 plastic package, offering a cost-effective solution for temperature monitoring in consumer, industrial, and automotive systems.

Features

• Direct Celsius Calibration: Output voltage is directly proportional to °C, eliminating the need for signal conditioning.
• High Accuracy: Typical accuracy of ±¼°C at room temperature (±¾°C over full range).
• Wide Operating Range: -40°C to +110°C (LM35CZ variant).
• Low Power Consumption: Draws only 60 µA, reducing self-heating effects (<0.1°C in still air).
• Linear Output: 10 mV/°C scale factor for straightforward interfacing.
• Low Output Impedance: Simplifies connection to readout or control circuits.
• No External Calibration Required: Factory-trimmed for precision.
• Single or Dual Supply Operation: Compatible with +4V to +30V single supply or ±2V to ±15V split supplies.
• Cost-Effective Packaging: Available in TO-92 plastic package for easy integration.

Applications

• Thermal Monitoring: Power supplies, battery chargers, and HVAC systems.
• Consumer Electronics: Smartphones, laptops, and appliances.
• Industrial Control: Process automation, machinery temperature feedback.
• Automotive Systems: Engine management, cabin climate control.
• Medical Devices: Patient monitoring and diagnostic equipment.
• Environmental Sensing: Weather stations and agricultural monitoring.

Electrical Characteristics

(Typical values at +25°C, V_S = +5V unless otherwise specified)

• Output Voltage: 10 mV/°C (linear slope).
• Accuracy: ±¼°C (at +25°C), ±¾°C (-40°C to +110°C).
• Supply Voltage Range: +4V to +30V (single supply), ±2V to ±15V (dual supply).
• Current Consumption: 60 µA (typical).
• Output Impedance: 0.1 Ω (typical) for 1 mA load.
• Non-Linearity: ±0.2°C (typical) over full range.
• Long-Term Stability: ±0.08°C/month (typical).

Package Information

The LM35CZ is housed in a TO-92 plastic package, which is widely used for through-hole PCB mounting. Key package details include:

• Package Type: TO-92 (3-pin).
• Pin Configuration:
  • Pin 1: V_OUT (Output Voltage).
  • Pin 2: GND (Ground).
  • Pin 3: V_S (Supply Voltage).
• Dimensions: 4.95 mm (L) x 3.94 mm (W) x 4.95 mm (H).
• Operating Temperature Range: -40°C to +110°C.
• Storage Temperature Range: -60°C to +150°C.
• Moisture Sensitivity Level (MSL): 1 (Unlimited floor life at ≤30°C/85% RH).

Detailed Performance Considerations

The LM35CZ's linear output and low impedance make it suitable for direct connection to microcontrollers, ADCs, or analog circuits. For optimal performance:

• Noise Immunity: Use bypass capacitors (0.1 µF) near the supply pin to minimize noise.
• Long-Distance Wiring: Shielded cables are recommended to reduce EMI interference.
• Thermal Coupling: Ensure proper thermal contact between the sensor and the measured surface for accurate readings.
• Self-Heating Effects: Minimal (<0.1°C) due to low current draw, but avoid high thermal resistance in mounting.

Conclusion

The LM35CZ is a versatile, high-precision temperature sensor that simplifies Celsius measurements with its linear voltage output and minimal external component requirements. Its robust performance across industrial, automotive, and consumer applications makes it a preferred choice for designers seeking reliability and ease of integration. With its TO-92 package and wide operating range, the LM35CZ delivers cost-effective temperature sensing for both prototyping and mass production.