LM393 Low Offset Voltage Dual Comparator

LM393 Low Offset Voltage Dual Comparator Overview

The LM393 is a dual comparator that offers low offset voltage and is widely used in various electronic applications. This integrated circuit (IC) facilitates voltage comparison and can be utilized for signal conditioning, level shifting, and other tasks that require sensing and threshold detection.

Key Features:

• Dual Comparator: Contains two independent, high-gain comparators.
• Low Offset Voltage: The typical input offset voltage is around 2 mV, which enhances accuracy in applications where precise voltage thresholds are needed.
• Wide Supply Voltage Range: Operates with a single supply voltage of 2 V to 36 V or dual supplies of ±1 V to ±18 V.
• Open-Collector Output: The output stage is open-collector, allowing the output to be connected to higher voltages and enabling wired-AND configurations.
• Low Power Consumption: Consumes minimal power, typically around 0.5 mA per comparator.
• High Voltage Gain: Provides a high gain of 100 V/V (minimum) and high input impedance.
• Temperature Range: Standard temperature range of 0°C to +70°C, with industrial versions available for wider ranges.

Applications:

The LM393 is suited for a variety of applications, including:

1. Voltage Level Detection: Used to compare two voltage levels and trigger an output based on predetermined thresholds.
2. Zero-Crossing Detectors: Ideal for detecting when an AC signal crosses zero volts.
3. Oscillators: Can be configured to create pulse-width modulation (PWM) signals or other oscillator-type circuits.
4. Analog Signal Processing: Used for signal conditioning and shaping in various electronic systems.
5. Window Comparators: Can be used to create a window comparator circuit that checks if an input voltage falls within a specified range.

Pin Configuration:

The LM393 typically comes in a 8-pin DIP or a surface-mount package. The pin configuration for the 8-pin DIP is as follows:

Copy       +Vcc
          |
      ------- 
     |       |
     |       |
  1  |      8|  Vcc
  2  |  -   7|  Output 1
  3  | -|+   6|  Output 2
  4  |  -   5|  GND
      -------

• Pin 1: Comparator 1 Input (-)
• Pin 2: Comparator 1 Input (+)
• Pin 3: Comparator 2 Input (-)
• Pin 4: Comparator 2 Input (+)
• Pin 5: Ground (GND)
• Pin 6: Output 2
• Pin 7: Output 1
• Pin 8: Supply Voltage (Vcc)

Basic Operating Principle:

The LM393 compares the voltages at the inverting (-) and non-inverting (+) inputs of each comparator:

• If the voltage at the non-inverting input is greater than the inverting input (for example, V+ > V-), then the output will switch to low (0 V) in an open-collector configuration.
• Conversely, if V+ is less than V-, the output will go high (near Vcc). Resistor pull-up is required for non-active states.

Example Application:

Voltage Level Detection Circuit:

• Connect the inverting input of comparator 1 to a reference voltage (using a voltage divider).
• Connect the non-inverting input to the signal you want to monitor.
• Use the output to drive an LED or trigger another device when the signal exceeds the reference voltage.

Important Considerations:

1. Power Supply: Ensure that the supply voltage does not exceed the rated maximum of 36 V.
2. Input Range: Maintain the input voltage within the specified limits to avoid damaging the IC.
3. Thermal Management: If using in high-temperature environments, ensure the IC operates within specified limits.
4. Output Configuration: Since the output is open-collector, you’ll need to use a pull-up resistor to define the high state.