LM2901DTBR2G Quad Differential Comparator: Datasheet, Pinout, and Application Circuits
The LM2901DTBR2G is a industry-standard, quad independent precision voltage comparator from ON Semiconductor. It is designed to operate from a single power supply over a wide range of voltages or from split supplies, making it an exceptionally versatile component for a vast array of electronic circuits. This device is characterized by its low supply current drain, which is independent of the magnitude of the supply voltage, and its compatibility with TTL, MOS, and CMOS logic outputs.
Datasheet Overview: Key Specifications
A thorough review of the datasheet is crucial for proper implementation. The LM2901DTBR2G's key specifications include:
Supply Voltage Range: A wide range from 2V to 36V (single supply) or ±1V to ±18V (dual supplies).
Low Supply Current: Typically 0.8 mA per comparator, which is very low for a quad device.
Input Common-Mode Voltage Range: Includes ground (GND), allowing it to sense signals below the negative rail.
Low Input Bias Current: Typically 25 nA.
Low Input Offset Voltage: Typically 2 mV.
Differential Input Voltage Range: Equal to the supply voltage, offering robust operation.
Output Voltage Swing: Compatible with TTL, CMOS, and MOS logic systems.
Operating Temperature Range: -40°C to +125°C, suitable for industrial and automotive applications.
Pinout Configuration
The LM2901DTBR2G is available in a TSSOP-14 surface-mount package. Its pinout is standardized for quad comparators:
Pins 1, 7, 8, 14: Outputs for comparators 1, 2, 3, and 4, respectively.
Pins 2, 4, 5, 6: Inverting Inputs (-) for comparators 1, 2, 3, and 4.
Pins 3, 4, 9, 10: Non-Inverting Inputs (+) for comparators 1, 2, 3, and 4.
Pin 11: VCC+ (Positive Supply Voltage)
Pin 12: GND (Ground / Negative Supply Voltage)
Application Circuits
The LM2901DTBR2G is a fundamental building block in electronics. Here are three classic application circuits:
1. Basic Comparator Circuit: The simplest use case. The inverting (-) or non-inverting (+) input is connected to a fixed reference voltage, while the other input monitors a variable signal. The output switches states when the variable signal crosses the reference threshold. Open-collector outputs require a pull-up resistor to the desired logic voltage rail (e.g., 5V or 3.3V).
2. Window Comparator Circuit: This circuit uses two of the device's four comparators to determine if a signal is within a predefined high and low voltage "window." The output of the two comparators can be wired together (open-collector allows this) or fed into logic gates to provide a single digital signal indicating whether the input is inside or outside the designated range. This is ideal for undervoltage/overvoltage monitoring.
3. Relaxation Oscillator (Square Wave Generator): A single comparator can be configured as a simple oscillator. By using positive feedback through a resistor network (creating hysteresis/schmitt trigger action) and an RC timing circuit connected to the input, the comparator will continuously switch states, generating a square wave at its output. The frequency is determined by the values of the resistor and capacitor.
The LM2901DTBR2G stands as a robust, reliable, and cost-effective solution for countless analog signal processing tasks. Its wide supply voltage range, low power consumption, and ground-sensing capability make it a superior choice over many newer alternatives for industrial control systems, automotive electronics, battery-powered devices, and voltage monitoring applications. Its quad package offers excellent functional density, simplifying board design and reducing component count.
Keywords: Voltage Comparator, Open-Collector Output, Wide Supply Voltage, Ground Sensing, Window Detector.
