LM211N - Voltage Comparator

Overview

The LM211N is a high-performance voltage comparator designed to operate over a wide range of supply voltages, from standard ±15V operational amplifier supplies down to a single 5V supply used for logic systems. The LM211N is part of the LM111, LM211, and LM311 series of voltage comparators, which are known for their fast response times, high accuracy, and versatility in both analog and digital applications.

This device is particularly suited for applications requiring low input currents, such as precision analog-to-digital conversion, zero-crossing detectors, and level shifting. The LM211N is characterized for operation from -25°C to +85°C, making it suitable for industrial and automotive environments.

Features

• Wide Supply Voltage Range: Operates from ±15V down to a single 5V supply.
• Low Input Bias Current: Typically 150nA, ensuring minimal loading on the input signal source.
• Fast Response Time: 200ns typical for a 5mV overdrive, enabling high-speed applications.
• Strobe Capability: Allows for output control, useful in multiplexed applications.
• High Output Drive Capability: Can source or sink up to 50mA, compatible with TTL, MOS, and CMOS logic.
• Differential Input Voltage Range: Equal to the supply voltage, providing flexibility in signal conditioning.
• Low Input Offset Voltage: Typically 2mV, ensuring high accuracy in comparison tasks.

Applications

The LM211N is widely used in various electronic systems due to its robust performance and flexibility. Key applications include:

• Analog-to-Digital Converters (ADCs): Used as a precision comparator in successive approximation and flash ADCs.
• Zero-Crossing Detectors: Ideal for detecting the point where an AC signal crosses zero, useful in power control circuits.
• Level Shifters: Converts signals from one voltage level to another, often used in interfacing analog and digital circuits.
• Voltage Monitoring: Provides over-voltage or under-voltage protection in power supplies and battery management systems.
• Oscillators and Pulse Generators: Used in timing circuits and waveform generation.
• Industrial Control Systems: Suitable for harsh environments due to its wide operating temperature range.

Electrical Characteristics

The following table summarizes the key electrical specifications of the LM211N under typical operating conditions (V_CC = ±15V, T_A = 25°C unless otherwise noted):

DC Characteristics

• Input Offset Voltage: 2mV (max 5mV)
• Input Bias Current: 150nA (max 300nA)
• Input Offset Current: 20nA (max 50nA)
• Large Signal Voltage Gain: 200V/mV (min 50V/mV)
• Supply Current: 5mA (max 7.5mA)

AC Characteristics

• Response Time (5mV Overdrive): 200ns (max 400ns)
• Output Saturation Voltage (Low State): 0.4V (max 0.7V) at 6mA sink
• Output Saturation Voltage (High State): 1.5V (max 2.5V) at 6mA source

Package Information

The LM211N is available in a standard 8-pin PDIP (Plastic Dual In-line Package), which is widely used for through-hole PCB mounting. The package dimensions and pinout are as follows:

Package Dimensions

• Package Type: PDIP-8
• Length: 9.81mm (max)
• Width: 6.35mm (max)
• Height: 3.3mm (max)
• Lead Pitch: 2.54mm

Pin Configuration

• Pin 1: Output
• Pin 2: Ground
• Pin 3: V_CC⁺ (Positive Supply)
• Pin 4: Non-Inverting Input (+)
• Pin 5: Inverting Input (-)
• Pin 6: Balance
• Pin 7: Strobe
• Pin 8: V_CC^- (Negative Supply)

Conclusion

The LM211N is a versatile and reliable voltage comparator suitable for a wide range of applications, from precision analog circuits to robust industrial systems. Its combination of fast response, low power consumption, and wide supply voltage range makes it a preferred choice for designers requiring high-performance signal comparison. The PDIP-8 package ensures easy integration into existing designs, while its electrical characteristics guarantee accurate and stable operation under varying conditions.