LM393M Comparator: Equivalents, Features and Layout Guidelines
06 November 2023
Ⅰ. Overview of LM393M comparator
Ⅱ. Symbol, footprint and pin configuration of LM393M comparator
Ⅲ. Features of LM393M comparator
Ⅳ. Technical parameters of LM393M comparator
Ⅴ. Layout guidelines for LM393M comparator
Ⅵ. Applications of LM393M comparator
Ⅶ. How to enhance the performance of LM393M comparator?
The LM393M, a popular voltage comparator IC, comprises two independent high-precision comparator op-amps, accommodating both single and dual supply configurations. Its extensive supply voltage range renders it versatile for various applications, and its minimal current consumption makes it well-suited for portable and battery-powered devices. With the ability to produce logic-level outputs, this chip finds utility in digital circuits, especially in tasks involving transistor control and logic systems. Moreover, the LM393M boasts a maximum output current of 20mA, fulfilling the requirements for driving transistors and logic systems in the majority of applications.
Replacements and equivalents:
• LM393MX
The symbol, footprint and pin configuration of LM393M are shown in the figure below.
LM393M has a total of 8 pins, its pins and descriptions are as follows.
Pin 1 (OUTPUT1): Output of op-amp 1
Pin 2 (INPUT1-): Inverting input of op-amp 1
Pin 3 (INPUT1+): Non-inverting input of op-amp 1
Pin 4 (GND): Ground or negative supply voltage
Pin 5 (INPUT2+): Non-inverting input of op-amp 2
Pin 6 (INPUT2-): Inverting input of op-amp 2
Pin 7 (OUTPUT2): Output of op-amp 2
Pin 8 (V+): Positive supply voltage
• Its current consumption is relatively small, ICC is only 0.4mA. In battery-powered devices, it can effectively extend battery life.
• It has a wide common-mode input voltage range, VIC=0 to VCC-1.5V
• The output of LM393M is compatible with TTL, DTL, MOS, CMOS and other electronic components.
• It features a low input offset voltage of VIO=±2mV, allowing us to disregard its impact on the output result when comparing two input signals.
• The maximum output current of LM393M is 20mA, which is enough to drive transistors and logic systems.
• LM393M has a wide operating power supply voltage range and can work with both single power supply and dual power supply. Among them, the single power supply is 2V to 36V, and the dual power supply is ±1 to ±18V.
Minimize parasitic impedances at the inputs to prevent oscillation. Any positive feedback used as hysteresis should place the feedback components as close as possible to the input pins. Care should be taken to ensure that the output pins do not couple to the inputs. This can occur through capacitive coupling if the traces are too close and lead to oscillations on the output. The optimum placement for the bypass capacitor is closest to the V+ and ground pins. Take care to minimize the loop area formed by the bypass capacitor connection between V+ and ground. The ground pin should be connected to the PCB ground plane at the pin of the device. The feedback components should be placed as close to the device as possible minimizing strays.
• Photosensitive circuit: It can be used in a photosensitive circuit, where one comparator can detect the output of the photosensitive sensor, and the other comparator can be used for a reference voltage to determine whether the light intensity is sufficient to trigger a certain reaction, such as turning on a lighting device.
• Battery voltage monitoring: It can monitor the voltage of the battery. When the battery voltage is lower than a predetermined threshold, the LM393M will trigger a warning or automatically power off, effectively preventing the battery from over-discharging, thus protecting the battery and extending its service life.
• Pulse detection: It is capable of identifying the frequency or pulse signal width. By comparing the input pulse signal to a predefined threshold, it can assess whether the signal fulfills specific criteria, depending on whether its amplitude exceeds or falls short of the threshold.
• Switch control: The LM393M has the capability to compare the input signal to the reference voltage, enabling it to manage the operation of a switch or relay, and subsequently determine whether to open or close the circuit, depending on the outcome of the comparison. This functionality is commonly employed in various applications, including motor control and automatic control systems.
1. Optimize bandwidth
The bandwidth is constrained, and to enhance the performance of high-speed comparator applications, it is essential to optimize it. This can be achieved by refining layout and routing, as well as incorporating suitable RC filters and other techniques.
2. Increase gain
The gain of the LM393M mainly depends on the selection of the external feedback resistor. In order to increase the gain, we can appropriately increase the resistance of the feedback resistor. However, we need to pay attention to the accuracy and stability of the feedback resistor to ensure that it does not negatively affect the performance of the comparator.
3. Improve linearity
Linearity is one of the important indicators for evaluating the performance of a comparator and has a great impact on its performance. The higher the linearity, the higher the accuracy of the comparator and the more stable the performance. Therefore, in order to improve the linearity of LM393M, we adjust the bias current, change the static operating point of the comparator, and increase the linear range of the circuit, thereby reducing errors and improving linearity.
4. Reduce power consumption
The LM393M is a low power comparator, but in some applications further power reduction is required. We can reduce power consumption by selecting appropriate devices, optimizing circuit design, reducing bias current, etc.
5. Reduce offset voltage
LM393M is a high-performance voltage comparator. One of its outstanding performances is that the offset voltage specification can be as low as 2mV. In order to further reduce the offset voltage, we can use high-quality resistors, optimized layout and wiring, etc. to improve its accuracy and performance to meet more stringent application requirements.
Frequently Asked Questions
1. What is the replacement and equivalent of LM393M?
You can replace the LM393M with the LM393MX/NOPB, LM393M/NOPB or LM393MX.
2. What is the LM393M?
The LM393M is an integrated circuit that functions as a voltage comparator. It is commonly used in electronics for comparing two voltages and providing a digital output based on the comparison.
3. What is the operating temperature range of LM393M?
The operating temperature of LM393M ranges from 0°C to 70 °C.
4. What are common applications for the LM393M?
The LM393M is commonly used in applications where you need to compare two voltages, such as in window comparators, threshold detectors, and overvoltage/undervoltage protection circuits.
5. Can the LM393M be used with a single power supply?
Yes, the LM393M can be used with a single power supply. It can operate with both single-supply and dual-supply configurations, depending on the application requirements.
