The model "LM339N" belongs to Texas Instruments (previously manufactured by National Semiconductor, which was acquired by TI). It is an LM339 family of quad comparator s, meaning it contains four independent comparators in a single package.
LM339N Package and Pinout:
The LM339N comes in a 14-pin Dual In-line Package (DIP) format, and the pinout consists of 14 pins. The function of each pin is described in detail below.
Pin Function Specification and Circuit Principle:
The LM339N is typically used as a comparator that compares two input voltages and outputs a result based on the comparison. It is commonly used in applications like signal conditioning, analog-to-digital conversion, and as a threshold detector.
Pin Function Table:
Pin Number Pin Name Pin Function Description 1 Output 1 Output of Comparator 1. The output is open-collector, meaning it requires an external pull-up resistor. 2 Inverting Input 1 Inverting input for Comparator 1 (inverted signal input). 3 Non-Inverting Input 1 Non-inverting input for Comparator 1 (positive signal input). 4 Ground Ground reference (0V) for the IC. 5 Non-Inverting Input 2 Non-inverting input for Comparator 2. 6 Inverting Input 2 Inverting input for Comparator 2. 7 Output 2 Output of Comparator 2. Same as Output 1 (open-collector output). 8 Vcc Positive power supply (typically +5V to +30V). 9 Output 3 Output of Comparator 3 (open-collector output). 10 Inverting Input 3 Inverting input for Comparator 3. 11 Non-Inverting Input 3 Non-inverting input for Comparator 3. 12 Non-Inverting Input 4 Non-inverting input for Comparator 4. 13 Inverting Input 4 Inverting input for Comparator 4. 14 Output 4 Output of Comparator 4 (open-collector output).Detailed Pin Description:
Output Pins (1, 7, 9, 14): These are the output pins for each of the four comparators in the IC. Since the LM339N is an open-collector output device, these pins must have an external pull-up resistor connected to provide a defined high-level voltage output when the comparator is "on."
Inverting Inputs (2, 6, 10, 13): These are the inverting inputs for the four comparators. A voltage applied to these pins is compared against the voltage at the non-inverting input. A comparator will output a logic low if the voltage at the inverting input is higher than that at the non-inverting input.
Non-Inverting Inputs (3, 5, 11, 12): These are the non-inverting inputs for the four comparators. A voltage applied to these pins is compared with the voltage at the inverting input. The comparator will output a logic high when the voltage at the non-inverting input is higher than that at the inverting input.
Ground (Pin 4): This pin connects to the ground of the circuit to provide a common reference for all the components within the LM339N.
Vcc (Pin 8): This is the power supply pin for the LM339N. It provides the voltage needed for the IC to operate, usually from +5V to +30V.
20 FAQ (Frequently Asked Questions):
Q1: What is the operating voltage range for the LM339N? A1: The LM339N operates within a voltage range of +3V to +30V (Vcc) with a ground reference.
Q2: How do I connect the LM339N to a 5V power supply? A2: Connect Pin 8 (Vcc) to the +5V supply and Pin 4 (Ground) to the ground of your circuit.
Q3: What is the output type of the LM339N? A3: The LM339N provides an open-collector output, meaning it requires an external pull-up resistor to work correctly.
Q4: Can I use the LM339N for analog signal processing? A4: Yes, the LM339N can be used for analog signal processing as a comparator, useful in various analog systems like threshold detection and level shifting.
Q5: How many comparators are in the LM339N? A5: The LM339N contains 4 independent comparators within a single package.
Q6: What is the main advantage of using an open-collector output? A6: The main advantage is that the open-collector output allows multiple comparators to share the same pull-up resistor, making it easier to interface with other logic circuits.
Q7: What is the function of the pull-up resistor on the output pins? A7: The pull-up resistor ensures that when the output is not active (low), the output voltage is pulled to the high state defined by the supply voltage.
Q8: Can I use the LM339N for digital logic applications? A8: While the LM339N is not specifically a logic gate, its open-collector outputs can be used in logic circuits when appropriately interfaced with pull-up resistors.
Q9: Can the LM339N be used in a voltage divider configuration? A9: Yes, the LM339N can be used in voltage divider circuits for comparing the divided voltages.
Q10: What is the significance of the comparator's hysteresis? A10: Hysteresis adds a feedback loop to the comparator, preventing the output from rapidly switching between high and low due to noise in the input signal.
Q11: What happens when the inputs to the LM339N are equal? A11: If the inputs are equal, the output of the comparator may not be well-defined due to the nature of the open-collector output.
Q12: How should the inputs be configured for the LM339N to function correctly? A12: The input pins should be connected to the signals being compared, with the non-inverting and inverting inputs receiving the appropriate voltages for comparison.
Q13: How do I use the LM339N for threshold detection? A13: Set one input (usually the non-inverting input) to a reference voltage and the other to the signal you want to monitor. The comparator will output a high or low signal when the signal exceeds the threshold.
Q14: Can the LM339N be used in temperature sensing circuits? A14: Yes, by using a temperature sensor like an NTC thermistor or diode, the LM339N can compare the sensor output against a threshold voltage to monitor temperature.
Q15: Is there a recommended method for minimizing output noise in the LM339N? A15: To minimize noise, you can add hysteresis or use filtering components like capacitor s at the inputs.
Q16: What is the typical current draw for the LM339N? A16: The LM339N typically draws around 1mA per comparator when operating at 5V, depending on the load and external components.
Q17: Can the LM339N be used with both single and dual power supplies? A17: Yes, the LM339N can be used with either single or dual power supplies, as long as the voltages are within the specified range.
Q18: What is the response time of the LM339N? A18: The response time of the LM339N varies depending on the supply voltage and load conditions but is typically around 300ns to 1µs.
Q19: What should I do if the output does not reach the supply voltage? A19: Ensure the pull-up resistor is correctly chosen and that the comparator is not overloaded by excessive current draw.
Q20: How can I troubleshoot if the LM339N is not working properly? A20: Verify the power supply connections, check the pull-up resistors on the output pins, and ensure the input signals are within the proper voltage range for comparison.
This table and FAQ section contains all the essential details of the LM339N. The information is comprehensive and designed to assist you in working with the LM339N for various applications.
