The part number " LM2675M-ADJ/NOPB " refers to a switching regulator from Texas Instruments. It is a part of the LM2675 family, which is a series of 5-pin step-down voltage regulators. The "ADJ" indicates that this is an adjustable version, and "NOPB" signifies that the part is lead-free and complies with environmental regulations.
Pinout and Functions:
For the LM2675M-ADJ/NOPB, the device comes in the TO-220 package, which has 5 pins in total. Here's the pinout description and the function of each pin:
Pin Number Pin Name Pin Function Description Pin 1 VOUT Output Voltage: This is the output of the regulator where the regulated voltage is delivered. It is a low-voltage output regulated by the feedback loop. Pin 2 GND Ground: This is the reference ground for the regulator. All voltages in the system are referenced to this pin. Pin 3 VIN Input Voltage: This is where the input voltage is supplied to the regulator. The input voltage needs to be higher than the output voltage by a certain margin, usually around 1V. Pin 4 FB (Feedback) Feedback: This is the feedback pin for the adjustable version of the regulator. It is used to set the output voltage based on the resistor divider network. Pin 5 SW (Switch) Switching Pin: This pin is connected to an external transistor (internal in the IC), which controls the on-off cycling of the inductor. It is the key part of the regulator’s switching mechanism to step down the input voltage.Function of Each Pin in Detail:
Pin 1 - VOUT (Output Voltage Pin): Function: Supplies the regulated voltage to the load. The voltage at this pin is determined by the feedback mechanism involving the external resistors (for the adjustable version). Usage: This pin should be connected to the load circuit that requires a regulated output. It typically needs proper decoupling using capacitor s for stability. Pin 2 - GND (Ground Pin): Function: Establishes the system's common ground reference for all components. Usage: Connect this pin to the ground of the external circuit. It is crucial that the ground path is low-impedance to avoid voltage fluctuations. Pin 3 - VIN (Input Voltage Pin): Function: Supplies the input voltage to the regulator. The input voltage must be higher than the output voltage to enable proper step-down regulation. Usage: Connect this pin to the supply that provides power to the regulator. Ensure the input voltage stays within the specified limits (typically between 8V and 40V). Pin 4 - FB (Feedback Pin): Function: This pin is used to adjust the output voltage by using a resistor divider network between the output and ground. Usage: In the adjustable version (LM2675M-ADJ/NOPB), use two resistors to set the desired output voltage. The feedback voltage at this pin should be equal to the internal reference voltage (typically 1.23V). Pin 5 - SW (Switch Pin): Function: The switch pin is connected to the internal switching transistor that regulates the flow of energy to the inductor. The switching operation is crucial for voltage regulation. Usage: This pin drives the external inductor and determines the switching frequency. It must be connected to the external inductor for proper operation.FAQ for LM2675M-ADJ/NOPB
Here are 20 commonly asked questions about this regulator:
What is the input voltage range of the LM2675M-ADJ/NOPB? The input voltage range is between 8V and 40V. Can the LM2675M-ADJ/NOPB be used to step up the voltage? No, it is a step-down (buck) voltage regulator, meaning it can only reduce the input voltage to a lower output voltage. What is the typical output voltage range of the LM2675M-ADJ/NOPB? The output voltage is adjustable via an external resistor divider. The output voltage range can be set from 3.3V to 15V. What is the output current capability of the LM2675M-ADJ/NOPB? The device can supply up to 1A of continuous output current. What type of capacitors are recommended for the LM2675M-ADJ/NOPB? Typically, a 220µF capacitor is recommended at the input and a 330µF capacitor at the output for proper filtering and stability. What is the switching frequency of the LM2675M-ADJ/NOPB? The typical switching frequency is 52kHz. What is the purpose of the feedback pin (FB)? The feedback pin is used to adjust the output voltage by using a resistor divider. What happens if the input voltage drops below the required level? If the input voltage falls below the necessary threshold, the regulator will stop regulating, and the output voltage will drop. What is the maximum output voltage for the LM2675M-ADJ/NOPB? The maximum output voltage depends on the external resistors but is typically adjustable up to 15V.Can the LM2675M-ADJ/NOPB be used in a battery-powered application?
Yes, but the input voltage should be maintained above the output voltage by a sufficient margin for stable operation.What is the efficiency of the LM2675M-ADJ/NOPB?
The efficiency can be up to 80%, depending on the input-output voltage differential and the load current.Is there any protection built into the LM2675M-ADJ/NOPB?
Yes, it has built-in thermal shutdown, overcurrent protection, and undervoltage lockout.Can I connect the output directly to the load without a capacitor?
No, a capacitor is required at the output for stability and to prevent high-frequency oscillations.What are the thermal limitations of the LM2675M-ADJ/NOPB?
The maximum junction temperature is 125°C, and proper heat dissipation should be ensured to avoid overheating.What is the recommended inductor value for the LM2675M-ADJ/NOPB?
The recommended inductor value is typically in the range of 100µH to 150µH, depending on the application.How do I calculate the output voltage of the LM2675M-ADJ/NOPB?
Use the formula: VOUT = VREF(1 + R1/R2), where VREF is typically 1.23V, and R1 and R2 are the resistors in the divider.Can the LM2675M-ADJ/NOPB be used with other types of inductors?
Yes, but ensure the inductor is suitable for the operating frequency and current rating.What is the typical dropout voltage of the LM2675M-ADJ/NOPB?
The typical dropout voltage is around 1.1V under full load conditions.How do I choose the right resistors for the feedback network?
The resistors should be selected based on the desired output voltage. Refer to the datasheet for recommended calculations.Can I use this regulator with a higher current load?
For loads greater than 1A, consider using a higher current version of the LM2675 or another suitable regulator.This is a comprehensive explanation of the LM2675M-ADJ/NOPB, including the pin functions and common FAQs. Let me know if you'd like more specific details or clarifications!