LM3481MM NOPB Converter Features, Pin Configuraiton and Other Details
13 October 2023
Ⅱ. Symbol and footprint of LM3481MM/NOPB
Ⅲ. Technical parameters of LM3481MM/NOPB
Ⅴ. Pin configuration of LM3481MM/NOPB
Ⅵ. Application of LM3481MM/NOPB
Ⅶ. How to improve the efficiency of LM3481MM/NOPB?
Ⅷ. How to choose the external components of LM3481MM/NOPB?
The LM3481MM/NOPB is a high-efficiency switching converter that includes a 600mA N-channel power MOSFET within its design. This converter is well-suited for applications that necessitate low-side FETs, like boost, flyback, and SEPIC configurations. Operating at a 1MHz switching frequency and boasting an output current of 10 A, it is offered in an MSOP package and is also available in tape and reel (TR) packaging. The LM3481MM/NOPB device is equipped with integrated safety features, including safeguards against over-voltage, short-circuits, and thermal overloads. Furthermore, it features a power-saving shutdown mode, which can reduce the overall supply current to 5HA and enable power sequencing.
Replacement and equivalent：
• LM3481MM
• LM3481MMX/NOPB
• RF100310
• Adjustable switching frequency: The switching frequency of this device can be adjusted to any value between 100KHZ and 1MHZ by using an external resistor or by synchronizing it with an external clock.
• High efficiency: LM3481MM/NOPB uses an advanced 600mA N-channel power MOSFET, making it highly efficient in power conversion applications.
• High switching frequency: It is a high-frequency switch with a switching frequency of up to 1MHz. It has a wide range of external component compatibility and can be used with a variety of components to achieve more flexible application solutions.
• Overcurrent protection and thermal shutdown: When overcurrent occurs in the circuit, the chip will automatically cut off the switch to prevent overcurrent from damaging the circuit. The thermal shutdown function can detect the temperature of the chip itself. When the temperature is too high, the chip will automatically enter the protection state.
• Programmable soft-start function: It is a power management integrated circuit featuring a programmable soft-start capability. This feature serves to mitigate abrupt current surges during initialization, thereby safeguarding the circuit's integrity. In the startup phase, LM3481MM/NOPB meticulously ramps up the output voltage to avert any sudden current spikes that could potentially harm the circuit.
1. Pins of LM3481MM/NOPB
LM3481MM/NOPB has a total of 10 pins, as shown in the figure below:
Pin1 (ISEN): Current sense input pin. Voltage generated across an external sense resistor is fed into this pin.
Pin2 (UVLO): Under voltage lockout pin. A resistor divider from VIN to ground is connected to the UVLO pin. The ratio of these resistances determine the input voltage which allows switching and the hysteresis to disable switching.
Pin3 (COMP): Compensation pin. A resistor and capacitor combination connected to this pin provides compensation for the control loop.
Pin4 (FB): Feedback pin. Inverting input of the error amplifier.
Pin5 (AGND): Analog ground pin. Internal bias circuitry reference. Should be connected to PGND at a single point.
Pin6 (FA/SYNC/SD): Frequency adjust, synchronization, and shutdown pin. A resistor connected from this pin to ground sets the oscillator frequency. An external clock signal at this pin will synchronize the controller to I/A the frequency of the clock. A high level on this pin for ≥ 30 µs will turn the device off and the device will then draw 5 µA from the supply typically.
Pin7 (PGND): Power ground pin. External power circuitry reference. Should be connected to AGND at a single point.
Pin8 (DR): Drive pin of the IC. The gate of the external MOSFET should be connected to this pin.
Pin9 (VCC): Driver supply voltage pin. A bypass capacitor must be connected from this pin to PGND.
Pin10 (VIN): Power supply input pin.
2. Package of LM3481MM/NOPB
LM3481MM/NOPB is an operational amplifier that comes in an MSOP package, known for its compact design, which is ideal for applications with limited space.
* Note: The Micro Small Outline Package (MSOP) represents a surface mount component packaging format characterized by its distinctive wing-shaped or J-shaped short leads on both sides. It is widely employed in the packaging of integrated circuits ranging from 8 pins to 16 pins. The 8-pin and 10-pin versions of this compact package measure just 3mm×3mm, while the 12-pin and 16-pin versions are slightly larger at 3mm×4mm. Notably, the MSOP offers several advantages, including a compact footprint, short interconnections for enhanced electrical performance, robust moisture resistance, and a maximum height of 1.10mm, which is lower than the traditional SOP package.
1. Circuit design: LM3481MM/NOPB is versatile and can be employed in a wide range of circuit configurations, including flyback converters, forward converters, buck-boost converters, and more. Whether utilized in low-voltage or high-voltage scenarios, LM3481MM/NOPB guarantees a reliable output voltage to maintain the system's stability during operation.
2. Electronic equipment: LM3481MM/NOPB can be applied to various electronic equipment, such as mobile phones, tablet computers, digital cameras, DVDs, game consoles, etc. In these devices, the LM3481MM/NOPB enables efficient power management, thereby extending the battery life of the device.
• Reduce switching frequency: Reducing the switching frequency can effectively minimize switching losses, leading to enhanced power efficiency. Nonetheless, this adjustment does affect the overall solution size. As the switch's duty cycle is inversely linked to the switching frequency, a decrease in the switching frequency will elevate the duty cycle, consequently enlarging the solution's dimensions. Therefore, while considering lowering the switching frequency to improve efficiency, we should also pay close attention to its impact on the overall solution size.
• Optimize voltage and current: This can be accomplished by selecting an appropriate input voltage range and fine-tuning the load resistor. These actions minimize energy inefficiency and enhance the longevity of the power source.
• Use synchronous rectification: If the current application permits, we have the opportunity to enhance circuit efficiency by opting for synchronous rectifiers in lieu of diode-based rectification. Synchronous rectifiers, as an innovative rectifier component, offer advantages such as reduced conduction voltage drop and a higher switching frequency. These characteristics effectively mitigate energy losses within the rectifier circuit and enhance its overall performance.
• Optimized heat dissipation design: Since LM3481MM/NOPB has a thermal shutdown protection function, optimized heat dissipation design can avoid efficiency decrease caused by overheating.
• Choose the appropriate on-resistance: The LM3481MM/NOPB incorporates an integrated power MOSFET with low on-resistance, effectively minimizing conduction losses. Additionally, the meticulous configuration of surrounding circuits plays a pivotal role. Reasonable selection of external components and connection methods can further reduce on-resistance, thereby achieving more efficient and energy-saving purposes.
• Protection functions: LM3481MM/NOPB has built-in protection functions, such as thermal shutdown, short circuit protection and overvoltage protection. We should select appropriate external components to ensure safe and stable operation of the circuit.
• Component matching: The LM3481MM/NOPB requires careful consideration and coordination of external components. To ensure circuit performance and stability, it's essential to choose suitable magnetic components like transformers and inductors that can work with the switching devices.
• Inrush current: The internal soft-start limitation serves to control the initial surge of current during startup. We should choose suitable external components to manage this initial current surge and guarantee the circuit's stable operation.
• Voltage and current: The voltage and current range that LM3481MM/NOPB can withstand depends on the specific application scenario and the requirements of the specification. We should select appropriate external components to ensure that the input and output voltages and currents are within the device specifications.
• Switching frequency: The LM3481MM/NOPB offers versatile switching frequency control. We can tune the switching frequency by employing a single external resistor or align it with an external clock source. The adjustable range for the switching frequency spans from 100KHz to 1MHz.
Frequently Asked Questions
1. What is the LM3481MM/NOPB?
The LM3481MM/NOPB is a voltage-mode DC/DC converter, typically used for step-up or step-down applications.
2. What factors need to be considered when using the LM3481MM/NOPB?
We need to consider circuit protection, selection and matching of external components, switching frequency adjustment range, heat dissipation design, current and voltage limitations, etc.
3. What is the function of the power-saving shutdown mode of LM3481MM/NOPB?
It reduces total supply current to 5HA and allows power sequencing. This mode extends the life of your device and optimizes power management.
4. What are the typical applications of the LM3481MM/NOPB?
The LM3481MM/NOPB is commonly used in a variety of power supply and voltage regulation applications, including battery-powered devices, LED drivers, and other DC/DC converter applications.
5. Does LM3481MM/NOPB have overcurrent protection function?
Yes, LM3481MM/NOPB has overcurrent protection function. When an overcurrent occurs in the circuit, the chip will automatically cut off the switch to prevent overcurrent from damaging the circuit.
