Onsemi MURS320T3 Ultrafast Rectifier: Datasheet, Application Circuits, and Replacement Guide
The Onsemi MURS320T3 is a prominent member of the ultrafast rectifier family, designed for high-efficiency power conversion applications. This rectifier is engineered to offer superior switching performance and high reliability, making it a preferred choice in demanding electronic circuits. Understanding its key specifications, typical applications, and potential replacements is crucial for design engineers and procurement specialists.
Datasheet Overview and Key Specifications
The MURS320T3 is a 3 A, 200 V ultrafast recovery rectifier. Its most critical feature is its ultrafast reverse recovery time (trr), typically rated at 35 ns. This rapid recovery minimizes switching losses and reduces noise, which is essential for high-frequency operation in switch-mode power supplies (SMPS). The device is housed in a DO-214AA (SMB) surface-mount package, offering a good balance between compact size and power handling capability. Key absolute maximum ratings include a repetitive peak reverse voltage (VRRM) of 200 V and an average forward rectified current (IF(AV)) of 3 A. Its low forward voltage drop (VF) enhances overall system efficiency by minimizing conduction losses.
Primary Application Circuits
The MURS320T3 is predominantly used in circuits where high-speed switching is paramount. Its primary applications include:
1. Freewheeling Diode in SMPS: In flyback and boost converter topologies, it serves as a crucial freewheeling or clamp diode, protecting the switching MOSFET by providing a path for inductive current.
2. Output Rectification: It can be used in the output stage of power supplies, though it is often outclassed by Schottky diodes for very low voltage outputs due to its inherent VF.
3. Reverse Polarity Protection: The diode is effective in circuits requiring protection against reverse voltage connection, safeguarding sensitive components.
4. Snubber Circuits: Its fast recovery characteristics make it suitable for use in snubber networks, where it helps to suppress voltage spikes and ringing across switches.
A typical application circuit in a flyback converter shows the MURS320T3 placed across the transformer's primary or secondary winding, clamping the voltage spike generated when the main switch turns off.
Replacement and Cross-Reference Guide
While the MURS320T3 is a robust component, sourcing alternatives may be necessary due to supply chain constraints or design revisions. Suitable replacements must match or exceed its key parameters: 200 V VRRM, 3 A current rating, and an ultrafast trr. Potential direct or functional replacements include:
Diodes Incorporated DFLS1300-7: A similar 3A, 200V Schottky diode with even lower VF, but check for voltage ringing and stability.
Vishay VS-3ETU02-M3: Another ultrafast rectifier in a compatible SMB package with comparable specifications.
STMicroelectronics STPS3L20U: A low-drop power Schottky diode, though its lower voltage rating (20V) makes it unsuitable for 200V applications and highlights the importance of verifying voltage requirements.
When selecting a replacement, it is critical to consult the datasheets to ensure compatibility in forward voltage, recovery time, and package thermal characteristics.
ICGOODFIND: The Onsemi MURS320T3 stands out as a highly efficient and reliable ultrafast rectifier essential for modern high-frequency power conversion. Its optimal blend of fast recovery, low loss, and robust packaging makes it an excellent solution for freewheeling, clamping, and protection roles in switch-mode power supplies and other electronic systems.
Keywords: Ultrafast Recovery Rectifier, Switch-Mode Power Supply (SMPS), Freewheeling Diode, Reverse Recovery Time, SMB Package.
