onsemi MUR480ERLG Ultrafast Rectifier: Datasheet, Application Circuit, and Replacement Guide
The onsemi MUR480ERLG is a high-efficiency ultrafast rectifier diode designed for high-frequency power conversion applications. As a critical component in switch-mode power supplies (SMPS), freewheeling diodes, and reverse battery protection circuits, its performance is vital for system efficiency and reliability. This article provides a detailed overview of its datasheet specifications, typical application circuits, and guidance for selecting a suitable replacement.
Datasheet Overview and Key Specifications
The MUR480ERLG belongs to a family of ultrafast rectifiers featuring a very low reverse recovery time, which is essential for minimizing switching losses and electromagnetic interference (EMI). Key electrical characteristics from its datasheet include:
Repetitive Peak Reverse Voltage (VRRM): 800 V
Average Forward Current (IF(AV)): 4.0 A
Peak Forward Surge Current (IFSM): 100 A (non-repetitive)
Forward Voltage Drop (VF): Typically 1.25 V at 4.0 A
Reverse Recovery Time (trr): A maximum of 50 ns, defining its "ultrafast" switching capability.
The device is housed in a DO-201AD package, offering a robust physical form factor for through-hole mounting (THT) and good thermal characteristics.
Typical Application Circuit
A primary application for the MUR480ERLG is as a freewheeling diode in switch-mode power supplies, such as flyback and boost converters. In these circuits, the diode provides a critical path for inductor current when the main power switch (e.g., a MOSFET) turns off. This action prevents voltage spikes that could otherwise damage the switch and ensures continuous current flow to the output.
For instance, in a standard boost converter circuit:
1. When the MOSFET is switched ON, current flows through the inductor, storing energy. The diode is reverse-biased, isolating the output.
2. When the MOSFET is switched OFF, the inductor’s collapsing magnetic field reverses its polarity, forward-biasing the MUR480ERLG. This allows the stored energy, combined with the input voltage, to be transferred to the output capacitor and load.
The ultrafast recovery of the MUR480ERLG is crucial here, as a slow diode would lead to significant crossover conduction losses and high-frequency noise during the brief switching period.
Replacement Guide
When the MUR480ERLG is unavailable, selecting an appropriate replacement requires careful cross-referencing of key parameters to ensure compatibility and system integrity.
1. Voltage and Current Ratings: The replacement must have a VRRM of at least 800V and an IF(AV) of 4A or higher. Exceeding these values is acceptable and often desirable for a safety margin.
2. Switching Speed: The most critical parameter is the reverse recovery time (trr). Choose a replacement listed as "ultrafast" or "hyperfast" with a comparable or lower trr value (e.g., ≤ 50 ns).
3. Forward Voltage (VF): A lower VF is generally better as it reduces conduction losses and heat generation.
4. Package Type: The DO-201AD package is common. Ensure the physical package and pin configuration (axial lead) are identical for drop-in compatibility.
Suitable direct or near-equivalent replacements often come from manufacturers like Vishay, STMicroelectronics, or Diodes Incorporated. Common part numbers for cross-reference include the UF5408 (3A, 1000V, 50ns) or the STTH8R06D (from a different, higher-performance family). Always consult the latest datasheets to verify all parameters before substitution.
ICGOODFIND Summary
The onsemi MUR480ERLG is an 800V, 4A ultrafast rectifier essential for high-efficiency power conversion. Its low reverse recovery time minimizes switching losses, making it ideal for SMPS freewheeling applications. When replacing it, prioritize matching the voltage, current, and trr ratings to maintain circuit performance and reliability.
Keywords: Ultrafast Rectifier, Reverse Recovery Time, Freewheeling Diode, Switch-Mode Power Supply (SMPS), High Voltage Rectifier.
