Overview
MUR840G from onsemi is an ultrafast recovery rectifier diode rated for 400 V repetitive reverse voltage and 8 A average rectified current in a through-hole TO-220-2 package. It is intended for power conversion circuits that need fast reverse recovery, low stored charge, and robust rectifier behavior in switching environments.
This part is a practical choice for engineers and sourcing teams working on switch-mode power supplies, freewheeling paths, polarity protection, snubber networks, and high-speed rectifier stages where a general-purpose rectifier may recover too slowly. The TO-220-2 body supports board-level assembly and thermal design approaches commonly used in medium-power equipment.
Package Sale Basis
Order quantity 1 equals one full tube containing 50 MUR840G diodes. The product is sold as a complete tube to keep handling, receiving, and production kitting aligned with the package basis shown for this component.
Key Benefits
- 400 V reverse voltage rating supports many offline and high-voltage power-conversion designs.
- 8 A average rectified current rating gives useful headroom for medium-current rectifier and freewheel applications.
- Ultrafast 60 ns reverse recovery helps reduce switching loss and recovery stress compared with slower rectifiers.
- TO-220-2 through-hole package is familiar for heatsinked or board-mounted power diode layouts.
- onsemi MUR family documentation provides the electrical and thermal parameters needed for design review.
Product Features
- Single ultrafast rectifier diode in TO-220-2 / TO-220AC style package.
- 400 V DC reverse voltage listed for the MUR840G device.
- 8 A average rectified current rating at the stated test conditions.
- 1.3 V forward voltage listed at 8 A.
- 60 ns reverse recovery time listed for fast-switching rectifier behavior.
- 10 uA reverse leakage current listed at 400 V.
- 150 pF capacitance listed at 4 V and 1 MHz.
- Operating junction temperature range listed from -65 C to 175 C.
Technical Specifications
| Manufacturer Part Number | MUR840G |
|---|---|
| Manufacturer | onsemi |
| Product Category | Discrete semiconductor diode, rectifier, single |
| Diode Type | Standard ultrafast recovery rectifier |
| Voltage - DC Reverse | 400 V |
| Current - Average Rectified | 8 A |
| Forward Voltage | 1.3 V at 8 A |
| Reverse Recovery Time | 60 ns |
| Reverse Leakage Current | 10 uA at 400 V |
| Capacitance | 150 pF at 4 V, 1 MHz |
| Mounting Type | Through hole |
| Package / Case | TO-220-2 / TO-220AC |
| Operating Junction Temperature | -65 C to 175 C |
| Package Sale Unit | Full tube of 50 pieces |
Design and Selection Notes
When selecting MUR840G, confirm the reverse voltage, average current, surge current, thermal resistance, and mounting method against the complete datasheet. Ultrafast rectifiers are often chosen because reverse recovery loss and switching noise matter in the application; the surrounding transformer, inductor, MOSFET, snubber, and PCB layout can strongly affect the final thermal and EMI result.
For replacement work, compare the exact voltage rating, current rating, reverse recovery time, forward voltage, package outline, lead spacing, tab connection, and thermal path. A different TO-220 diode may fit mechanically but still change switching loss, temperature rise, or reliability margin. Designers should also confirm whether the circuit needs an ultrafast rectifier, a Schottky diode, or a standard recovery rectifier before substitution.
Applications
- Switch-mode power supply secondary rectification and clamp paths.
- Freewheeling diodes in inductive switching circuits.
- DC-DC converters, inverter auxiliary circuits, and power-control boards.
- Snubber and recovery paths where fast switching behavior is required.
- General power rectification where 400 V and 8 A ratings fit the design limits.
- Maintenance and repair sourcing for equipment already designed around MUR840G.
Sourcing and Documentation Notes
Review the attached Product Specification PDF before use, especially the absolute maximum ratings, thermal derating curves, package drawing, and recommended soldering information. The product image is derived from a distributor package photo for the matching TO-220-2 style package and prepared as a square transparent product image with no visible marking text. Incoming inspection should confirm the full manufacturer marking and packaging against your purchase and quality requirements.
FAQ
What is MUR840G best suited for?
MUR840G is best suited for switching power supplies, inverters, freewheeling paths, and clamp circuits where an 8 A, 400 V ultrafast rectifier is required.
Why choose an ultrafast diode instead of a standard rectifier?
Ultrafast reverse recovery helps reduce switching loss, diode recovery stress, and noise in high-frequency power circuits. Confirm that the circuit actually requires this recovery behavior.
What are the headline ratings?
DigiKey lists MUR840G as a 400 V, 8 A through-hole TO-220-2 diode, with 60 ns reverse recovery and 10 uA reverse leakage at 400 V.
What does order quantity 1 include?
Order quantity 1 means one full tube containing 50 MUR840G diodes.
Is MUR840G a Schottky diode?
No. It is an ultrafast recovery silicon rectifier. Do not substitute a Schottky or standard recovery diode unless voltage, current, leakage, recovery, and thermal behavior are reviewed.
Does the TO-220-2 package need thermal design?
Yes. Average current rating depends on thermal conditions, PCB copper, airflow, mounting, and heatsinking. Use the datasheet thermal curves and derating data for the actual assembly.
Can another TO-220 diode replace MUR840G?
Only after matching reverse voltage, average and surge current, reverse recovery time, forward voltage, leakage, package outline, lead spacing, tab connection, and temperature range.
Where is this diode commonly used?
Typical use cases include secondary rectification, freewheel paths around inductive loads, snubber or clamp networks, and auxiliary converter stages.
Where can I find the datasheet?
Use the attached Product Specification PDF for onsemi MUR820/MUR840 family maximum ratings, thermal limits, electrical curves, and package information.