Description
The UF4007 is a Fast Recovery Rectifier diode. While it shares the same 1A current rating and 1000V voltage rating as the standard 1N4007, it is engineered with a much faster switching speed, making it suitable for high-frequency applications.
Technical Specifications
| Parameter | Rating |
| Peak Repetitive Reverse Voltage ($V_{RRM}$) | 1000 V |
| Average Rectified Forward Current ($I_{O}$) | 1.0 A |
| Reverse Recovery Time ($t_{rr}$) | 75 ns |
| Forward Voltage Drop ($V_{F}$) | ~1.7 V (at 1A) |
| Package Type | DO-41 (Axial) |
The Critical Difference: Fast Recovery vs. Standard
The “UF” in UF4007 stands for Ultra-Fast.
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Standard Diodes (1N4007): Have a slow reverse recovery time (often >2000 ns). In high-frequency circuits, they cannot turn off fast enough, causing them to conduct briefly in the reverse direction, which leads to heat, energy loss, and potential failure.
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Fast Recovery Diodes (UF4007): Are designed to switch off in just 75 nanoseconds. This speed allows them to operate efficiently in circuits where the current direction changes rapidly.
Key Design Considerations
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Power Loss: Note that the Forward Voltage Drop ($V_F$) of the UF4007 is higher (~1.7V) compared to the standard 1N4007 (~1.1V). This means the UF4007 will dissipate more heat under the same load conditions. Ensure your design accounts for this extra thermal load.
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Efficiency: The UF4007 is the preferred choice for Switch Mode Power Supplies (SMPS), DC-DC converters, and high-frequency inverters where efficiency and thermal management at speed are paramount.
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Polarity: Like all standard rectifier diodes, the silver band denotes the Cathode (-), and the body side is the Anode (+).
When to use UF4007 instead of 1N4007
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High-Frequency Rectification: If your circuit operates at frequencies above 1 kHz (e.g., SMPS, PWM motor controllers), the UF4007 is mandatory.
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Switching Regulators: Used in “freewheeling” applications where the diode must respond instantly to the switching of a transistor.
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Avoid in 50/60 Hz Mains: For simple 50/60 Hz power supplies (like a standard transformer plug), the UF4007 provides no benefit over a 1N4007 and is more expensive with a higher forward voltage drop.
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