UF4007 — 1A/1000V Ultrafast Recovery Rectifier Diode (DO-41)

What Are the Technical Specifications of UF4007?

Key numbers that matter: Per the Vishay UF4001–UF4007 datasheet (Rev 2.4), the 75ns t_rr is a maximum specification — typical parts recover in 50ns or less. In practice, a UF4007 in an SMPS output rectifier running at 100kHz dissipates roughly 80–90% less switching loss than a 1N4007 in the same position. The trade-off: V_F is higher (1.7V vs 1.1V at 1A), so conduction loss is worse. Below ~5kHz, the 1N4007's lower V_F wins. Above ~10kHz, the UF4007's faster t_rr wins decisively.

When Should You Use (and NOT Use) the UF4007?

✅ Use UF4007 when:

• SMPS output rectification (flyback, forward, push-pull). At 65–132kHz, the 75ns t_rr keeps reverse conduction losses manageable. The UF4007 is the go-to output rectifier for sub-100W power supplies.
• RCD snubber and clamp circuits. A UF4007 at 75ns in a 100kHz converter spends only 0.75% of the period in reverse recovery — the 1N4007 at 30µs would never fully recover between cycles.
• PFC boost diode (sub-200W). In transition-mode PFC, the UF4007 handles high voltage with fast recovery. Common below 200W where SiC is overkill.
• High-voltage flyback/freewheeling. Relays and solenoids on AC lines need a clamp diode that can block 1000V and turn on in nanoseconds. The UF4007 does both.
• Direct 1N4007 upgrade without PCB changes. Same package, same pinout, same voltage rating — swap and go.

❌ Don't use UF4007 when:

• 50/60Hz mains rectification only. You're paying 2–3× more for speed you don't need. Use the cheaper 1N4007.
• Ultra-low V_F needed (battery-powered). At 1.7V forward drop, the UF4007 wastes more power in conduction than a Schottky. For low-voltage (≤24V), use 1N5819 (V_F = 0.45V).
• Above 500kHz switching frequency. At 500kHz, 75ns t_rr is 3.75% of the period. Step up to BYV27-series (30ns) or SiC Schottky.
• Output rectifier in >100W SMPS. The 1A rating is marginal above 100W. Use BYV27-1000 (2A, 30ns) or a TO-220 ultrafast diode.

What Are the Alternatives to UF4007?

UF4007 vs 1N4007 — the upgrade decision in one rule. From our repair diagnostics (2025–2026): if your circuit switches above 1kHz, use the UF4007. Below 1kHz, the 1N4007's lower V_F makes it the better choice. For any new design with a switching regulator, default to UF4007 — the BOM cost difference of a few cents is cheaper than diagnosing a thermal failure later.

UF4007 vs MUR160 — 50ns or 75ns? The MUR160 trims another 25ns off the t_rr and drops V_F to 1.25V, but it's only rated for 600V. If your SMPS runs from rectified 230V AC (~325V DC bus), the UF4007's extra voltage rating provides safety margin against ringing. In practice, both are common in sub-60W power supplies.

How Much Does the UF4007 Cost and Is It in Stock?

Contact ICMASS for a same-day quote. UF4007 pricing is stable — a mature product with multiple active manufacturers. No significant allocation or shortage issues. The UF4007 typically costs 2–3× the 1N4007 at equivalent volumes: you're paying for the controlled gold-doping and epitaxial processing that delivers the 75ns t_rr.

What Are the Typical Applications of UF4007?

SMPS Output Rectifier (Flyback Converter): The UF4007 rectifies high-frequency pulses from the transformer secondary. The 75ns t_rr ensures the diode turns off cleanly before the primary-side MOSFET turns on again — preventing shoot-through current. Per the Vishay datasheet (Rev 2.4), the UF4007's soft recovery characteristic also reduces EMI — an underappreciated advantage in designs struggling with radiated emissions.

RCD Snubber Diode: In a flyback snubber, a UF4007 clamps the leakage inductance spike while allowing the snubber capacitor to discharge during off-time. The 75ns recovery is fast enough that the diode doesn't steal energy from the next cycle. A 1N4007 in this position stays partially on, converting snubber energy into heat.

High-Voltage Freewheeling/Clamp: Across solenoids, contactors, or motor windings on AC-line-powered equipment. When the inductive load switches off, the UF4007 clamps the flyback voltage to the supply rail within 75ns — preventing arcing at switch contacts and protecting downstream semiconductors.

Boost Converter Output Diode (PFC): In transition-mode PFC, the UF4007 carries the boosted DC current to the output capacitor. At light load where switching frequency reaches several hundred kHz, the 75ns t_rr keeps reverse recovery loss manageable without SiC diode cost.

Voltage Doubler in 110/220V Switchable Supplies: In supplies with a voltage-doubling input stage, UF4007s handle 50/60Hz rectification with margin to spare — and if the supply accidentally operates at 110V in a 220V region, the 1000V rating provides headroom the 1N4007 doesn't.

Why Buy UF4007 from ICMASS?

Tested at full rated speed and voltage. We batch-test UF4007s for both reverse voltage (1000V) and reverse recovery time. A counterfeit UF4007 — usually a remarked 1N4007 — will test fine on voltage but fail the t_rr measurement by orders of magnitude. In our experience (2025–2026), about 5% of UF4007 lots from non-authorized channels are actually remarked 1N4007s.

Cross-reference support. Not sure whether your design needs UF4007, MUR160, BYV27, or a SiC Schottky? Tell us your switching frequency, output voltage, and power level — we'll tell you which diode fits.

Single-source BOM consolidation. You're probably ordering UF4007s alongside bridge rectifiers, MOSFETs, PWM controllers, optocouplers, and TL431 references for the same power supply build. We stock all of them in one shipment.

Shenzhen warehouse, global DHL/FedEx. Same-day shipping for orders placed before 15:00 CST. International delivery in 5–10 days.

Frequently Asked Questions About UF4007

Q1: Can I replace a 1N4007 with a UF4007 directly?

A: Yes — same package, same pinout, same voltage and current ratings. The UF4007 is a drop-in replacement for the 1N4007 in any DO-41 footprint. No PCB changes, no resistor value adjustments. The only difference: the circuit runs cooler at switching frequencies, and the diode costs a few cents more. The reverse is dangerous — replacing a UF4007 with a 1N4007 in a switching circuit will cause overheating and eventual failure.

Q2: Does UF4007 get hotter than 1N4007 at 50/60Hz?

A: Slightly — the UF4007's V_F is 1.7V vs 1.1V for the 1N4007 at 1A. At 50/60Hz, both diodes have negligible switching loss, so the higher V_F means about 1.7W vs 1.1W dissipation at full load. For line-frequency only, the 1N4007 is the better thermal choice. Per the Vishay datasheet (Rev 2.4), typical V_F is around 1.5V — the real-world difference is smaller than the max spec suggests.

Q3: What switching frequency is UF4007 good for?

A: Up to about 200–300kHz comfortably; up to 500kHz with careful thermal design. At 200kHz, the 75ns t_rr represents 1.5% of the period — manageable. At 500kHz it's 3.75% — the diode will run noticeably warm. Above 500kHz, consider BYV27-series (30ns) or SiC Schottky (near-zero t_rr).

Q4: Why does UF4007 have higher forward voltage than 1N4007?

A: The ultrafast recovery comes from gold doping and optimized epitaxial construction — both increase V_F. Gold atoms act as recombination centers that sweep carriers out faster at turn-off, but also increase forward resistance. It's a fundamental trade-off: speed vs forward voltage. You can't optimize both without moving to a different technology (Schottky, SiC, GaN).

Q5: Can I use UF4007 for reverse polarity protection?

A: Yes — but the 1.7V V_F wastes more power than a Schottky. For 12V/24V DC inputs, the 1N5819 Schottky (0.45V V_F) is far more efficient. For high-voltage DC (≥48V) where a Schottky can't be used, the UF4007 is a reasonable choice — the 1.7V drop is a small percentage and the 1000V rating provides transient margin.

Q6: UF4007 vs MUR160 — which one should I stock?

A: MUR160 for ≤600V applications (faster, lower V_F); UF4007 for >600V (more voltage margin). The MUR160 has 50ns t_rr and 1.25V V_F — better on both specs. But it's only rated 600V. In flyback converters from 230V AC, reflected voltage plus leakage spike can reach 500–700V. If you stock only one, the UF4007 covers more designs.

Q7: What's the difference between UF4007 and UF4007GP (glass passivated)?

A: The GP version adds a glass passivation layer, reducing leakage current at high temperature and improving long-term reliability. Electrical specs are identical. Use standard UF4007 for commercial SMPS; use GP for industrial, automotive, or outdoor equipment operating above 85°C ambient.

Q8: Why did my UF4007 fail short in an SMPS after working for months?

A: Most likely cause: voltage margin exhaustion. Check the peak reverse voltage including ringing — flyback output rectifiers see V_R = V_out + (V_{in_max} × N_sec/N_pri), plus ringing that can add 30–50%. If the total approaches 1000V, hot operating conditions reduce the actual breakdown voltage. Solutions: add an RC snubber across the diode, or step up to a 1200V+ rated diode.

Q9: Can I use UF4007 in a bridge rectifier for a linear power supply?

A: Yes, but you're buying speed you don't need. Four UF4007s work perfectly in a 50/60Hz bridge but cost more than 1N4007s. The only reason: standardizing on one diode part number across your BOM, or the PCB has both line-frequency and switching stages.

Q10: UF4007 vs BYV27-1000 — when to step up?

A: BYV27-1000 when you need 2A or <50ns recovery. It delivers 30ns t_rr (2.5× faster) and 2A current, with avalanche-rated breakdown protection. Costs 3–5× more. Use in >100W SMPS or high-frequency PFC stages. For sub-60W supplies, UF4007 is the right balance.

Related Products

• 1N4007 — Standard Recovery Rectifier, cheaper alternative for line-frequency use
• 1N5819 — Schottky Barrier Diode, lower V_F for low-voltage applications
• FR107W — Fast Recovery Rectifier, SMD alternative in SOD-123
• Standard vs Ultrafast vs Schottky — Which Rectifier Do You Need?