What Is the 1F5G Fast Recovery Rectifier?

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The 1F5G is a 1 A, 600 V glass-passivated fast recovery rectifier diode in an R-1 axial package. It combines a 250 ns maximum reverse recovery time, low leakage, and a 30 A surge rating for compact power supplies and battery chargers. Designers should verify voltage margin, thermal conditions, switching frequency, polarity, and supplier-specific datasheet limits before selection or replacement.

(Last modified date: August 31, 2026)

Key Takeaways

  • The 1F5G is a fast recovery rectifier in the 1 A class, aimed at switching supplies and high-frequency rectification.
  • Review reverse-recovery time and softness at the operating current — fast recovery diodes cover the fundamentals.
  • Compare 1F4G and 1F3G for the same package with different recovery classes and voltage ratings.
  • The 1F5G fast recovery rectifier suits high-frequency rectification at 600 V, 1 A.
Good-Ark 1F5G fast recovery rectifier in R-1 axial package
The 1F5G is a 600 V, 1 A glass-passivated fast recovery rectifier in an R-1 axial package.

What Is a 1F5G Fast Recovery Rectifier?

The 1F5G is a single silicon fast recovery rectifier designed to conduct current in one direction and block reverse voltage. It supports a 1 A average forward current and 600 V repetitive peak reverse voltage, and its faster recovery behavior makes it better suited to switching circuits than conventional slow rectifiers with comparable ratings. The device uses a glass-passivated chip junction for improved junction stability, controlled leakage, and reliable operation across a wide temperature range, supplied in an R-1 axial through-hole package with the cathode identified by a polarity band.

The 1F5G is part of the 1F1G through 1F7G family: members share a 1 A current class and R-1 package but provide different reverse-voltage ratings, with the 1F5G occupying the 600 V position. It is a discrete rectifier diode, not a four-terminal bridge rectifier — a complete full-wave bridge circuit requires four properly connected 1F5G diodes or a separate integrated bridge component.

What Are the Main 1F5G Specifications?

The principal 1F5G ratings are 600 V repetitive peak reverse voltage, 1 A average forward current, 30 A peak surge current, 1.30 V maximum forward voltage, and 250 ns maximum reverse recovery time. These values describe electrical limits under stated test conditions and should not automatically be treated as normal continuous operating targets.

Parameter Symbol 1F5G rating Design meaning
Repetitive peak reverse voltage VRRM 600 V Maximum repetitive reverse-voltage rating
RMS reverse voltage VRMS 420 V RMS voltage associated with the blocking class
DC blocking voltage VDC 600 V Maximum rated continuous DC blocking voltage
Average forward current IF(AV) 1 A Average rectified current under specified thermal conditions
Peak forward surge current IFSM 30 A Single 8.3 ms half-sine surge capability
Maximum forward voltage VF 1.30 V at 1 A Upper forward-drop limit at the stated current
Reverse leakage current IR 5 µA at 25 °C Maximum reverse current under the specified test
Reverse recovery time trr 250 ns Maximum recovery time under the stated switching test
Typical junction capacitance CJ 12 pF Measured at 4 V and 1 MHz
Junction temperature range TJ −55 °C to +150 °C Permitted junction-temperature range
Package — R-1 axial Through-hole, two-lead package

The 30 A surge rating applies to a short, non-repetitive event and does not mean the diode can continuously carry 30 A. Similarly, the 1 A rating depends on lead temperature, ambient conditions, PCB construction, conduction angle, and heat dissipation. Values from another manufacturer should be confirmed separately, because parts with the same base number can have different test conditions, surge ratings, package dimensions, or qualification status.

Why Does Reverse Recovery Time Matter?

Reverse recovery time determines how quickly the diode stops conducting after its voltage polarity reverses. The 1F5G has a maximum recovery time of 250 ns under specified test conditions; faster recovery can reduce switching loss, current spikes, EMI, and stress on transistors in power-conversion circuits. During forward conduction, charge is stored around the junction; when the voltage reverses, that charge must be removed before the diode blocks effectively, and the resulting reverse recovery current briefly flows in the wrong direction. In an SMPS, that current can increase MOSFET turn-on loss and create ringing with parasitic inductance.

The 1F5G offers a practical improvement over general-purpose rectifiers that may recover over several microseconds. However, reverse recovery time is not the only criterion: also consider reverse recovery charge, peak reverse recovery current, junction capacitance, forward voltage, operating temperature, and switching topology. At 50/60 Hz, a 250 ns recovery time usually provides little direct efficiency advantage; the benefit becomes relevant in higher-frequency converters, snubbers, auxiliary supplies, and fast-switching rectification stages.

Which Applications Can Use the 1F5G Diode?

The 1F5G suits small battery chargers, compact power supplies, auxiliary rectification, reverse-polarity blocking, and general fast-switching circuits within its electrical and thermal limits. Its combination of 600 V blocking, 1 A current capacity, and axial construction supports straightforward through-hole assembly and repair. Typical possibilities include AC-to-DC rectification in low-power supplies, small battery charger circuits, auxiliary windings in flyback supplies, relay and solenoid suppression, reverse-polarity protection, voltage-clamping and snubber networks, low-current industrial controls, and through-hole board maintenance.

Suitability depends on voltage waveforms rather than nominal supply voltage alone: a 230 V AC input has a peak near 325 V before line tolerance, switching overshoot, or external surges are considered. Although 600 V may appear sufficient, the margin can become inadequate in poorly clamped environments. Calculate worst-case repetitive voltage, transient voltage, current waveform, temperature, and surge exposure; for high-reliability or surge-prone mains equipment, a higher-voltage member of the series may be more appropriate. The 1F5G should not automatically be used for high-current outputs, extremely high-frequency converters, or safety-critical automotive systems without complete validation and required qualification documentation.

How Does the 1F5G Compare With Other Rectifiers?

Rectifier type Typical strength Typical limitation Suitable selection case
1F5G fast recovery rectifier 600 V rating, 250 ns recovery, simple axial package Not as fast as ultrafast or SiC options Moderate-frequency, low-power switching circuits
1N4005-class standard rectifier Low cost, effective at line frequency Slow reverse recovery 50/60 Hz rectification
High-voltage Schottky diode Low forward drop, negligible stored charge Higher leakage, limited voltage options Lower-voltage, high-efficiency outputs
Ultrafast silicon diode Faster recovery for higher switching frequencies May cost more or have different surge behavior Higher-frequency power conversion
SiC Schottky diode Very low recovery loss, high-voltage capability Higher cost, often larger ratings High-frequency, high-efficiency power stages

A substitute should not be selected from voltage and current alone: the replacement must also match or exceed recovery performance, forward voltage, surge current, temperature range, leakage, package size, lead spacing, and polarity. The suffix in a part number may also have manufacturer-specific meaning — never assume two components marked 1F5G are fully interchangeable without comparing their current datasheets.

How Should Engineers Manage Heat and PCB Layout?

Keep the 1F5G junction below its 150 °C maximum by estimating conduction loss, switching loss, ambient temperature, and thermal resistance; use short, adequately sized PCB traces, suitable lead length, airflow, and separation from heat-producing components. A first approximation of conduction loss is P ≈ VF × IF(AV) — intentionally conservative when the maximum 1.30 V forward voltage is used, but do not interpret a theoretical 1.3 W result as a guaranteed operating condition.

For switching circuits, minimize the loop formed by the diode, switching transistor, transformer or inductor, and local capacitor; excess loop area increases parasitic inductance, voltage overshoot, and noise. The cathode band must match the schematic orientation, lead bending should not place mechanical force directly against the package body, and soldering must remain within specified assembly conditions (Good-Ark specifies high-temperature soldering capability of 260 °C for 10 seconds for this series).

How Can Buyers Verify a 1F5G Replacement?

  1. Identify the complete manufacturer part number and suffix.
  2. Compare maximum ratings under matching test conditions.
  3. Confirm R-1 body dimensions and lead diameter.
  4. Check cathode-band orientation and PCB hole spacing.
  5. Review recovery time and switching waveforms.
  6. Calculate worst-case junction temperature.
  7. Verify surge and repetitive peak-current requirements.
  8. Request lot traceability and quality documentation.
  9. Test samples in the real circuit before mass production.

A distributor may mark one manufacturer’s version obsolete while another still offers an active equivalent, so lifecycle status belongs to the exact manufacturer part number. Good-Ark Electronics supports discrete-device production through an integrated supply chain covering wafer development, packaging, testing, manufacturing, and sales; founded in 1990, the company offers more than 1,500 product varieties across over 50 series, giving OEM buyers access to related rectifiers, protection diodes, MOSFETs, SiC devices, IGBTs, and power modules.

Good-Ark Electronics Expert Views

“For reliable 1F5G selection, begin with the worst-case reverse-voltage waveform and junction temperature. A 600 V rating does not mean every 600 V transient environment is safe, and a 1 A rating does not guarantee 1 A operation in an enclosed assembly. Verify recovery behavior with the intended MOSFET, transformer, and PCB layout. When field conditions are uncertain, use adequate derating, control overshoot, and validate representative production samples under maximum line, load, and ambient temperature.”

Frequently Asked Questions

Is the 1F5G a bridge rectifier?

No. It is a single two-terminal rectifier diode. Four individual diodes are normally required to create a full-wave bridge rectifier.

What does the cathode band indicate?

The band printed near one end of the axial package identifies the cathode. Correct orientation is essential because reversing the diode changes its conduction and blocking direction.

Can a 1F5G replace a 1N4005?

It may be suitable when the circuit requires a 600 V, 1 A axial rectifier and the mechanical dimensions and other ratings match. The 1F5G generally provides faster recovery, but the exact datasheets must still be compared.

Can the 1F5G continuously carry 1 A?

Only when the manufacturer’s thermal conditions are satisfied. Ambient temperature, lead temperature, PCB construction, waveform, enclosure, and airflow may require derating below 1 A.

Is the 1F5G suitable for 230 V AC rectification?

Its 600 V rating may support some 230 V AC circuits, but engineers must include line tolerance, surges, ringing, and safety margin. A higher-voltage rectifier may be preferable when transient control or operating conditions are uncertain.

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