IRFB4020PBF - 200V 18A N-Channel Digital Audio MOSFET | Infineon
MPN: IRFB4020PBF β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.85 | $2.85 |
| 10 | $2.45 | $24.50 |
| 100 | $1.95 | $195.00 |
| 500 | $1.62 | $810.00 |
| 1,000 | $1.38 | $1,380.00 |
IRFB4020PBF Overview
A MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) is a voltage-controlled three-terminal device used for switching and amplifying electronic signals. Power MOSFETs, as a subcategory, are specifically designed for high-current, high-voltage switching applications and form part of the broader discrete semiconductor hierarchy: power MOSFET -> MOSFET -> discrete semiconductor -> semiconductor -> electronic component. Within a Class-D audio amplifier, the MOSFET acts as the high-frequency switching element that drives the output LC low-pass filter and speaker load, directly influencing amplifier efficiency and total harmonic distortion (THD).
Key features include low R_DS(on) for improved efficiency, low gate charge (QG) and switch charge (QSW) for reduced THD, low reverse recovery charge (QRR) for better THD and lower EMI, and a 175C maximum operating junction temperature. The part carries a "PbF" (lead-free) suffix indicating RoHS-compliant lead-free plating. The part has been designed and qualified for the consumer market per Infineon/IR qualification standards.
Typical applications include Class-D audio amplifiers (subwoofer, home theater, automotive audio), DC-DC converters, motor drivers, power inverters, and switching power supplies. For Class-D audio specifically, the device's optimized switching parameters directly translate into lower THD and improved efficiency.
When designing with this device, ensure adequate heatsinking because the 100W power dissipation figure assumes TC=25C and a case-mounted heatsink; without a sufficient heatsink the practical dissipation is limited by the thermal resistance from junction to ambient. Also note that TO-220AB is not recommended for surface-mount applications per the datasheet.
Drop-in alternatives for IRFB4020PBF β same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with IRFB4020PBF (same form factor and footprint) β differing in Drain-Source Voltage (VDS), Lead-Free / RoHS, Operating Junction Temperature, Package, Technology.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
IRFB5620PBF
β Drop-Inπ Reference alternative (not in catalog)
IRFB4115PBF
β Drop-Inπ Reference alternative (not in catalog)
IRFB4227PBF
β Drop-Inπ Reference alternative (not in catalog)
STP17NF25
β Drop-Inπ Reference alternative (not in catalog)
FDP18N20F
β Drop-Inπ Reference alternative (not in catalog)
IRFB4020PBF Maximum Ratings & Electrical Characteristics
| FET Type | N-Channel |
| Technology | IR MOSFET (HEXFET) |
| Drain-Source Voltage (VDS) | 200 V |
| Continuous Drain Current (ID) at TC | 18 A |
| Power Dissipation (PD) at TC | 100 W |
| RDS(on) Maximum | 100 mOhm |
| Gate-Source Voltage (VGS) Maximum | 20 V |
| Thermal Resistance, Junction-to-Case (RthJC) | 1.43 C/W |
| Operating Junction Temperature | 175 C (max) |
| Package | TO-220AB (through-hole) |
| Mounting Type | Through Hole |
| Pin Count | 3 (Gate, Drain, Source) |
| Lead-Free (PbF suffix) | Yes |
| Market Qualification | Consumer |
| Recommended Use | Class-D audio amplifier and high-efficiency switching applications |
IRFB4020PBF Pin Configuration
| Pin 1 | Gate β Gate control input (voltage-controlled) |
| Pin 2 | Drain β Drain terminal (electrically connected to the metal tab) |
| Pin 3 | Source β Source terminal |
Safe Operating Area (DC)
Typical Applications
IRFB4020PBF is suitable for 6 applications: Class-D Audio Amplifier Output Stage, Subwoofer and Home Theater Amplifiers, DC-DC Converters, Motor Drive H-Bridges, Power Inverters and Solar Micro-Inverters, Switching Power Supplies (SMPS).
Class-D Audio Amplifier Output Stage
The IRFB4020PBF is specifically designed for Class-D audio amplifier output stages per the Infineon datasheet. The 200V VDS rating covers bus voltages up to approximately Β±85V in BTL configurations, supporting amplifiers from 100W to 500W per channel. The optimized gate charge (QG) and switch charge (QSW) directly reduce total harmonic distortion (THD), while the low body-diode reverse recovery charge (QRR) lowers EMI emissions that could otherwise interfere with audio circuitry. Placed in the half-bridge switching positions feeding the LC output filter and speaker load, the part provides high efficiency (typically >90%) that eliminates the heavy heatsinks required by Class-A/B designs. The 175C maximum junction temperature provides thermal margin in sealed enclosures.
Recommended
Subwoofer and Home Theater Amplifiers
The IRFB4020PBF's 200V/18A rating and TO-220AB footprint make it ideal for subwoofer and home theater amplifier designs where high peak current delivery is critical for low-frequency reproduction. The HEXFET technology's low R_DS(on) of 100 mOhm maximum minimizes conduction losses, enabling multi-channel Class-D amplifiers to fit in compact 1U chassis without excessive heatsinking. The part's high 175C junction temperature supports sealed enclosure designs where ambient temperatures can reach 60-70C. When paired with a Class-D controller such as IRS2092 or TPA3251, the IRFB4020PBF delivers THD+N performance well below 0.1% at full output.
Recommended
DC-DC Converters
The IRFB4020PBF functions effectively as the main switching element in 200V-class DC-DC converters for telecom, industrial, and renewable energy applications. The 200V VDS provides adequate margin for 150V rectified bus voltages, while the 18A continuous current rating supports converters up to approximately 1kW at typical duty cycles. The low QRR characteristic reduces switching losses at high frequencies (100kHz-1MHz), improving overall converter efficiency. The TO-220AB package with 1.43 C/W junction-to-case thermal resistance enables direct mounting to a chassis or external heatsink for thermal management.
Recommended
Motor Drive H-Bridges
In H-bridge and three-phase motor drive circuits, the IRFB4020PBF serves as the high-side or low-side switching element for brushed DC and BLDC motors operating at bus voltages up to 150V. The 18A continuous current rating supports motor power ratings up to approximately 2HP at 48-96V nominal bus. The low R_DS(on) keeps conduction losses manageable in PWM-driven applications at 20-50kHz switching frequencies. Combined with proper gate drive ICs (such as IR2104 or IRS21844), the IRFB4020PBF provides reliable motor control in industrial automation and electric vehicle auxiliary systems.
Recommended
Power Inverters and Solar Micro-Inverters
The IRFB4020PBF's 200V rating suits grid-tied micro-inverter and solar power conversion stages operating from 60-150V PV string voltages. The HEXFET's avalanche-rated construction absorbs energy from inductive switching transients common in inverter topologies, enhancing reliability. The 18A rating supports micro-inverters up to approximately 2kW when paired with appropriate heatsinking. The TO-220AB through-hole package enables robust mechanical mounting required for outdoor inverter enclosures subject to thermal cycling.
Recommended
Switching Power Supplies (SMPS)
The IRFB4020PBF is well-suited as the primary-side MOSFET in 100-200W SMPS designs, including offline flyback, forward, and half-bridge converters. The 200V VDS supports universal-input (85-265VAC) rectified bus voltages of approximately 380V through adequate derating, while the 18A rating handles peak primary currents for 100-200W power levels. The low gate charge reduces drive losses at high switching frequencies, allowing smaller magnetics. The TO-220AB package and 175C junction temperature enable reliable operation in convection-cooled open-frame power supply designs.
Recommended
Recommended Products Summary
Engineering reference data for IRFB4020PBF β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | IRFB5620PBF | IRFB4115PBF | IRFB4227PBF | STP17NF25 | FDP18N20F |
|---|---|---|---|---|---|---|
| Brand | Infineon | Infineon | Infineon | Infineon | STMicroelectronics | onsemi |
| Package | TO-220AB | TO-220AB (same) | TO-220AB (same) | TO-220AB (same) | TO-220AB (same) | TO-220AB (same) |
| Drain-Source Voltage (VDS) | 200 V | 100 V | 150 V | 200 V | 250 V | 200 V |
| Continuous Drain Current (ID) | 18 A | 25 A | 34 A | 65 A | 17 A | 18 A |
| RDS(on) Maximum | 100 mOhm | 33 mOhm | 39 mOhm | 26 mOhm | 150 mOhm | 120 mOhm |
| Technology / Family | HEXFET (Class-D optimized) | HEXFET (Class-D optimized) | HEXFET | HEXFET | STripFET | UniFET FRFET |
| Class-D Audio Optimized | Yes | Yes | No | No | No | No |
| Lead-Free / RoHS | Yes (PbF suffix) | Yes | Yes | Yes | Yes | Yes |
Key Differentiators
- Specifically optimized for Class-D audio (vs STP17NF25)
- Lower R_DS(on) than legacy IRF640PBF (vs IRF640PBF)
- Higher VDS rating than IRFB5620PBF (vs IRFB5620PBF)
Design Notes
The IRFB4020PBF is rated for 100W power dissipation at TC=25C, with junction-to-case thermal resistance of 1.43 C/W. Without a heatsink, the practical dissipation is limited by junction-to-ambient thermal resistance (typically 62 C/W for TO-220AB on a 1 oz copper pad). Estimated: for 10W dissipation in free air, junction temperature rise is approximately 10W x 62 C/W = 620C above ambient, which is unacceptable. A heatsink with thermal resistance below 5 C/W is required for any application dissipating more than approximately 2W continuously. Mount the tab to the heatsink with thermal compound and an insulator if the heatsink is electrically floating.
TO-220AB is a through-hole package and is NOT recommended for surface-mount applications per the Infineon datasheet. For new designs, use the surface-mount equivalent IRFR4020PBF (D-PAK/TO-252). When laying out the PCB, provide adequate copper pour area on the drain tab pad (the through-hole via the tab itself) and route the source lead to minimize inductance in the gate drive loop. Gate drive traces should be short and direct, with a 10-100 ohm gate resistor to dampen ringing. Place a local gate-source pull-down resistor (10-100 kOhm) to ensure the MOSFET stays off during controller power-up.
Several common pitfalls: (1) Exceeding VGS max of Β±20V - even brief transients from a poorly clamped gate driver can puncture the gate oxide; add a 12V Zener between gate and source. (2) Operating above the SOA curve - the IRFB4020PBF can handle high pulse currents but must stay within the SOA boundary during turn-on transients and short circuits. (3) Driving the gate too slowly - slow gate drive causes the MOSFET to spend too long in the linear region, dramatically increasing switching losses and THD in Class-D audio. Use a gate driver capable of sourcing/sinking 1A peak for fast switching.
For Class-D audio amplifier layouts, minimize the loop area of the high-side and low-side MOSFET half-bridge to reduce parasitic inductance that causes voltage ringing and EMI. Use a low-ESR decoupling capacitor (1-10uF X7R ceramic) placed within 5mm of the MOSFET drain-source connections. The output LC filter inductor and capacitor should be placed close to the switching node to minimize radiated EMI. Star-ground the analog input circuitry separately from the power ground to prevent audio ground loops.
Compliance Information
RoHS compliant per PbF suffix in part number. Lead-free plating confirmed. Consumer market qualification per datasheet. Halogen-free status not explicitly stated in datasheet snippet.
