The FD15C120U is a high-performance 1200V/15A ultrafast recovery diode, engineered for high-voltage, high-efficiency power conversion systems. With ultra-short reverse recovery time (typ. 38 ns), low forward voltage drop (2.8 V @ 15 A, 25°C), soft recovery characteristics, and excellent thermal stability, it is widely used in SMPS, motor drives, inverters, PFC (Power Factor Correction) circuits, and industrial inverters.
1. Key Specifications (from FD15C120U.pdf)
Repetitive Peak Reverse Voltage (VRRM): 1200 V
Average Forward Current (IF(AV)): 15 A (TC = 100°C)
Peak Surge Forward Current (IFSM): 200 A (8.3 ms half-sine wave)
Forward Voltage (VF):
Typ. 2.8 V (Max 3.2 V) @ IF = 15 A, Tj = 25°C
Typ. 1.9 V (Max 2.6 V) @ IF = 15 A, Tj = 150°C (negative tempco enables paralleling)
Reverse Leakage Current (IR):
≤ 10 μA @ Tj = 25°C
≤ 500 μA @ Tj = 150°C
Reverse Recovery Time (trr):
38 ns (typ.) @ IF=0.5A, IR=1A, Tc=25°C (JEDEC condition)
64 ns @ IF=15A, VR=600V, dI/dt=–100 A/μs, Tj=25°C
110 ns @ IF=15A, VR=600V, dI/dt=–200 A/μs, Tj=25°C
Reverse Recovery Charge (Qrr): 120 nC (@100 A/μs, 25°C)
Junction Temperature (Tj): –55°C to +175°C (industry-leading)
Storage Temperature (TSTG): –55°C to +150°C
Package: TO-220 (through-hole with metal tab)
Thermal Resistance (RθJC): 1.1 °C/W
Mounting Torque: ≤ 8.0 kgf·cm
Weight: ~2.1 g
2. Key Usage Guidelines
(1) Ideal for High-Frequency Hard-Switched Topologies
Ultra-low trr (38–110 ns) and Qrr (120–370 nC) minimize switching loss and EMI—perfect for PFC boost diodes, inverter freewheeling diodes, snubber circuits, and motor drive free-wheeling paths.
(2) Soft Recovery Enhances System Reliability
"Soft" recovery reduces di/dt during turn-off, suppressing voltage overshoot and ringing—protecting paired MOSFETs/IGBTs from excessive voltage stress.
(3) Exceptional High-Temperature Performance
+175°C Tj rating enables reliable operation in harsh industrial environments.
Negative VF temperature coefficient promotes current sharing in parallel configurations.
(4) Heatsink Is Mandatory
Power dissipation at 15 A can reach 42 W (15 A × 2.8 V)—far beyond natural convection capability.
Must be mounted on an adequate heatsink with thermal grease; do not exceed 8.0 kgf·cm torque to avoid mechanical damage.
(5) trr/Qrr Are Highly Application-Dependent
trr and Qrr increase with higher dI/dt (e.g., trr rises from 64 ns to 110 ns as dI/dt doubles).
trr lengthens significantly at high Tj (210 ns @ Tj=125°C)—design for worst-case (high temp + high di/dt).
(6) Respect Absolute Maximum Ratings
Do not exceed 1200 V VRRM under any transient condition.
200 A IFSM is for single 8.3 ms pulses only—repeated surges degrade reliability.
3. Typical Applications
PFC boost diode in universal AC-DC SMPS
Freewheeling/clamping diode in industrial VFDs and servo drives
DC-link clamping and commutation in solar/UPS inverters
Free-wheeling diode in motor controllers
Secondary-side rectification in high-frequency LLC or phase-shifted full-bridge converters (verify frequency suitability)
4. Summary
The FD15C120U stands out with its 1200V/15A rating, 38 ns ultrafast recovery, soft recovery behavior, industry-leading +175°C junction temperature, and low 1.1 °C/W thermal resistance. When implemented with proper heatsinking, derating, and EMI mitigation, it delivers high efficiency and long-term reliability in demanding industrial and energy conversion systems.
