The US1M is an industry-standard surface-mount ultra-fast recovery rectifier diode housed in a compact SMA (DO-214AC) package. Designed for high-frequency power rectification and freewheeling applications, the US1M features a high repetitive peak reverse voltage of 1000V, a continuous forward current rating of 1.0A, and an ultra-fast reverse recovery time (t_rr) of typically 50ns to 75ns. It is widely used in high-frequency switch-mode power supplies (SMPS), inverters, DC-DC converters, and inductive kickback clamping networks.

Specifications

• Brand / Manufacturer: Vishay / ON Semiconductor / Diodes Inc. / Industry Standard
• Part Number / Marking: US1M / U1M
• Diode Type: Ultra-Fast Recovery Rectifier
• Maximum Repetitive Peak Reverse Voltage (V_RRM): 1000V
• Maximum RMS Voltage (V_RMS): 700V
• Maximum DC Blocking Voltage (V_DC): 1000V
• Average Forward Rectified Current (I_F(AV)): 1.0A (at T_L = 110°C)
• Non-Repetitive Peak Forward Surge Current (I_FSM): 30A (8.3ms single half sine-wave)
• Maximum Instantaneous Forward Voltage (V_F): 1.7V (at I_F = 1.0A, T_J = 25°C)
• Maximum Reverse Recovery Time (t_rr): 50ns to 75ns (at I_F = 0.5A, I_R = 1.0A, I_rr = 0.25A)
• Maximum Reverse Leakage Current (I_R): 5µA @ 25°C / 50µA @ 100°C (at rated V_DC)
• Typical Junction Capacitance (C_J): Approx. 15pF (at 4.0V, 1MHz)
• Operating Junction Temperature: -55°C to +150°C
• Package / Case: SMA (DO-214AC) Surface Mount (Cathode indicated by white polarity band)

Features

• Ultra-Fast Reverse Recovery: Minimizes switching losses and transient reverse recovery current spikes during high-frequency PWM operation.
• High Voltage Endurance: 1000V reverse blocking voltage makes it suitable for off-line AC-DC rectifiers, boost converters, and high-voltage flyback topologies.
• High Forward Surge Capability: Can withstand non-repetitive surge currents up to 30A during circuit startup or load transients.
• Glass Passivated Junction: Enhances long-term thermal stability, high reliability, and low reverse leakage current over temperature.
• Low-Profile SMA Package: Space-saving DO-214AC surface-mount footprint ideal for automated pick-and-place high-density PCB assembly.

Common Applications

• High-Frequency SMPS Secondary Rectification: Output rectification in flyback converters, LED drivers, and compact AC-DC power adapters.
• Freewheeling & Snubber Clamping: Suppressing inductive voltage spikes across power MOSFETs and IGBTs in motor drivers, inverters, and solenoid drivers.
• DC-DC Boost & Buck Converters: High-speed freewheeling catch diode in high-voltage switching regulator topologies.
• Polarity & Reverse Voltage Protection: Protecting sensitive input stages against reverse DC voltages and high-voltage transients.

Usage Tips

• Polarity Identification: Ensure correct orientation on the PCB; the white band printed on the SMA package indicates the Cathode terminal (negative in forward bias).
• Thermal PCB Layout: For continuous forward currents approaching 1A, provide adequate copper pad area on the cathode and anode leads to facilitate thermal transfer into the PCB.
• Snubber Circuit Pairing: When used as a snubber clamp diode across high-voltage transformer primaries, pair with a suitable RC network or TVS diode to absorb fast ringing transients.
• High-Frequency Decoupling: Keep PCB trace loops between the diode, power switch, and output capacitor as short and wide as possible to minimize parasitic inductance and EMI emissions.

Datasheet