STPS20120CR - 120V 2x10A Schottky Rectifier | STMicroelectronics

SMPS Secondary Rectification

In switch-mode power supplies the secondary-side rectifier converts the transformer's switched waveform into DC. The STPS20120CR fits this role because its Schottky barrier eliminates reverse-recovery losses, so switching dissipation is negligible at typical SMPS frequencies of tens to hundreds of kilohertz, leaving only conduction loss of roughly VF x IF(AV). The 120 V VRRM rating provides margin for flyback and forward converters operating from 48 V or higher-voltage primaries, including the ringing headroom that plain 60 V or 100 V parts may lack. The dual common-cathode arrangement lets one TO-262AA device serve push-pull or center-tapped secondary topologies, and the tab-as-cathode construction ties the rectifier directly to the output rail heatsink. Mount with a proper thermal interface and verify junction temperature at worst-case load and minimum input voltage, since VF rises slightly with temperature while leakage rises exponentially.

DC-DC Converter Output Stage

High-current DC-DC converters - telecom 48 V bricks, solar-input buck converters, and battery-charger outputs - need output rectifiers that combine high blocking voltage with low conduction loss. The STPS20120CR's 120 V rating covers 48 V-class buses with margin for inductive spikes, and its avalanche capability absorbs leakage-inductance energy that would destroy ordinary diodes. At 10 A per leg it supports 10-20 A continuous output with a modest heatsink, because Schottky VF contributes less dissipation than a P-N ultrafast diode at the same current. In synchronous designs it can also serve as the freewheeling device in non-synchronous bucks. The through-hole TO-262AA package simplifies prototyping and gives low thermal resistance to a chassis-mounted heatsink, which matters in fanless industrial converters. Keep loop inductance low by placing the rectifier close to the transformer secondary and output capacitors to limit voltage overshoot during commutation.

Reverse Polarity and ORing Protection

Battery-powered and redundant-supply systems use Schottky diodes for reverse-polarity blocking and diode-ORing of parallel supplies. The STPS20120CR is attractive here because each of its two common-cathode legs can protect or OR a separate input from one small through-hole device, halving component count in dual-battery or dual-rail front ends. The 120 V rating covers 48 V telecom batteries and industrial 24 V systems with large transient margin, while the low leakage current stated in the ST datasheet limits standby drain in battery-backed equipment. Because the cathode tab is the common node, the output bus can be bolted directly to a grounded or heatsunk tab where isolation permits. Designers should budget the Schottky forward drop (typically well under a volt at rated current) into low-voltage margin calculations, or choose an ideal-diode controller where every millivolt counts.

Freewheeling and Clamping in Motor Drives

Relay coils, solenoids, and DC motor windings generate inductive kickback when switched off, and a clamp or freewheel diode must absorb that energy repetitively. The STPS20120CR suits these roles: its avalanche rating tolerates the residual energy that arrives after the diode conducts, the 120 V VRRM covers 24 V, 48 V and 72 V motor buses with ample margin, and the 2 x 10 A dual die handles stall-current peaks common in actuator loads. Schottky technology means the device turns on and off without recovery charge, protecting low-side MOSFETs from secondary breakdown during PWM chopping. In H-bridge and unidirectional drive circuits the common-cathode pair can clamp two switch nodes at once. The TO-262AA flange lets designers bolt the diode to the motor-driver heatsink shared with the power stage. Size the heatsink for the stall condition, not the running condition, as freewheel dissipation peaks exactly when mechanical load is highest.

Battery Charger Rectification

Battery chargers and DC power adapters use output rectifiers that see both high average current and reverse-voltage stress during the switching cycle. The STPS20120CR addresses both: 10 A per leg supports 5-20 A charger outputs depending on topology, and 120 V blocking accommodates chargers fed from rectified mains via a transformer secondary with switching spikes. The avalanche capability protects against transformer leakage-inductance transients, a common failure mode in flyback chargers. Because the common cathode connects to the tab, the output-positive rail can share the heatsink, simplifying mechanical design in enclosed adapter housings where airflow is minimal. The Schottky forward characteristic also improves efficiency and reduces case temperature, extending electrolytic capacitor life nearby. Verify leakage at maximum ambient, since hot leakage raises standby power - a parameter charger standards increasingly limit.

Welding and Power Supply Input Rectification

Medium-power input bridges and welding-plant auxiliary supplies need rectifiers that tolerate harsh line transients. The STPS20120CR's 120 V VRRM and avalanche rating give robustness against surge events on 24 V, 48 V and battery-fed inputs, while the dual common-cathode topology permits efficient full-wave center-tap rectification with a single device instead of two. The 10 A per leg rating supports substantial continuous current when the TO-262AA flange is mounted to an adequately sized heatsink, and the long-leads through-hole format suits the heavy-duty, hand-assembled construction typical of industrial power equipment. Schottky low forward drop reduces self-heating, improving reliability in the high-ambient environments of welding and motor-control cabinets. For higher-voltage mains-side rectification, a fast-recovery part such as the STTH family should be used instead, since 120 V is below off-line peak voltages.