VS-20ETS12-M3

The VS-20ETS12-M3 is a 20 ampere, 1200 volt standard recovery rectifier diode from Vishay Semiconductors. It belongs to the high-voltage ETS series of glass-passivated power rectifiers designed for demanding industrial and power supply applications.

The device features a glass-passivated chip junction, which provides superior reliability and stable electrical characteristics compared to passivated glass mesa or planar alternatives. Glass passivation ensures consistent reverse leakage performance across temperature and time, maintaining low IR even at the maximum rated junction temperature of 150 degC. The device is qualified according to JEDEC JESD 47 standards and meets Moisture Sensitivity Level 1 (MSL 1), meaning it can be stored indefinitely without dry packing and requires no preconditioning before soldering.

With a typical forward voltage drop of 1.1V at 20A and 25 degC, the VS-20ETS12-M3 offers reasonable conduction loss for a 1200V rectifier. The forward voltage exhibits a positive temperature coefficient, making the device suitable for parallel operation in high-current designs. The surge current rating of 300A (10ms half-sine, no reapplied reverse voltage) provides robustness against line transients and inrush currents during power supply startup.

The TO-220AC 2-lead package allows for straightforward through-hole assembly and easy heatsink mounting. The two leads are the anode (pins 1 and 3, connected internally) and cathode (pin 2), with the mounting tab also at cathode potential. The -M3 suffix indicates Vishay’s halogen-free, RoHS-compliant, lead-free termination finish (100% matte tin).

The VS-20ETS12-M3 is a standard recovery silicon rectifier diode that operates based on the fundamental PN junction diode principle:

1. PN Junction Structure: At the core of the rectifier is a silicon PN junction fabricated using diffusion technology. The P-type region forms the anode, and the N-type region forms the cathode. When forward-biased (anode positive with respect to cathode), majority carriers are injected across the junction, allowing current to flow with a relatively low voltage drop.

2. Forward Conduction: When forward voltage exceeds the threshold voltage (approximately 0.85V for this device), the PN junction becomes conductive and current flows from anode to cathode. The total forward voltage drop consists of the threshold voltage plus the resistive drop across the drift region and ohmic contacts. At 20A and 25 degC, the typical VF is 1.1V. At higher temperatures, the threshold voltage decreases but the resistive component increases, resulting in a crossover point where the temperature coefficient changes from negative to positive (enabling parallel operation).

3. Reverse Blocking: When reverse-biased (cathode positive with respect to anode), the depletion region of the PN junction widens, effectively blocking current flow. A small reverse leakage current (IR) flows due to minority carrier generation and surface effects. The 1200V VRRM rating indicates the maximum repetitive reverse voltage the device can safely block. Glass passivation of the chip edge suppresses surface leakage pathways, maintaining low IR even at elevated temperatures.

4. Recovery Characteristics: As a standard recovery rectifier, when switching from forward conduction to reverse blocking, stored minority carriers must be swept out or recombined before the diode regains its blocking capability. The recovery time (trr) is relatively long compared to fast recovery or Schottky diodes, making these devices most suitable for low-frequency rectification (line-frequency 50/60Hz) rather than high-frequency switching applications.

5. Surge Capability: The device can withstand very high non-repetitive surge currents (up to 300A for 10ms) because the large silicon die area can absorb the energy of a single surge pulse without exceeding the maximum junction temperature. This makes the device robust against power-on inrush currents and transient line surges.

6. Thermal Operation: Power dissipated in the diode (VF x IF) raises the junction temperature. Heat flows from the junction through the die, solder, and package to the heatsink. The thermal resistance junction-to-case (RthJC) of 1.3 degC/W determines how much the junction temperature rises above the case temperature for a given power dissipation. Proper heatsinking is required to keep TJ within the -40 degC to +150 degC operating range.

Package: TO-220AC 2L (2-lead through-hole plastic package). Body width: 10.16mm, lead spacing: 2.54mm. Standard TO-220 form factor with vertical mounting tab for heatsink attachment. Tab is at cathode potential. Note: This is a 2-lead configuration with pins 1 and 3 both connected to anode (parallel), pin 2 is cathode.

• AC-DC Power Supply Input Rectification: Primary-side bridge rectifiers in offline switch-mode power supplies, linear power supplies, and battery chargers, converting 50/60Hz AC line voltage to DC. Multiple diodes can be paralleled for higher current requirements, leveraging the positive VF temperature coefficient for current sharing.
• Industrial Power Converters: Output rectification in industrial DC power supplies, welding equipment, and plasma cutters, where high voltage and moderate frequency operation demand robust rectifiers with high surge current capability to handle load transients and startup inrush.
• Motor Drive and Control Circuits: Freewheeling diodes and snubber circuits in motor drive inverters, DC motor controllers, and variable frequency drives, providing current paths for inductive load current during switch-off and protecting switching devices from voltage transients.
• Uninterruptible Power Supplies (UPS): Rectifier and inverter stages in online and line-interactive UPS systems, where reliable high-voltage rectification combined with surge withstand capability ensures continuous power delivery during utility outages and voltage fluctuations.
• Inverter and Welding Equipment: High-voltage rectification in inverter welding machines, induction heating systems, and plasma power supplies, where the 1200V rating and high surge current capability handle the demanding electrical conditions of these applications.
• Battery Charging Systems: Rectifier stages in industrial battery chargers for forklifts, golf carts, and stationary battery banks, providing efficient AC-to-DC conversion with robust overload and surge performance suitable for industrial battery chemistries.
• High-Voltage Industrial Systems: HV power supplies for electrostatic precipitators, X-ray generators, and laboratory equipment, where the 1200V rating provides adequate voltage margin and glass passivation ensures long-term reliability at elevated temperatures.
• Renewable Energy Systems: Rectification and blocking diode applications in solar charge controllers, small wind turbine converters, and off-grid power systems, where the 1200V rating provides adequate voltage margin and glass passivation ensures long-term reliability.