STMicroelectronics STTH212S

Overview

STTH212S from STMicroelectronics is an ultrafast high-voltage planar silicon diode in SMC package, rated for 1200 V repetitive peak reverse voltage and 2 A average forward current at T_lead = 105 °C, with 75 ns max reverse recovery time and soft switching behavior-used for snubbering, freewheeling, and clamping in offline SMPS and PFC stages.

For engineers reviewing the STTH212S datasheet, STTH212S pinout, STTH212S application, or STTH212S equivalent, key selection criteria include verified soft recovery (SFACTOR > 4.0 at dIF/dt = 200 A/µs), low conduction loss equation (P = 1.26 × I_F(AV) + 0.12 × I_F(RMS)²), thermal resistance of 20 °C/W (junction-to-lead), and SMC package compatibility with high-power board layouts requiring ≥10 A RMS current handling.

Technical Context

This diode employs planar junction technology to achieve stable high-voltage blocking and controlled minority-carrier lifetime, enabling predictable trr < 75 ns under IF = 1 A, dIF/dt = –100 A/µs, VR = 30 V conditions. Its soft recovery characteristic (SFACTOR > 4.0) minimizes EMI by suppressing reverse recovery current overshoot and oscillation.

Thermal design relies on low R_th(j–l) = 20 °C/W in SMC package, supported by FR4 PCB copper area optimization (R_th(j–a) drops from 85 °C/W to ~45 °C/W with 4 cm² copper). The device operates up to T_j = 175 °C, with VF = 1.07–1.50 V across 25–150 °C at IF = 2 A.

Key Specifications

Pinout & Package

Housed in SMC (DO-214AB) surface-mount package with two terminals: anode (A) and cathode (K). Leads are gull-wing, coplanar, and RoHS-compliant per ECOPACK® specifications. Thermal pad not present; heat transfer occurs through leadframe mass and solder joint interface.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar ultrafast high-voltage diode applications.

Compared with STTH2R06D and ES1J-M3/57T, STTH212S uniquely balances 1200 V blocking, soft recovery, and SMC thermal robustness-making it irreplaceable in 30–300 W industrial SMPS where both voltage margin and EMI control are non-negotiable.

Availability

STTH212S is available at Aetrix Electronics and suitable for AC-DC front-end rectification, boost PFC output stages, snubber networks, and inductive load demagnetization requiring stable component supply and long-term industrial lifecycle support.

Supply support for STTH212S includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing microcontrollers, power devices, sensors, and analog ICs for automotive, industrial, and consumer markets.

The STTH ultrafast diode product line targets high-efficiency, high-reliability power conversion systems-specifically engineered for reduced EMI, high-temperature operation, and robust surge immunity in offline and DC-DC converters.

FAQ

What is the maximum allowable PCB copper area for optimal thermal performance of STTH212S?

Per Figure 13 in the datasheet, R_th(j–a) improves from ~85 °C/W to ~45 °C/W when copper surface area under each lead increases from 0 to 4 cm² on FR4. For reliable 2 A continuous operation at 60 °C ambient, ≥2.5 cm² per lead is recommended-achievable with standard SMC footprint plus 1.5 mm thermal relief traces extending to internal ground planes.

Does STTH212S require a heatsink in typical 2 A applications?

No heatsink is required if PCB layout provides ≥2.5 cm² copper per lead and ambient temperature stays ≤60 °C. With R_th(j–l) = 20 °C/W and P_cond ≈ 2.2 W (using P = 1.26×2 + 0.12×10²), junction temperature rise is ~44 °C above lead temperature-keeping T_j well below 175 °C even with modest copper area.

How does the softness factor (SFACTOR) of STTH212S impact EMI filter design?

With SFACTOR > 4.0, reverse recovery current exhibits no overshoot and minimal dI/dt-induced ringing. This reduces high-frequency spectral content above 30 MHz, allowing smaller X/Y capacitors and fewer ferrite beads-typically cutting total EMI filter BOM cost by 15–20% versus standard fast diodes with SFACTOR < 2.0.

Can STTH212S be used in place of STTH212U in the same PCB footprint?

No-STTH212U uses SMB (DO-214AA) package (E = 5.1–5.6 mm), while STTH212S uses SMC (DO-214AB) package (E = 7.75–8.15 mm). The SMC body is wider and longer; direct substitution requires footprint redesign, though both share identical electrical specs and thermal modeling methodology.