STMicroelectronics STTH312B

Overview

STTH312B from STMicroelectronics is an ultrafast recovery silicon rectifier diode rated for 1200 V repetitive peak reverse voltage, 3 A average forward current, and 55 ns typical reverse recovery time at 125 °C. It features soft recovery, low conduction losses (VF = 1.15 V typ. at 150 °C), and high junction temperature capability (Tj = 175 °C), making it suitable for high-frequency freewheeling and snubber circuits in industrial motor drives and switch-mode power supplies.

For engineers reviewing the STTH312B datasheet, STTH312B pinout, STTH312B application, or STTH312B equivalent, key selection criteria include verified soft recovery behavior (S factor ≥ 2), thermal resistance (Rth(j-c) = 3.8 °C/W), low leakage (<100 µA at 125 °C), and DPAK package compatibility with surface-mount thermal management requirements.

Technical Context

This diode employs a planar passivated junction structure optimized for controlled minority-carrier lifetime, enabling ultrafast and soft reverse recovery with minimal voltage overshoot and EMI generation. Its dynamic performance is characterized under standardized conditions: trr measured at IF = 1 A, dIF/dt = −100 A/µs, VR = 30 V, Tj = 25 °C (55 ns typ.), and IRM up to 14 A at Tj = 125 °C.

The device operates with intrinsic ruggedness across −65 °C to +175 °C junction temperature range and supports pulsed operation up to IFRM = 35 A (5 µs square wave). Thermal design relies on its 3.8 °C/W junction-to-case resistance and DPAK package's copper tab for conductive cooling.

Key Specifications

Pinout & Package

The STTH312B is housed in a DPAK (TO-252AA) surface-mount package with exposed copper drain tab for thermal conduction. The package complies with ECOPACK® environmental standards and JEDEC JESD97 marking for lead-free second-level interconnect.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STTH312B, STTH3L06 offers faster recovery but lacks voltage headroom for 800 V systems, while MUR3120CT provides same voltage rating but requires through-hole layout and delivers higher conduction loss-making STTH312B optimal for thermally constrained, high-frequency SMT designs demanding soft recovery.

Availability

STTH312B is available at Aetrix Electronics and suitable for industrial motor drives, switch-mode power supplies, and snubber circuits requiring stable component supply, long-lifecycle support, and consistent parametric performance across production batches.

Supply support for STTH312B 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 analog, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

The STTH series targets high-reliability power conversion applications, with STTH312B specifically engineered for ultrafast, soft-recovery rectification in high-voltage, high-frequency industrial systems where thermal robustness and EMI control are critical.

FAQ

What is the maximum junction temperature and how does it affect thermal design?

The STTH312B has a maximum junction temperature of 175 °C. This allows operation in high-ambient environments without active cooling, provided the thermal resistance from junction to case (3.8 °C/W) and case to ambient are managed via adequate PCB copper area and airflow. Derating curves in the datasheet define safe IF(AV) vs. Tc.

Is the STTH312B suitable for use in PFC boost diodes?

Yes-its 1200 V VRRM, 55 ns trr, and soft recovery make it appropriate for continuous conduction mode (CCM) PFC stages in 3–5 kW industrial supplies. However, designers must verify that peak reverse voltage under worst-case line transients remains within 80% of VRRM and that thermal design accommodates RMS current harmonics.

Does the DPAK package require special PCB layout considerations?

Yes-the exposed anode tab must be connected to a minimum 4 cm² copper pour on the top layer, thermally vias (≥6×0.3 mm) to inner ground planes, and no solder mask over the tab area. Per Figure 13 in the datasheet, the DPAK footprint requires precise 6.1 mm × 6.5 mm pad dimensions to ensure mechanical reliability and thermal performance.

How does soft recovery impact EMI in motor drive inverters?

Soft recovery (S factor ≥ 2) limits the rate of diode current collapse (di/dt) during turn-off, reducing high-frequency spectral content in voltage transients. In 15–20 kHz motor drives, this lowers common-mode noise by 6–10 dB and decreases filtering requirements on DC bus capacitors and EMC input filters.