STMicroelectronics STTH208RL

Overview

STTH208RL from STMicroelectronics is an ultrafast recovery silicon rectifier diode optimized for high-voltage switching applications, featuring 800 V repetitive peak reverse voltage (V_RRM), 2 A average forward current (I_F(AV)), and 75 ns maximum reverse recovery time (t_rr). It serves as a freewheeling, clamping, or snubber diode in offline SMPS, PFC stages, and flyback converters operating up to 175 °C junction temperature.

For engineers reviewing the STTH208RL datasheet, STTH208RL pinout, STTH208RL application, or STTH208RL equivalent, key selection criteria include verified t_rr ≤ 75 ns at 1 A, soft-switching behavior confirmed by low stored charge (Q_rr not specified but implied by trr < 100 ns), thermal resistance R_th(j-l) = 25 °C/W in SMB package, and ECOPACK-compliant lead-free construction.

Technical Context

The STTH208RL employs ST's planar ultrafast high-voltage technology to achieve soft reverse recovery with minimal EMI generation-critical for high-frequency power supplies above 100 kHz. Its t_rr of 75 ns (max) and t_fr of 200 ns (max) are measured under standardized conditions (I_F = 0.5–1 A, I_rr = 0.25 A), ensuring predictable turn-off behavior in hard-switched topologies.

Thermal performance is defined by R_th(j-l) = 25 °C/W (SMB) and R_th(j-a) = 110 °C/W (DO-15), with junction-to-lead resistance enabling direct heatsinking via PCB copper. The device operates reliably up to T_j(max) = 175 °C, supporting compact designs in constrained thermal environments.

Key Specifications

Pinout & Package

SMB (Surface Mount) package: molded epoxy body per JEDEC DO-214AA standard, lead-free, UL94 V0 rated, dimensions 3.95 × 5.60 × 2.20 mm (L × W × H). Pin 1 (cathode band) and Pin 2 (anode) are unidirectional terminals with no internal symmetry.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar ultrafast recovery diode applications.

Compared with STTH2R08 and ES2J, STTH208RL uniquely balances 800 V blocking, 2 A average current, and 75 ns recovery in a single SMB footprint-enabling drop-in replacement in legacy 800 V designs without compromising surge margin or thermal headroom.

Availability

STTH208RL is available at Aetrix Electronics and suitable for AC/DC adapters, active-clamp flyback converters, PFC boost stages, and motor drive freewheeling circuits requiring stable component supply and long-term industrial availability.

Supply support for STTH208RL 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 series targets high-efficiency power conversion, with STTH208RL specifically engineered for ultrafast, high-voltage rectification in space-constrained, thermally demanding offline power supplies.

FAQ

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

The STTH208RL has a maximum junction temperature of 175 °C. To maintain reliability, PCB layout must provide sufficient copper area under both leads (≥1 cm² per lead recommended for SMB) to achieve R_th(j-a) ≤ 110 °C/W. Thermal vias under pads and 2 oz copper improve heat spreading, especially in enclosed enclosures.

Is STTH208RL pin-compatible with DO-15 versions of the same part number?

No. STTH208RL uses the SMB (DO-214AA) surface-mount package, while STTH208 uses the through-hole DO-15 package. They share identical electrical specs but differ mechanically-SMB requires reflow soldering and footprint design per Figure 8; DO-15 needs axial lead hole spacing and wave soldering.

How is soft recovery verified and why does it matter in my design?

Soft recovery is confirmed by measurement of reverse recovery waveform showing low tail current and absence of abrupt current zero-crossing-documented in ST's application notes AN5088 and AN4021. It matters because soft recovery reduces high-frequency ringing and EMI, easing EMC certification and preventing false triggering of overvoltage protection circuits.

Does STTH208RL require a heatsink in typical 2 A applications?

No external heatsink is required if PCB copper provides adequate thermal path. With 2 A average current and R_th(j-l) = 25 °C/W, junction-to-lead temperature rise is ~50 °C. Using ≥2 cm² total copper area (including thermal vias) keeps T_j below 125 °C at 60 °C ambient-well within safe operating limits.