The STTH108 is HEROMICRO a high-voltage ultrafast rectifier diode based on planar technology, designed for applications such as freewheeling, clamping, snubbing, and demagnetization in power supplies. To ensure reliable and safe operation, the following usage guidelines should be observed:
1. Electrical Ratings
Maximum Repetitive Reverse Voltage (VRRM): 800 V, with a maximum RMS voltage (V(RMS)) of 560 V. Operating voltages must not exceed these limits to prevent device breakdown.
Average Forward Current (IF(AV)): The rated current is 1 A under specified conditions: for the SMA package (STTH108A) at TL = 110°C with δ = 0.5; for the DO-41 package (STTH108) at TL = 130°C with δ = 0.5. Derating is recommended based on actual thermal conditions.
Forward Surge Current (IFSM): The device can withstand a surge of 20 A for 8.3 ms in the SMA package and 25 A in the DO-41 package. Although robust, repeated or prolonged surges should be avoided.
2. Thermal Management
The maximum junction temperature (Tj) is 175°C, and the storage temperature range is from -50°C to +175°C.
Thermal resistance values are critical for thermal design:
Junction-to-lead thermal resistance (Rth(j-l)) is 30°C/W for SMA (with 10 mm lead length) and 45°C/W for DO-41.
Junction-to-ambient thermal resistance (Rth(j-a)) for DO-41 is 110°C/W.
It is recommended to use sufficient copper area on the PCB under each lead to improve heat dissipation. Figures 5 and 6 illustrate that increasing copper area significantly reduces thermal resistance.
3. Dynamic Characteristics
The reverse recovery time (trr) is typically 75 ns (Tj = 25°C, IF = 0.5 A), with a soft recovery characteristic that helps reduce EMI.
The forward recovery voltage (VFP) can reach up to 12 V, so transient voltage spikes should be considered in circuit design.
4. Package and Mounting
Both SMA and DO-41 packages use epoxy material rated UL 94 V0 for flammability.
For DO-41, lead forming should follow Application Note AN1471.
The cathode is marked by a band on the device body; correct polarity must be observed during installation.
5. Reliability and Lifetime
The STTH108 offers high reliability, but prolonged operation at high temperature or voltage may reduce lifespan. Adequate design margins are recommended for critical applications.
By following these guidelines, engineers can ensure optimal performance and longevity when using the STTH108 in power electronic systems.
