Nowadays, SiC MOSFETs are widely adopted in fast‑charging power solutions thanks to their low‑loss characteristics. A controller compatible with SiC devices, featuring complete protection and simple peripheral circuits, is critical for power‑supply project implementation. The TN3300 from Tioner Semiconductor is a small‑form‑factor SOT23‑6 primary‑side feedback PWM controller, specially designed for driving external SiC power MOSFETs. It supports both constant‑voltage (CV) and constant‑current (CC) modes and is widely used in chargers, adapters and lithium‑ion battery power supplies.

Adopting primary‑side sensing architecture, TN3300 requires no optocoupler or secondary‑side compensation circuit, simplifying peripheral components and saving PCB space. It supports multi‑mode control covering CCM/QRM/DCM/PFM for full‑range operating conditions. The maximum switching frequency reaches 145 kHz at high input voltage and 100 kHz at low input voltage. Under light‑load or standby conditions, it enters green frequency‑reduction mode down to 25 kHz to achieve excellent light‑load efficiency and low standby power consumption. Combined with valley‑switching technology, it further reduces switching losses and makes full use of the high‑speed advantages of SiC MOSFETs.

A built‑in 2.5 ms soft‑start together with frequency dithering suppresses EMI noise and eases EMC optimization. It features a unique high‑temperature current fold‑back function: when junction temperature exceeds 131 °C, the constant‑current output decreases automatically at 5 %/°C until the output reaches 40 % of rated current. This smart power‑reduction mechanism improves system reliability under high‑temperature conditions, different from simple thermal shutdown used by ordinary power ICs.

It provides comprehensive protection functions. External resistors connected to the ZCD pin configure input undervoltage, input overvoltage, output overvoltage and output short‑circuit protection. VCC over‑voltage protection, cycle‑by‑cycle CS current limiting, CS‑pin short‑circuit protection and 155 °C thermal protection are all integrated. The 400 ns CS leading‑edge blanking filters current spikes at turn‑on to prevent false current‑limiting. The constant‑current output can be precisely set via the CS sense resistor and transformer turns ratio for convenient parameter tuning by engineers.

Housed in tiny SOT23‑6 package, it saves board area. Low startup‑current design reduces loss in the startup circuit. For 5‑65 W fast chargers, lithium‑battery chargers and various AC‑DC CV‑CC power supplies, TN3300 delivers high‑performance output with simple circuitry. It balances development efficiency, BOM cost and system reliability and serves as a cost‑effective choice for flyback designs using external SiC MOSFETs.