FST83100SM

FST83100SM application field and working principle

In the field of Diodes - Rectifiers - Arrays, FST83100SM is a multi-channel non-isolated synchronous rectifier integrated circuit driver. This attractive surface mount device features an integrated step-down switch, high side driver, and low side driver, making it suitable for applications such as Permanent-Magnet Alternators (PMA) rectifier or brushless motors (BLDC) rectifier.

FST83100SM is feature packed and offers a wide variety of functions, such as: Sync Mode, that allows the main MOSFETs to be synchronized to the switching frequency of the system; Low Voltage Lockout, that prevents the device turn on the FETs when the input voltage is below the safe threshold; Soft Start and Stop, that allows the FETs to be turned on and off softly, without current surges; Proportional Gate Drive, that provides a proportional and smooth adjustment of gate drive current/voltage to improve gate drive efficiency and reduce EMI; and Peak Current Mode, that allows the device to operate in a current peak control mode for improved light load efficiency.

This non-isolated synchronous rectifier IC driver has an operating temperature range of -40°C to +85°C. It comes in an attractive 4 x 4 mm QFN48 package, making it suitable for smaller, confined spaces.

Working Principle

The FST83100SM driver is based on synchronous rectification, where it converts the alternating current passing through two anti-parallel MOSFETs into a standing direct current. When in sync mode, the FETs are switched on and off in a synchronous manner and at the same time with the operating voltage. This reduces losses and allows for a high-efficiency conversion.

FST83100SM uses a high-side and a low-side MOSFET driver to control the opening and closing of the MOSFETs, providing a low-loss control of the current flow in the circuit. The high-side and low-side drivers are continuously enabled and always present during the entire PWM cycle. The MOSFET’s gate voltage is adjusted by comparing the output voltage to a reference in order to obtain the desired output voltage.

FST83100SM also includes a protection circuit, allowing a rapid response when conditions such as overvoltage, undervoltage, over current or over temperature are met. The protection circuit turns off the driver in order to prevent any damage to the device.

Conclusion

The FST83100SM is an ideal driver for permanent-magnet alternators (PMA) and brushless motors (BLDC) rectifiers, thanks to its features, such as Sync Mode, Low Voltage Lockout, Soft Start and Stop, Proportional Gate Drive, and Peak Current Mode. This chip is feature packed for applications requiring efficient and reliable power conversion, and provides a high level of reliability and robustness for the most demanding applications.