Fairchild Announces New Boost Switch For High-Frequency Step-Up DC-DC Designs

Fairchild Semiconductor states that it is bringing designers of cell phones, medical, portable and consumer applications a boost switch that provides high efficiency in boost conversion circuits. The FDFME3N311ZT combines a 30V integrated N-Channel PowerTrench® MOSFET and Schottky diode for what is described as exceptionally low input capacitance (55pF typical) and total gate charge (1nC) to improve efficiency in dc-dc boost designs.

Designed with Fairchild’s proprietary PowerTrench process technology, the boost switch delivers low switching losses through the careful optimization of dynamic characteristics. Its Schottky diode has low reverse leakage current over temperature to prevent a lowering of the converter efficiency as the package temperature rises. The FDFME3N311ZT integrates two discrete devices into a compact (1.6 x 1.6mm) and low-profile (0.55mm) MicroFET™ thin package, answering the need for compact dc-dc boost designs and offering a 36% space savings over prior boost switch products.

In applications such as cell phones, the FDFME3N311ZT offers a 30V breakdown voltage to drive up to seven or eight white LEDs, depending on the LEDs selected and design guardband. White LEDs are typically used for display backlighting in mobile devices such as cell phones, and are normally connected in a series path to ensure a uniform forward current and brightness for each LED. With each white LED having a forward voltage of around 3-3.5V, this boost switch is instrumental in "stepping-up" the available battery voltage and in most cases, a single cell lithium type.

The FDFME3N311ZT is priced (each, 1k pcs.) at $0.25, with a delivery of 8 to12 weeks ARO.