The SN6505x is a low-noise, low-EMI push-pull transformer driver, specifically designed for small form factor, isolated power supplies. The device drives low-profile, center-tapped transformers from a 2.25-V to 5-V DC power supply. Ultra-low noise and EMI are achieved by slew rate control of the output switch voltage and through Spread Spectrum Clocking (SSC). The SN6505x consists of an oscillator followed by a gate drive circuit that provides the complementary output signals to drive ground-referenced N-channel power switches. The device includes two 1-A power-MOSFET switches to provide start-up under heavy loads. The switching clock can also be provided externally for accurate placement of switcher harmonics, or when operating with multiple transformer drivers. The internal protection features include a 1.7-A current limiting, undervoltage lockout, thermal shutdown, and break-before-make circuitry. The SN6505x includes a soft-start feature that prevents high inrush current during power up with large load capacitors. The SN6505A has a 160-kHz internal oscillator for applications that need to minimize emissions whereas the SN6505B has a 420-kHz internal oscillator for applications that require higher efficiency and smaller transformer size. The SN6505x is available in a small 6-pin SOT23 or DBV package. The device operation is characterized for a temperature range from –55°C to 125°C.