The SN6505x is alow-noise, low-EMI push-pull transformer driver, specifically designed for small form factor,isolated power supplies. It 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 throughSpread Spectrum Clocking (SSC). The SN6505x consists of an oscillator followed by a gate drive circuit thatprovides the complementary output signals to drive ground-referenced N-channel power switches. Thedevice includes two 1-A Power-MOSFET switches to ensure start-up under heavy loads. The switchingclock can also be provided externally for accurate placement of switcher harmonics, or whenoperating with multiple transformer drivers. The internal protection features include a 1.7 Acurrent limiting, under-voltage lockout, thermal shutdown, and break-before-make circuitry.SN6505xincludes a soft-start feature that prevents high inrush currentduring power up with large load capacitors. SN6505A has a 160 kHz internaloscillator for applications that need to minimize emissions whereas SN6505Bhas a 420 kHz internaloscillators for applications that require higher efficiency and smaller transformer size. TheSN6505x is available in asmall 6-pin SOT23/DBV package. The device operation is characterized for a temperature range from–55°C to 125°C.