The STR-X6737 is a quasi-resonant topology IC designed for
SMPS applications. It shows lower EMI noise characteristics
than conventional PWM solutions, especially at greater than
2 MHz. It also provides a soft-switching mode to turn on the
internal MOSFET at close to zero voltage (VDS bottom point)
by use of the resonant characteristic of primary inductance
and a resonant capacitor.
The package is a fully molded TO-3P, which contains the
controller chip (MIC) and MOSFET, enabling output power
up to 280 W at 120 VAC input. The bottom-skip mode skips
the first bottom of VDS and turns on the MOSFET at the second
bottom point, to minimize an increase of operating frequency
at light output load, improving system-level efficiency over
the entire load range.
There are two standby modes available to reduce the input power
under very light load conditions. The first is Auto-Standby
mode, which is internally triggered by periodic sensing, and
the other is a manual standby mode, which is executed by
clamping the secondary output. In general applications, the
manual standby mode reduces the input power further compared
to Auto-Standby mode.
Features and Benefits
â–ª Quasi-resonant topology IC - Low EMI noise and soft switching
â–ª Bottom-skip mode - Improved system efficiency over the entire output load by avoiding increase of switching frequency
â–ª Auto-Standby mode - Lowers input power at very light output load condition
â–ª Avalanche-guaranteed MOSFET - Improves system-level reliability and does not require VDSS derating
▪ 500 VDSS / 0.36 Ω RDS(on)
â–ª Various protections - Improved system-level reliability
â–« Pulse-by-pulse drain overcurrent limiting
â–« Overvoltage Protection (bias winding voltage sensing), with latch
â–« Overload Protection with latch
â–« Maximum on-time limit