STR-X6737_V Datasheet, PDF (1/9 Pages) Allegro MicroSystems – Off-Line Quasi-Resonant Switching Regulators_V

STR-X6737
Off-Line Quasi-Resonant Switching Regulators
Features and Benefits
▪ Quasi-resonant topology IC  Low EMI noise and soft
switching
▪ Bottom-skip mode  Improved system efficiency over
the entire output load by avoiding increase of switching
frequency
▪ Auto-Standby mode  Lowers input power at very light
output load condition
▪ Avalanche-guaranteed MOSFET  Improves system-level
reliability and does not require V_DSS derating
▪ 500 V_DSS / 0.36 Ω R_DS(on)
▪ Various protections  Improved system-level reliability
▫ Pulse-by-pulse drain overcurrent limiting
▫ Overvoltage Protection (bias winding voltage sensing),
with latch
▫ Overload Protection with latch
▫ Maximum on-time limit
Package: 7-Pin TO-3P
Description
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 (V_DS 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 V_DS 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.
Not to scale
Continued on the next page…
Typical Application
STR-X6737
SANKEN ELECTRIC CO., LTD.
http://www.sanken-ele.co.jp