STR-X6737
Off-Line Quasi-Resonant Switching Regulators
▪
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
Features and Benefits
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.
Continued on the next page…
Package: 7-Pin TO-3P
Not to scale
Typical Application
28103.30-9
ALLEGRO [ ALLEGRO MICROSYSTEMS ]
