STR-X6768N Datasheet, PDF (1/11 Pages) Allegro MicroSystems – Off-Line Quasi-Resonant Switching Regulators

STR-X6768N
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
▪ 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
▪ 800 V_DSS / 1.00 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-X6768N 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 220 W at 230 VAC and 150 W at universal 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.
A standby mode is executed by clamping the secondary output.
In general applications, standby mode reduces input power.
The soft-start mode minimizes surge voltage and reduces power
stress to the MOSFET and to the secondary rectifying diodes
during the start-up sequence.
Various protections such as overvoltage, overload, overcurrent,
maximum on-time protections and avalanche-energy guaranteed
MOSFET secure good system-level reliability.
Not to scale
Continued on the next page…
Typical Application
28103.30-11