STR-W6765 Datasheet, PDF (1/14 Pages) Allegro MicroSystems – Quasi-Resonant Topology Primary Switching Regulators

STR-W6765
Quasi-Resonant Topology
Primary Switching Regulators
Features and Benefits
▪ Quasi-resonant topology IC  Low EMI noise and soft
switching
▪ Bottom-skip operation  Improved system efficiency
over the entire output load by avoiding increase of
switching frequency
▪ Standby burst mode operation  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 / 1.8 Ω, 52 to 110 W (Universal/230 VAC input)
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Package: 6-pin TO-220
Description
The STR-W6765 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-220, which contains the
controller chip (MIC) and MOSFET, enabling output power up
to 52 W with universal input or 110 W with a 230 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-burst
mode operation that 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-burst mode.
The soft-start mode minimizes surge voltage and reduces
power stress to the MOSFET and to the secondary rectifying
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Typical Application
P
S1
+B
ErrAmp A
D
VCC
1
4
STR-W6765
3
S/GND
ROCP
Cont
7
OCP
/BD
6
FB
5
RX
SS
/OLP
CX
D
S2
B SI
GND
Standby
ON/OFF
LowB
Standby
Out
GND
A For ErrAmp, Sanken SE series device recommended
B For SI, Sanken linear regulator IC recommended
28103.30-6, Rev. 1
SANKEN ELECTRIC CO., LTD.
http://www.sanken-ele.co.jp/en/