STRW6756 transistor integrated circuit Integrated Circuit Chip QuasiResonant Flyback Switching Regulator

Switching Regulators STR-W6756

Universal-Input/140 W Off-Line QuasiResonant Flyback Switching Regulator

The STR-W6756 is a quasi-resonant regulator specifically designed to satisfy the requirements for increased integration and reliability in switch-mode power supplies. It incorporates a primary control and drive circuit with an avalanche-rated power MOSFET. The regulator exhibits only low-level high-frequency EMI noise because of soft switching of the MOSFET close to ground (bottom point). A bottom-skip function minimizes an increase of operational frequency during light loads to improve system efficiency over the entire load range.

Covering the power range from below 240 watts for a 230 VAC input, or 140 watts for a universal input (85 to 264 VAC), this device can be used in a range of applications, from DVD and VCR players to ac adapters for cellular phones and digital cameras. An auto-standby function, which is internally triggered by sensing on time, reduces power consumption at light load. An externally triggered standby mode reduces the input power further. Multiple protections, including the avalanche-energy-guaranteed MOSFET, provide high reliability of system design.

Cycle-by-cycle current limiting, undervoltage lockout with hysteresis, and overvoltage protection protect the power supply during the normal overload and fault conditions. Overvoltage protection is latched after a short delay. The latch may be reset by cycling the input supply. Low start-up current and a low-power standby mode selected from the secondary circuit completes a comprehensive suite of features. The STR-W6756 is provided in a fully molded TO-220-style flangemounted, high power, isolated plastic package.

FEATURES AND BENEFITS

■ Rugged 650 V Avalanche-Rated MOSFET Simplified Surge Absorption No VDSS Derating Required

■ 0.73 Ω Maximum rDS(on)

■ Two Operational Modes by Automatic Switching: Quasi-Resonant Mode for Normal Operation Burst Mode for Standby Operation or Light Loads

■ Automatic or Manually Triggered Burst Standby Input Power <0.1 W at No Load

■ Low Operating Current (6 mA typ)

■ Auto-Bias Function Stable Burst Operation Without Generating Interference

■ Internal Off-Timer Circuit

■ Built-In Constant-Voltage Drive

■ Multiple Protections: Pulse-by-Pulse Overcurrent Protection Overload Protection with Auto Recovery Latching Overvoltage Protection Undervoltage Lockout with Hysteresis

■ RoHS Compliant

ABSOLUTE MAXIMUM RATINGS at TA = +25°C

Control Supply Voltage, V_CC . . . . 35 V

Drain-Source Voltage, V_DSS . . . . . . 650 V

Drain Switching Current, I_D . . . . . 15 A*

Peak Drain Switching Current,

   I_DM . . . . . . . . . . . . . . . . . . . . . . 15 A

Single-Pulse Avalanche Energy,

   E_AS . . . . . . . . . . . . . . . . . . . 400 mJ

OCP/BD Voltage Range,

   V_OCP . . . . . . . . . . . . –1.5 V to +5 V

FB Input Current, I_FB . . . . . . . . 10 mA

FB Voltage Range, V_FP   –0.5 V to +9 V

Package Power Dissipation, P_D

   control (V_CC × I_CC(ON)) . . . . . . 0.8 W

   MOSFET (V_DSS × I_D). . . See Graph

MOSFET Channel Temp., T_J . +150°C

Internal Frame Temp., T_F . . . . +115°C

Operating Temperature Range,

   T_A . . . . . . . . . . . -20°C to +115°C†

Storage Temperature Range,

   T_S . . . . . . . . . . . . -40°C to +125°C

* Drain switching current is limited by temperature and safe operating area.

†For the availability of parts meeting -40°C requirements, contact Allegro’s Sales Representative.

FUNCTIONAL BLOCK DIAGRAM

PACKAGE DIMENSIONS in Millimeters

Product weight: approx. 2.3 g.

Recommended mounting hardware torque: 0.588 ~ 0.785 Nm, 6 ~ 8 kgf × cm.

Recommended silicon grease: Dow Corning SC102, Toshiba YG6260, Shin-Etsu G746, or equivalent.

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