OB5284C

GENERAL DESCRIPTION

OB5284C is a highly integrated current mode PWM control IC with high voltage startup, optimized for high performance, low standby power consumption and cost effective offline flyback converter applications. The controller‘s HV pin is used for high voltage startup, AC off detection, and X-cap Voltage discharge , this structure allows the brownout detection as well.

At full loading, the IC operates in fixed frequency (65KHz) mode. When the loading goes low, it operates in Green mode for high power conversion efficiency. When the load is very small, the IC operates in ‘Extended Burst Mode’ to minimize the standby power loss. As a result, high conversion efficiency can be achieved in the whole loading range.

High voltage startup is implemented in OB5284C, which features with short startup time and low standby power loss.

OB5284C offers complete protection coverage including cycle-by-cycle current limiting (OCP), over load protection (OLP), over temperature protection (OTP), output and VDD over voltage protection, output short protection. Excellent EMI performance is achieved with On-Bright proprietary frequency shuffling technique.

The tone energy at below 25KHz is minimized to avoid audio noise during operation.

OB5284C is offered in SOP8 package.

FEATURES

■ High voltage startup

■ Power on soft start reducing MOSFET Vds stress

■ Frequency shuffling for EMI

■ Fixed 65KHz (typical) switching frequency

■ Audio noise free operation

■ Tighten and programmable output over current protection

■ Comprehensive protection coverage

o VDD under voltage lockout with hysteresis (UVLO)

o Cycle-by-cycle over current protection (OCP) with auto-recovery

o Overload protection (OLP) with auto-recovery

o Over temperature protection (OTP) with auto-recovery

o VDD over voltage protection with auto-recovery

o Output over voltage protection with auto-recovery

o Output short protection with auto-recovery.

o Brownout protection with auto-recovery

o Output diode short protection with auto-recovery

■ Intelligent AC off detection with X-CAP discharge function

APPLICATIONS

Offline AC/DC flyback converter for

■ General power supply

■ Power Adapter

TYPICAL APPLICATION