OB2365A

GENERAL DESCRIPTION

OB2365A is a highly integrated current mode PWM control IC optimized for high performance, low standby power and cost effective offline flyback converter applications.

At normal load condition, it operates in QR mode in high line input voltage. To minimize switching loss, the maximum switching frequency in QR mode is internally limited to 77 KHz. When the loading goes low, it operates in PFM mode with valley switching for high power conversion efficiency. When the load is very small, the IC operates in ‘Extended Burst Mode’ to minimize the standby power loss. Additionally, in the low line input voltage, the IC operates in fixed frequency (65KHz) CCM mode at the heavy loading. As a result, high conversion efficiency can be achieved in the whole loading range.

VCC low startup current and low operating current contribute to a reliable power on startup and low standby design with OB2365A.

OB2365A offers comprehensive protection coverage with auto-recovery including Cycle-by-Cycle current limiting (OCP), over load protection (OLP), VCC under voltage lockout (UVLO), external over temperature protection (OTP), and over voltage protection (OVP).  Excellent EMI performance is achieved with On-Bright proprietary frequency shuffling technique.

The tone energy at below 23KHz is minimized in the design and audio noise is eliminated during operation.

OB2365A is offered in SOT23-6 package.

APPLICATIONS

Offline AC/DC flyback converter for

■   General power supply

■   Power Adapter

FEATURES

■   Power on soft start reducing MOSFET Vds stress

■   Multi-Mode Operation

77KHz maximum clamping frequency in QR mode @ Full Load in high line voltage

65KHz minimum clamping frequency in CCM mode @ Heavy Load in low line voltage

Valley switching operation @ Green mode

  Burst Mode @ Light Load & No Load

■   Frequency shuffling for EMI

■   Extended burst mode control for improved efficiency and low standby power design

■   Audio noise free operation

■   Comprehensive protection coverage

o    VCC Under Voltage Lockout with hysteresis (UVLO)   

o    VCC Over Voltage Protection (VCC OVP)  

o    Cycle-by-cycle over current threshold setting for constant output power limiting over universal input voltage range

o    Over Load Protection (OLP) with auto-recovery

o    External (if NTC resistor is connected at DEM pin)or internal Over Temperature Protection (OTP) with auto-recovery

o    Output Over Voltage Protection(Output OVP) with auto-recovery, and  the OVP triggered voltage can be adjusted by the resistor connected between auxiliary winding and DEM pin

o    Output diode short protection with auto-recovery

TYPICAL APPLICATION