AT1687Z High Voltage Quasi-Resonant PWM Controller
General Description
AT1687Z is a highly integrated quasi-resonant (QR) mode PWM control for flyback converter, optimized for high
performance, low standby power consumption and cost effective offline flyback converter applications.
The AT1687Z internal valley detector ensures minimum drain voltage switching at QR operation. At low line and
heavy loading, it operates in continuous conduction mode(CCM) via an external resistor sets minimum fixed frequency.
At high line and normal loading, it operates in QR mode. When light load, it operates in pulse frequency
modulation (PFM) mode. When the output power falls below a given level, it enters the burst mode.
The AT1687Z built-in multiple protection with VCC under voltage lockout (UVLO), VCC over voltage protection
(OVP), VCC clamp, GATE clamp, internal over temperature protection (OTP), Output over voltage protection, DEM
high level protection, cycle-by-cycle current limiting (OCP), over load protection (OLP), and leading-edge blanking
(LEB) of the current sensing to prevent circuit damage occurred under abnormal conditions.
The AT1687Z is available in an SOP-10L package and require very few external devices for operation.
AT1687Z High Voltage Quasi-Resonant PWM Controller
