Current Mode PWM Power Switch Freq Shuffling
A good tradeoff is achieved through the
built-in totem pole gate design with right output
strength and dead time control. The low idle loss
and good EMI system design is easier to achieve
with this dedicated control scheme.
In addition to the gate drive control scheme
mentioned, the gate drive strength can also be
adjusted externally by a resistor connected between
VDD and VDDG, the falling edge of the Drain
output can be well controlled. It provides great
flexibility for system EMI design.
• Protection Controls
Good power supply system reliability is achieved
with its rich protection features including Cycle-by-
Cycle current limiting (OCP), Over Load
Protection (OLP) and over voltage clamp, Under
Voltage Lockout on VDD (UVLO).
With On-Bright Proprietary technology, the OCP is
line voltage compensated to achieve constant
output power limit over the universal input voltage
At overload condition when FB input voltage
exceeds power limit threshold value for more than
TD_PL, control circuit reacts to shut down the
switcher. Switcher restarts when VDD voltage
drops below UVLO limit.
VDD is supplied by transformer auxiliary winding
output. It is clamped when VDD is higher than 30V.
The output of OB2358 is shut down when VDD
drops below UVLO_ON limit and Switcher enters
power on start-up sequence thereafter.