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OB2211CP View Datasheet(PDF) - On-Bright Electronics

Part Name
Description
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OB2211CP
On-Bright
On-Bright Electronics  On-Bright
OB2211CP Datasheet PDF : 10 Pages
1 2 3 4 5 6 7 8 9 10
OB2211/OB2212
Primary-Side Regulation PWM Power Switch
z Frequency shuffling for EMI improvement
The frequency Shuffling/jittering (switching
frequency modulation) is implemented in
OB2211/2. The oscillation frequency is modulated
with a pseudo random source so that the tone
energy is spread out. The spread spectrum
minimizes the conduction band EMI and therefore
eases the system design.
protection triggering. The output of OB2211 is shut
down when VDD drops below UVLO(ON) limit
and Switcher enters power on start-up sequence
thereafter.
z Current Sensing and Leading Edge
Blanking
Cycle-by-Cycle current limiting is offered in
OB2211/2 current mode PWM control. The switch
current is detected by a sense resistor into the CS
pin. An internal leading edge blanking circuit chops
off the sensed voltage spike at initial internal power
MOSFET on state due to snubber diode reverse
recovery and surge current of power MOSFET due
to Drain/Source Cap so that the external RC
filtering on sense input is no longer needed. The
PWM duty cycle is determined by the current sense
input voltage and the EA output voltage.
z Adjustable Drive Capability
The internal power MOSFET in OB2211/2 is
driven by a dedicated gate driver for power switch
control. Too weak the gate drive strength results in
higher conduction and switch loss of MOSFET
while too strong gate drive compromises EMI.
A good tradeoff is achieved through the built-in
totem pole gate design with right output strength
control. The gate drive strength can be adjusted
externally by a resistor connected between VDD
and VDDG The low idle loss and good EMI system
design is possible with this dedicated control
scheme.
z Protection Control
Good power supply system reliability is achieved
with its rich protection features including Cycle-by-
Cycle current limiting (OCP), VDD over voltage
protection and clamp, Power on Soft Start, and
Under Voltage Lockout on VDD (UVLO).
VDD is supplied by transformer auxiliary winding
output. PWM output of OB2211 is shut down when
VDD is higher than 30V due to over voltage
©On-Bright Electronics
On-Bright Confidential to MicroBridge
-8-
OB_DOC_DS_1100
 

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