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| UPSRB02 Datasheet, PDF (6/7 Pages) Unisonic Technologies – HIGH PRECISION CC/CV PRIMARY SIDE SWITCHING REGULATOR | |||
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UPSRB02
Preliminary
ï® OPERATION DESCRIPTION (Cont.)
LINEAR INTEGRATED CIRCUIT
At no load, the actual CS threshold is:
VCS_no_Load=0.5-(ICS_MAX)ÃRd
(V)
Current Sensing and Leading Edge Blanking
Cycle-by-cycle current limiting is offered in UTC UPSRB02. The switch current is detected by a sense resistor into
the CS pin. When the power switch is turned on, a turn-on spike will occur on this resistor. A 500ns leading-edge
blanking is built in to avoid false-termination of the switching pulse so that the external RC filtering is no longer
needed.
Drive BJT
The driver is a push pull stage with the supply voltage VDD. It provides the driving current for the external power
bipolar transistor. The output signal is current-limited to IOUT(SOURCE).
Protection Control
Good power supply system reliability is achieved with its comprehensive protection features including output
over-voltage protection, VDD over voltage protection, OTP, feedback loop open protection, Cycle-by-cycle current
limiting, short circuit protection, leading edge blanking and UVLO, etc.
VDD is supplied by transformer auxiliary winding output. The output of UTC UPSRB02 is shutdown when VDD drops
below VTH(OFF) and the power converter enters power on start-up sequence thereafter.
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
6 of 7
QW-R103-079.a
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