UC3874DW-1 ,1UC1874-1,-2UC2874-1,-2UC3874-1,-2High Efficiency, Synchronous, Step-down (Buck) Controllers
UC3874N-1 , High Efficiency, Synchronous, Step-down (Buck) Controllers
UC3874N-2 , High Efficiency, Synchronous, Step-down (Buck) Controllers
UC3874N-2 , High Efficiency, Synchronous, Step-down (Buck) Controllers
UC3874N-2 , High Efficiency, Synchronous, Step-down (Buck) Controllers
UC3875 ,Phase Shift Resonant ControllerBLOCK DIAGRAMFREQSET HIGH SPEED OSCILLATORCLOCKSYNCRAMP GENERATOR &SLOPE SLOPE COMPENSATIONIII 1.3V ..
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UN9113 ,Silicon PNP epitaxial planer transistorElectrical Characteristics (Ta=25˚C)nParameter Symbol Conditions min typ max UnitI V = –50V, I = 0 ..
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UN9114 ,Silicon PNP epitaxial planer transistorFeaturesn1l Costs can be reduced through downsizing of the equipment and– –reduction of the number ..
UC3874DW-1
High Efficiency, Synchronous, Step-down (Buck) Controller 18-SOIC 0 to 70
DESCRIPTIONThe UC3874 familyof synchronous step-down (Buck) regulators provides
high efficiency power conversion from an input voltage rangeof 4.5to 36
volts. The UC3874is tailored for battery powered applications such as
laptop computers, consumer products, communications systems, and
aerospace which demand high performance and long battery life. The
synchronous regulator replaces the catch diodein the standard buck
regulator witha low Rds(on) N-channel MOSFET switch allowing for
significant efficiency improvements. The high side N-channel MOSFET
switchis driven outof phase from the low side N-channel MOSFET switch an on-chip bootstrap circuit which requires onlya single external
capacitorto develop the regulated gate drive. Fixed frequency, average
current mode control provides the regulator with inherent slope
compensation, tight regulationof the output voltage, and superior load and
line transient response. Switching frequencies up to 300kHz are possible.
Light load efficiencyis improvedbya fully programmable standby mode,in
which the quiescent current consumptionof the controlleris significantly re-
duced. The reductionis achievedby disabling the MOSFET driver outputs
and the internal oscillator when the controller has sensed that the the out-
put load current has dropped a user programmable amount from full load.
(continued)High Efficiency, Synchronous, Step-down (Buck) Controllers
FEATURES Operation to 36V Input Voltage Fixed Frequency Average Current
Mode Control Standby Mode for Improved
Efficiency at Light Load Drives External N-Channel
MOSFETs for Highest Efficiency Sleep Mode Current < 50mA Complementary 1 Amp Outputs with
Regulated Gate Drive Voltage LDO (Low Drop Out) Virtual 100%
Duty Cycle Operation Non-Overlapping Gate Drives
BLOCK DIAGRAM
UC1874-1,-2
UC2874-1,-2
UC3874-1,-2
