<strong>Description
The UC3845BD1R2G series are high performance fixedfrequency current mode controllers. They are designed forOff−Line and dc−dc converter applications offering the designer external .UC3845BD1R2G （购买请点击）circuits feature a temperature high amplifier, current sensing comparator, and ahigh current totem pole output ideallysuited for drivinMOSFETUC3845BD1R2G （购买请点击）.
Also included are protective features consisting of input andreference undervoltage lockouts each with hysteresis, cycle−by−cyclecurrent limiting, a latch for single pulse metering, and a flip−flopwhich blanks the output off every other oscillator cycle, allowingoutput deadtimes to be programmed from 50% to 70%UC3845BD1R2G （购买请点击）.
These devices are available in an 8−pin dual−in−line and surfacemount (SOIC−8) plastic package as well as the 14−pin plastic surfacemount (SOIC−14)UC3845BD1R2G （购买请点击）The SOIC−14 package has separate power andground pins for the totem pole output stage.
The UCX844B has UVLO thresholds of 16 V (on) and 10 V (off),ideally suited for off−line converters. The UCX845B is tailored forlower voltage applications having UVLO thresholds of 8.5 V (on) and7.6 V (off).
Features
Pb−Free Packages are Available;
Trimmed Oscillator for Precise Frequency Control;
Oscillator Frequency Guaranteed at 250 kHzUC3845BD1R2G （购买请点击）;
Current Mode Operation to 500 kHz Output Switching Frequency;
Output Deadtime Adjustable from 50% to 70%;
Automatic Feed Forward Compensation;
Latching PWM for Cycle−By−Cycle Current Limiting;
Internally Trimmed Reference with Undervoltage Lockout;
High Current Totem Pole Output;
Undervoltage Lockout with Hysteresis;
Low Startup and Operating Current.
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