The UC3845BD1013TR (购买请点击) series are high performance fixedfrequency current mode controllers. They are specifically designed forOff−Line and dc−dc converter applications offering the designer acost−effective solution with minimal external components. Theseintegrated circuits feature an oscillator, compensatedreference, high gain error amplifier, current sensing comparator, and ahigh current totem pole output ideally suited for driving a powerMOSFET.
Also included are protective features consisting of input andreference undervoltage lockouts each with hysteresis, cycle−by−cyclecurrent limitingUC3845BD1013TR (购买请点击), 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%.
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). The SOIC−14 package has separate power andground pins for the totem pole output stage.
The UC3845BD1013TR (购买请点击) 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 kHzUC3845BD1013TR (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 LimitingUC3845BD1013TR (购买请点击);
Internally Trimmed Reference with Undervoltage Lockout;
High Current Totem Pole Output;
Undervoltage Lockout with Hysteresis;
Low Startup and Operating Current。
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