Datasheet

UC1842A-EP, UC1843A-EP, UC1844A-EP, UC1845A-EP
CURRENT-MODE PWM CONTROLLER
SGLS134D − SEPTEMBER 2002 − REVISED JANUARY 2013
8
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
APPLICATION INFORMATION
High peak currents associated with capacitive loads necessitate careful grounding techniques. Timing and bypass capacitors should be
connected close to pin 5 in a single point ground. The transistor and 5k potentiometer are used to sample the oscillator waveform and apply an
adjustable ramp to pin 3.
Figure 7. Open-Loop Laboratory Text Fixture
A fraction of the oscillator ramp can be resistively summed
with the current sense signal to provide slope compensation
for converters requiring duty cycles over 50%.
Note that capacitor, C, forms a filter with R2 to suppress the
leading edge switch spikes.
Figure 8. Slope Compression