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UC3842A Datasheet(PDF) 5 Page - STMicroelectronics |
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UC3842A Datasheet(HTML) 5 Page - STMicroelectronics |
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5 / 15 page 
Figure 1: Open Loop Test Circuit. RT A 2N2222 4.7K Ω 1K Ω ERROR AMP. ADJUST 4.7K Ω 5K Ω ISENSE ADJUST 100K Ω COMP V FB ISENSE RT/CT 1 2 3 4 C T 7 6 5 8 VREF V i OUTPUT GROUND 0.1 µF 0.1 µF VREF V i OUTPUT GROUND 1W 1K Ω D95IN343 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 Ω potentiometerareusedto samplethe oscillator waveform and apply an adjustable ramp to pin 3. 300 1K 3K 10K 30K RT(Ω) 1K 10K 100K 1M fo (Hz) D96IN362 CT=470pF 1nF 2.2nF 4.7nF Figure 2: Oscillator Frequency vs Timing Resis- tance 300 1K 3K 10K 30K RT(Ω) 0 20 40 60 fo (Hz) D96IN363 80 Figure 3: Maximum Duty Cycle vs Timing Resis- tor UC3842A UC2842A/3A/4A/5A - UC3842A/3A/4A/5A 5/15 |
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