All the values are in the picture as shown. Problem 1) This problem relates to t
ID: 3349485 • Letter: A
Question
All the values are in the picture as shown.
Problem 1) This problem relates to the ramp generator circuit, op-amp error amplifier, and comparator from the lab "Buck Converter with Feedback Control." Answer the questions as best you can RAMP GENERATOR Assume that B 50 for Q,and VSAT 1 V for 02. For the R and C values shown above a) What is the approximate value of Ic (in mA) when the capacitor is charging? b) What is rate of increase (in V/ms) of vRAMp when the capacitor is charging? (Neglect the loading effects of R4, Rs, and the TRIG pin on vc.) The 555 timer will trigger its internal "discharge" transistor, initiating a capacitor dump, when the voltage at the THRESHOLD (pin 6) reaches the value applied to the () terminal of the internal comparator Based on the R-R-R voltage divider inside the 555 timer, and given the values of the external attenuator resistors R4 and Rs... c) What will be the peak voltage of vRAMP just before the capacitor dump occurs? Based on your answer to questions (b) and (c), d) What will be the frequency of the ramp? (If you have trouble reading this circuit, it's the same as the one in the lab experiment) RAMP R. 3.3k 4.7 K CURREN SOURCE 2N2907 TIMER GND 2% 2907 U1 TRIG OUT RST DIS 47k 0.1 uF THR Timing Capacitor NE555 R.4 220k CVCFILTER VCC 15v RAMP GENERATOR CIRCUIT ERROR AMPLIFIER: For the circuit shown in the lab experiment, e) What is the gain A of the amplifier if R,-R,-5.6 k? and R3-R4-100 k? ? COMPARATOR: If the inputs to the comparator are properly connected, then When VERRORVRAMP, will the comparator output be high or low?Explanation / Answer
1.Ic =1/10= 0.1
4.If we run the 555 from +10 and -5 volts instead of +15 and ground, the bottom of the sawtooth will be approximately at 0 volts. Or, we can use an operational amplifier to shift our voltage levels by 5 volts, but also we require using a negative power supply.