Hi Team,
UC2842 datasheet shows the recommended range of timing resistor values is between 5 kΩ and 100 kΩ, my customer would like to know what if he puts a resistor value below than 5kΩ? Does the equation of fosc=1.72/(Rrt*Cct) still work?
Thanks very much.
Vincent Chen
Hello Vincent,
I have two comments:
1. Using a lower value of Rt will result in much higher current feeding into Ct from Vref, this will increase the dead time because it will take longer for the capacitor to discharge. Have the customer thought about this.
2. The equation in the datasheet will not hold when they move outside the recommended region because the graph becomes non linear. Attached is a graph(fosc Vs Rt) outside the recommended region.
The UCx84x’s oscillator allows for operation to 500 kHz.
Can I ask what values of Rt and Ct have they decided to move forward with keeping the oscillator max in mind.
Regards,
Sonal
