Hi,
I would like to synchronizing the UC3843 with a clock signal generated by a microcontroller. My microcontroller is supplied by a 3V3 voltage source. The datasheet recommand to use a small resitor but doesn't specify a range of value. Nevertheless the schematic showed into the datasheet shows a 24 Ohm resistor.
Nevertheless with a 24 Ohm resistor and clock signal 0 - 3V3 for having a peak voltage of 0V5 across the 24 Ohm resistor, I need to put a 134 Ohm resistor. So the microcontroler have to source 3V3/(134+24) mA which is a lot. So I would like to raise the 24 Ohm resistor. But how much I can ? According to my simulation if i took a 100 Ohm resistor instead of a 24 Ohm resistor for having around 5 mA to source, the oscillator does not work anymore but I do not know if my oscillator simulation is representative of the UC3843 oscillator. Does anyone know what is the maximum resistor allowed for operating under normal condition ?
Here is my simulation,
Thank you very much and have a nice day !
