The oscillator circuit for almost any microcontroller is a fairly simple design with very few components. Select- ing the values for capacitors and resistors from the manufacturers’ data books will get you a circuit that oscillates. However, many conditions can adversely affect the performance of your oscillator design. Higher temperatures and lower supply voltages can lower the amplifier gain (and thus the loop gain in the oscillator circuit) causing poor, slow, or no start-up. Colder tem- peratures and higher supply voltages can increase amplifier gain, causing the circuit to be forced to a higher harmonic and throw off the timing. The crystal can also be overdriven and become potentially dam- aged and cease functioning altogether. It is also possi- ble to waste power through the improper selection of components or Clock modes. AN849 Basic PICmicro Oscillator Design The Oscillator Circuit Author: Dan Matthews Microchip Technology Inc. The circuit shown in Figure 1 is a typical parallel reso- nant oscillator circuit, as used with the Microchip PIC- micro family of devices. The output of an inverting INTRODUCTION amplifier is fed back to its input to create an "unstable" ……