1 Introduction

The TCAN455x family of devices uses a Pierce oscillator based design that operates in the inductive region between a crystal’s parallel and series resonant frequencies for a wide range of quartz crystals up to 40 MHz with a maximum ESR of 60 ohms and with load capacitance (CL1=CL2) requirements ranging between 8 pF and 24 pF. It is also capable of operating with a single-ended clock source instead of a quartz crystal supplied to the OSC1 pin, automatically detecting when a single-ended clock is used, and disabling the quartz crystal amplifier and biasing circuit.

This design creates flexibility for how the device is used in the end application, but results in a few additional design requirements that need to be understood to ensure stable operation. This document discusses these requirements and serves as a guide on optimizing the oscillator clock circuit components.