80C186

AMENDMENT 80C186 and 80C188 Integrated 16-Bit Microprocessors This document amends the 80C186 and 80C188 Integrated 16-Bit Microprocessors Data Book, order #16514D, and replaces the discontinued 80C186/80C188 CMOS High-Integration 16-Bit Microprocessors Amendment (specifications for the 20-MHz industrial operating range). This amendment consists of two parts: n Clock generation information changes for the 80C186 and 80C188 microcontrollers. If the guidelines in this bulletin are not followed, you may experience problems with clock start-up. n Industrial operating information at 20 MHz. This is the same information that was published in the discontinued 80C186/80C188 CMOS High-Integration 16-Bit Microprocessors Amendment. CLOCKING INFORMATION CHANGES Crystal-Driven Clock Source The internal oscillator circuit of the microcontroller is designed to function with a parallel resonant fundamental or third-overtone crystal. The 80C186 and 80C188 microprocessors use a crystal frequency that is twice the processor frequency. AMD does not recommend that you replace a crystal with an LC or RC equivalent for any member of the Am186™ family. The X1 and X2 signals are connected to an internal inverting amplifier (oscillator) that provides, along with the external feedback loading, the necessary phase shift (Figure 1 on page 2). In such a positive feedback circuit, the inverting amplifier has an output signal (X2) 180 degrees out of phase of the input signal (X1). The external feedback ne...