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80C186 Dataheets PDF



Part Number 80C186
Manufacturers AMD
Logo AMD
Description 16-Bit Microprocessors
Datasheet 80C186 Datasheet80C186 Datasheet (PDF)

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, y.

  80C186   80C186


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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 network provides an additional 180 degree phase shift. In an ideal system, the input to X1 has 360 or zero degrees of phase shift. The external feedback network is designed to be as close as possible to ideal. If the feedback network is not providing necessary phase shift, negative feedback dampens the output of the amplifier and negatively affects the operation of the clock generator. Values for the loading on X1 and X2 must be chosen to provide the necessary phase shift and crystal operation. Selecting a Crystal When selecting a crystal, you should always specify the load capacitance (CL). This value can cause variance in the oscillation frequency from the desired specified value (resonance). The load capacitance and the loading of the feedback network have the following relationship: CL = (( C1 • C2)/( C1+ C2)) + CS where CS is the stray capacitance of the circuit. Placing the crystal and CL in series across the inverting amplifier and tuning these values (C1, C2) allows the crystal to oscillate at resonance. This relationship is true for both fundamental and third-overtone operation. Finally, there is a relationship between C1and C2. To enhance the oscillation of the inverting amplifier, these values must be offset with the larger load on the output (X2). Equal values of these loads tend to balance the poles of the inverting amplifier. The characteristics of the inverting amplifier set limits on the following parameters for crystals: ESR (Equivalent Series Resistance) ........... 40 Ω Max Drive Level .................................................. 1 mW Max The recommended range of values for C1and C2 are as follows: C1.............................................................15 pF ± 20% C2.............................................................22 pF ± 20% You must determine the specific values for C1 and C2. The values are dependent on the characteristics of the chosen crystal and board design. The C1 and C2 values include the stray capacitances of the design. Figure 1 on page 2 shows the correct connection of the oscillator configurations. Figure 1a shows the inverting amplifier configuration. This is the equivalent circuitry with the inverter integrated into the microcontroller. Figure 1b shows the crystal configuration. The diagram shows the correct connection for third-overtone crystals. The fundamental mode crystals do not require the L1 or the 200-pF capacitor. Figure 1c shows the recommended crystal mode based on the crystal frequency. The 80C186 and 80C188 microprocessors use a crystal twice the CPU frequency and can use either fundamental or third-overtone mode crystals, depending on the CPU frequency. This document contains information on a product under development at Advanced Micro Devices. The information is intended to help you evaluate this product. AMD reserves the right to change or discontinue work on this product without notice. Publication# 16514 Rev: D Amendment/1 Issue Date: October 1998 AMENDMENT Crystal C1 C2 a. Inverting Amplifier Configuration C1 X1 Crystal X2 C2 Microcontroller L11 200 pF b. Crystal Configuration Notes: 1. Use for third overtone mode crystals. Fundamental mode crystals do not use L1 or the 200-pF capacitor. XTAL Frequency 20 MHz 25 MHz 32 MHz 40 MHz 50 MHz L1 Value (Max) 12 µH ±20% 8.2 µH ±20% 4.7 µH ±20% 3.0 µH ±20% 2.2 µH ±20% Fundamental Third Overtone 20 MHz 25 MHz 32 MHz 40 MHz 50 MHz c. Recommended Crystal Mode Figure 1. Oscillator Conf.


L9958 80C186 SQD30N05-20L


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