EN80C186EA20 데이터 시트보기 (PDF) - Intel

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EN80C186EA20

16-Bit High-Integration Embedded Processors

Intel 

Intel® 80C186XL and Intel® 80C186EA Differences

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Intel® 80C186XL and Intel® 80C186EA Differences

The 80C186EA is intended as a direct functional upgrade for 80C186XL designs. In many cases, it

will be possible to replace an existing 80C186XL with little or no hardware redesign. The

following sections describe differences in pinout, operating modes, and AC and DC specifications

to keep in mind.

Pinout Compatibility

The 80C186EA requires a PDTMR pin to time the processor's exit from Powerdown Mode. The

original pin arrangement for the 80C186XL in the PLCC package did not have any spare leads to

use for PDTMR. The arrangement of all the other leads in the 68-lead PLCC is identical between

the 80C186XL and the 80C186EA. Therefore, upgrading a PLCC 80C186XL to PLCC 80C186EA

is straightforward.

Operating Modes

The 80C186XL has two operating modes, Compatible and Enhanced. Compatible Mode is a pin-

to-pin replacement for the NMOS 80186, except for numerics coprocessing. In Enhanced Mode,

the processor has a Refresh Control Unit, the Power-Save feature and an interface to the 80C187

Numerics Coprocessor. The MCS0, MCS1, and MCS3 pins change their functions to constitute

handshaking pins for the 80C187.

The 80C186EA allows all non-80C187 users to use all the MCS pins for chip-selects. In regular

operation, all 80C186EA features (including those of the Enhanced Mode 80C186) are present

except for the interface to the 80C187. Numerics Mode disables the three chip-select pins and

reconfigures them for connection to the 80C187.

TTL vs. CMOS Inputs

The inputs of the 80C186EA are rated for CMOS switching levels for improved noise immunity,

but the 80C186XL inputs are rated for TTL switching levels. In particular, the 80C186EA requires

a minimum VIH of 3.5V to recognize a logic one while the 80C186XL requires a minimum VIH of

only 1.9V (assuming 5.0V operation). The solution is to drive the 80C186EA with true CMOS

devices, such as those from the HC and AC logic families, or to use pull-up resistors where the

added current draw is not a problem.

Timing Specifications

80C186EA timing relationships are expressed in a simplified format over the 80C186XL. The AC

performance of an 80C186EA at a specified frequency will be very close to that of an 80C186XL

at the same frequency. Check the timings applicable to your design prior to replacing the

80C186XL.

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