80C51BH单片机设计指南

The original CMOS logic families were the 4000-series
and the 74C-series circuits. The 74C-series circuits are
functional equivalents to the corresponding numbered
74-series TTL circuits, but have CMOS logic levels and
retain the other well known characteristics of CMOS
logic.
These characteristics are: low power consumption, high
noise immunity, and slow speed. The low power consumption
is inherent to the nature of the CMOS circuit.
The noise immunity is due partly to the CMOS logic
levels, and partly to the slowness of the circuits. The
slow speed is due to the technology used to construct
the transistors in the circuit.
CONTENTS PAGE
CMOS EVOLVES  1
WHAT IS CHMOS?  1
THE MCS-51 FAMILY IN CHMOS  1
LATCHUP  2
LOGIC LEVELS AND INTERFACING
PROBLEMS  2
NOISE CONSIDERATIONS  2
UNUSED PINS  3
PULLUP RESISTORS  4
PULLDOWN RESISTORS  4
DRIVE CAPABILITY OF THE
INTERNAL PULLUPS  5
POWER CONSUMPTION  6
Idle  7
Power Down  7
USING THE POWER DOWN MODE  8
USING POWER MOSFETs TO
CONTROL VCC  9
BATTERY BACKUP SYSTEMS  9
POWER SWITCHOVER CIRCUITS  11
80C31BH a CHMOS EPROM  12
SCANNING A KEYBOARD  13
DRIVING AN LCD  16
Using an LCD Driver  17
RESONANT TRANSDUCERS  18
Frequency Measurements  18
Period Measurements  20
Pulse Width Measurements  21
HMOS/CHMOS
INTERCHANGEABILITY  21
External Clock Drive  21
Unused Pins  22
Logic Levels  22
Idle and Power Down  22
REFERENCES  23