MC68HC05X4 Datasheet, PDF (23/156 Pages) Motorola, Inc – HCMOS Microcontroller Unit

Freescale Semiconductor, Inc.
Modes of Operation and Pin Descriptions
Pin descriptions
Pin descriptions
PB7/TCMP
1
RESET
2
OSC1
3
OSC2
4
MDS/TCAP (VPP)
5
PA0
6
PA1
7
PA2
8
PA3
9
PA4
10
PA5
11
PA6
12
PA7
13
VSS
14
28
PB6
27
PB5
26
PB4
25
PB3
24
PB2
23
PB1
22
PB0
21
VDDH
20
RX1
19
RX0
18
VSS1
17
TX1
16
TX0
15
VDD
VDD and VSS
Figure 6. 28-pin SOIC pinout
Power is supplied to the microcomputer via these two pins. VDD is the
positive supply and VSS is ground.
It is in the nature of CMOS designs that very fast signal transitions occur
on the MCU pins. These short rise and fall times place very high
short-duration current demands on the power supply. To prevent noise
problems, special care must be taken to provide good power supply
by-passing at the MCU. By-pass capacitors should have good
high-frequency characteristics and be as close to the MCU as possible.
By-passing requirements vary, depending on how heavily the MCU pins
are loaded.
11-modes
MOTOROLA
Modes of Operation and Pin Descriptions
For More Information On This Product,
Go to: www.freescale.com
MC68HC05X4 Rev 1.0
23