68HC05JB3 Datasheet, PDF (16/134 Pages) Freescale Semiconductor, Inc – 8-bit microcontroller units (MCUs)

Freescale Semiconductor, Inc.
GENERAL RELEASE SPECIFICATION November 5, 1998
RESET 1
PA0 2
PA1 3
PA2 4
PA3 5
PA4 6
PB0/TCAP 7
PB1 8
PB2 9
IRQ 10
20 VDD
19 OSC1
18 OSC2
17 VSS
16 3.3V
15 D+
14 D–
13 _PA7
12 _PA6
11 _PA5
20-pin package
RESET 1
PA0 2
PA1 3
PA2 4
PC2 5
PA3 6
PC3 7
PA4 8
PB5 9
PB4 10
PB0/TCAP 11
PB1 12
PB2 13
IRQ 14
28 VDD
27 OSC1
26 OSC2
25 VSS
24 PC0/OCMP
23 PC1
22 3.3V
21 _D+
20 _D–
19 _PB7
18 _PB6
17 _PA7
16 PA6
15 PA5
28-pin package
Figure 1-2. MC68HC05JB3 Pin Assignments
1.4 FUNCTIONAL PIN DESCRIPTION
The following paragraphs give a description of the general function of each pin
assigned in Figure 1-2.
1.4.1 V_DD and V_SS
Power is supplied to the MCU through V_DD and V_SS. V_DD is the positive supply,
and V_SS is ground. The MCU operates from a single power supply.
Very fast signal transitions occur on the MCU pins. The short rise and fall times
place very high short-duration current demands on the power supply. To prevent
noise problems, special care should be taken to provide good power supply
bypassing at the MCU by using bypass capacitors with good high-frequency char-
acteristics that are positioned as close to the MCU as possible. Bypassing
requirements vary, depending on how heavily the MCU pins are loaded.
1.4.2 OSC1, OSC2
The OSC1 and OSC2 pins are the connections for the on-chip oscillator. The
OSC1 and OSC2 pins can accept the following sets of components:
1. A crystal as shown in Figure 1-3(a)
2. A ceramic resonator as shown in Figure 1-3(a)
3. An external clock signal as shown in Figure 1-3(b)
MOTOROLA
1-4
GENERAL DESCRIPTION
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MC68HC05JB3
REV 1