68HC705JB3 데이터 시트보기 (PDF) - Freescale Semiconductor

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68HC705JB3

8-bit microcontroller units (MCUs)

Freescale Semiconductor 

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 VDD and VSS

Power is supplied to the MCU through VDD and VSS. VDD is the positive supply,

and VSS 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

For More Information On This Product,

Go to: www.freescale.com

MC68HC05JB3

REV 1

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