MC68HC05JJ6 Datasheet, PDF (25/216 Pages) Freescale Semiconductor, Inc – General Release Specification Microcontrollers

General Description
1.6 V_DD and V_SS Pins
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 characteristics that are positioned
as close to the MCU as possible. Bypassing requirements vary,
depending on how heavily the MCU pins are loaded.
1.7 OSC1 and OSC2 Pins
The OSC1 and OSC2 pins are the connections for the external pin
oscillator (EPO). The OSC1 and OSC2 pins can accept these 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 resistor as shown in Figure 1-3 (b)
4. An external clock signal as shown in Figure 1-3 (c)
The selection of the crystal/ceramic resonator or RC oscillator
configuration is done by product part number selection as described in
Section 15. Ordering Information.
The frequency, f_OSC, of the EPO or external clock source is divided by
two to produce the internal operating frequency, f_OP. An internal 2 MΩ
resistor may be selected between OSC1 and OSC2 by the shunt resistor
mask option.
MC68HC05JJ6/MC68HC05JP6 — Rev. 3.2
Freescale Semiconductor
General Description
General Release Specification
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