mc68hc912bc32 Freescale Semiconductor, Inc, mc68hc912bc32 Datasheet - Page 27

• Manufacturer Part Number: mc68hc912bc32
• Description: M68hc12 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

1.6.2.5 V
V
MC68HC912B32 and MC68HC912BC32 only.
1.6.3 Signal Descriptions
The MCU signals are described here and summarized in
1.6.3.1 XTAL and EXTAL
XTAL and EXTAL are the crystal driver and external clock input pins. They provide the interface for either
a crystal or a CMOS compatible clock to control the internal clock generator circuitry. Out of reset the
frequency applied to EXTAL is twice the desired E-clock rate. All the device clocks are derived from the
EXTAL input frequency.
XTAL is the crystal output. The XTAL pin must be left unterminated when an external CMOS compatible
clock input is connected to the EXTAL pin. The XTAL output is normally intended to drive only a crystal.
The XTAL output can be buffered with a high-impedance buffer to drive the EXTAL input of another
device.
Freescale Semiconductor
FP
is the FLASH EEPROM programming voltage and supply voltage during normal operation for the
FP
(MC68HC912B32 and MC68HC912BC32 only)
Mnemonic
In all cases, take extra care in the circuit board layout around the oscillator
pins. Load capacitances shown in the oscillator circuits include all stray
layout capacitances. Refer to
oscillator circuits.
V
V
V
V
V
V
V
V
V
DDX
SSX
DDA
SSA
DD
SS
RH
RL
FP
Table 1-2. Power and Ground Connection Summary
Pin Number
10, 47
11, 48
31, 78
30, 77
59
60
49
50
69
M68HC12B Family Data Sheet, Rev. 9.1
Internal power and ground
External power and ground supply to pin drivers
Operating voltage and ground for the ATD; allows the supply
voltage to be bypassed independently
Reference voltages for the analog-to-digital converter
Programming voltage for the FLASH EEPROM and required
supply for normal operation — MC68HC912B32 and
MC68HC912BC32 only.
Pin 69 is a no connect (NC) on the MC68HC12BE32 and
MC68HC12BC32.
Figure 1-5
NOTE
and
Table
Figure 1-6
Description
1-3.
for diagrams of
Pinout and Signal Descriptions
27