MC908AZ60ACFU Freescale Semiconductor, MC908AZ60ACFU Datasheet - Page 142

• Manufacturer Part Number: MC908AZ60ACFU
• Description: IC MCU FLASH 8.4MHZ 60K 64QFP
• Manufacturer: Freescale Semiconductor
• Series: HC08r

Specifications of MC908AZ60ACFU

• Core Processor: HC08
• Core Size: 8-Bit
• Speed: 8.4MHz
• Connectivity: CAN, SCI, SPI
• Peripherals: LVD, POR, PWM
• Number Of I /o: 52
• Program Memory Size: 60KB (60K x 8)
• Program Memory Type: FLASH
• Eeprom Size: 1K x 8
• Ram Size: 2K x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Data Converters: A/D 15x8b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 64-QFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Clock Generator Module (CGM)
Temperature and processing also can affect acquisition time because the electrical characteristics of the
PLL change. The part operates as specified as long as these influences stay within the specified limits.
External factors, however, can cause drastic changes in the operation of the PLL. These factors include
noise injected into the PLL through the filter capacitor, filter capacitor leakage, stray impedances on the
circuit board, and even humidity or circuit board contamination.
10.9.3 Choosing a Filter Capacitor
As described in
to the stability and reaction time of the PLL. The PLL is also dependent on reference frequency and supply
voltage. The value of the capacitor must, therefore, be chosen with supply potential and reference
frequency in mind. For proper operation, the external filter capacitor must be chosen according to this
equation:
For acceptable values of C
the voltage potential at which the MCU is operating. If the power supply is variable, choose a value near
the middle of the range of possible supply values.
This equation does not always yield a commonly available capacitor size, so round to the nearest
available size. If the value is between two different sizes, choose the higher value for better stability.
Choosing the lower size may seem attractive for acquisition time improvement, but the PLL may become
unstable. Also, always choose a capacitor with a tight tolerance (±20% or better) and low dissipation.
10.9.4 Reaction Time Calculation
The actual acquisition and lock times can be calculated using the equations below. These equations yield
nominal values under the following conditions:
The K factor in the equations is derived from internal PLL parameters. K
is configured in acquisition mode, and K
(See
Note the inverse proportionality between the lock time and the reference frequency.
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10.3.2.2 Acquisition and Tracking
Correct selection of filter capacitor, C
Room temperature operation
Negligible external leakage on CGMXFC
Negligible noise
10.9.2 Parametric Influences on Reaction
MC68HC908AZ60A • MC68HC908AS60A • MC68HC908AS60E Data Sheet, Rev. 6
fact
, (see
Chapter 28 Electrical
t
acq
t
al
Modes).
trk
C
t
=
=
Lock
F
is the K factor when the PLL is configured in tracking mode.
F (see
⎛
⎝
=
⎛
⎝
------------------- -
f
------------------- -
f
CGMRDV
CGMRDV
C
=
V
V
fact
10.9.3 Choosing a Filter
DDA
DDA
t
ACQ
⎛
⎝
------------------ -
f
C G M R D V
V
⎞
⎠
⎞
⎠
+
DDA
⎛
⎝
Time, the external filter capacitor, C
Specifications). For the value of V
⎛
⎝
----------- -
K
------------ -
K
t
AL
TRK
4
ACQ
8
⎞
⎠
⎞
⎠
⎞
⎠
acq
Capacitor).
is the K factor when the PLL
Freescale Semiconductor
DDA
F
, is critical
, choose