MC908GR16VFAE Freescale Semiconductor, MC908GR16VFAE Datasheet - Page 77
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MC908GR16VFAE
Manufacturer Part Number
MC908GR16VFAE
Description
IC MCU 16K FLASH 8MHZ 48-LQFP
Manufacturer
Freescale Semiconductor
Series
HC08r
Specifications of MC908GR16VFAE
Core Processor
HC08
Core Size
8-Bit
Speed
8MHz
Connectivity
LIN, SCI, SPI
Peripherals
LVD, POR, PWM
Number Of I /o
37
Program Memory Size
16KB (16K x 8)
Program Memory Type
FLASH
Ram Size
1K x 8
Voltage - Supply (vcc/vdd)
3 V ~ 5.5 V
Data Converters
A/D 8x10b
Oscillator Type
Internal
Operating Temperature
-40°C ~ 105°C
Package / Case
48-LQFP
Controller Family/series
HC08
No. Of I/o's
37
Ram Memory Size
1KB
Cpu Speed
8MHz
No. Of Timers
2
Embedded Interface Type
SCI, SPI
Rohs Compliant
Yes
Processor Series
HC08GR
Core
HC08
Data Bus Width
8 bit
Data Ram Size
512 B
Interface Type
SCI, SPI
Maximum Clock Frequency
8 MHz
Number Of Programmable I/os
33
Number Of Timers
4
Maximum Operating Temperature
+ 105 C
Mounting Style
SMD/SMT
Development Tools By Supplier
FSICEBASE, DEMO908GZ60E, M68CBL05CE, M68EML08GPGTE
Minimum Operating Temperature
- 40 C
On-chip Adc
8 bit, 8 Channel
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Eeprom Size
-
Lead Free Status / Rohs Status
Details
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Company:
Part Number:
MC908GR16VFAE
Manufacturer:
Freescale Semiconductor
Quantity:
10 000
4.8.2 Parametric Influences on Reaction Time
Acquisition and lock times are designed to be as short as possible while still providing the highest possible
stability. These reaction times are not constant, however. Many factors directly and indirectly affect the
acquisition time.
The most critical parameter which affects the reaction times of the PLL is the reference frequency, f
This frequency is the input to the phase detector and controls how often the PLL makes corrections. For
stability, the corrections must be small compared to the desired frequency, so several corrections are
required to reduce the frequency error. Therefore, the slower the reference the longer it takes to make
these corrections. This parameter is under user control via the choice of crystal frequency f
R value programmed in the reference divider. (See
4.5.6 PLL Reference Divider Select
Another critical parameter is the external filter network. The PLL modifies the voltage on the VCO by
adding or subtracting charge from capacitors in this network. Therefore, the rate at which the voltage
changes for a given frequency error (thus change in charge) is proportional to the capacitance. The size
of the capacitor also is related to the stability of the PLL. If the capacitor is too small, the PLL cannot make
small enough adjustments to the voltage and the system cannot lock. If the capacitor is too large, the PLL
may not be able to adjust the voltage in a reasonable time. (See
Also important is the operating voltage potential applied to V
characteristics of the PLL. A fixed value is best. Variable supplies, such as batteries, are acceptable if
they vary within a known range at very slow speeds. Noise on the power supply is not acceptable,
because it causes small frequency errors which continually change the acquisition time of the PLL.
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.
4.8.3 Choosing a Filter
As described in
stability and reaction time of the PLL. The PLL is also dependent on reference frequency and supply
voltage.
Figure 4-10
the PLL are not critical, the three component filter network of
capacitor, C
reference frequencies. For reference frequencies between the values listed in the table, extrapolate to the
nearest common capacitor value. In general, a slightly larger capacitor provides more stability at the
expense of increased lock time.
Freescale Semiconductor
F
shows two types of filter circuits. In low-cost applications, where stability and reaction time of
, shown in
4.8.2 Parametric Influences on Reaction
Figure 4-10
MC68HC908GR16 Data Sheet, Rev. 4.0
(A). Refer to
Register.)
Table 4-4
4.3.3 PLL
Time, the external filter network is critical to the
for recommended filter components at various
DDA
Figure 4-10
Circuits,
. The power supply potential alters the
4.8.3 Choosing a
4.3.6 Programming the
Acquisition/Lock Time Specifications
(B) can be replaced by a single
Filter.)
XCLK
PLL, and
and the
RDV
77
.