MC68HC908MR16CFU Freescale Semiconductor, MC68HC908MR16CFU Datasheet - Page 61

• Manufacturer Part Number: MC68HC908MR16CFU
• Description: IC MCU 8MHZ 16K FLASH 64-QFP
• Manufacturer: Freescale Semiconductor
• Series: HC08r

Specifications of MC68HC908MR16CFU

• Core Processor: HC08
• Core Size: 8-Bit
• Speed: 8MHz
• Connectivity: SCI, SPI
• Peripherals: LVD, POR, PWM
• Number Of I /o: 44
• Program Memory Size: 16KB (16K x 8)
• Program Memory Type: FLASH
• Ram Size: 768 x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Data Converters: A/D 10x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 64-QFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -

The PLL also may operate in manual mode (AUTO = 0). Manual mode is used by systems that do not
require an indicator of the lock condition for proper operation. Such systems typically operate well below
f
4.3.2.4 Programming the PLL
Use this 9-step procedure to program the PLL.
Freescale Semiconductor
BUSMAX
1. Choose the desired bus frequency, f
2. Calculate the desired VCO frequency, f
3. Using a reference frequency, f
4. Calculate the VCO frequency, f
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•
•
•
•
ACQ is a writable control bit that controls the mode of the filter. Before turning on the PLL in manual
mode, the ACQ bit must be clear.
Before entering tracking mode (ACQ = 1), software must wait a given time, t
Acquisition/Lock Time
register (PCTL).
Software must wait a given time, t
clock source to CGMOUT (BCS = 1).
The LOCK bit is disabled.
CPU interrupts from the CGM are disabled.
multiplier, N. Round the result to the nearest integer.
and require fast startup. These conditions apply when in manual mode:
Example: f
Example: f
Example: N =
BUSDES
VCLKDES
Variable
f
f
VCLKDES
Example: f
BUSDES
f
f
f
f
f
RCLK
VCLK
NOM
MC68HC908MR32 • MC68HC908MR16 Data Sheet, Rev. 6.1
BUS
VRS
32 MHz
4 MHz
Specifications), after turning on the PLL by setting PLLON in the PLL control
= 8 MHz
N =
= 4 x 8 MHz = 32 MHz
VCLK
Table 4-1. Variable Definitions
f
RCLK
VCLKDES
= 8 MHz
VCLK
Desired bus clock frequency
Desired VCO clock frequency
Chosen reference crystal frequency
Calculated VCO clock frequency
Calculated bus clock frequency
Nominal VCO center frequency
Shifted FCO center frequency
f
RCLK
AL
f
= 8 x 4 MHz = 32 MHz
VCLKDES
, equal to the crystal frequency, calculate the VCO frequency
, after entering tracking mode before selecting the PLL as the
.
BUSDES
f
VCLK
VCLKDES
Table 4-1
= N x f
= 4 x f
.
.
RCLK
BUSDES
Definition
lists the variables used and their meaning.
ACQ
Functional Description
(see
4.8
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