MC68331CEH25 Freescale Semiconductor, MC68331CEH25 Datasheet - Page 53

• Manufacturer Part Number: MC68331CEH25
• Description: IC MCU 32BIT 25MHZ 132-PQFP
• Manufacturer: Freescale Semiconductor
• Series: M683xxr

Specifications of MC68331CEH25

• Core Processor: CPU32
• Core Size: 32-Bit
• Speed: 25MHz
• Connectivity: EBI/EMI, SCI, SPI, UART/USART
• Peripherals: POR, PWM, WDT
• Number Of I /o: 18
• Program Memory Type: ROMless
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 132-QFP
• Controller Family/series: 68K
• No. Of I/o's: 18
• Cpu Speed: 25MHz
• No. Of Timers: 1
• Embedded Interface Type: QSPI, SCI, UART
• No. Of Pwm Channels: 2
• Digital Ic Case Style: PQFP
• Rohs Compliant: Yes
• Processor Series: M683xx
• Core: CPU32
• Data Bus Width: 32 bit
• Data Ram Size: 80 B
• Interface Type: QSPI, SCI, UART
• Maximum Clock Frequency: 25 MHz
• Number Of Programmable I/os: 18
• Number Of Timers: 1
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Eeprom Size: -
• Ram Size: -
• Program Memory Size: -
• Data Converters: -
• Lead Free Status / Rohs Status: Details

MC68331
USER’S MANUAL
1. Maintain low-leakage on the XFC node. See Appendix A electrical characteristics for more information.
2. Recommended loop filter for reduced sensitivity to low-frequency noise.
cy. When an external system clock signal is applied and the PLL is disabled, V
should be connected to the V
AD) for more information regarding system clock power supply conditioning.
A voltage controlled oscillator (VCO) generates the system clock signal. To maintain
a 50% clock duty cycle, VCO frequency is either two or four times system clock fre-
quency, depending on the state of the X bit in SYNCR. A portion of the clock signal is
fed back to a divider/counter. The divider controls the frequency of one input to a
phase comparator. The other phase comparator input is a reference signal, either from
the crystal oscillator or from an external source. The comparator generates a control
signal proportional to the difference in phase between the two inputs. The signal is low-
pass filtered and used to correct VCO output frequency.
Filter geometry can vary, depending upon the external environment and required clock
stability. Figure 4-6 shows two recommended filters. XFC pin leakage must be as
specified in APPENDIX A ELECTRICAL CHARACTERISTICS to maintain optimum
stability and PLL performance.
An external filter network connected to the XFC pin is not required when an external
system clock signal is applied and the PLL is disabled. The XFC pin must be left float-
ing in this case.
The synthesizer locks when VCO frequency is equal to EXTAL frequency. Lock time
is affected by the filter time constant and by the amount of difference between the two
comparator inputs. Whenever comparator input changes, the synthesizer must relock.
Lock status is shown by the SLOCK bit in SYNCR. During power-up, the MCU does
not come out of reset state until the synthesizer locks. Crystal type, characteristic fre-
quency, and layout of external oscillator circuitry affect lock time.
When the clock synthesizer is used, control register SYNCR determines operating fre-
quency and various modes of operation. The SYNCR W bit controls a three-bit pres-
caler in the feedback divider. Setting W increases VCO speed by a factor of four. The
V
SSI
0.01 F
0.1 F
C3
C4
NORMAL OPERATING
ENVIRONMENT
Figure 4-6 System Clock Filter Networks
Freescale Semiconductor, Inc.
0.1 F
For More Information On This Product,
C1
SYSTEM INTEGRATION MODULE
DD
Go to: www.freescale.com
V
XFC
DDSYN
supply. Refer to the SIM Reference Manual (SIMRM/
1
V
SSI
0.01 F
0.1 F
C3
C4
HIGH-STABILITY OPERATING
ENVIRONMENT
0.1 F
C1
0.01 F
C2
18k
R1
V
XFC
DDSYN
1, 2
16/32 XFC CONN
DDSYN
4-11
4