scf5250 Freescale Semiconductor, Inc, scf5250 Datasheet - Page 7

• Manufacturer Part Number: scf5250
• Description: Scf5250 Integrated Coldfire Microprocessor Data Sheet
• Manufacturer: Freescale Semiconductor, Inc

1.2.24 Crystal and On-chip PLL
Typically, an external 16.92 Mhz or 33.86 Mhz clock input is used for CD R/W applications, while an
11.2896 MHz clock is more practical for Portable CD player applications. However, the on-chip
programmable PLL, which generates the processor clock, allows the use of almost any low frequency
external clock (5-35 Mhz).
Two clock outputs (MCLK1 and MCLK2) are provided for use as Audio Master Clock. The output
frequencies of both outputs are programmable to Fxtal, Fxtal/2, Fxtal/3, and Fxtal/4. The Fxtal/3 option is
only available when the 33.86 Mhz crystal is connected.
The SCF5250 supports VCO operation of the oscillator by means of a 16-bit pulse density modulation
output. Using this mode, it is possible to lock the oscillator to the frequency of an incoming IEC958 or IIS
signal. The maximum trim depends on the type and design of the oscillator. Typically a trim of +/- 100
ppm can be achieved with a crystal oscillator and over +/- 1000 ppm with an LC oscillator.
1.2.25 Boot ROM
The boot ROM on the SCF5250 serves to boot the CPU in designs which do not have external Flash
memory or ROM. Typically this occurs in systems which have a separate MCU to control the system,
and/or the SCF5250 is used as a stand-alone decoder.
The SCF5250 can be booted in one of three modes:
1.2.26 Voltage Regulator
The SCF5250 contains an on-chip linear regulator that generates 1.2V from a 3.3V input. The regulator is
self-contained and drives the 1.2V core voltage out on one pin that can be used to power the core supply
pins at the board level. In battery powered portable applications, it is recommended that an external dc-dc
converter be used to generate the 1.2V core voltage to minimize power consumption.
Freescale Semiconductor
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External ROM
Internal ROM Master mode – boots from I2C, SPI, or IDE
Internal ROM Slave mode – boots from I2C or UART
SCF5250 Integrated ColdFire® Microprocessor Data Sheet, Rev. 1.1
Introduction
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