68HC05CL48 datasheet(108/145 Pages) MOTOROLA

108 / 145 page

GENERAL RELEASE SPECIFICATION

June 11, 1997

MOTOROLA

PHASE-LOCKED LOOP

MC68HC05CL48

13-2

REV 2.0

13.1

PLL CONTROL AND STATUS REGISTER (PCSR $000D)

PON - PLL power on/off bit.

1 =

PLL is switched on.

0 =

PLL is switched off.

PCLK - PLL Clock select bit.

1 =

Use PLL clock.

0 =

Use external clock.

FREQ1 - Frequency select bit 1.

FREQ0 - Frequency select bit 0.

13.2

PLL OPERATIONS

The PLL consists of an on chip VCO, a phase comparator and a divider. A ﬁlter is

required to ﬁlter the phase comparator output to provide a DC signal to control the

VCO frequency Figure 13-1.

13.3

PLL LOCK TIME

The PLL will lock in less than 10msec after the PON-bit is set. The PCLK should

not be set before the PLL is locked.

13.4

PLL CLOCK FREQUENCY

When the PLL is in lock, the VCO output frequency is given by:

The VCO output frequency is further divided by a frequency divider circuit to give

three other frequencies as shown in Figure 13-1.

PCSR

$000D

READ

PON

PCLK

FREQ1

FREQ0

WRITE

RESET

Fvco = 114 * Fosc

where Fosc = oscillator frequency

Example: Fosc = 32.768kHz, Fvco = 3.604MHz.

68HC05CL48 Datasheet(PDF) 108 Page - Motorola, Inc

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