mc68hc916y3 Freescale Semiconductor, Inc, mc68hc916y3 Datasheet - Page 386

• Manufacturer Part Number: mc68hc916y3
• Description: Mc68hc16y3 16 Bit Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

W — Frequency Control (VCO)
X — Frequency Control (Prescaler)
Y[5:0] — Frequency Control (Counter)
EDIV — E Clock Divide Rate
SLOCK — Synthesizer Lock Flag
STSCIM — Stop Mode SCIM Clock
STEXT — Stop Mode External Clock
D-8
MOTOROLA
With a fast reference frequency between 1 and 6 MHz (typically a 4.194-MHz crystal),
the reference frequency is divided by 128 before it is passed to the PLL system. The
clock frequency is determined by the following equation:
This bit controls a prescaler tap in the synthesizer feedback loop. Setting this bit
increases the VCO speed by a factor of four. VCO relock delay is required.
This bit controls a divide by two prescaler that is not in the synthesizer feedback loop.
Setting the bit doubles clock speed without changing the VCO speed. No VCO relock
delay is required.
The Y field controls the modulus down counter in the synthesizer feedback loop,
causing it to divide by a value of Y + 1. Values range from 0 to 63. VCO relock delay
is required.
The MCU remains in reset until the synthesizer locks, but SLOCK does not indicate
synthesizer lock status until after the user writes to SYNCR.
0 = ECLK frequency is system clock divided by 8.
1 = ECLK frequency is system clock divided by 16.
0 = VCO is enabled, but has not locked.
1 = VCO has locked on the desired frequency or VCO is disabled.
0 = When LPSTOP is executed, the SCIM clock is driven from the external crystal
1 = When LPSTOP is executed, the SCIM clock is driven from the internal VCO.
0 = When LPSTOP is executed, the CLKOUT signal is held negated to conserve
1 = When LPSTOP is executed and EXOFF
oscillator and the VCO is turned off to conserve power.
power.
is driven from the SCIM2 clock, as determined by the state of the STSCIM bit.
Freescale Semiconductor, Inc.
For More Information On This Product,
f
sys
Go to: www.freescale.com
REGISTER SUMMARY
=
--------- - 4 Y
128
f
ref
+
1
2
1 in SCIMCR, the CLKOUT signal
2W
+
X
MC68HC16Y3/916Y3
USER’S MANUAL