MPC555 / MPC556
ELECTRICAL CHARACTERISTICS
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
G-59
G.21 MIOS Timing Characteristics
All MIOS output pins are slew rate controlled. Slew rate control circuitry adds 90 ns as
minimum to the output timing and 650 ns as a maximum. This slew rate is from 10%
V
DDH
to 90% V
DDH
, an additional 100 ns should be added for total 0 to V
DDH
slew rate.
Figure G-34 MCPSM Enable to vs_pclk Pulse Timing Diagram
Table G-21 MCPSM Timing Characteristics
Characteristic
Symbol
Delay
Unit
MCPSM Enable to vs_pclk Pulse
1
NOTES:
1. The MCPSM clock prescaler value (MCPSMSCR_PSL[3:0]) should be written to the MCPSMSCR (MCPSM sta-
tus/control register) before rewriting the MCPSMSCR to set the enable bit (MCPSMSCR_PREN). If this is not
done the prescaler will start with the old value in the MCPSMSCR_PSL[3:0] before reloading the new value into
the counter.
vs_pclk is the MIOS prescaler clock which is distributed to all the counter (e.g., MPWMSM and MMCSM) submod-
ules.
t
CPSMC
(MCPSMSCR_PSL[3:0]) -1
2
2. After reset MCPSMSCR_PSL[3:0] is set to 0b0000.
IMB Clock
Cycles
f
SYS
bit (PREN)
MIOB vs_pclk
t
CPSMC
Prescaler enable
Note 1: f
SYS
is the internal system clock for the IMB3 bus.
Note 2: The numbers associated with the f
SYS
ticks refer to the IMB3 internal state.
Note 3: vs_pclk is the MIOS prescaler clock which is distributed around the MIOS to counter modules such as the
MMCSM and MPWMSM.
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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