66-MHz Electrical Characteristics
MPC561/MPC563 Reference Manual, Rev. 1.2
G-18
Freescale Semiconductor
G.10.2
Keep-Alive RAM
PORESET or HRESET must be asserted during power-down prior to any supply dropping out of specified
operating conditions.
An additional constraint is placed on PORESET assertion since it is an asynchronous input. To assure that
the assertion of PORESET does not potentially cause stores to keep-alive RAM to be corrupted (store
single or store multiple) or non-coherent (store multiple), either of the following solutions is
recommended:
•
Assert HRESET at least 0.5
µ
s prior to when PORESET is asserted.
•
Assert IRQ0 (non-maskable interrupt) at least 0.5 µs prior to when PORESET is asserted. The
service routine for IRQ0 should not perform any writes to keep-alive RAM.
The amount of delay that should be added to PORESET assertion is dependent upon the frequency of
operation and the maximum number of store multiples executed that are required to be coherent. If store
multiples of more than 28 registers are needed and if the frequency of operation is lower that 66 MHz, the
delay added to PORESET assertion will need to be greater than 0.5 µs. In addition, if KAPWR features
are being used, PORESET should not be driven low while the V
DDH
and V
DDL
supplies are off.
G.11 AC Timing
displays generic examples of MPC561/MPC563 timing. Specific timing diagrams are shown
in
through
.
Summary of Contents for MPC561
Page 84: ...MPC561 MPC563 Reference Manual Rev 1 2 lxxxiv Freescale Semiconductor...
Page 144: ...Signal Descriptions MPC561 MPC563 Reference Manual Rev 1 2 2 46 Freescale Semiconductor...
Page 206: ...Central Processing Unit MPC561 MPC563 Reference Manual Rev 1 2 3 62 Freescale Semiconductor...
Page 302: ...Reset MPC561 MPC563 Reference Manual Rev 1 2 7 14 Freescale Semiconductor...
Page 854: ...Time Processor Unit 3 MPC561 MPC563 Reference Manual Rev 1 2 19 24 Freescale Semiconductor...
Page 968: ...Development Support MPC561 MPC563 Reference Manual Rev 1 2 23 54 Freescale Semiconductor...
Page 1144: ...Internal Memory Map MPC561 MPC563 Reference Manual Rev 1 2 B 34 Freescale Semiconductor...
Page 1212: ...TPU3 ROM Functions MPC561 MPC563 Reference Manual Rev 1 2 D 60 Freescale Semiconductor...
Page 1216: ...Memory Access Timing MPC561 MPC563 Reference Manual Rev 1 2 E 4 Freescale Semiconductor...