Clocks and Power Control
MPC561/MPC563 Reference Manual, Rev. 1.2
Freescale Semiconductor
8-25
Figure 8-12. External Power Supply Scheme
The MPC561/MPC563 asserts the TEXP signal, if enabled, when the RTC or TB time value matches the
value programmed in the associated alarm register or when the PIT or DEC value reaches zero. The TEXP
signal is negated when the TEXPS status bit is written to one.
The KAPWR power supply feeds the main crystal oscillator (OSCM). The condition for the main crystal
oscillator stability is that the power supply value changes slowly. The maximum slope must be less than 5
mV per oscillation cycle (
τ
> 200-300/freq
oscm
).
8.8.3.2
Keep-Alive Power Registers Lock Mechanism
The USIU timer, clocks, reset, power, decrementer, and time base registers are powered by the KAPWR
supply. When the main power supply is disconnected after power-down mode is entered, the value stored
in any of these registers is preserved. If power-down mode is not entered before power disconnect, there
is a chance of data loss in these registers. To minimize the possibility of data loss, the MPC561/MPC563
includes a key mechanism that ensures data retention as long as a register is locked. While a register is
locked, writes to this register are ignored.
Each of the registers in the KAPWR region have a key that can be in one of two states: open or locked. At
power-on reset the following keys are locked by default: RTC, RTSEC, RTCAL, and RTCSC. All other
registers are unlocked. Each key has an address associated with it in the internal map.
Main Power
Backup
VDDSYN
2.6 V
VDD
KAPWR
Supply
Switch
Logic
TEXP
2.6-V
SW1
SW2
Power
Supply
IRAMSTBY
Power Supply
IRAMSTBY
O
O
O
O
MPC561/MPC563
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...