Clocks and Power Control
MPC885 PowerQUICC Family Reference Manual, Rev. 2
14-16
Freescale Semiconductor
A complete tabulation of modules and power supplies is given in
Table 14-7
.
To assure that the part works correctly, use the following power up and power down instruction sequences.
•
Power-up sequence: The designer should power up the I/O voltage supply (VDDH) first and the
core voltage source (VDDL) next. The VDDH and VDDL voltage supplies maybe raised at the
same time, but in no case, should the core voltage supply (VDDL) be raised before I/O voltage
supply (VDDH).
•
Power-down sequence: The designer should power down the core voltage supply (VDDL) first and
the I/O voltage supply (VDDH) next. They may be powered down together, but in no case, is the
I/O voltage supply (VDDH) to be powered down before core voltage supply (VDDL).
14.4.1
I/O Buffer Power (VDDH)
The I/O buffers are fed by a 3.3-V power supply.
14.4.2
Internal Logic Power (VDDL)
The internal logic are to be fed by the 1.8-V source.
14.4.3
Clock Synthesizer Power (VDDSYN, VSSSYN, VSSSYN1)
To improve stability, the power supply pins for the DPLL are uniquely identified in order to allow special
filtration to be provided for them.
A well-regulated voltage should be applied to VDDSYN via a low-impedance path to the VDDL power
rail. The allowable noise on the VDDSYN power plane is 20 mV peak up to a bandwidth of 100 MHz.
This typically requires isolation of the VDDSYN power plane from the VDDL power plane. An example
implementation of this is a split power plane, with the VDDSYN plane implemented as an island in the
VDDL power plane, connected to the VDDL power plane with an inductor and to the ground plane with
Table 14-7. MPC885
Modules vs. Power Rails
Block
VDDH
VDDL
VDDSYN
I/O Pad
X
X
CLKOUT
X
Digital SPLL
X
Clock Control
X
Internal Logic
X
Clock Drivers
X
Analog DPLL
X
OSCM
X
SCCR, PLPRCR, and RSR
X
PIT, TB, and DEC
X
Summary of Contents for PowerQUICC MPC870
Page 98: ...MPC885 PowerQUICC Family Reference Manual Rev 2 I 4 Freescale Semiconductor ...
Page 118: ...MPC885 Overview MPC885 PowerQUICC Family Reference Manual Rev 2 1 20 Freescale Semiconductor ...
Page 158: ...The MPC8xx Core MPC885 PowerQUICC Family Reference Manual Rev 2 3 18 Freescale Semiconductor ...
Page 288: ...MPC885 PowerQUICC Family Reference Manual Rev 2 III 4 Freescale Semiconductor ...
Page 554: ...MPC885 PowerQUICC Family Reference Manual Rev 2 V 6 Freescale Semiconductor ...
Page 1090: ...UTOPIA Interface MPC885 PowerQUICC Family Reference Manual Rev 2 43 8 Freescale Semiconductor ...
Page 1312: ...Byte Ordering MPC885 PowerQUICC Family Reference Manual Rev 2 A 8 Freescale Semiconductor ...
Page 1336: ...MPC885 PowerQUICC Family Reference Manual Rev 2 D 16 Freescale Semiconductor ...
Page 1358: ...MPC885 PowerQUICC Family Reference Manual Rev 2 D 38 Freescale Semiconductor ...
Page 1370: ...MPC880 MPC885 PowerQUICC Family Reference Manual Rev 2 E 4 Freescale Semiconductor ...
Page 1386: ...Revision History MPC885 PowerQUICC Family Reference Manual Rev 2 I 2 Freescale Semiconductor ...