Datasheet
NOTE
In these descriptions, star route layout means a track split as
close as possible to the power supply source. Each of the split
tracks is routed individually to the intended end connection.
1.
For both LDO mode and SMPS mode, V
DDPMC
and V
DDPWR
must be connected
together (shorted) to ensure aligned voltage ramping up/down. In addition:
• For SMPS mode, a star route layout of the power track is required to minimize
mutual noise. If SMPS mode is not used, the star route layout is not required.
V
DDPWR
is the supply pin for the SMPS circuitry.
• For 3.3 V operation, V
DDFLA
must also be star routed and shorted to V
DDPWR
and V
DDPMC
. This triple connection is required because 3.3 V does not guarantee
correct functionality of the internal V
DDFLA
regulator. Consequently, V
DDFLA
is
supplied externally.
2. V
DDA_MISC
: IRC operation is required to provide the clock for chip startup.
• The V
DDPMC
, V
DD
, and V
DDEH1
(reset pin pad segment) supplies are monitored.
They hold IRC until all of them reach operational voltage. In other words,
V
DDA_MISC
must reach its specified minimum operating voltage before or at the
same time that all of these monitored voltages reach their respective specified
minimum voltages.
• An alternative is to connect the same supply voltage to both V
DDEH1
and
V
DDA_MISC
. This alternative approach requires a star route layout to minimize
mutual noise.
3. Multiple V
DDEx
supplies can be powered up in any order.
During any time when V
DD
is powered up but V
DDEx
is not yet powered up: pad
outputs are unpowered.
During any time when V
DDEx
is powered up before all other supplies: all pad output
buffers are tristated.
4. Ramp up V
DDA_EQ
before V
DD
. Otherwise, a reset might occur.
5. When the device is powering down while using the internal SMPS regulator,
V
DDPMC
and V
DDPWR
supplies must ramp down through the voltage range from 2.5
V to 1.5 V in less than 1 second. Slower ramp-down times might result in reduced
lifetime reliability of the device.
Electrical characteristics
MPC5777C Microcontroller Data Sheet Data Sheet, Rev. 13, 08/2018.
NXP Semiconductors 47