TC1775 Datasheet, PDF (66/101 Pages) Infineon Technologies AG – 32-Bit Single-Chip Microcontroller

TC1775
Preliminary
Ports Power Supply
The TC1775’s port power supply concept is shown in Figure 21. The ports assigned with
the External Bus Unit (EBU) are in a separate power supply group for 2.5 V nominal
operating voltage. The general purpose input/outputs (GPIOs) except the EBU provide
3.3 to 5 V input/output acceptance and drive characteristics.
V _DDP05
(2.5 V)
V _DDP813
(3.3 - 5 V)
V _SS
Ports 0 to 5
(P a d s)
&
Schmitt Trigger
Ports 8 to 13
(Pads)
&
Schm itt Trigger
V_DD
(2.5 V)
Port Logic
M C A04752
Figure 21 Ports Power Supply Concept
Power-up Sequence
During Power-up the reset pin PORST has to be held active until both power supply
voltages have reached at least their minimum values.
During the Power-up time (rising of the supply voltages from 0 to their regular operating
values) it has to be ensured, that the difference between V_DDP813 and V_DDI (i.e.
V_DDP813 - V_DDI) never drops below -0.3 V (V_DDI = V_DD and V_DDP05).
Power Loss
If V_DDP813 is dropping below V_DDI, external circuitry in the power supply has to ensure,
that V_DDI is also limited to the same level.
If V_DDI is dropping below the operating range, V_DDP813 may stay active.
Powering Down
During powering down (falling of the supply voltages from their regular operating values
to zero), it has to be ensured, that the difference between V_DDP813 and V_DDI
(V_DDP813 - V_DDI) never drops below -0.3 V.
Data Sheet
62
V1.2, 2002-05