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4.1 Power Supply
4.1.1 Supply Voltage Connection
The supply voltage should be connected using 2-wire line to the Power clamp
(CO102). Both solid as well as flexible wire can be used. The recommended diameter
is 0.5 to 2.5 mm
Observe polarity (+,-) and voltage range (7..36V)!
The current consumption at a supply voltage of 12 Volts is as follows (without external
load):
• Debug mode: 120 - 150mA
• Standby mode: 20 - 30mA
Additional current is required at startup and during high I/O activity.
4.1.2 Standby
After connecting the external supply voltage, the evaluation board is in standby mode.
Only the SRAMs and the standby power pin of the MPC555 are supplied with power.
The MPC555 is in reset. This mode is shown by the Standby Power LED (LD703,
yellow).
4.1.3 Power On
The toggle switch Power On (SW703) is used for activating the operating voltage of
the EVB555. The activated state is shown by the additional LED Power On (LD702,
green). All modules on the evaluation board are now supplied with power.
4.2 Single Chip/External Bus Mode
The MPC555 can be operated as a single-chip microcontroller or by using the external
bus interface (16-bit or 32-bit wide). The operating mode is set using the "SC" bits in
the SIU module configuration register or in the hard reset configuration word (see
MPC555 Manual).
4.2.1 Single Chip Mode
The external resources on the evaluation board, such as SRAM, flash or port replace-
ment unit (PRU), are not used. The pins, which have a second assignment to the
external bus interface are now available as general purpose I/O pins. The external bus
must be disconnected in this operating mode. Set the DIP switch "ext. Bus" (SW100-
6) to "Off" for this purpose.
EVB555
Quick Reference
SECTION 4
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2
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MOTOROLA
4-15
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