S1C63808 TECHNICAL MANUAL
EPSON
147
APPENDIX PERIPHERAL CIRCUIT BOARDS FOR S1C63808
A.4 Usage Precautions
To ensure correct use of the peripheral circuit board, please observe the following precautions.
A.4.1 Operational precautions
(1) Before inserting or removing cables, turn off power to all pieces of connected equipment.
(2) Do not turn on power or load mask option data if all of the input ports (K00–K03) are held low. Doing
so may activate the multiple key entry reset function.
(3) Before debugging, always be sure to load mask option data.
A.4.2 Differences with the actual IC
(1) Differences in I/O
<Interface power supply>
S5U1C63000P1 and target system interface voltage is set to +3.3 V. To obtain the same interface
voltage as in the actual IC, attach a level shifter circuit, etc. on the target system side to accommodate
the required interface voltage.
<Each output port’s drive capability>
The drive capability of each output port on S5U1C63000P1 is higher than that of the actual IC. When
designing application system and software, refer to Chapter 7, "Electrical Characteristics", to confirm
each output port’s drive capability.
<Each port’s protective diode>
All I/O ports incorporate a protective diode for VDD and VSS, and the interface signals between
S5U1C63000P1 and the target system are set to +3.3 V. Therefore, S5U1C63000P1 and the target system
cannot be interfaced with voltages exceeding VDD by setting the output ports for open-drain mode.
<Pull-down resistance value>
The pull-down resistance values on S5U1C63000P1 are set to 220 k
which differ from those for the
actual IC. For the resistance values on the actual IC, refer to Chapter 7, "Electrical Characteristics".
Note that when using pull-down resistors to pull the input pins low, the input pins may require a
certain period to reach a valid low level. Exercise caution if a key matrix circuit is configured using a
combination of output and input ports, since fall delay times on these input ports differ from those of
the actual IC.
(2) Differences in current consumption
The amount of current consumed by the peripheral circuit boards differ significantly from that of the
actual IC. Inspecting the LEDs on S5U1C63000P1 may help you keep track of approximate current
consumption. The following factors/components greatly affect device current consumption:
<Those which can be verified by LEDs and monitor pins>
a) Run and Halt execution ratio (verified by LEDs and monitor pins on the ICE)
b) OSC3 oscillation on/off (OSCC)
c) CPU clock select (CLKCHG)
d) SVD circuit on/off (SVDON)
e) EPD system voltage circuit on/off (LPWR)
<Those that can only be counteracted by system or software>
f) Current consumed by the internal pull-down resistors
g) Input ports in a floating state