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2.1 Device Handling Notes
It is also recommended to connect a ceramic capacitor of about 0.1 F close to the device
between Vcc and Vss as a bypass capacitor.
r Crystal oscillation circuit
Noise near the X0 and X1 pins may cause the device to malfunction. A PC board should be
designed so that the X0 and X1 pins, crystal oscillator (or ceramic oscillator), and bypass
capacitor are as close to the ground as possible.
It is strongly recommended to surround the X0 and X1 pins with a ground because this PC-
board artwork is expected to stabilize operations.
r Treatment of NC pin
The NC pin shall always be open.
r Treatment of mode pins (MD0 to MD2)
Connect these pins directly to Vcc or Vss.
To prevent noise from changing the device to test mode, minimize the pattern length and
impedance between each mode pin and Vcc or Vss on the PC board.
r Power-on
At power-on, always start the RSTX pin from the low level. Change the signal level to high at
least five cycles of the internal operation clock after the power supply reaches the Vcc level.
r Oscillation input at power-on
At power-on, keep clock signal input until the oscillation stabilization wait status is released.
r Hardware standby at power-on
If the power is turned on when the HSTX pin level is low, the device does not enter the standby
status. Although this pin becomes valid after reset, the level should be returned once to high.
r Power-on reset
Be sure to apply power-on reset if power-on fails or the power-supply voltage becomes lower
than the operation guarantee voltage.
r Restrictions on standby status
For the stop or sleep the status, a program should be placed in ROM on the C-bus or in the
address area of external memory. If the program is placed in the ROM address area on the I-
bus, the operation after reset cannot be guaranteed.
r Program execution in I-ROM/RAM area
When executing a program in the I-ROM/RAM area, be sure to enter the area using a JMP-type
instruction. Use a JMP-type instruction also for access from a program in the I-ROM/RAM area
to a different program area.