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MB90560 series
CHAPTER 1 OVERVIEW
21
G
Notes on external clock
When an external clock is used, the oscillation stabilization wait time is required at power-on
reset or at cancellation of stop mode. As shown in Figure 1.8-1, when an external clock is
used, connect only the X0 pin and leave the X1 pin open.
Figure 1.8-1 Sample connection of external clock
G
Power supply pins
When a device has two or more Vcc or Vss pins, the pins that should have equal potential
are connected within the device in order to prevent a latchup or other malfunction. To reduce
extraneous emission, to prevent a malfunction of the strobe signal due to an increase in the
group level, and to maintain the local output current rating, connect all these power supply
pins to an external power supply and ground them.
The current source should be connected to the Vcc and Vss pins of the device with minimum
impedance. It is recommended that a bypass capacitor of about 0.1
μ
F be connected near
the terminals between Vcc and Vss.
G
Analog power-on sequence of A/D converter
The power to the A/D converter (AVcc, AVRH, AVRL) and analog inputs (AN0 to AN7) must
be turned on after the power to the digital circuits (Vcc) is turned on. When turning off the
power, turn off the power to the digital circuits (Vcc) after turning off the power to the A/D
converter and analog inputs. When the power is turned on or off, AVR should not exceed
AVcc. Also, when a pin that is used for analog input is also used as an input port, the input
voltage should not exceed AVcc. (The power to the analog circuits and the power to the
digital circuits can be simultaneously turned on or off.)
X0
X1
OPEN
MB90560 Series