MB90540/540G/545/545G Series
(6) Pull-up/down resistors
The MB90540/545 Series does not support internal pull-up/down resistors (except Port0 − Port3 : pull-up resis-
tors) . Use external components where needed.
(7) Crystal Oscillator Circuit
Noises around X0 or X1 pins may be possible causes of abnormal operations. Make sure to provide bypass
capacitors via the shortest distances from X0, X1 pins, crystal oscillator (or ceramic resonator) and ground lines,
and make sure, to the utmost effort, that lines of oscillation circuits do not cross the lines of other circuits.
It is highly recommended to provide a printed circuit board artwork surrounding X0 and X1 pins with a ground
area for stabilizing the operation.
(8) Turning-on Sequence of Power Supply to A/D Converter and Analog Inputs
Make sure to turn on the A/D converter power supply (AVCC, AVRH, AVRL) and analog inputs (AN0 to AN7) after
turning-on the digital power supply (VCC) .
Turn-off the digital power after turning off the A/D converter supply and analog inputs. In this case, make sure
that the voltage does not exceed AVRH or AVCC (turning on/off the analog and digital power supplies simulta-
neously is acceptable) .
(9) Connection of Unused Pins of A/D Converter
Connect unused pins of A/D converter to AVCC = VCC, AVSS = AVRH = VSS.
(10) N.C. Pin
The N.C. (internally connected) pin must be opened for use.
(11) Notes on Energization
To prevent the internal regulator circuit from malfunctioning, set the voltage rise time during energization at
50 µs or more (0.2 V to 2.7 V) .
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