MB90822 데이터 시트보기 (PDF) - Fujitsu

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MB90822

16-bit Proprietary Microcontroller

Fujitsu 

MB90820 Series

5. Power supply pins (VCC/VSS)

• If there are multiple VCC and VSS pins, from the point of view of device design, pins to be of the same potential

are connected the inside of the device to prevent such malfunctioning as latch up.

To reduce unnecessary radiation, prevent malfunctioning of the strobe signal due to the rise of ground level,

and observe the standard for total output current, be sure to connect the VCC and VSS pins to the power supply

and ground externally.

• Connect VCC and VSS to the device from the current supply source at a low impedance.

• As a measure against power supply noise, connect a capacitor of about 0.1 µF as a bypass capacitor between

VCC and VSS in the vicinity of VCC and VSS pins of the device.

VCC

VSS

VSS

VCC

MB90820

VCC

Series

VSS

VCC

VSS

VCC

VSS

6. Pull-up/pull-down resistors

The MB90820 series does not support internal pull-up/pull-down resistors option (Port 0 to Port 3 : built-in pull-

up resistors) . 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 shortest distance from X0, X1 pins, crystal oscillator (or ceramic oscillator) and ground lines, and

make sure, to the utmost effort, that lines of oscillation circuit do not cross the lines of other circuits while you

design a printed circuit board.

It is highly recommended to provide a printed circuit board art work 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 D/A converter, and analog inputs

Make sure to turn on the A/D converter power supply, D/A converter power supply (AVCC, AVRH, AVR) and analog

inputs (AN0 to AN15) after turning-on the digital power supply (VCC).

Turn-off the digital power after turning off the A/D converter power supply, D/A converter power supply, and

analog inputs. In this case, make sure that the voltage not exceed AVR or AVCC (turning on/off the analog and

digital power supplies simultaneously is acceptable).

9. Connection of unused pins of A/D converter and D/A converter if A/D converter and

D/A converter are unused

Connect unused pins of A/D converter and D/A converter to AVCC = VCC, AVSS = AVRH = AVRL = VSS.

10. 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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