MB91F528 datasheet(55/241 Pages) SPANSION

55 / 241 page

D a t a S h e e t

MB91F528_DS705-00016-1v0-E, March 28, 2014

CONFIDENTIAL

 HANDLING DEVICES

This section explains the latch-up prevention and pin processing.

 For latch-up prevention

If a voltage higher than VCC (VCCE in case of terminal corresponding to VCCE power supply.) or a voltage

lower than VSS is applied to an I/O pin, or if a voltage exceeding the ratings is applied between VCC and VSS

pins or VCCE and VSS pins, a latch-up may occur in CMOS IC. If the latch-up occurs, the power supply

current increases excessively and device elements may be damaged by heat. Take care to prevent any

voltage from exceeding the maximum ratings in device application.

Also, the analog power supply (AVCC, AVRH), analog input and digital power supply (VCCE) must not be

exceed the digital power supply (VCC) when the power supply to the analog system and digital power

supply (VCCE) are turned on or off.

In the correct power-on sequence of the microcontroller, turn on the digital power supply (VCC), analog

power supplies (AVCC, AVRH) and digital power supply (VCCE) simultaneously. Or, turn on the digital

power supply (VCC), and then turn on analog power supplies (AVCC, AVRH) and digital power supply

(VCCE).

 Treatment of unused pins

If unused input pins are left open, they may cause a permanent damage to the device due to malfunction or

latch-up. Connect at least a 2kΩ resistor to each of the unused pins for pull-up or pull-down processing.

Also, if I/O pins are not used, they must be set to the output state for releasing or they must be set to the

input state and treated in the same way as for the input pins.

 Power supply pins

The device is designed to ensure that if the device contains multiple VCC or VSS pins, the pins that should be

at the same potential are interconnected to prevent latch-up or other malfunctions. Further, connect these

pins to an external power supply or ground to reduce unwanted radiation, prevent strobe signals from

malfunctioning due to a raised ground level, and fulfill the total output current standard, etc. As shown in

figure 1, all Vss power supply pins must be treated in the similar way. If multiple Vcc or Vss systems are

connected, the device cannot operate correctly even within the guaranteed operating range.

Figure 1 Power Supply Input Pins

The power supply pins should be connected to VCC and VSS pins of this device at the low impedance from

the power supply source.

In the area close to this device, a ceramic capacitor having the capacitance larger than the capacitor of C pin

is recommended to use as a bypass capacitor between VCC and VSS pins.

Vss

Vcc

Vss

Vcc

Vss

Vcc

MB91F528 데이터시트(PDF) 55 Page - SPANSION