MSM80C88A-10RS Ver la hoja de datos (PDF) - Oki Electric Industry

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Fabricante

MSM80C88A-10RS

8-Bit CMOS MICROPROCESSOR

Oki Electric Industry 

¡ Semiconductor

MSM80C88A-10RS/GS/JS

BUS HOLD CIRCUITRY

To avoid high current conditions caused by floating inputs to CMOS devices, and to eliminate

the need for pull-up/down resistors, “bus-hold” circuitry has been used on MSM80C88A-10

pins 2-16, 26-32, and 34-39 (Figures 6a, 6b). These circuits will maintain the last valid logic state

if no driving source is present (i.e. an unconnected pin or a driving source which goes to a high

impedance state). To overdrive the “bus hold” circuits, an external driver must be capable of

supplying approximately 400 mA minimum sink or source current at valid input voltage levels.

Since this “bus hold” circuitry is active and not a “resistive” type element, the associated power

supply current is negligible and power dissipation is significantly reduced when compared to

the use of passive pull-up resistors.

"Pull-Up/Pull-Down"

Output

Driver

Bond External

Pad Pin

Input

Buffer

Input

Protection

Circuitry

Input Buffer exists only on I/O pins

Figure 6a. Bus Hold Circuitry Pin 2-16, 35-39

"Pull-Up"

Output

Driver

PCC

P

Bond External

Pad Pin

Input

Buffer

Input

Protection

Circuitry

Input Buffer exists only on I/O pins

Figure 6b. Bus Hold Circuit Pin 26-32, 34

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