msm80c86a-10js Oki Semiconductor, msm80c86a-10js Datasheet - Page 25

• Manufacturer Part Number: msm80c86a-10js
• Description: 16-bit Cmos Microprocessor
• Manufacturer: Oki Semiconductor

¡ Semiconductor
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 MSM80C86A-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 600 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.
Figure 6a. Bus Hold Circuitry Pin 2-16, 35-39
Figure 6b. Bus Hold Circuitry Pin 26-32, 34
OUTPUT
DRIVER
OUTPUT
DRIVER
BUFFER
Input Buffer exists only on I/O pins
INPUT
BUFFER
Input Buffer exists only on I/O pins
INPUT
V
CC
"PULL-UP/PULL-DOWN"
"PULL-UP"
P
PROTECTION
CIRCUITRY
PROTECTION
CIRCUITRY
INPUT
INPUT
BOND
PAD
BOND
PAD
EXTERNAL
PIN
MSM80C86A-10RS/GS/JS
EXTERNAL
PIN
25/37