4-276

Application Information

Decoupling Capacitors

The transient current required to charge and discharge the

300pF load capacitance specified in the 82C82 data sheet is

determined by:

Assuming that all outputs change state at the same time and

that dv/dt is constant;

outputs.

This current spike may cause a large negative voltage spike

To filter out this noise, it is recommended that a 0.1

µF

and GND at each device, with placement being as near to

the device as possible.

IC

L

=

(dv/dt)

(EQ. 1)

IC

L

=

(EQ. 2)

V

()

tR/tF

-----------------------------------

(EQ. 3)

I = 8 x 300 x 10

-12

()x (5.0V x 0.8)/ 20 x 10

9

–

() = 480mA

(EQ. 4)

FIGURE 18. SYSTEM EFFECTS OF GATED INPUTS

ADDRESS

ADDRESS

ALE

MULTIPLEXED

ICC

BUS

P

P

N

N

STB

DATA IN

INTERNAL

DATA

P

N

82C82