Application Examples
System Requirements
The following example assumes a ZT 8809A configured with the
factory default jumper assignments, with the following exceptions.
1.
If detecting AC power failure:
•
wire-wrap jumper W1 as if installed, and continue the wire
to attach to W46B
•
if a ZT 8844 EGA video board is installed in the system,
be sure to disable AutoSwitch by removing W5 and SW5
(since AutoSwitch takes over the NMI vector)
2.
If detecting system battery failure (not the on-board battery):
•
change the resistor divider network R1 and R2 according
to the equation
V
Sense
=
R1 + R2
x 2.15 V
R1
where: V
Sense
= battery voltage minimum allowed
Note: R1 is a variable 10 k
Ω
resistor, so use a nominal
value of 5 k
Ω
(variable from 0 to 10 k
Ω
)
4-29
