Teknor Industrial Computers VIPer 821 Technical Reference Manual page 40

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The Power Fail Detection feature can be used to monitor a power fail condition that could
be initiated by either the onboard battery or an external power source (W10 jumper).
SETUPS
Related Jumpers
Refer to W11 Power Fail jumper to select the power source to be controlled.
BIOS Level
No setting required.
OPERATION
The power fail status is available through the bit 0 of the Supervisor Register x91h
The bit is trigged from High to Low when the power source that is controlled drops below a
threshold:
. 3.08V, when the onboard battery voltage is controlled
. A user-defined value when an external battery placed under the control of the board.
The user-defined threshold is determined by a resistor divider, made up of R132
(1Kohm) and R18 to be installed by the user. Use the following formula to calculate the
value of R18: R18 = 1Kohm . (Vext –1.25)/1.25
Use the J11 (pin 6) Power connector to connect an external battery to the board.
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