B. Specifications
117
Battery Backup Characteristics
Battery Voltage:
3 V
Battery Capacity:
255 mAH
Real-time
clock
requirements:
5 µA maximum (when Vcc is below acceptable
operating limits)
Real-time clock data retention:
5 years minimum, 10 years typical
Electrochemical Construction:
Poly-carbonmonofluoride
STD-80 Compatibility
The ZT 8904 is designed for use in an
STD 32 backplane environment. While designed
to be backward compatible with STD-80 systems, the ZT 8904 is not guaranteed to
work in all system topologies.
STD Bus Loading Characteristics
The unit load is a convenient method for specifying the input and output drive capability
of STD bus cards. With this method, one unit load is equal to one LSTTL load as
follows:
•
Current for single input load: 20 µA
•
Current for single output drive:-400 µA
The unit load reflects current requirements at worst case conditions over the
recommended supply voltage and operating temperature ranges. An output drive of
60 unit loads drives 60 STD bus cards having input ratings of one unit load. The table
"
STD Bus Signal Loading, P Connector
" includes load values for STD-80 connections.
The "
STD Bus Signal Loading, E Connector
" table includes load values for STD 32
connections.
