Data Translation DT9820 Series, User Manual

Page: 90 / 112

Appendix A
78
Table 9 lists the specifications for the digital input subsystem.
Table 9: DIN Subsystem Specifications
Feature Specifications
Number of lines 8 (Port A)
a
a. A high to low transition on digital input lines 0 to 3 interrupts the
module to start A/D conversions, where line 0 corresponds to A/D
channel 0, line 1 corresponds to A/D channel 1, line 2 corresponds
to A/D channel 2, and line 3 corresponds to A/D channel 3.
A low to high transition on digital input lines 4 to 7 interrupts the
module to stop A/D conversions, where line 4 corresponds to A/D
channel 0, line 5 corresponds to A/D channel 1, line 6 corresponds
to A/D channel 2, and line 7 corresponds to A/D channel 3.
Termination 22 k
Ω
Pullup to +5V_I
b
b. You can drive the +5V_I isolated output pin from an external power
supply. This will allow the last digital output value to be latched to
the input stage; therefore, if the power is reduced by the host, the
digital output values will not change. Current requirements are 1
mA plus load.
Inputs
Input type:
Input load:
High-level input voltage:
Low-level input voltage:
High-level input current:
Low-level input current:
Level sensitive
1 (HCT)
2.0 V minimum
0.8 V maximum
3
µ
A
−
3
µ
A
Back EMF diodes No