Technical information

OPTO DIO Reference Opto DIO48
UDN2984 ULN2804 Driver Selection.________________________________
The card can be configured to use one of two types of
high voltage drive chips ULN2804 or UDN 2984 chips. Chapter
1 explains the difference and function of these two driver types.
The two jumper pins directly below and just to the left of
the driver chips is used to made the selection.
Source Driver Output Connection.______________________________
UDN2984 Drivers.
The UDN2984 chips are high voltage, high current SOURCE
drivers, output voltage range 35 to 80 Volts, these could be
directly replaced by UDN2981 drivers for output voltages in the
range 5 to 50 Volts. Whilst the 2984/81 drivers have built in
output transient suppression diodes, extra diodes are provided on
card the Opto DIO48 card for extra protection. The socketed 10k
resistor networks RN14, 16 and 18 should be left installed.
For normal operation, with UDN2984 chips installed, sockets
U30, U28 and U26 contain non inverting buffers chips 74LS541.
For inverse operation, inverting buffers chips 74LS540 should be
installed in sockets U30, U28 and U26.
Sink Driver Output Connection.____________________________
ULN2804 Drivers.
The ULN2804 chips are high voltage, high current NPN
DARLINGTON drivers, output voltage range to 50 Volts, these
could be directly replaced by ULN2824 chips for output voltages
up to 95 Volts. The 2804 have open collector outputs. When
changing from 2984 to 2804 drivers note than the 2804 are
INVERTING drivers, thus to produce the same logical output
from a bit pattern written to the output port the 74LS541 chips
would have to be replaced by the inverting 74LS540 chips.
Remove the socketed 10k resistor networks RN14, 16 & 18.
For inverse operation, then the non inverting buffers chips
74LS541 should be installed in sockets U30, U28 and U26.
Page 20 Chapter 2