Test-Ok eC-test-mate, Hardware Reference Manual

Page: 9 / 35

Copyright © TEST-OK. All Rights Reserved.
9 / 35
Digital Outputs (Group 101 and 102)
For optimal flexibility, the digital outputs are separated into two groups. The output voltage corresponding to
a '1' can be programmed separately for group 101. Group 102 has open drain outputs meaning that
'configuration' of the '1' output level must be done via an external pull-up resistor if necessary.
All outputs are switched off when communication is lost with the PC.
Group 101
Specifications: V
outH
= 2.5..24V,
V
outL
= 0V
I
source
max = 40mA, Isink Max 20mA,
R
out
= 100Ω
Group 101, is protected against short circuit by means of a 100Ω series resistor. Clamping diodes protect
the outputs against voltages above 25V and below 0V if such voltages were inadvertently applied to the
outputs.
Note: the internal 100R resistor can only dissipate 100mW. E.g. when the output is programmed for 5V and
24V is applied on the corresponding EC-test-mate pin, then there will be a voltage of 18.5V across the 100R
resistor which would result in 3.4W dissipation!
Note: besides the maximum current, there is also a limit on dissipated power by the outputs. The total
power dissipated by bits 1..4 shall not exceed 500mW
Note: the configured output voltage of Group 101 is also used to determine the logic '1' output level of the
serial channel as long as the voltage is less or equal to 5V (above this voltage, the serial output is fixed to
5V independently of the Group 101 voltage)
Note: the outputs of group 101 are not rail-to-rail (LM324) and special care must be taken when the outputs
must sink a pull-up on the UUT. If the load to be sinked is less than 10kΩ, then an offset voltage will be
present on the output. As an example, if a 1KΩ pull-up to 5V is connected to an output, then the output
voltage will not go lower than 1.4V!!
Group 102
Group 102 consists of four 'open drain' outputs, pulling the output to GND via a 330R series resistor. The