AVTECH ELECTROSYSTEMS AVRQ-4-B, Instructions Manual

Page: 35 / 75

The circuit diagram in the BASIC TEST ARRANGEMENTS section (page 42) show how
the socket and daughterboard pins mesh, electrically.
STANDARD DAUGHTERBOARD COMPONENTS
The circuit diagram for the included sample daughterboards shown on page 34
includes more that just the socket for the 8-pin DUT.
A battery holder (BT1) is provided to hold one A23-type 12V battery. When installed by
the user, this battery will apply +12V to the regulator IC (U2), which provides a floating
+5.0V power source (VCC1) to the DUT. An A23 battery is supplied with each sample
daughterboard, and additional ones can be easily purchased from Digi-Key (see stock
number N403-ND,
www.digikey.com/product-detail/en/A23C/N403-ND ). The battery is
not required if the DUT does not require a voltage or current bias (for example, when
testing current-drive opto-couplers in the LED “off” state).
A number of bypass capacitors are installed by default.
Two resistor footprints are associated with each of pins 1 – 4 of the DUT, allowing
these pins to be individually tied to VCC1, GND1, or be left open.
Resistor footprints R4 and R6 allow either pin 6 or 7 (or both) of the DUT to be used as
the logic output. R2 can be used to pull-up the DUT output (if it is an open-collector
output, in particular) and C6 can be used to add a load capacitance to the logic output.
These component values are sometimes specified by particular test standards.
35
Align the daughterboard with the front-left pin sockets. (Some
pin sockets are not used in the AVRQ-4-B.)