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CUSTOM DAUGHTERBOARDS
The daughterboards provided with the AVRQ-5-B are meant as samples.
The user may construct their own daughterboards, which may incorporated a preferred
physical layout, different bias circuits, or different DUT packages and socketing.
When designing your own daughterboard, take care to isolate the input and output
sides as much as possible, to both provide sufficient high-voltage clearance and to
minimize parasitic coupling of the HV pulse onto the output signal.
If the user designs a custom daughterboard, the same connections must be made to
the 32 pins of the daughterboard. That is, pins 3, 7, 12, and 16 on J1 (GND1) must be
shorted together, VCC2 must go to J1:1, GND2 to J1:13-16, and the logic output to J1:8.
The battery occupies a relatively large portion of the top side of the standard
daughterboard. It may be necessary to locate the footprints for large SMT DUTs (e.g., 32-
pin SOICs) on the bottom side of the PCB. It may also be possible to mount the battery
vertically to provide more DUT space on the top side.
Do not use coin batteries to power the floating side of the DUT. They are normally
severely restricted in their output current rating and can not supply the 2-20 mA
typically required to power the floating side of the DUT, regardless of their mA·hr rating.
The A23-style 12V battery has an appropriate combination of voltage output, current
rating, and physical size.
The sample daughterboard uses a simple DIP socket for the DUT, rather than the more
convenient ZIF-style of socket. This is done because ZIF sockets have higher parasitic
capacitance between the various pins, which can be very harmful to the DUT's CMTI
performance. Avoid ZIF sockets for the DUT. (A ZIF socket is used for the
daughterboard installation, but parasitic capacitances there do not degrade the
measured DUT's CMTI.)
DIFFERENTIAL PROBING
The mainframe uses a two-pin header near the DUT area door to transmit the output
waveform to a user-supplied Tektronix P6246 differential probe. The use of a differential
probe helps reduce spurious transient signal artefacts on the oscilloscope, which are
typically caused by ground bounce and interference in general.
When designing custom daughterboards, a similar approach should be used.
Please note that the P6246 has a maximum differential input voltage range of 7V. If higher
values of VCC2 will be used, a different probe will be required. Other probes may be used
by installing a matching two-pin socket as an extender.
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Summary of Contents for AVRQ-5-B
Page 52: ...Bottom side 52 ...
Page 57: ...PCB 299B FOR ADUM241E0BRWZ 57 ...
Page 82: ...PCB 158R2 LOW VOLTAGE POWER SUPPLY ...
Page 87: ...DUT WIRING ON STANDARD DAUGHTERBOARD PCB 267C ...
Page 88: ...DUT WIRING ON CUSTOMIZED TLP2366 DAUGHTERBOARD PCB 298B ...
Page 89: ...DUT WIRING ON CUSTOMIZED ADUM241E0BRWZ DAUGHTERBOARD PCB 299B ...
Page 91: ...PERFORMANCE CHECK SHEET 91 ...