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A very large spurious signal is observed on the logic output! If the impedance of the
logic output is reduced by adding a 1 kilohm pull-up resistor (R2 on the sample
daughterboards) to VCC2 = +5V, a smaller transient of shorter duration is observed:
Top: +1.5 kV HV pulse
Bottom: Logic out into open circuit
no DUT, R2 = 1kΩ, 100 ns/div
Top: -1.5 kV HV pulse
Bottom: Logic out into open circuit
no DUT, R2 = 1kΩ, 100 ns/div
In the above waveform photos, both channels of the oscilloscope are used
simultaneously. To eliminate the possibility of oscilloscope inter-channel interference, it
is better to record the HV pulse (typically using the oscilloscope “REF” storage
function), then full disconnect the HV probe from the HV signal, and then observe the
logic output. If this is done, the logic signal in last two images become much cleaner:
Top: +1.5 kV HV pulse
Bottom: Logic out into open circuit
no DUT, R2 = 1kΩ, 100 ns/div
Top: -1.5 kV HV pulse
Bottom: Logic out into open circuit
no DUT, R2 = 1kΩ, 100 ns/div
It becomes clear that both effects (capacitive coupling on the daughterboard, and in the
oscilloscope) are important. The oscilloscope portion is easily eliminated, at least.
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Содержание AVRQ-5-B
Страница 52: ...Bottom side 52 ...
Страница 56: ...Top side Bottom side A P6246 differential probe was used to observe the logic outputs in the TLP2366 tests 56 ...
Страница 57: ...PCB 299B FOR ADUM241E0BRWZ 57 ...
Страница 82: ...PCB 158R2 LOW VOLTAGE POWER SUPPLY ...
Страница 87: ...DUT WIRING ON STANDARD DAUGHTERBOARD PCB 267C ...
Страница 88: ...DUT WIRING ON CUSTOMIZED TLP2366 DAUGHTERBOARD PCB 298B ...
Страница 89: ...DUT WIRING ON CUSTOMIZED ADUM241E0BRWZ DAUGHTERBOARD PCB 299B ...
Страница 91: ...PERFORMANCE CHECK SHEET 91 ...