PGA26E07BA-SWEVB008 Ver. 1.2
17
2) Switching Loss
Initial steps:
Do all the necessary connection between the evaluation board, components and equipment.
Connect DC power
①
to VPN and VS of the board with the screw terminal block.
Connect dead time circuit to the IN_H, IN_L, VDD, EN and GND terminal of the board. The loss test is
done in boost mode (low side test). Therefore, Inductor is connected from VPN to LX.
The VDD voltage must be the same as the Isolator VDD voltage. Fix the dead time to 100ns.
Connect the dead time generator to a pulse generator.
Probe the point where you want to monitor and observe the waveform using oscilloscope.
Be careful not to short with other parts. Use the coil wire fixture mounted on the evaluation board for V
DS
and IL monitoring.
Use the semi-rigid to monitor V
RS
waveform. Use the Math Function on the oscilloscope to get
I
DS
waveform. I
DS
= V
RS
/RS. RS
is 47mΩ as shown in the BOM List (page 9).
Use the math function on oscilloscope to find the multiplication of V
DS
and I
DS
, then use the
measure function on the oscilloscope to find the area under the curve (power loss). See Figure 16.
Figure 16: Power Loss measurement waveform
Start-up:
Set up the Dead time generator circuit with the amplitude 0-5V and having the double pulse profile as
shown in the Figure 13.
Again, ensure that the pulse generated occurs only in the burst mode. If the pulse is generated
continuously, the transistor will be damaged by high current flows.
Set the DC power
②
to 5V gradually. Set the DC power
③
to 12V gradually.
Check V
GS
waveform when a double pulse is inputted from pulse generator. Please carry out this step
with DC power
①
is set to 0V.
Then, the voltage of DC power
①
is gradually increased from 0V to predetermined voltage (400V).
Monitor the V
DS
voltage with oscilloscope and confirm that the V
DS
voltage rises to the set value.
Input a double pulse with the pulse generator again and check the V
GS
, V
DS
, I
DS
and power loss (area
under the curve for multiplication of V
DS
and I
DS
) waveform.
Observation of waveform will be easier if the trigger is applied at the rising / falling edge of V
GS
or V
DS
as
shown on Figure 16 above.
If different inductor value is used other than the one provided, please set the pulse width until the desired
IL value is achieved.
Shutdown:
Set the DC power
①
slowly to 0V and then follow by the DC power
②
and
③
to 0V.
Turn off the power. Check the V
DS
waveform and ensure that the capacitor between VPN and VS terminals
has fully discharged. There is risk of electric shock due to the residual charge.
QA V
DS
QA I
DS
Power Loss
(Turn On)
