Vicor PI2007-EVAL1 48V Bus High Side Active ORing Evaluation Board - Manual (Page 7)

Picor Corporation • picorpower.com PI2007-EVAL1 User Guide Rev. 1.1 Page 7 of 10
4.9. Verify that Vin2 is low. This verifies that the Q2
MOSFET is off.
4.10. D2 should be on. This is due to a reverse
voltage fault condition caused by the bus
voltage being high with respect to the input
voltage (Vin2).
4.11. Enable (turn on) PS2 output.
4.12. Verify that both PS1 and PS2 are sharing load
current evenly by looking at the supply current.
Power supplies output may need adjustment to
set current sharing between the supplies.
4.13. Disable (turn off) PS1, PS2, and PS3 outputs.
4.14. Enable (turn on) PS2 output then Enable PS3
outputs.
4.15. Verify that the electronic load voltage reading is
few millivolts below 48V. This verifies that the
MOSFET is in conduction mode.
4.16. D2 should be off. This verifies that there is no
fault condition.
4.17. Verify that Vin1 is low. This verifies that the
MOSFET Q1 is off.
4.18. D1 should be on. This is due to a reverse
voltage fault condition caused by the bus
voltage being high with respect to the input
voltage (Vin1).
5. Input short circuit test:
PI2007 has a very fast response (80ns) to a reverse
current (Input short) fault condition. Measuring a short
period event requires attention to the test set-up. Before
proceeding, consider the following:
5.1. To emulate a real application, the BUS supplies
for this test should have a solid output source
such as a DC-DC converter that supplies high
current and can be connected very close to the
evaluation board to reduce stray parasitic
inductance, or use the prospective supply
sources of the end application where the PI2007
will be used. Typical bench power supplies have
slow response to output load change. In this test
when the power supply output is shorted and
then released, the bench power supply may
produce high output voltage with high current
capability that may damage the device under
test.
5.2. Do not install Input capacitors (C1 and/or C2) in
this test.
5.3. Output capacitor (C7) should be installed.
5.4. Place the scope probes very close to the MOSFET
drain and source to measure Vout and Vin, and
make sure that the scope ground leads are very
short. You may use a close by ground pad for the
scope probe return, such as C1, C2, C3 and C4
Rtn pads.
5.5. Apply a short at one of the inputs (Vin1 or Vin2)
when both controllers (U1 and U2) are on, PS1
and PS2 are enabled. The short can be applied
electronically using a MOSFET connected
between Vin and Rtn or simply by connecting Vin
to Rtn. Then measure the response time
between when the short being applied and the
MOSFET being disconnected (or turned off). An
example for PI2007 response time to an input
short circuit is shown in Figure 4.