PI2001-EVAL1 Datasheet, PDF (8/11 Pages) Vicor Corporation – PI2001-EVAL1 Active ORing

6.9 Enable (turn on) PS1 output:
6.10 Verify that the electronic load input voltage reading is
a few millivolts below 3.3 V and PS1 and PS2 are
sharing the load current evenly. This verifies that both
MOSFET's, Q1 and Q2, are in conduction mode.
7.0 Input short circuit test
7.1 To emulate a real application, the BUS supplies for this
test should have a solid output source such as 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 PI2001 will be used.
7.2 Stray parasitic inductance in the circuit can contribute
to significant voltage transient conditions, particularly
when the MOSFET is turned-off after a reverse current
fault has been detected. When a short is applied at
the output of the input power sources and the .
evaluation board input (Vin), a large reverse current is
sourced from the evaluation board output through
the ORing MOSFET. The reverse current in the MOSFET
may reach over 60 A in some conditions before the
MOSFET is turned off. Such high current conditions
will store high energy even in a small parasitic
element, and can be represented as ½ Li2. A 1 nH
parasitic inductance with 60 A reverse current will
generate 1.8 µJ. When the MOSFET is turned off, the
stored energy will be released and will produce a high
negative voltage at the MOSFET source and high
positive voltage at the MOSFET drain. This event will
create a high voltage difference across the drain and
source of the MOSFET.
7.3 Apply a short at one of the inputs (Vin1 or Vin2) when
the evaluation board is configured with both
controllers (U1 and U2) in master mode. The short can
be applied electronically using a MOSFET connected
between Vin and Gnd or simply by connecting Vin to
Gnd. Then measure the response time between when
the short is applied and the MOSFET is disconnected
(or turned off). An example for PI2001 response time
to an input short circuit is shown in Figure 6.
Figure 6 – Plot of PI2001 response time to reverse current detection
Picor Corporation • www.picorpower.com
P12001-EVAL1 User Guide Rev 1.1 Page 8 of 11