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P12001-EVAL1 User Guide Rev 1.1 Page 8 of 11

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