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PI2002-EVAL1 User Guide Rev 1.0 Page 7 of 11

6.0 Hook Up of the Evaluation Board

6.1 OV and UV resistors values are configured for a 3.3 V

input voltage. If you are using the evaluation board in

a different input voltage level you have to adjust the

resistor values by replacing R1, R2, R12 and R13, or

remove R2, R3, R13 and R14 to disable UV and OV.

Please refer to the UV/OV section for details to set R1,

R2, R12 and R13 proper values.

6.2 Verify that the jumpers J5 and J6 are installed for

high gate current [across the two pins at Vin side].

6.3 Connect the positive terminal of PS1 power supply to

Vin1. Connect the ground terminal of PS1 to its local

Gnd. Set the power supply to 3.3 V. Keep PS1 output

disabled (OFF).

6.4 Connect the positive terminal of PS2 power supply to

Vin2. Connect the ground terminal of PS2 to its local

Gnd. Set the power supply to 3.3 V. Keep PS2 output

disabled (OFF).

6.5 Connect the positive terminal of PS3 power supply to

Vaux1 and Vaux2. Connect the ground terminal of this

power supply to Rtn1 and Rtn2. Set the power supply

to 12 V. Keep PS3 output disabled (OFF).

6.6 Connect the electronic load to the output between

Vout and Gnd. Set the load current to 10 A.

6.7 Enable (turn ON) PS1 power supply output.

6.8 Turn on the electronic load.

6.9 Verify that the electronic load input voltage

reading is 0V.

6.10 Enable (turn ON) PS3 power supply output.

6.11 Verify that the electronic load voltage reading is few

millivolts below 3.3 V. This verifies that the MOSFETs

are in conduction mode.

6.12 D1 should be off. This verifies that there is no fault

condition.

6.13 Reduce PS1 output voltage to 2 V,

6.14 D1 should turn on, and the output voltage is 0V, this

verifies that the circuit is in an under-voltage fault

condition and the MOSFETs are turned off.

6.15 Increase PS1 output to 3.3 V, D1 should turn off and

output voltage is 3.3V. Then increase PS1 output to

4 V, D1 should turn on indicating an over-voltage fault

condition and output voltage should go to 0 V

indicating that the MOSFETs are turned off.

6.16 Verify that Vin2 is at 0 V. This verifies that the PI2002

(U2) MOSFETs are off.

6.17 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).

6.18 Enable (turn ON) PS2 output.

6.19 Verify that both PS1 and PS2 are sharing load current

evenly by looking at the supply current.

6.20 Disable (turn OFF) PS1, PS2 and PS3 outputs.

6.21 Enable (turn ON) PS2 output then Enable PS3 output.

6.22 Verify that the electronic load voltage reading is few

millivolts below 3.3 V. This verifies that the MOSFET is

in conduction mode.

6.23 D2 should be off. This verifies that there is no fault

condition.

6.24 Reduce PS2 output voltage to 2 V,

6.25 D2 should turn on, and the output voltage is 0V, this

verifies that the circuit is in an under-voltage fault

condition and the MOSFETs are turned off.

6.26 Increase PS2 output to 3.3 V, D2 should turn off and

output voltage goes back to 3.3V. Then increase PS2

output to 4 V, D2 should turn on indicating an over

voltage fault condition and ouput voltage goes to 0V

indicating that its MOSFETs are off.

6.27 Verify that Vin1 is at 0V. This verifies that the

MOSFETs (Q1 and Q2) are off.

6.28 D1 should be on. This is due to a reverse voltage fault

condition caused by the output voltage being high

with respect to the input voltage (Vin1).

5.4.3. For example, if the minimum Vaux = 22 V and the maximum Vaux = 28 V

Rbias =

=

22 V – 16 V

= 1.429 K

Ω, use 1.43 KΩ 1% resistor

4.2 mA

=

= 137 mW

Rbias

1.43 K

Ω

Note: Minimize the resistor value for low Vaux voltage levels to avoid a voltage drop that may reduce the VC voltage lower than required to

drive the gate of the internal MOSFET.