Picor Corporation • www.picorpower.com
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 =
Vaux
min
– VC
clampMAX
=
22 V – 16 V
= 1.429 K
Ω
, use 1.43 K
Ω
1% resistor
IC
max
4.2 mA
Pd
Rbias
=
(Vaux
max
– VC
clampMIN)2
=
(28 V – 14.0 V)
2
= 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.
