25VT6A5VGEVB
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5
TEST SET UP AND PROCEDURE
Test Setup
The test set up, test points and components present on the
25VT6A5VGEVB Evaluation Board are shown in Figure 4.
The MOSFET parts placed on the evaluation board are the Q1
and Q4 (Refer to Figure 1).
Figure 4. Schematic of the Test Setup
Start up and Shut down Procedures
Before starting the test, the oscilloscope probes should be
connected. IR or k
−
type thermo
−
couples can be used to
monitor the temperature of the parts. IR monitoring requires
the removal of the oscilloscope probes due to the IR beam
interference.
Start up Procedure (VOUT 0.8 V
−
1.56 V):
1. Initially set all the power supplies to 0 V.
2. Set the output voltage to the desired value by
changing the VID settings on SW2 (see
Appendix). The SW2 must be changed while the
driver and controller are off.
3. Set the driver voltage and controller voltage to 5 V.
4. Set the input voltage to the desired value
(8 V – 16 V).
5. V
OUT
Adjustments: the output voltage may be
fine
−
tuned at this time, by adjusting the R60
potentiometer.
6. Set the load current to required value. The load
current must be incremented slowly to prevent the
controller from shutting down due to transient
spikes on the inductor current sense lines (CS1,
CS2 in Figure 2). If the controller shuts down,
there are two different methods that can be used to
reset the controller. The first method is to toggle
Pin 8 (EN) of the Grayhill switch (SW2) to 0
(down position) and then back to 1 (up position).
The second method is to set VIN to 0 V and then
back up to the desired voltage, then turned on and
Vin re
−
established.
Start up Procedure (VOUT 1.56 V
−
1.8 V):
1. Initially set all the power supplies to 0 V.
2. Set the output voltage to 1.56 V by changing the
VID settings on SW2 (see Appendix). The SW2
must be changed while the driver and controller
are off.
3. Set the driver voltage and controller voltage to 5 V.
4. Set the input voltage to the desired value
(8 V – 16 V).
5. Adjust the output voltage using the R60
potentiometer until the desired output voltage is
reached (1.8 V maximum).
6. Set the load current to required value. The load
current must be incremented slowly to prevent the
controller from shutting down due to transient
spikes on the inductor current sense lines (CS1,
CS2 in Figure 2). If the controller shuts down,
there are two different methods that can be used to
