Datasheet

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4.1.5 Other
4.1.5.1 Fan
4.1.5.2 Oscilloscope
4.2 Equipment Setup
4.2.1 Procedure
Test Set Up
This evaluation module includes components that can get hot to the touch, because this EVM is not
enclosed to allow probing of circuit nodes, a small fan capable of between 200 LFM and 400 LFM is
required to reduce component surface temperatures to prevent user injury. The EVM should not be left
unattended while powered or probed while the fan is not running.
A 60 MHz or faster oscilloscope can be used to determine the ripple voltage on 1V5_OUT. The
sscilloscope should be set for 1 M Ω impedance, AC coupling, 1 µ s/division horizontal resolution, 20
mV/division vertical resolution for taking output ripple measurements. TP15 and TP16 can be used to
measure the output ripple voltage by placing the oscilloscope probe tip through TP15 and holding the
ground barrel to TP16 as shown in Figure 3 . For a hands free approach, the loop in TP16 can be cut and
opened to cradle the probe barrel. Using a leaded ground connection may induce additional noise due to
the large ground loop area.
Shown in Figure 3 is the basic test set up recommended to evaluate the TPS40075EVM-001. Note that
although the return for J1 and J2 are the same, the connections should remain separate as shown in
Figure 2 .
1. Working at an ESD workstation, make sure that any wrist straps, bootstraps or mats are connected
referencing the user to earth ground before power is applied to the EVM. Electrostatic smock and
safety glasses should also be worn.
2. Prior to connecting the DC input source, V
12V_IN
, it is advisable to limit the source current from V
12V_IN
to 5.0A maximum. Make sure V
12V_IN
is initially set to 0V and connected as shown in Figure 2.
3. Connect the ammeter A1 (0–5A range) between V
12V_IN
and J1as shown in Figure 2 .
4. Connect voltmeter V1 to TP1 and TP2 as shown in Figure 2 .
5. Connect LOAD1 to J2 as shown in Figure 1 . Set LOAD1 to constant current mode to sink 0Adc before
V
12V_IN
is applied.
6. Connect voltmeter, V2 across TP17 and TP18 as shown inFigure 2 .
7. Connect Oscilloscope probe to TP16 and TP15 as shown in Figure 3 .
8. Place Fan as shown in Figure 2 . and turn on, making sure air is flowing across the EVM.
SLUU254 – DECEMBER 2006 Using the TPS40075: A 12-V to 1.5-V @ 15-A Synchronous Buck Converter 7
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