Installation and Operation
2018 Microchip Technology Inc.
DS50002833A-page 13
FIGURE 2-5:
Efficiency vs. I
OUT
at 3.3V
2.3.1.4
LOOP GAIN MEASUREMENT
The MIC23350 Evaluation Board provides injection points and a termination resistor
(R12) for AC loop gain measurements. If needed, the value of R12 can be changed to
optimize the injection signal level. Inject the oscillator at J9 through the insulation
transformer (for instance, across resistor R12), and connect the A (CH1) and B (CH2)
channels at TP1 and TP2, respectively, or as indicated by the operating instructions of
the particular loop gain analyzer in use.
2.3.1.5
BENCH TESTING AT HIGH CURRENT
When testing the MIC23350 device at high load currents, or when checking the over-
current protection behavior, it may be necessary to remove the series A-meter, shown
in
, or to replace it with a very low-value shunt resistor. This is because the
internal resistance of many Digital Multimeters (DMMs) used for current measurements
is generally too high.
The MIC23350 Evaluation Board also comes populated with a 470 µF electrolytic bulk
capacitor, especially recommended when long wires are used in combination with high
currents or load transitions. This capacitor prevents the input voltage from exceeding
the device rating due to voltage spikes and allows for a more stable, controlled input
voltage.
0
10
20
30
40
50
60
70
80
90
100
0.001
0.01
0.1
1
10
Efficiency
(%
)
I
OUT
(A)
V
OUT
= 3.3V
V
IN
= 5.0V
NOTICE
In order to obtain the best performance with the minimum occupied board space, proper
layout techniques must be followed. First, the input and output capacitors should be
placed as close to the MIC23350 device as possible, and on the same layer as the IC. This
ensures low ripple and improved performance. Secondly, vias must be used under the
MIC23350 device, from its exposed pad to the GND plane, in order to allow for best heat
dissipation. Lastly, the switching node (from the SW pin of the MIC23350 device to the
inductor) should be as small as possible to decrease EMI emission.
