Installation and Operation
2018 Microchip Technology Inc.
DS50002834A-page 14
FIGURE 2-5:
Efficiency vs. I
OUT
at 0.6V.
2.3.1.4
LOOP GAIN MEASUREMENT
The MIC23356 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 trans-
former (i.e., across resistor R12).
2.3.1.5
I
2
C PULL-UP VOLTAGE SELECTION
The MIC23356 Evaluation Board is equipped with a jumper for selecting the I
2
C pull-up
supply voltage. The J8 header can be used to select the I
2
C pull-up voltage to either
V
USB
or V
IN
. If a different pull-up voltage is desired, it can be injected into the PWR pin
of J2. In this case, make sure that no jumper is installed on header J8, to prevent short-
ing of the externally injected pull-up voltage to either V
USB
or V
IN
.
2.3.1.6
USING THE MIC23356 EVALUATION BOARD WITH THE EXTERNAL I
2
C
MASTER
In order to use the MIC23356 with an external I
2
C master (like a microcontroller,
microprocessor or another I
2
C master), the on-board MCP2221 must be disabled. To
accomplish this, the pull-down resistor R10 must be populated to avoid any interfer-
ence between the MCP2221 and the external I
2
C master. Then, the desired I
2
C master
can be connected to J2. If the external I
2
C master already provides pull-up resistors for
the SDA and SCL lines, then the I
2
C pull-up resistors R6 and R9, present on the
MIC23356 Evaluation Board, are not needed and must be removed to prevent pull-up
voltage conflicts.
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
= 0.6V
V
IN
= 3.3V
V
IN
= 5.0V
V
IN
= 2.5V
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