Installation and Operation
2019 Microchip Technology Inc.
DS50002914A-page 13
2.3.1
Power Input and Output Connection
2.3.1.1
POWERING THE MIC33M656 EVALUATION BOARD
When the Evaluation Board is ready for evaluation, apply positive input voltage to the
V
IN
terminal and the corresponding return to the GND_IN terminal. The maximum input
voltage should not exceed 5.5V. An electronic load or resistive load can be used for
evaluation. Some electronic loads can sink the programmed current, starting from very
low output voltage levels during start-up. For a more realistic start-up behavior evalua-
tion, a resistive load or Constant Resistance mode for electronic load is recommended.
Connect the positive voltage terminal of the load to the V
OUT
terminal on the Evaluation
Board and connect the negative or return side of the load to the GND_OUT terminal. If
changing the regulator parameters is required, or simply to monitor the part, make sure
to connect the Micro-USB cable between the Evaluation Board and the PC. Then,
install the GUI according to
Chapter 3. “GUI Installation and Operation”
and follow
Chapter 2. “Installation and Operation”
for more extensive
evaluation.
2.3.1.2
EVALUATION BOARD POWER-UP PROCEDURE
For the power-up procedure, follow the steps bellow:
1. Connect the PC, input supply, voltmeter, ammeter and load as shown in
. Set the ammeter on a 10A range.
2. Fit a jumper on the EN position across the J6 header, as marked on the
silkscreen.
3. Once the input voltage is greater than 2.35V typical at the board input (V
IN
), the
device begins to switch.
4. The voltmeter should now indicate an output voltage according to the preset
register values. Adjusting the input voltage, temperature or load should not
cause the output to vary more than ±1.5% over the operating range of the
converter.
5. Set the input voltage and the load to the desired values, with a maximum of 5.5V
on the input voltage and a maximum load of 6A.
6. Adjust the regulator output and monitor the STATUS Register, as described in
.
7. Optionally, for more advanced readings, place Oscilloscope Probe 1 in the “SW”
test point to monitor the switching waveforms and Probe 2 on the output header
to measure the AC ripple of the output voltage. Please note that for a more accu-
rate output voltage ripple measurement, probing is facilitated by the availability
of test points for probe tip and ground spring connections close to the output
capacitor. A U.FL connector is also available for the same purpose.
Note:
The inductance associated with long wires on the board input may cause
voltage spikes at load stepping or start-up into a heavy load. If the spikes
exceed the 5.5V maximum input voltage rating, the MIC33M656 may fail.
This can be prevented by populating a 470
µ
F electrolytic capacitor on the
C8 footprint.
