Installation and Operation

 2017 Microchip Technology Inc.

DS50002686A-page 17

2.5

EXTRA INPUT CAPACITANCE

An extra capacitor place (C3) is available on the MCP1665 12V Output Boost

Regulator Evaluation Board (see Figure 2-2).

It is useful for input decoupling if, for some reason, the power supply’s impedance can

derived from another power supply with a slow response, fast load, as well as stepping,

causing high-input current spikes.

If intermittent operation or a bus-pumping behavior is noticed, this should be one of the

first steps in troubleshooting. Check to see if the input voltage of the MCP1665 is

permanently above the UVLO threshold. Probing the input voltage should be done by

attaching the oscilloscope probes to the GND and VIN test points on the board.

The recommended BOM part to be soldered in the DNP position is a tantalum polymer

330 μF/10V capacitor with a low ESR.

2.6

RT SPARE RESISTORS AREA

The RT Feedback options board area contains the four spare R Top feedback resistors.

The resistor values are chosen to closely match the four output voltage options labeled

next to them (6V, 9V, 24V, 32V). These resistors should be soldered in the RT position

on the board, by replacing the 12V option resistor provided by default.