Installation and Operation

© 2007 Microchip Technology Inc.

DS51608B-page 9

2.3.1.2

APPLY LOAD TO MCP1630 AUTOMOTIVE INPUT BOOST CONVERTER

DEMO BOARD

A variable resistive load can be used to verify the line and load regulation. The load

resistance is connected between the points TP3 and TP4. To measure the output

voltage, connect the common point of a multimeter to TP4 and the positive terminal to

TP3. By varying the load, the load regulation can be verified by measuring the output

voltage over the entire load range of 0 mA to 400 mA. Similarly, the line regulation can

be calculated by varying the line voltage from 9V to 18V and checking the output

voltage.

Evaluating the Application

The best way to evaluate the MCP1630 is to dig into the circuit and measure voltages

and currents with a Digital Voltage Meter (DVM) and probe the board with an

oscilloscope.

The firmware program in the PIC12F683 can also be edited to modify the operation of

the application.

Firmware

The PIC12F683 comes pre-programmed with firmware to operate the system as

described above. The file listing and firmware flow diagram are shown in Appendix

C. “Demo Board Firmware”.

The program is fairly simple and straight forward. There is an initialization routine at the

beginning of the program.

The TRISIO register controls the direction of GPIO pins, and is configured to set GP2

output port.

The Capture/Compare/PWM (CCP) module contains a 16-bit register which can

operate in PWM mode. The PWM period can be calculated by writing to the PR2

register. The PWM duty cycle is specified by writing to the CCPR1L register and to the

CCP1CON <5:4> bits. Up to 10-bit resolution is available. The CCPR1L contains the

eight MSbs and the CCP1CON <5:4> contains the two LSbs. This 10-bit value is

represented by CCPR1L:CCP1CON<5:4>. The switching frequency is set to 500 kHz.

The user can obtain different output voltages by programming the MCU to obtain

Programming

Header J1 is provided for in-circuit programming. This is an optional feature since the

MCP1630 Automotive Input Boost Converter Demo Board comes pre-programmed

with firmware to operate the system. The PIC12F683 can be reprogrammed with the

Baseline Flash Microcontroller Programmer (BFMP).