Datasheet

MCP1640 Single Quadruple-A Battery Boost Converter Reference Design
DS51922B-page 16  2010-2011 Microchip Technology Inc.
By pressing the button S1, the GP1 microcontroller port switches the P-MOS
transistor ON (Q2), powering the load. The load is supplied for a fixed period of time
(approximately 25 seconds), unless the button is pressed.
FIGURE 2-5: Waveforms when Reference Board is Turned ON by pressing S1
Button.
The PIC12F617 measures the battery voltage when the switch load (Q2) is ON. If the
battery voltage is lower than 0.8V, the LED (D1) will flash. Battery voltage is measured
using the R7-C4 filter and the A/D channel present on pin 3 (GP4) of the
microcontroller.
2.2.3 Programming the PIC12F617 Microcontroller
For board evaluation, Microchip provides a firmware package, downloadable from
Microchip’s web site. The board is factory programmed for an active 10 seconds output,
after the button S1 is pressed. The green LED on the board flashes when a low battery
condition (less than 0.8V input) is detected, but the board will operate at the lowest
input voltage possible. All parameters may be changed in firmware to the desired value,
according to the output/input capability. The source code is rich in comments and helps
the user to define the board.
The HI-TECH C
®
compiler is used to compile the source code and create the hex files
for downloading to the reference board. The HI-TECH compiler is available for down-
load on Microchip’s web site. The compiler is not included with the evaluation board kit.
Header J3 can be used for in-system circuit programming. J3 is not populated on the
board. A five-pin header connector may be soldered in J3’s place. A PICkit™ 3
programmer may be connected to J3 to program the evaluation board.