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2 layers25.3 × 25.3 mmLM49270-PIC, the printed circuit board in 3D

LM49270-PIC

JSnowden33/LM49270-PIC8

Method for controlling LM49270 with a PIC microcontroller.

Full screenGitHub.kicad_pcb
Size
25.3 × 25.3 mm
Copper layers
2
Thickness
1.6 mm
Parts
47
Nets
41
Pads
128
Tracks, vias
222, 36
Pours
2
Routed
Yes
KiCad
KiCad 4
Created
28 Dec 2017
Updated
29 Dec 2017

Overview

LM49270-PIC is an open-source printed circuit board by JSnowden33, from the JSnowden33/LM49270-PIC repository on GitHub. It is a 2-layer board of 25.3 × 25.3 mm with 47 parts on 41 nets, routed with 222 tracks and 36 vias.

It is built around the PIC16F1503-E/P and LM49270SQ. Its parts include 12 capacitors, 12 resistors, 2 ICs and 2 connectors. It belongs with the PIC boards of this library.

Main components

2

README

README.md

LM49270-PIC

This is a program allowing for digital or analog volume control on the LM49270 headphone/speaker amplifier using a PIC16F1503 microcontroller. It is in the form of an MPLAB X project and can be compiled using MPLAB X IDE with XC8. You can also use the pre-compiled program found at Software/LM49270-PIC.X/dist/default/production/LM49270-PIC.X.production.hex with MPLAB IPE. The board can be programmed using a PICkit 3.

The program allows for 32 steps of volume. Speaker volume is allowed the full range from 0 to 31. Headphone volume is restricted from 0 to 21. This can be changed by modifying HP_OFFSET in Config.h.

The operating mode is selected by soldering a jumper located behind the headphone jack on the PCB. When soldered to GND, it operates in digital mode and volume is controlled with two tact switches connected between UP/DN and GND. When the jumper is soldered to V+, it operates in analog mode and volume is controlled with a potentiometer soldered to V+, VOL, and GND.

The PCB for this circuit can be ordered here: https://oshpark.com/shared_projects/Wy4lnqzu
The circuit requires 3.3V to 5V input. It uses a headphone jack with a NC switch. Speaker output is automatically toggled off by hardware when headphones are detected. The amp works best with speakers between 0.7W and 1.2W.

Parts

47
QtyValueFootprintReferences
16TEST_1PAmp:PadW1, W2, W3, W4, W5, W6, W7, W8, W9, W10, W11, W12, W13, W14, W15, W16
12RAmp:R_0402R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, R12
11CAmp:C_0402C1, C2, C3, C4, C5, C6, C7, C8, C9, C11, C12
3ScrewAmp:ScrewScrew, Screw, Screw
1CONN_01X06Amp:Pin_Header_Straight_1x06_Pitch2.54mmJ2
1CPAmp:C_1206C10
1JACK_TRS_4PINSAmp:SJ-3524-SMT-TRJ1
1LM49270Amp:QFN-28-LM49270U2
1PIC16F1503Amp:QFN-16-1EP_3x3mm_Pitch0.5mmU1

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Questions

How big is the LM49270-PIC PCB?

It measures 25.3 × 25.3 mm and has 2 copper layers, 1.6 mm thick.

What parts does the LM49270-PIC use?

47 parts, built around the PIC16F1503-E/P and LM49270SQ. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.

Where can I download the LM49270-PIC KiCad files?

From the JSnowden33/LM49270-PIC repository on GitHub, at the commit this page was made from: the board is PCB/LM49270-PIC.kicad_pcb. PCBKit opens the board in the browser, with nothing to install.

Can I use the LM49270-PIC design in my own project?

Its repository states no licence, so its author keeps all rights: ask JSnowden33 before reusing the design.