Mono Audio Amplifier Quickstart Guide

The tiny Texas Instruments TPA2005D1 audio amplifier based on. It is up to 1.4 Watts in an 8-ohm speaker, and you can drive; It will not shake a stadium, but it will provide plenty of volume for your audio projects.

Quick Start

• Connect your line-level audio inputs only the + and - header.
• Header - Out + and connect your speaker.
• 5.5V to + 2.5V and the ability to connect - header. (Yet S (shutdown) pin some connections.)

Send some audio input, and you will hear it on speaker! Sound, not loud enough to hear you buzzing, or you would like to add a volume control, read on.

Mono Audio Amplifier Quickstart Guide

How it works

Traditional audio power amplifiers use transistors with a gain of a certain number of analog inputs to produce an analog output. This sounds great, but the areas between transistors on and off to work. Transistors work most efficiently when they are fully switched on or off, and a lot of waste heat as energy when they're in the middle run.

Class-D amplifier radically different. At any moment, the output transistors are fully on or fully off, which is very efficient. This means that the audio is not output, but the truth is, most of it off for low output value (GND) PWM- like a digital waveform for the high output value (VCC) is mostly, and.

Mono Audio Amplifier Quickstart Guide

The PWM signal of 250 kHz, which is much higher than the encoded audio frequency (<20 kHz) is the clock. Mechanical devices that are only audio frequency response of the speakers, PWM signal to the frequency of the original audio is filtered by the speaker coil itself. You can hear all the music!

TPA2005D1 datasheet check out if you want to know more about this amplifier.

To use amplifier

Header - IN + and add your input source. Because the input is differential, it technically does not matter which direction you have to connect them, but if you are one of the inputs or the slope of the ground, the line connection - terminal. (If you encounter problems with hum, see tips below).

Header - Out + and connect your speaker. Polarity does not matter if you're using a speaker, but if you will be using multiple speakers, make sure that all of them the same way you avoid the problem of phase wire. The speaker can be 4 or 8 Ohms. Watts into 8 Ohms maximum output amplifier is 1.4. This small-wattage speakers with amplifier can drive, but you do not turn up the volume too high to avoid damage to the speaker should be careful. You can also decrease the volume of the speakers can drive greater than 1.4W. In general, the speakers sound much better than smaller speakers; We've had great fortune with old automotive speaker.

Pins - + Connect a power source. 5.5V to 2.5V power source may be a source of at least 280 milliamps, and you should be able to get the maximum volume. The red LED will illuminate when the board is powered up..

Apply an audio signal input, and you should be able to hear the speaker. To change the volume, change the volume of the source signal, or a board (instructions below), add a volume control potentiometer.

Adding a volume control knob

If you want, you can easily add this board is a 10K potentiometer to control volume. You can control the volume from 0% to 100% reduction of the input signal will allow you to control the volume. Note that the amplifier will not be any loud - you can do it if you want to see change in the gain resistors. Here's how to add a volume control potentiometer:

Remove the solder jumper SJ1. On the white board in the bottom right corner of the small blob of solder are in parentheses. The easiest way to do this jumper solder wick application, and it is with your soldering iron is hot. When you're done, to ensure that the two sides are separated electrically from each other.

Now, on the bottom right of the board 10K potentiometer connected to the pad. The following link has been shown to the right of the board silkscreen. With 0.1 "board pins (such as the COM-09806) -spacing directly on, or a chassis you use a cable to connect the board to the potentiometer, etc. You can solder a trimpot

Note: Potentiometers come in two styles: "Linear Candles" and "audio (or logarithmic) taper". Audio Potentiometers a logarithmic taper volume control of the audio like this one in favor of the application is to give a more natural feel, but the linear taper will work just fine.

How to use the shutdown pin

SDN * input when it is being used to stop the amplifier can be used to save energy. SDN * When disconnected, or a high logic signal (> 2V) connected, the amplifier will work normally. SDN * pin to ground or logic signal is low (<0.8V) when connected, amplifier and LED will be closed. You can use this feature to save battery power-driven projects can.

Change the Gain Resistors

Gain amplifier chip, which sets how much the input signal to be amplified using two fixed resistors. 150K resistors that we're using on this board, as recommended by the datasheet for a profit 2. If you want the output to be loud, you can install a small resistor.

The amplifier gain for the equation 2 * (150K / R) is. So if you use a 100K gain resistor, 50K resistor will receive 3 to 6, etc. The datasheet for the smallest value that should be used for a profit of 20 to 15K, but we've gone down to 3K (fair results obtained = 100).

Amplifier board to add your own two positions through the hole resistors. The white rectangle on the keyboard are in. You can just put them over the top of your hole resistors, remove the existing surface mount resistors do not need to. (New resistors in parallel with the surface of the resistance value of the resistor will reduce a little left, but this usually is not a problem).

For best results, the gain resistors should be matched as closely as possible. If you have a bag of identical resistors, all of them with a multimeter to measure the resistance and the earliest that could pick up.

Counsel

The output of the amplifier into a coil (a speaker or a magnetic transducer) is designed to be connected with something. Since the output is not a true analog signal, a preamplifier, etc., should not expect to use this board

The board differential input such as MP3 and MP3 Shield trigger for direct connection to the audio signal, such as a floating ground is not safe.

And amplifier to your audio source (such as audio coming from a desktop computer) is different AC power supply, the output you could hear a loud hum. Audio input side and the ground power supply (PWR - - headers) in order to fix it, a jumper cable connections.

Like a 250 kHz PWM- signal output of the amplifier, it is possible to radiate interference from nearby sensitive circuitry. For this reason, as small as possible to keep the wires between amplifier and speaker.

Questions?

If you have any questions or problems, tell us in the tech support@sparkfun.com and we will do our best to help you. If you're building our part of the project we want to hear about cool!

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