PmodAMP2 Audio Amplifier
PmodAMP2TM Reference Manual
Product Information:
The Digilent PmodAMP2 is an audio amplifier module designed to
amplify low power audio signals and drive a monophonic output. It
features a digital gain select option, allowing output at either a
6 dB or 12 dB gain with pop-and-click suppression. The module
utilizes the Analog Devices SSM2377 Mono Class-D audio amplifier,
which accepts analog voltage signals as incoming audio inputs. It
also supports pulse-width modulated signals after passing through
the reconstruction filter. The internal modulator within the
SSM2377 ensures a clean audio output signal by smoothing out the
incoming analog signal.
Product Usage Instructions:
To interface with the PmodAMP2, it communicates with the host
board using the GPIO protocol. There is no specific timing protocol
to follow. As long as your incoming digital data has a sample rate
of at least 16 kHz, the amplifier will handle it effectively.
Alternatively, you can provide an analog signal for sound output.
The PmodAMP2 offers a gain selection pin and active-low shutdown
pins for additional control. When the gain pin is driven high, a 6
dB gain is applied to the incoming audio signals. When the gain pin
is driven low, a 12 dB gain is applied. The shutdown pin can be
driven to a logic low level to put the SSM2377 into a low power
state with a shutdown current of only 100 nA. This minimizes strain
on the power source. To bring the Pmod back into normal operation
mode, bring the shutdown pin back to a logic high level for a
maximum speaker output of 2.5W. The PmodAMP2 has the following pin
configuration:
| Pin | Signal | Description |
|---|---|---|
| 1 | AIN | Audio Input |
| 2 | GAIN | Gain Selection |
| 3 | NC | Not Connected |
| 4 | ~SHUTDOWN | Active Low Shutdown |
| 5 | GND | Power Supply Ground |
| 6 | VCC | Power Supply (3.3V/5V) |
When using external power, make sure it is within the range of
2.5V to 5.5V. However, it is recommended to operate the PmodAMP2 at
3.3V.
The physical dimensions of the PmodAMP2 are as follows:
- Pins on the pin header are spaced 100 mil apart.
- The PCB is 1.25 inches long on the sides parallel to the pins
on the pin header and 0.8 inches long on the sides perpendicular to
the pin header.
PmodAMP2TM Reference Manual
Revised April 15, 2016 This manual applies to the PmodAMP2 rev. A
1300 Henley Court Pullman, WA 99163
509.334.6306 www.digilentinc.com
Overview
The Digilent PmodAMP2 amplifies low power audio signals to drive a monophonic output. This module offers a digital gain select to allow output at a 6 or 12 dB gain with pop-and-click suppression.
The PmodAMP2.
Features include:
Filterless, high efficiency audio amplifier Monophonic audio output Standard 1/8″ (0.32 cm) mono speaker jack Micropower shutdown mode Popand-click suppression Digital gain select Small PCB size for flexible design at 1.25″ × 0.8″ (3.2 cm
× 2.0 cm) 6-pin Pmod port with GPIO interface Follows Digilent Pmod Interface Specification Type 1
1 Functional Description
The PmodAMP2 utilizes Analog Devices SSM2377 Mono Class-D audio amplifier. This module is designed to accept an analog voltage signal as the incoming audio input, although a pulse-width modulated signal can also be easy accepted after it passes through the reconstruction filter. A – modulator internal to the SSM2377 nicely smoothes out the incoming analog signal to get a clean audio output signal.
2 Interfacing with the Pmod
The PmodAMP2 communicates with the host board via the GPIO protocol. What this entails for us is that there is not a timing protocol that we need to follow. Rather, as long as your incoming digital data has a sample rate of at least 16 kHz, the amplifier will be able to nicely handle the incoming data. Alternatively, an analog signal can be provided and will also result in a corresponding sound output.
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PmodAMP2TM Reference Manual
A gain selection pin and active-low shutdown pins are also available for use. When the gain pin is driven high there is a 6 dB gain applied to the incoming audio signals and a 12 dB gain applied to audio signals when the pin is driven low.
The shutdown pin can be driven to a logic low level to place the SSM2377 into a very low power state with a shutdown current of only 100 nA placing very little strain on the power source. The Pmod can be brought back into normal operation mode by bringing the shutdown pin back to a logic high level for a maximum speaker output of 2.5W.
Pin Signal
Description
1 AIN
Audio Input
2 GAIN
Gain Selection
3 NC
Not Connected
4 ~SHUTDOWN Active Low Shutdown
5 GND
Power Supply Ground
6 VCC
Power Supply (3.3V/5V)
Table 1. Connector J1: Pin descriptions as labeled on the Pmod.
Any external power applied to the PmodAMP2 must be within 2.5V and 5.5V; however, it is recommended that Pmod is operated at 3.3V.
3 Physical Dimensions
The pins on the pin header are spaced 100 mil apart. The PCB is 1.25 inches long on the sides parallel to the pins on the pin header and 0.8 inches long on the sides perpendicular to the pin header.
Copyright Digilent, Inc. All rights reserved. Other product and company names mentioned may be trademarks of their respective owners.
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