2x20W Amp click
PID: MIKROE-2779
Weight: 30 g
20W, stereo, high-performance digital amplifier
2x20W Amp click carries the MAX9744 stereo class D audio power amplifier from Maxim
Integrated. This click brings the Class AB sound performance with Class D efficiency. The
perfect combination for your speakers. 2x20W Amp click also offers 64 step volume
control,single-supply operation, adjustable gain, and industry-leading click-and-pop suppression.
How the click works
Class-D amplifiers work by producing a series of square-shaped pulses of fixed amplitude, but
varying duty cycle, representing the amplitude variations of the analog signal.
The output of the modulator is used to gate the output transistors on and off, alternately. The
high efficiency of a Class D amplifier is due to the switching operation of the output stage
transistors. Since the transistors are either fully ON or fully OFF, they spend a small amount of
time in the linear region and consume little amounts of power.
In a Class D amplifier, the output transistors act as current steering switches and don't use a lot of
additional power. A low-pass filter made of an inductor and a capacitor is used to produce a path
for the low-frequencies of the audio signal (leaving the high-frequency pulses behind).
When the output current exceeds the current limit, 5.5A (typ), the MAX9744 disables the outputs
and initiates a 220µs startup sequence. The shutdown and startup sequence is repeated until the
output fault is removed.
When the die temperature exceeds the thermal-shutdown threshold, +165°C (typ), the MAX9744
outputs are disabled. Normal operation resumes when the die temperature decreases by a factor
equal to the thermal-shutdown threshold minus the thermal-shutdown hysteresis, (typically
below +150°C).
Power supply
The board logic is powered from the 3.3V supply over the mikroBUS™ socket, while the
amplifier circuit is powered by the onboard 5V power supply or an external source that can go
from 4.5V to 14V. In order to use an external power source, the jumper JP1 must be positioned
to the EXT position (see more in the Jumpers and Settings table).
Shutdown mode
The MAX9744 features a shutdown mode that reduces power consumption and extends battery
life. Driving SHDN pin low places the device in low-power shutdown mode. Connect SHDN pin
to digital high for normal operation.
Volume control
For maximum flexibility, the click features volume control operation using an analog voltage
input or through the I2C interface. To set the device to analog mode, connect ADDR1 and
ADDR2 to GND. In analog mode, SDA/VOL pin is an analog input for volume control. The
analog input range is ratiometric between 0.9 x VDD and 0.1 x VDD where 0.9 x VDD = full
mute and 0.1 x VDD = full volume.
Use ADDR1 and ADDR2 to select I2C mode. There are three addresses that can be chosen,
allowing for multiple devices on a single bus. In the I2C mode, the volume is controlled by
choosing the speaker volume control register in the command byte. There are 64 volume
settings, where the lowest setting is full mute.
Specifications
Type
Amplifier
Applications
Battery powered devices, mobile phones, portable sound systems, etc.
Programming
MAX9744 20W stereo Class D audio power amplifier
Key Features
20W Stereo Output, integrated volume control, high 93% efficiency
Key Benefits
64 step volume control
Interface
I2C
Input Voltage
3.3V,5V
Click board size
L (57.15 x 25.4 mm)
Pinout diagram
This table shows how the pinout on 2x20W Amp click corresponds to the pinout on the
mikroBUS™ socket (the latter shown in the two middle columns).
Notes
Pin
Pin
Notes
NC
1
AN
PWM
16
ADDR1
Address Select Input
Shutdown Input
#SHDN
2
RST
INT
15
ADDR2
Address Select Input
Mute Input
MUTE
3
CS
TX
14
NC
NC
4
SCK
RX
13
NC
NC
5
MISO
SCL
12
SCL
I2C Serial Clock
NC
6
MOSI
SDA
11
SDA
I2C Serial Data
Power supply
+3.3V
7
3.3V
5V
10
+5V
Ground
GND
8
GND
GND
9
GND
Ground
ADDR1 and ADDR2 - Sets the device address for the I2C address option. Connect
ADDR1 and ADDR2 to GND to select analog volume control mode.
MUTE - Drive the MUTE pin high to mute the speaker outputs. Connect MUTE to GND
for normal operation (mute function controls speaker outputs).
SHDN - Drive SHDN low to disable the audio amplifiers. Connect SHDN to VDD or
drive high for normal operation.
SCL - I2C Serial Clock Input and Modulation Scheme Select. In I2C mode (ADDR1 and
ADDR2 ≠ GND), acts as the I2C serial clock input. When ADDR1 and ADDR2 = GND,
set SCLK = 1 for standard PWM output scheme, or set SCLK = 0 for filterless
modulation output scheme.
SDA - I2C Serial Data I/O and Analog Volume Control Input.
Jumpers and settings
Designator
JP1
Name
PWR.SEL.
Default
Position
Left
Default
Option
5V
Description
Power Supply Voltage Selection
between 5V and VDD ext. (4.5V-14V)
Programming
We provide a specific library for the 2x20W Amp click on our LibStock page, as well as a demo
application (example), coded using MikroElektronika compilers. The demo can run on all the
main MikroElektronika development boards.
Library Description
The library covers all functionalities of the 2x20W Amp click with just 6 functions implemented
in addition to 2 HAL init functions.
Key functions :
void
void
void
void
C2X20AMP_init() - Driver Initialization
C2X20AMP_setVolume(uint8_t newVolume) - Volume Setup
C2X20AMP_increaseVolume() - Increase volume by one step
C2X20AMP_decreaseVolume() - Decrease volume by one step
More detailed description of library functions you can be found inside the library documentation.
Examples Description
The application is composed of three sections :
System Initialization - Initializes I2C peripheral alongside with GPIO Pins
Application Initialization - Initializes GPIO HAL, I2C HAL and driver related to 2x20
Amp click board and the sets the initial volume to 0x15.
Application Task - (code snippet) Increases and decreases volume periodically every 5
seconds by 6 steps.
void applicationTask()
{
C2X20AMP_decreaseVolume();
C2X20AMP_decreaseVolume();
C2X20AMP_decreaseVolume();
C2X20AMP_decreaseVolume();
C2X20AMP_decreaseVolume();
C2X20AMP_decreaseVolume();
Delay_ms (5000);
C2X20AMP_increaseVolume();
C2X20AMP_increaseVolume();
C2X20AMP_increaseVolume();
C2X20AMP_increaseVolume();
C2X20AMP_increaseVolume();
C2X20AMP_increaseVolume();
Delay_ms(5000);
}
The example application also carries implementation of three functions for GPIO pin control
(CS, PWM, INT) provided during HAL GPIO initialization.
The full application code, and ready to use projects can be found on our LibStock pages.
Other mikroE Libraries used in the example:
I2C
https://shop.mikroe.com/2x20w‐amp‐click 11‐3‐17
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