Headphone AMP 2 Click

How does it work?

Headphone AMP 2 Click is based on the MAX9723, a stereo DirectDrive headphone amplifier with BassMax, volume control, and I2C from Analog Devices. The headphone amplifier uses a DirectDrive architecture that produces a ground-referenced output from a single supply, thus eliminating the need for large DC-blocking capacitors. Its outputs are biased at 0V, making the amplifier outputs not have a DC component, improving a low-frequency response. The DirectDrive architecture uses a charge pump to create an internal negative supply voltage, which makes the dynamic range from a single supply almost double.

Software-enabled bass boost (BassMax) boosts the bass response of the amplifier, improving audio reproduction when using inexpensive headphones. This, in particular, comes in handy when reproducing low frequencies, where the limitations of the small physical size of the diaphragm are compensated by increasing the amplifier gain. The maximum amplifier gain on this chip is +6dB. The volume control adjusts the gain of the output amplifiers according to your needs over the software. The amplifier can enter the low-power shutdown mode, where the host MCU controls the shutdown mode.

Headphone AMP 2 Click uses a standard 2-Wire I2C interface to communicate with the host MCU supporting clock rates of up to 400KHz. The shutdown control is available on the SHD pin of the mikroBUS™ socket. In addition to the 3.5mm input and output audio jacks, there are corresponding two channels input and output headers in case of the need to connect inputs or outputs incompatible with jack connectors (wire-types).

This Click board™ can be operated only with a 3.3V logic voltage level. The board must perform appropriate logic voltage level conversion before using MCUs with different logic levels. However, the Click board™ comes equipped with a library containing functions and an example code that can be used, as a reference, for further development.

Specifications

Pinout diagram

This table shows how the pinout on Headphone AMP 2 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	SHD	Shutdown Mode
	NC	2	RST	INT	15	NC
	NC	3	CS	RX	14	NC
	NC	4	SCK	TX	13	NC
	NC	5	MISO	SCL	12	SCL	I2C Clock
	NC	6	MOSI	SDA	11	SDA	I2C Data
Power Supply	3.3V	7	3.3V	5V	10	NC
Ground	GND	8	GND	GND	9	GND	Ground

Onboard settings and indicators

Headphone AMP 2 Click electrical specifications

Software Support

We provide a library for the Headphone AMP 2 Click as well as a demo application (example), developed using MIKROE compilers. The demo can run on all the main MIKROE development boards.

Package can be downloaded/installed directly from NECTO Studio Package Manager(recommended), downloaded from our LibStock™ or found on Mikroe github account.

Library Description

This library contains API for Headphone AMP 2 Click driver.

Key functions

• headphoneamp2_set_command Headphone AMP 2 set the command function.

• headphoneamp2_enable Headphone AMP 2 enable the device function.

• headphoneamp2_disable Headphone AMP 2 disable the device function.

Example Description

This example demonstrates the use of the Headphone AMP 2 Click board™, the headphone amplifier with BassMax and volume control.

void application_task ( void )  
 { 
     static headphoneamp2_cmd_t cmd_ctrl; 
     cmd_ctrl.wakes_up = HEADPHONEAMP2_CMD_ENABLE; 
     cmd_ctrl.bass_max = HEADPHONEAMP2_CMD_ENABLE; 
     cmd_ctrl.gain_max = HEADPHONEAMP2_CMD_ENABLE; 
     cmd_ctrl.volume   = HEADPHONEAMP2_VOL_MUTE; 

     log_printf( &logger, " Volume : " ); 
     for ( uint8_t volume = HEADPHONEAMP2_VOL_LVL_1; volume <= HEADPHONEAMP2_VOL_LVL_MAX; volume++ ) 
     { 
         cmd_ctrl.volume = volume; 
         if ( HEADPHONEAMP2_OK == headphoneamp2_set_command( &headphoneamp2, cmd_ctrl ) ) 
         { 
             log_printf( &logger, "|" ); 
         } 
         Delay_ms( 1000 ); 
     } 
     log_printf( &logger, "rn-------------------------rn" ); 
 }

The full application code, and ready to use projects can be installed directly from NECTO Studio Package Manager(recommended), downloaded from our LibStock™ or found on Mikroe github account.

Other Mikroe Libraries used in the example:

• MikroSDK.Board
• MikroSDK.Log
• Click.HeadphoneAMP2

Additional notes and informations

Depending on the development board you are using, you may need USB UART click, USB UART 2 Click or RS232 Click to connect to your PC, for development systems with no UART to USB interface available on the board. UART terminal is available in all MIKROE compilers.

mikroSDK

This Click board™ is supported with mikroSDK – MIKROE Software Development Kit. To ensure proper operation of mikroSDK compliant Click board™ demo applications, mikroSDK should be downloaded from the LibStock and installed for the compiler you are using.

For more information about mikroSDK, visit the official page.