Headphone AMP Click Board™

How Does The Headphone AMP Click Board™ Work?

The Headphone AMP Click Board™ as its foundation uses the LM4811, a stereo, analog input headphone amplifier with digital volume control from Texas Instruments. This headphone amplifier is designed to provide a high-quality output power using few external components and does not require bootstrap capacitors or snubber networks for stability improvement. The maximum power delivered by the LM4811 headphone amplifier is 105mW per one channel into 16Ω and 70mW with 16Ω load impedance. Other prominent features of the ML4811 also include digital volume control, "Click and Pop" suppression circuitry, and a low shutdown current of 0.3μA typical.

The Headphone AMP Click Board™ communicates with MCU using several GPIO pins. The signals from the CLK and U/D pins, routed to the PWM and INT pins of the mikroBUS™ socket, controls the LM4811's gain. At each rising edge of the CLK signal, the gain will increase or decrease by a 3dB step depending on the logic voltage level applied to the U/D pin. A logic high voltage level applied to the U/D pin causes the gain to increase by 3dB at each rising edge of the CLK signal and vice versa. Upon devices' Power-On features, the amplifier's gain is set to a default value of 0dB. Sixteen discrete gain settings are available, ranging from +12dB maximum to −33dB minimum.

The unity-gain stable LM4811 also features an externally controlled, active-high, micro-power consumption Shutdown mode, available on the RST pin of the mikroBUS™ socket, to reduce power consumption while not in use. However, when coming out of Shutdown mode, the LM4811 will revert back to its previous gain setting. Alongside all these features, the LM4811 also has an internal thermal shutdown protection mechanism.

The Headphone AMP Click Board™ can operate with both 3.3V and 5V logic voltage levels selected via the VCC SEL jumper. This way, it is allowed for both 3.3V and 5V capable MCUs to use the communication lines properly. However, the Click board™ comes equipped with a library containing easy-to-use 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 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	CLK	Clock Signal
Shutdown	RST	2	RST	INT	15	U/D	Gain Control
NC	3	CS	RX	14	NC
NC	4	SCK	TX	13	NC
NC	5	MISO	SCL	12	NC
NC	6	MOSI	SDA	11	NC
Power Supply	3.3V	7	3.3V	5V	10	5V	Power Supply
Ground	GND	8	GND	GND	9	GND	Ground

Onboard settings and indicators

Headphone Amp Click electrical specifications