MIKROE Headphone AMP Click is a compact add-on board that contains a stereo headphone amplifier. This board features the LM4811, Boomer® audio power amplifier capable of delivering 105mW per channel with digital volume control from Texas Instruments. The Boomer® amplifiers are specifically designed to provide high-quality output power with a minimal amount of external components. Since the LM4811 does not require bootstrap capacitors or snubber networks, it is optimally suited for low-power portable systems. It features a digital volume control that sets the amplifier's gain from +12dB to −33dB in 16 discrete steps, in addition to a micro-power consumption Shutdown mode. This Click board™ is suitable for portable electronics and audio systems, representing a perfect solution for remote, headphone audio-volume control applications.

Headphone AMP Click is supported by a mikroSDK compliant library, which includes functions that simplify software development.

Headphone AMP Click 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.

This 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.

This 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.

• Interface: GPIO, PWM
• Compatibility: mikroBUS™
• Dimensions: 57.15 x 25.4mm
• Input Voltage: 3.3V or 5V
• Output Power (@ 16Ω load): 105mW
• Operating Temperature Range: Min. -40°C. Typ. +25°C, Max. +85°C

• Schematic
• LM4811 Datasheet
• mikroSDK
• GitHub