HOW DOES IT WORK?

Headphone AMP 3 Click is based on the INA1620, a high-fidelity audio operational amplifier with integrated thin-film resistors and EMI filters from Texas Instruments. The amplifier has a high slew rate, high capacitive-load drive capability, high open-loop gain, low quiescent current per channel, low-power shutdown mode, and thermal shutdown. The internal amplifiers use a unique topology to deliver high output current with extremely low distortion while consuming minimal supply current. The amplifier input pins of the INA1620 are protected from excessive differential voltage with back-to-back diodes; thus, in most applications, the inputs will have no consequences.

The INA1620 has two functional modes: a Shutdown and an Enabled mode. In Shutdown mode, the INA1620 will have minimal power consumption. However, applying signals to the output while in Shutdown mode will parasitically power the output stage of the audio amplifier. While in Enabled mode, the INA1620 uses a few tricks to clean things up. The INA1620 uses efficient electromagnetic interference (EMI) rejection as an immunity to change in offset, thus having a higher EMIRR.

Onboard, there are two 3.5mm audio connectors for connecting the audio source and headphones. The INA1620 uses positive and negative power supplies; on this Click board™, +5V and -5V power supplies are provided by the TPS65133, a ±5V, 250mA dual output power supply from Texas Instruments. The TPS65133 provides fixed positive and negative 5V with ±1% output voltage accuracy and high efficiency. It also includes a boost converter that allows a 3.3V power supply from the mikroBUS™ socket to be used.

The INA1620 has integrated thin-film resistors in four blocks. You can use blocks 1 and 4 to create very high-performance audio circuit configurations. Blocks 2 and 3 are already used and configured in a circuit of this Click board™. All resistors are of 1K, where all A and C are internally connected to a B point. The Headphone AMP 3 Click comes with jumpers to set those configurations. Points R1B and R4B are connected by a trace with the appropriate A points. Cut the trace with a sharp knife and solder jumper resistors to connect B points to C.

The Headphone AMP 3 Click board uses two enable pins as its only connection with the host MCU. The ENA pin enables the INA1620 with a logic HIGH, as the pin is pulled LOW. The ENP is used similarly to enable the TPS65133 boost and buck-boost converter with a logic HIGH as the pin is pulled down.

This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the VCC SEL jumper. This way, both 3.3V and 5V capable MCUs can 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