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7 Analog Peripherals
Microphone Circuit, Speaker Circuit, Rotary Potentiometer, Voltage Reference.

Preface
1 Introduction
Kit Introduction, Kit Contents, Terminology, Image Legend.
2 Board Overview
Block Diagram, Board Image, Feature List.
3 Pinout and Remapping
Pinout and Remapping Area, Different Types of Remapping.
4 Power Supply and Monitor
Power supply, Power Monitor.
5 Buttons and LEDs
Digital Addressable LEDs, RGB LED, LED Row, Joystick, Tactile- and Touch Buttons.
6 Serial Communication
USB Bridge, UART, I²C and SPI Peripherals.
7 Analog Peripherals
Microphone Circuit, Speaker Circuit, Rotary Potentiometer, Voltage Reference.
8 External Connectivity
Servomotor Headers, MikroBUS™, Grove, Qwiic®, PICkit™ Header.
9 Revision History
Hardware and Document Revision History.
10 Appendix
MTCH1030 Touch Tune Data, Addressable LEDs Timing and Format, Schematics, Assembly Drawing.
Microchip Information

7 Analog Peripherals

Microphone Circuit, Speaker Circuit, Rotary Potentiometer, Voltage Reference.

7.1 Microphone Circuit


A MEMS microphone is available as an analog input peripheral on the Explorer and is connected to its amplifier through the 1x2 pin header J206. The dual operational amplifier MCP6022 is used to amplify the signal from the microphone with three selectable gain stages. The gain stages are 1, 221 (low) and 1001 (high), selectable using the slide switch S200.

Figure 7-1. Microphone Circuit Overview

Tip: The microphone output can be disconnected from the amplifier and accessed directly through the 1x2 pin header J206.

7.2 Speaker Circuit


The Explorer features an 8Ω, 0.2W miniature speaker. The speaker amplifier input signal is, by default, connected to the output of the 12-bit DAC MCP4821. A Class-D mono amplifier drives the speaker. Volume control is implemented with the rotary potentiometer R210, which provides an approximate logarithmic gain control for the amplifier input. Tip: Pin header J202 can be used to remap the speaker input signal and/or DAC output.

Figure 7-2. Speaker Circuit Overview

7.3 Rotary Potentiometer


A 10 kΩ ±20% rotary potentiometer is available to the user as an analog input (R421). The voltage output varies between 0V and 3.3V. The voltage output increases when turning the potentiometer clockwise. Figure 7-3. Rotary Potentiometer

7.4 Voltage Reference


The MCP1501 voltage reference circuit serves two purposes. Power supply for the MEMS microphone Two accurate buffered voltage references, 1.50V and 3.00V, based on the MCP6V02 dual operational amplifier

Figure 7-4. Voltage Reference Overview

Table 7-1. Voltage Domain Specifications
Voltage Reference	Vnom	Vmin - Vmax	Imax
VREF P3V000	3.000V	2.997-3.003V	20 mA
VREF P3V00B	3.00V	2.997-3.003V	5 mA
VREF P1V50B	1.50V	1.49-1.51V	5 mA

The online versions of the documents are provided as a courtesy. Verify all content and data in the device’s PDF documentation found on the device product page.