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PUI Audio’s AMP1X1 single-channel audio amplifier board features an Analog Device’s MAX98309 Class AB mono amplifier circuit for maximum signal fidelity. We opted for a cost-effective Class AB amplifier over a Class D, despite Class D’s slightly higher efficiency. With most audio signals and a typical crest factor, especially for low-voltage amplifiers, the efficiency difference is minimal, and Class AB amplifiers simply deliver better sound quality.
This amplifier delivers 1.4W per channel into 8Ω loads and 2.1W per channel into 4Ω loads, both at 1% THD+N while using a 5V DC supply.
The board features a small size of 25.4mm x 25.4mm and comes with 100 mil spaced header pins for easy design prototype development.
This amplifier offers low, 1.8mA (typical, VDD = 5VDC), an excellent 110dB (typical) SNR, and high linearity expressed in its 0.008% THD+N. The amplifier features circuitry that produces high suppression of output transients when the power supply voltage is applied. Additionally, the amplifier’s power supply rejection ratio (PSRR) is an outstanding 90dB.
The AMP1X1’s amplifier’s closed-loop gain is set by the value of external resistors.
The AMP1X1’s amplifier features a pin-selectable 10ms or 100ms turn-on time. The board is set to a default 10ms turn-on time.
The AMP1X1’s amplifier is designed to differentially drive loads connected between the OUT+ and OUT- pins. The output is a bridge-tied-load (BTL) meaning that speaker terminals are directly connected across the output pins. In this configuration, none of a speaker’s terminals are connected to ground. This configuration has advantages over a single-ended, ground referenced load. Differential output drive doubles the output voltage across the load when compared by the drive voltage across a single-ended load. Doubling the voltage applied across a load quadruples the power dissipated by the load. Additionally, this configuration eliminates the high value coupling capacitor that is necessary for single-supply, single-ended-output audio amplifiers .
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