HT66FV1x0 Integrated Audio Amplifier Application Guideline
AN0486EN V1.10
7 / 16
June 8, 2021
Hardware Description
The HT66FV1x0 MCU includes an integrated voice playing controller and voice data stored in an
external SPI Flash ROM can be read via the integrated SPI interface. This makes voice content
changes more convenient. A complete 5V application circuit is shown below.
AVDD_PA is connected to the V
CC
power and AVSS_PA is the power amplifier ground pin. SP+
and SP- are externally connected to a speaker. AUD is the DAC output pin and AUD_IN is the
power amplifier input pin. The audio signal output on the AUD pin will first be filtered by a low-
pass RC filter and then input to the AUD_IN pin via capacitive coupling. Whether to connect a
variable resistor to AUD/AUD_IN is optional according to the desired volume control method. A
10µF capacitor is connected to the BIAS pin for bias reference voltage stabilisation and filtering.
Pin
Description
SP+
Power amplifier output positive end
SP-
Power amplifier output negative end
AUD_IN
Power amplifier input
BIAS
Power amplifier internal reference voltage
AUD
16-bit DAC output
AVDD_PA
Power amplifier positive power supply
AVSS_PA
Power amplifier negative power supply
PCB Layout Considerations
When placing components, priority should be given to the power supply filter capacitors which
should be located as close to the MCU as possible. This is also the case for the SPI Flash ROM
and especially the SPI clock line which should be as short as possible.
To avoid noise interference caused by instantaneous large currents during audio amplifier
operations, two separate power supplies are required, VDD for digital power and AVDD_PA
for analog power.
