3W Stereo Differential Input CLASS-D Audio Amplifier with UP/DOWN Volume

  • Rajkumar Sharma
  • 1159
    Views
  • easy
  • Tested

The circuit presented here is a 3W stereo audio amplifier with memory UP/DOWN volume control. The project is based on PAM8408 IC from Diode Incorp which is a filter-less class-D amplifier with high SNR and Differential input which helps eliminate noise. Two tactile switches are provided to control the UP/DOWN volume in 32-steps and it will hold the setting when the chip is in shutdown mode. The operating supply is 2.5V to 6V DC and this supply range helps to operate it with batteries like the use of 4 x Alkaline batteries. The small PCB size, 87% efficiency, low cost, minimum external components make this project ideal for portable applications. The PAM8408 also has built-in auto-recovery SCP (Short Circuit Protection) and thermal shutdown. The circuit works with differential audio signal input. It is advisable to use shielded wire for the audio input signals. Jumper J3 is open in normal operation, and if you close it puts the amplifier into shutdown mode and the audio volume will memorize when shutdown mode is recovered. Solder jumpers J1 and J2 are optional and of no use, it is advisable to keep these jumpers open. Connector CN1 is for power supply, CN2 is for audio signal input, CN3, and CN4 are for the speaker, Jumper J3 is for Shutdown, D1 is the power LED, Switch 1 increased volume, and Switch 2 decreases volume.

Volume changes are affected by toggling either the UP or DOWN tactile switches. After a period of 1 cycle pulses with either the UP or DOWN switch press, the volume will change to the next specified step, either UP or DOWN, and followed by a short delay. This delay decreases the longer the line is held low, eventually reaching a delay of zero. The delay allows the user to pull the UP or DOWN terminal low once for one volume change, or hold down to ramp several volume changes. The delay is optimally configured for push-button volume control. If either the UP or DOWN pin remains low after the first volume transition the volume will change again, but this time after 10 cycles. The followed transition occurs at 4 cycles for each volume transition. This is intended to provide the user with volume control that pauses briefly after initial application, and then slowly increases the rate of volume change as it is continuously applied. There are 32 discrete gain settings ranging from +24dB as maximum to -80dB as a minimum. Upon device power on, the amplifier’s gain is set to a default value of 12dB, and the gain will remain when Shutdown Jumper J3 is closed.

Features

  • Operating Power Supply 5V (2.5V to 6V Range)
  • 2 x 3 W Power Output 4 Ohms Speaker @ 10% THD
  • Fully Differential Audio Signal Input for low noise operations
  • Onboard Shutdown Jumper J3
  • D1 Power LED
  • Ferrite Bead on outputs for Low EMI
  • 32-Step Memory Up/Down Volume Control from -80dB to 24dB
  • Low THD+N
  • Superior Low Noise: 60uV
  • Minimize Pop/Clip Noise
  • Auto Recovery Short Circuit Protection
  • Thermal Shutdown
  • PCB Dimensions 49.53 x 32.54 mm

Schematic

Parts List

NO.QNTY.REF.DESCMANUFACTURERSUPPLIERSUPPLIER PART NO
11CN14 PIN MALE HEADER 2.54MM PITCHWURTHDIGIKEY732-5317-ND
21CN26 PIN MALE HEADER 2.54MM PITCHWURTHDIGIKEY732-5319-ND
32CN3,J32 PIN MALE HEADER 2.54MM PITCHWURTHDIGIKEY732-5315-ND
41CN44 PIN MALE HEADER 2.54MM PITCHWURTHDIGIKEY732-5317-ND
52C1,C34.7uF/16V SMD SIZE1206MURATA/YAGEODIGIKEY
61C2470uF/16V or 25VUNICORNDIGIKEY565-2224-1-ND
74C4,C5,C6,C71uF/16V SMD SIZE 1206MURATA/YAGEODIGIKEY
81D1LED SMD SIZE 0805OSRAMDIGIKEY475-1278-1-ND
91J3JUMPER-SHUNTSULLINSDIGIKEYS9001-ND
101R11K 5% SMD SIZE 0805MURATA/YAGEODIGIKEY
114R2,R3,R4,R50E SMD SIZE 1206MURATA/YAGEODIGIKEY
121R60E SMD SIZE 0805MURATA/YAGEODIGIKEY
131SW14 PIN TACTILE SWITCHC&KDIGIKEYCKN9085TR-ND
141SW24 PIN TACTILE SWITCHC&KDIGIKEYCKN9085TR-ND
151U1PAM8408DIODE INCORPDIGIKEYPAM8408DRDICT-ND

Connections

Gerber View

Photos

Video

PAM8408 Datasheet

PAM8408-356125

PCB

Subscribe
Notify of
guest
0 Comments
Inline Feedbacks
View all comments

RELATED PROJECTS

X
Arduino Nano 33 IoT Giveaway

By continuing to use the site, you agree to the use of cookies. more info

The cookie settings on this website are set to "allow cookies" to give you the best browsing experience possible. If you continue to use this website without changing your cookie settings or you click "Accept" below then you are consenting to this.

Close