5 W + 5 W Dual BTL Class-D Audio Amplifier

Rajkumar Sharma
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SKU: EL112770
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The project described here is a high-efficiency dual BTL class-D audio amplifier with single supply operations. The project was built using TDA7491LP13TR from ST. The low profile PCB design can fit in a small area, operating power supply 9-12V DC, Project supports single-ended or differential audio signal inputs. Jumpers are provided to set the various gains, standby, and mute functions.

Key Features

5W + 5W Continuous Output Power, 10% THD, (8 Ohms Speaker) at 9V DC
Single Supply Operation 9V to 12V
Four Selectable Fixed Gains Settings of nominally 20dB, 26dB, 30dB, 32dB Using Jumpers
Differential Inputs Minimize Common-Mode Noise
Jumper for Single-Ended Inputs
No “Pop” Sound at Turn-On/Off
Thermal Over Load Protection
Standby and Mute Features Using Jumpers
PCB Dimensions 63.25 x 32.39 mm

Mode Selection

There are three operating modes defined bellow:

Standby mode: all circuits are turned off, very low current consumption
Mute mode: inputs are connected to the ground and the positive and negative PWM outputs are at 50% duty cycle.
Play mode: the amplifiers are active

Jumper Setting Standby, Mute and Play Mod (Low=GND, High=3.3V)

Standby Mode: Jumper J2 =Low, Jumper J1 (Don’t Care Whether low or high)
Mute Mode: Jumper J2=High, Jumper J1 Low
Play Mode: Jumper J2 = High, Jumper J1 High

Audio Signal Input (Single-Ended or Differential) Differential audio signal can be feed directly to CN1 , PIN 1 to 4

Pin 1 >> IA +Input A Channel, Pin 2>> AN -Input A Channel
Pin 3 >> NB +Input B Channel, Pin 4>> BN -Input B Channel
For Single Ended Input Solder Jumper J5 and J6 (Channel A Input Pin1 Signal and Pin 2 GND, Channel B Pin3 Signal and Pin 4 GND)

Gain Setting (PCB Solder Jumper J3 and J4)

The gain of the TDA7491LP is set by the two inputs, GAIN0 (pin 30) and GAIN1 (pin 31). Internally, the gain is set by changing the feedback resistors of the amplifier.

J3>>Low, J4>>Low =20dB (High=3.3V, Low=GND)
J3>>Low, J4>>High =26dB (High=3.3V, Low=GND)
J3>>High, J4>>Low =30dB (High=3.3V, Low=GND)
J3>>High, J4>>High =32dB (High=3.3V, Low=GND)

Schematic

Parts List

NO.	QNTY.	REF.	DESC.	MANUFACTURER	SUPPLIER	SUPPLIER PART NO

NO.	QNTY.	REF.	DESC.	MANUFACTURER	SUPPLIER	SUPPLIER PART NO
1	1	CN1	4 PIN MALE HEADER PITCH 2.54MM	WURTH	DIGIKEY	732-5317-ND
2	3	C1,C5,C28	10uF/25V SMD SIZE 1206	MURATA/YAGEO	DIGIKEY
3	2	C2,C7	2.2uF/16V SMD SIZE 0805	MURATA/YAGEO	DIGIKEY
4	11	C3,C4,C6,C8,C10,C14	0.1uF/50V SMD SIZE 0805	MURATA/YAGEO	DIGIKEY
		C17,C22,C24,C29,C30	0.1uF/50V SMD SIZE 0805	MURATA/YAGEO	DIGIKEY
5	6	C9,C12,C15,C18,C19,C23	0.22uF/25V SMD SIZE 0805	MURATA/YAGEO	DIGIKEY
6	4	C11,C16,C20,C25	1KPF/50V SMD SIZE 0805	MURATA/YAGEO	DIGIKEY
7	2	C13,C21	330PF/50V SMD SIZE 0805	MURATA/YAGEO	DIGIKEY
8	2	C26,C27	1uF/25V SMD SIZE 0805	MURATA/YAGEO	DIGIKEY
9	1	C31	1000uF/16V ELECTROLYTIC	VISHAY	DIGIKEY	56-MAL217055102E3-ND
10	4	J1,J2	3 PIN MALE HEADER PITCH 2.54MM	WURTH	DIGIKEY	732-5316-ND
11	2	J5,J6	PCB SOLDER JUMPER
12	2	LS1,LS2	4 PIN MALE HEADER PITCH 2.54MM	WURTH	DIGIKEY	732-5317-ND
13	4	L1,L2,L3,L4	33uH/1.4A	BOURNS	DIGIKEY	SRN6045-330MCT-ND
14	1	R1	220E 5% SMD SIZE 1206	MURATA/YAGEO	DIGIKEY
15	2	R2,R3	33K 5% SMD SIZE 0805	MURATA/YAGEO	DIGIKEY
16	1	R4	150E 5% SMD SIZE 1206	MURATA/YAGEO	DIGIKEY
17	3	R5,R6,R9	22E 5% SMD SIZE 0805	MURATA/YAGEO	DIGIKEY
18	1	R7	39K 5% SMD SIZE 0805	MURATA/YAGEO	DIGIKEY
19	1	R8	100K 5% SMD SIZE 0805	MURATA/YAGEO	DIGIKEY
20	3	R10,R11,R13	FERRITE-BEAD SMD SIZE 0805	MURATA	DIGIKEY	490-18596-1-ND
21	1	R12	DNP
22	1	U1	LM117-3.3V	TI	DIGIKEY	LM1117MP-3.3/NOPBCT-ND
23	1	U2	TDA7491LP13TR	ST	DIGIKEY	497-11056-1-ND
24	2	SHUNT FOR J1 AND J2	JUMPPER SHUNT	SULLINS	DIGIKEY	S9001-ND
25	2	J3,J4 SOLDER JUMPER	SOLDER JUMPER		DIGIKEY