AN2583

Audio characteristics

13/18

2.2.6

Automotive example

An automobile is a great example of the benefits of bridging. The standard supply of 12 V

limits the load voltage unless an expensive DC-DC power supply is added to the system.

Thus, the maximum continuous power delivered to an 8 ohm speaker would be 2.25 W.

most cars will be operating at a little more than 12 V, usually somewhere in the range 13.6 to

For the circuit of Figure 12, again with 12 V and 8 ohms, the power calculation is

Bridging delivers 9 W, four times the previous case, as expected. And with a 4 ohm speaker,

the load power goes up to 18 W.

For maximum power in the 12 V automotive environment, bridging offers a low cost

alternative to expensive power supplies by increasing the available audio power by a factor

of 4. Combined with 4-ohm speakers, users can achieve outstanding audio performance at

moderate cost.

Similarly, in any environment where the voltage supply options are limited, bridging provides

a significant power improvement for a nominal increase in silicon.

W

25

.

2

64

144

R

8

V

P

L

2

DD

max

-

AV

-

L

=

=

=

W

9

16

144

R

2

V

P

L

2

DD

max

-

AV

-

L

=

=

=