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AS1701, AS1706

9 Application Information

BTL Amplifier

The AS1701/AS1706 are designed to drive loads differentially in a bridge-tied load (BTL) configuration.

Figure 30. Bridge-Tied Load Configuration

Driving the load differentially doubles the output voltage (illustrated in Figure 30) compared to a single-ended amplifier

under similar conditions. Thus, the differential gain of the device is twice the closed-loop gain of the input amplifier. The

effective gain is calculated by:

age.

Since the differential outputs are biased at mid-supply, there is no net DC voltage across the load, eliminating the need

for the large, expensive, performance degrading DC-blocking capacitors required by single-ended amplifiers.

Power Dissipation and Heat Sinking

Normally, the devices dissipate a significant amount of power. The maximum power dissipation is given in Table 2 as

Continuous Power Dissipation, or it can be calculated by:

tor in °C/W.

The increased power delivered by a BTL configuration normally results in increased internal power dissipation versus

+1

-1

(EQ 2)

2 2

(EQ 3)

(EQ 4)

2

(EQ 5)

(EQ 6)

2