AS1701-T 查看數據表（PDF） - austriamicrosystems AG
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AS1701-T Datasheet PDF : 17 Pages
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AS1701, AS1706
Data Sheet - Application Information
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
+1
VOUT(P-P)
2 x VOUT(P-P)
-1
VOUT(P-P)
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:
RF
AVD = 2 x
RIN
(EQ 2)
Substituting 2 x VOUT(P-P) into (EQ 3) and (EQ 4) yields four times the output power due to doubling of the output volt-
age.
VOUT(P-P)
VRMS =
22
(EQ 3)
POUT = VRMS2
RL
(EQ 4)
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:
TJ(MAX) -TA
PDISSPKF(MAX) =
ΘJA
(EQ 5)
where TJ(MAX) is +150°C, TAMB (see Table 2) is the ambient temperature, and ΘJA is the reciprocal of the derating fac-
tor in °C/W.
The increased power delivered by a BTL configuration normally results in increased internal power dissipation versus
a single-ended configuration. The maximum internal power dissipation for a given VDD and load is calculated by:
PDISSPKF(MAX) = 2VDD2
π2RL
(EQ 6)
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Revision 1.52
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