AS1702_1 AMSCO [austriamicrosystems AG], AS1702_1 Datasheet - Page 13

• Manufacturer Part Number: AS1702_1
• Description: 1.8W Single-Channel Audio Power Amplifiers
• Manufacturer: AMSCO [austriamicrosystems AG]

AS1702 - AS1705
Data Sheet
BTL Amplifier
All devices are designed to drive loads differentially in a bridge-tied load (BTL) configuration.
Figure 32. Bridge Tied Load Configuration
The BTL configuration doubles the output voltage (illustrated in
similar conditions. Thus, the differential gain of the device (A
effective gain is given by:
Substituting 2 x V
the output voltage:
Since the BTL outputs are biased at mid-supply, there is no net DC voltage across the load. This eliminates 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
Continuous Power Dissipation, or it can be calculated by:
where T
tor in ºC/W as specified in
The increased power delivered by a BTL configuration results in an increase in internal power dissipation versus a sin-
gle-ended configuration. The maximum internal power dissipation for a given V
www.austriamicrosystems.com
J(MAX)
- A p p l i c a t i o n I n f o r m a t i o n
is +150ºC, T
OUT(P-P)
for V
Table
AMB
OUT(P-P)
(see
3. For example, Θ
Table
into (EQ 3) and (EQ 4) yields four times the output power due to doubling of
3) is the ambient temperature, and Θ
P
P
DISSPKF(MAX)
DISSPKF(MAX)
V
A
JA
RMS
P
+1
-1
VD
OUT
Revision 1.47
of the TQFN package is +59.2ºC/W.
= 2 x
=
=
V
=
=
OUT(P-P)
VD
V
2 2
RMS
R
R
2V
T
π
) is twice the closed-loop gain of the input amplifier. The
R
L
Figure
IN
J(MAX)
2
F
CC
R
Θ
2
L
JA
2
-T
32) compared to a single-ended amplifier under
A
CC
JA
V
2 x V
V
OUT(P-P)
OUT(P-P)
and load is given by:
is the reciprocal of the derating fac-
OUT(P-P)
Table 3
(EQ 2)
(EQ 3)
(EQ 4)
(EQ 5)
(EQ 6)
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