Datasheet
Gain 1 +
V
O
V
I1
+ 2
150 kW
R
I1
ǒ
V
V
Ǔ
(11)
Gain 2 +
V
O
V
I2
+ 2
150 kW
R
I2
ǒ
V
V
Ǔ
(12)
C
I1
+
1
ǒ
2p R
I1
f
c1
Ǔ
(13)
C
I2
+
1
ǒ
2p R
I2
f
c2
Ǔ
(14)
C
P
+ C
I1
) C
I2
(15)
R
P
+
R
I1
R
I2
ǒ
R
I1
) R
I2
Ǔ
(16)
_
+
IN–
IN+
PWM H–
Bridge
V
O+
V
O–
Internal
Oscillator
C
S
To Battery
V
DD
GND
Bias
Circuitry
R
I2
R
P
Filter-Free Class D
SHUTDOWN
R
I1
Single-Ended
Input 2
C
I2
C
P
Single-Ended
Input 1
C
I1
EFFICIENCY AND THERMAL INFORMATION
q
JA
+
1
Derating Factor
+
1
0.016
+ 62.5°CńW
(17)
T
A
Max + T
J
Max * q
JA
P
Dmax
+ 150 * 62.5 (0.2) + 137.5°C
(18)
TPA2005D1
www.ti.com
............................................................................................................................................................... SLOS369F – JULY 2002 – REVISED JULY 2008
Figure 37. Application Schematic With TPA2005D1 Summing Two Single-Ended Inputs
The maximum ambient temperature depends on the heat-sinking ability of the PCB system. The derating factor
for the 2,5-mm x 2,5-mm MicroStar Junior package is shown in the dissipation rating table. Converting this to θ
JA
:
Given θ
JA
of 62.5 ° C/W, the maximum allowable junction temperature of 150 ° C, and the maximum internal
dissipation of 0.2 W (worst case 5-V supply), the maximum ambient temperature can be calculated with equation
Equation 18 .
Equation Equation 18 shows that the calculated maximum ambient temperature is 137.5 ° C at maximum power
dissipation with a 5-V supply; however, the maximum ambient temperature of the package is limited to 85 ° C.
Because of the efficiency of the TPA2005D1, it can be operated under all conditions to an ambient temperature
of 85 ° C. The TPA2005D1 is designed with thermal protection that turns the device off when the junction
temperature surpasses 150 ° C to prevent damage to the IC. Also, using speakers more resistive than 8- Ω
dramatically increases the thermal performance by reducing the output current and increasing the efficiency of
the amplifier.
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