Thermal protection, Gain setting via gain0 and gain1 inputs – Texas Instruments TPA3200D1 User Manual
Page 21
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THERMAL PROTECTION
THERMAL CONSIDERATIONS: OUTPUT POWER AND MAXIMUM AMBIENT TEMPERATURE
T
Amax
+
T
Jmax
* q
JA
P
Dissipated
where : T
Jmax
+
150
Ę
C
q
JA
+
1
deratingfactor
+
1
0.0391
+
25.6
Ę
C
(2)
Efficiency
+ X
85% for an 8−
W
load
P
Dissipated
+
P
O(average)
ǒ
1
Efficiency
*
1
Ǔ
Efficiency
+ X
75% for an 4−
W
load
(3)
P
Dissipated
+
20 W
ǒ
1
0.85
*
1
Ǔ
+
3.53 W
T
Amax
+
150
Ę
C
*
(25.6
Ę
C
ń
W
1.76 W)
+
59.6
Ę
C
(4)
GAIN SETTING VIA GAIN0 AND GAIN1 INPUTS
TPA3200D1
SLOS442A – MAY 2005 – REVISED JULY 2005
Thermal protection on the TPA3200D1 prevents damage to the device when the internal die temperature
exceeds 150°C. There is a ±15°C tolerance on this trip point from device to device. Once the die temperature
exceeds the thermal set point, the device enters into the shutdown state and the outputs are disabled. This is not
a latched fault. The thermal fault is cleared once the temperature of the die is reduced by 15°C. The device
begins normal operation at this point with no external system interaction.
To calculate the maximum ambient temperature,
Equation 2
is used:
The derating factor for the 44-pin DCP package is given in the dissipation rating table.
To estimate the power dissipation,
Equation 3
is used:
Example. What is the maximum ambient temperature for an application that requires the TPA3200D1 to drive
20 W into an 8-
Ω
speaker?
This calculation shows that the TPA3200D1 can drive 20 W of RMS power into an 8-
Ω
speaker up to a maximum
ambient temperature rating of 60°C.
The gain of the TPA3200D1 is set by two input terminals, GAIN0 and GAIN1. See
.
Table 6. Gain Settings
AMPLIFIER GAIN
Output Voltage with Full Scale Input
(dB)
and V
DD
=5 V (V
RMS
)
GAIN1
GAIN0
TYP
TYP
0
0
12
5.63
0
1
18
11.23
1
0
23.6
21.4
(1)
1
1
Reserved
Reserved
(1)
Output clipping with V
CC
= 18 V
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