Hi,
Please help me to understand below two queries.
- I would like to understand the reason behind the recommendation of bulk capacitor 470uh for both VCC pins of tpa3121d2 audio amplifier, shall we use lower capacitance instead since we are using controlled 24V supply which has tolerance of 5% only to power the audio amplifier.
- We are using only the Left speaker output hence I am assuming one bulk capacitor would be enough on the VCC line, please advise.
-
We have seen that Power dissipation is 0.8W for 4W output power and 0.64W for 8W output power, please correct me if our calculation is wrong.
Current readings are measured values on the evaluation board with 8 ohms load and audio amplifier is powered with 24V supply.
TPA3121D2 @ 4W
TPA3121D2 @ 8W
Output Power requirement ( in W) Pout
4.00
8.00
Supply Voltage (in V) Vs
24.00
24.00
Supply Current (in A) Is
0.20
0.36
Input Power Ps = Vs* Is
4.80
8.64
Power Dissipation in Audio PD =Ps - Pout
0.80
0.64
efficiency (in %)
83.33
92.59
TA in °C
85.00
85.00
TJ in °C
127.50
127.50
Θja( Junction-to- ambient as per DATASHEET) (in °C/ W)
30.90
30.90
Θja( Junction-to- case as per DATASHEET) (in °C/ W)
29.60
29.60
Θja( Junction-to- board as per DATASHEET) (in °C/ W)
9.00
9.00
Temperature Rise (in °C)
23.68
18.94
Total Junction Temp. (in °C)
108.68
103.94
