TPA3132D2: Audio forum

ARSIRSN

Part Number: TPA3132D2
Other Parts Discussed in Thread: TPA3128D2, TAS5805M

If the speaker transducer has been chosen as 2 ohms @ 25 watt or @ 20 watt . Is the TPA3132D2 good choose to drive this transducer ?

( I assume we can use the 19V as VPP input )

Since checking from datasheet

1. it mentions 2 × 25 W into a 8-Ω BTL Load at 19 V ;

2. Section 6.3 ; mentions about the minimum load impedance requirement as BTL structure w/ 3.2 ohms above and PBTL w/ 1.6 ohms above .

Would you please help answer what is the majority factor to impact the load impedance selection ( 2 ohms )? And how to calculate ? Thanks

ARSIR

over 5 years ago

0 Matthew Miao over 5 years ago

TI__Expert 6720 points

Hi,

Lower impedance transducer is going to bring performance attenuation with ClassD:

Lower efficiency. (Rdson drain-source on-state resistance voltage divider)
Worse PCB thermal. (especially for larger Rdson devices with lower thermal resistance)
Overcurrent risk. (19V, 2ohm load, easy to hit 9.5A for burst audio)

Based on above concerns, it's highly suggested to use 4ohm speaker, and TPA3128D2 is preferred. Because it has lower Rdson (90mohm vs 120mohm), larger Overcurrent threshold (7.5A vs 7A), and better thermal resistance (22C/W vs 31.3C/W)

Regards,

Matthew

0 ARSIRSN over 5 years ago in reply to Matthew Miao

Prodigy 50 points

Hi Matthew ,

Thanks for your answer above , it's really help me to understand which amplifier specifications I need to check if it complies and meets amplifier's capability.

I agreed your suggestion of TPA3128D2 is better one solution than TPA3132D2 from over current /thermal perspective .

I want to clarify the calculation of the 3rd item you mentioned --> (Overcurrent risk. (19V, 2ohm load, easy to hit 9.5A for burst audio)

1. Could you address this calculation more detail ?

2. Any calculator for quick check for design parameters ?

Note: If I used the calculator of link below ( With the 20 Watt continuous speaker power as our application intention and 8 ohms )

* As the TPA3231D2 datasheet said : 2x 25W into 8 ohms BTL load @19V

https://geoffthegreygeek.com/amplifier-power-voltage-and-current-calculator/ , seems there is not such larger current as you said , maybe there are my misunderstanding about the calculator , is it due to BTL connection or ?

Please advise. Thanks again for your input if any.

ARSIR.

0 Matthew Miao over 5 years ago in reply to ARSIRSN

TI__Expert 6720 points

Hi Arsir,

My previous calculation is based on 2ohm load / 19V, so the easy current estimation is 19/2=9.5A.

As for several current estimations, it's suggested to refer below TAS5805M datasheet 10.1.2 inductor selection part current calculation:

Regards,

Matthew