TAS5782M: TAS5782M minimum Speaker load rating

Kazuki Kuramochi

Part Number: TAS5782M

Hello Expert,

I have 2 questions for minimum speaker load of TAS5782M.

1. Ordinary speaker has 20% tolerance. Do minimum speaker load on datasheet consider of speaker tolerance? For example, datasheet said 3ohm, however true minimum load is 2.4 ohm (= 3ohm x (100%-20%)).

2. Do minimum speaker load change depending on Po?(e.g. minimum speaker load decrease as Po is low)

I'm looking forward hearing back from you.

Best regards,

Kazuki Kuramochi

over 6 years ago

0 Matthew Miao over 6 years ago

TI__Expert 6720 points

Hi Kazuki,

Regarding the minimum speaker load of TAS5782M, the main concern is not to trigger 7.5A OCE (overcurrent error threshold) during normal audio playing. So it means PVDD / Speaker Load / Output power / LC filter selection / PWM switching frequency will influence the ripple output current through FETs (the same current via inductor)

Datasheet 3ohm (BTL) and 2ohm (PBTL) is the most critical situation requirement. Could you provide the above information? Then we can roughly calculate whether it is acceptable. What's more, we can also use EVM or system board to measure inductor current to judge the margin.

Rdgs,

Matthew

0 Kazuki Kuramochi over 6 years ago in reply to Matthew Miao

TI__Genius 10765 points

Hi Mathhew,

Thank you for your support.
Minimum output load is defined by OCE threshold. So minimum output load is typical value and the value is fluctuate depending on PVDD, Speaker Load, Output power, output filter setting, and etc. Is this understanding correct?

By the way, If you have the documents or information for roughly calculation whether output load is acceptable, would you provide me?

0 Matthew Miao over 6 years ago in reply to Kazuki Kuramochi

TI__Expert 6720 points

Hi Kazuki,

Your understanding is correct. There is no precise calculation document, and you can refer following rough TINA model for LC ripple current.

12V PVDD / 768kHz / 4.7uH+0.68uF / 3ohm load

Rdgs,

Matthew

0 Kazuki Kuramochi over 6 years ago in reply to Matthew Miao

TI__Genius 10765 points

Hi Matthew,

Thank you for your prompt reply and clearly description.

I found below thread on E2E.
e2e.ti.com/.../509034

This thread mentioned we usually assume a 20% variance regarding minimum output load. How about TAS5782M?

Best regards,
Kazuki Kuramochi

0 Matthew Miao over 6 years ago in reply to Kazuki Kuramochi

TI__Expert 6720 points

Hi Kazuki,

TAS5782M is the same situation, which means around 20% variance.

Rdgs,
Matthew

0 Kazuki Kuramochi over 6 years ago in reply to Matthew Miao

TI__Genius 10765 points

Hi Matthew,

Thank you for your strong support.
All questions have been resolved.

Best regards,
Kazuki Kuramochi

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TAS5782M: TAS5782M minimum Speaker load rating