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LM4780 bridged amplifier by using 4 amps

toshi-e2e
Genius 4705 points
Other Parts Discussed in Thread: LM3886

Hi! all,

According to the datasheet, LM4780 is possible to configure a parallel amplifier by using two or more amps.
Is it possible to configure a bridge amplifier by using two bridge amplifiers or two parallel amplifiers?
If yes, is it possible to drive 4-ohm impeadance?

Regards,
Toshi

  • 0
    TI__Guru**** 189399 points

    Hi, Toshi,

    Unfortunately, I don't have any information on that.

    I have asked a colleague who might have more information to comment.

    -d2

  • 0
    TI__Intellectual 1240 points

    Hello Toshi-san,

    I'll make some comments on LM4780 bridge.Parallel driving configuration.

    Yes, it is possible to configure both case-1 and case 2 for driving 4 ohms load.

    LM4780 is 2 chip in one pkg type device. LM4780 has 2 x LM3886 in a pkg.

    LM3886 or LM4780 can drive 4 ohms load but it depend on supply voltage and heat sink

    thermal resistance value and max Ta. . If customer’s supply voltage is high, the PD will be large,

    Then I’ll recommend parallel drive to sprit the thermal, but the supply voltage is not so high and

    Low thermal resistance heat sink are used then 1 LM4780 bridged configuration will be OK to drive 4 Ohms.

    I attached referenced ckt for bridged/parallel configuration as below.

    You will need to put ballast resistor about 0.1 ohm on each amplifier outputs.

    If the customer is very much worried about Vos and Iq increase due to each amps Vos,

    I’ll recommend to take DC serve configuration as attached below.

      2451.BTL-Parallel Configuration.docx

    Hope this info will help for you .

    T NAOKAWA