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SSM3302 to drive 3ohm 3.5W speaker in mono mode

Question asked by MaheshHM on Jul 25, 2014
Latest reply on Jul 28, 2014 by DaveThib


We would like to use SSM3302 in our application to drive a 3 ohm speaker.

The specification of the speaker is 3.5W 3ohm speaker.We also have a requirement of THD+N <1% @ 3.5W operation.



(1)Can SSM3302 support 3 ohm speaker in parallel BTL(mono mode) configuration?

(2 ohm speaker is supported in mono mode is given in data sheet).

(2)From the data sheet we infer that for test conditions of "RL = 2 Ω, THD = 1%, f = 1 kHz, 20 kHz BW, PVDD = 7 V (mono mode)".Typical power output power/channel is 9.4W.So in mono mode typical output power being (2X9.4W) will damage our 3.5W speaker.

(3)Can avoid this by adjusting the gain from CODEC and SSM3302 and keeping the output power <3.5W.The gain control available for this audio path in our design is as follows:

The input to SSM3302 will be a line-out from a CODEC with minimum differential swing of 1.7Vrms @ 0dB.

The gain is adjustable between 6dB to -52dB in steps of 2dB from the CODEC.SSM3302 has least gain of 9dB.

With these specs can we use SSM3302 to drive a load of 3.5W 3ohm speaker by adjusting the gain?