# Low power audio amp

#### tinusw7

Joined Dec 21, 2011
4
Hi
I have built an audio player based on the ATTiny85 and will run it with battery power. As the microcontroller does not deliver enough power for the speaker, I need an amplifier for the audio signal. When the player is not playing a song, it should consume almost no energy in order to have a long battery life. The microcontroller in sleep mode is no problem, but the amplifier quiet power consumption should be near 0 mA as well. The audio amplifier chips that I´ve found so far () have a quiet current of 4mA which is too high. Do you know a good low power audio amplifier solution? Thanks a lot for all advice.

Regards
Martin

#### jimkeith

Joined Oct 26, 2011
540

#### crutschow

Joined Mar 14, 2008
26,865
With the Maxim class D amp bertus suggested you just need to disable it when the μC is in the sleep mode. When disabled the amp only draws a few microamps.

#### tinusw7

Joined Dec 21, 2011
4
Thank you all for the info, will look closer to the Maxim chips (both of them).

/Martin

#### thatoneguy

Joined Feb 19, 2009
6,359
Here is a TPA3125D2N from DigiKey

$2.64 + cheap support components,Typical Circuit on page 1 of the datasheet 0.39mA quiescent current in shutdown/sleep mode TypeClass D Output Type1-Channel (Mono) or 2-Channel (Stereo) Max Output Power x Channels @ Load36W x 1 @ 8 Ohm; 10W x 2 @ 8 Ohm Voltage - Supply10 V ~ 26 V FeaturesDepop, Mute, Short-Circuit and Thermal Protection, Shutdown Mounting TypeThrough Hole Supplier Device Package20-PDIP Thread Starter #### tinusw7 Joined Dec 21, 2011 4 Thank you for the suggestion, looked good but then I realized that I forgot to say that the supply voltage is 3V, i.e. wont work with that one. Sorry for that but thanks anyway! Here is a TPA3125D2N from DigiKey$2.64 + cheap support components,Typical Circuit on page 1 of the datasheet

0.39mA quiescent current in shutdown/sleep mode

TypeClass D
Output Type1-Channel (Mono) or 2-Channel (Stereo)
Max Output Power x Channels @ Load36W x 1 @ 8 Ohm; 10W x 2 @ 8 Ohm
Voltage - Supply10 V ~ 26 V
FeaturesDepop, Mute, Short-Circuit and Thermal Protection, Shutdown
Mounting TypeThrough Hole
Supplier Device Package20-PDIP

#### thatoneguy

Joined Feb 19, 2009
6,359

No Through hole, but large surface mount is available

TDA749313

TypeClass D
Output Type2-Channel
Max Output Power x Channels @ Load3W x 2 @ 4 Ohm
Voltage - Supply3 V ~ 5.5 V
FeaturesDifferential Inputs, Short-Circuit and Thermal Protection, Shutdown
Mounting TypeSurface Mount
Supplier Device Package24-HTSSOP

#### tinusw7

Joined Dec 21, 2011
4
Yes, will remember that for the future

Thank you, this one looks really good, only 1uA standby current! I'll order this one and do some tests.

/Martin

No Through hole, but large surface mount is available

TDA749313

TypeClass D
Output Type2-Channel
Max Output Power x Channels @ Load3W x 2 @ 4 Ohm
Voltage - Supply3 V ~ 5.5 V
FeaturesDifferential Inputs, Short-Circuit and Thermal Protection, Shutdown
Mounting TypeSurface Mount
Supplier Device Package24-HTSSOP

#### skycarl

Joined Nov 16, 2011
1
That really is a nice amplifier. Kind of wants to make you put a circuit together just to
use it.

#### Audioguru

Joined Dec 20, 2007
11,249
The TDA7493 IC is rated only when its supply is 5V then its output power is 2.2W into 4 ohms at 1% distortion. It might barely have any output with a 3V supply and might have no output when the battery drops below 3V.