ADAU1961 - headphone and line outputs in 'headphone mode' - min. load? Short circuit save?

Hello AndiB,

this part was designed a long time ago so I do not have any more information on this detail. I do know that the THD performance will start to suffer the lower the load impedance and the outputs will have some short circuit protection but I do not think it was designed for a sustained constant over current situation. I do not think this is the right part for what you want to do. We have many other class-D amplifiers that can drive 4 ohms and are protected from shorts and thermal overloads. 

What are the needs of your application?

What is the power supply voltage for PVDD and IOVDD?

How much power output are you looking for?

How do you want to drive it? An analog signal? PDM or I2S for input into the amp?

Dave T

Hello Dave,

thanks for your response.

Power supply is 3.3V (all supplies).

For one of our devices we need about 50mW (not exactly defined yet). It's a sort of telephone handset. Source is I2S from an application processor which get it's audio data via LAN. We use the microphone inputs, line inputs, line outputs and with one device we drive a small speaker (handset). Audio performance requirements are very low. I can easily check THDN, noise, dynamic, .... once we build up a prototyp. But I'm sure every ADAU can easily fullfill our requirements :-).

Of course we don't wanna short circuit the output in regular operation. But the (mini-)speaker is connected with a short wire. I want to protect the ADAU1961 output in case of faulty speaker or short circuit of the wire/connector.

Currently we use a competitors part which we wanna replace by the ADAU1961 in future. The competitors part data sheet states it can drive 8 Ohm between differntial outputs (16 Ohm for ADAU). It also states the part includes a thermal shutdown which protects the device in case of short circuit. I didn't find similiar notes in the ADAU datasheet. Hence my questions.

To be on the save side I can put in a 16 Ohm series resistor. But then I waste a most of output power at the series resistor. To maximise power at the speaker (8 Ohm) I want ot keep the series resistor as small as possible. Question is how small can I make the series resistor to protect the ADAU. Guess way smaller than 16 Ohms, but... Thanks.

Hello Dave,

thanks for your response.

Power supply is 3.3V (all supplies).

For one of our devices we need about 50mW (not exactly defined yet). It's a sort of telephone handset. Source is I2S from an application processor which get it's audio data via LAN. We use the microphone inputs, line inputs, line outputs and with one device we drive a small speaker (handset). Audio performance requirements are very low. I can easily check THDN, noise, dynamic, .... once we build up a prototyp. But I'm sure every ADAU can easily fullfill our requirements :-).

Of course we don't wanna short circuit the output in regular operation. But the (mini-)speaker is connected with a short wire. I want to protect the ADAU1961 output in case of faulty speaker or short circuit of the wire/connector.

Currently we use a competitors part which we wanna replace by the ADAU1961 in future. The competitors part data sheet states it can drive 8 Ohm between differntial outputs (16 Ohm for ADAU). It also states the part includes a thermal shutdown which protects the device in case of short circuit. I didn't find similiar notes in the ADAU datasheet. Hence my questions.

To be on the save side I can put in a 16 Ohm series resistor. But then I waste a most of output power at the series resistor. To maximise power at the speaker (8 Ohm) I want ot keep the series resistor as small as possible. Question is how small can I make the series resistor to protect the ADAU. Guess way smaller than 16 Ohms, but... Thanks.