Capability of driving 2 vibrators

Hi Antony,

You can calculate the current drive from the information in the electrical characteristics. The total internal resistance (summed up) is 8ohms which is a voltage divider. So, the output at the pin is VBAT/2. You can use the vibra load on the output and calculate the current.

I hope this information will be helpful.

Regards,

Gandhar.

Hi Gandhar,

Thanks for the reply, but I didn't understand it well. 

You mention that the total internal resistance (summed up) is 8ohms, does it correspond to the parameter "Output resistance (summed for both sides)=8ohms" in DM?  What does it mean regarding "summed up"?  The sum of vibra.p & vibra.m?   And why the output voltage at either  vibra.p or vibra.m is VBAT/2?

So, do you mean the vibrator current  =  (VBAT/2) / (Vibrator resistance)  ?  Is there current limit for our chip?

Thanks,

Antony

Hi Antony,

Yes, sum is the  total load. It acts as a voltage divider and hence we calculate VBAT/2.

We have done tests for a typical 8ohm load. So, any load higher than this is going to be fine as the current will be lower.

What is the load of the vibra motor customer will use?

Regards,

Gandhar.

Hi Gandhar,

The load is 26(1+/-10%) ohm.

The Rated Voltage is 2.0Vrms Square wave or Sine wave, and the Operating Voltage range 1.7-2.3Vrms.

Therefore the Rated current (2.0Vrms 150Hz Square wave) is ≤88mArms, and the Starting current (3.2Vrms 150Hz Square wave) is ≤136mArms.

It seems current is ok, but how do you think about the voltage?  Is Vbat/2 ok?

Thanks,

Antony