MEMS devices

A method for protecting a MEMS transducer of a MEMS audio device from electrostatic capture, the method comprising:

• operating the MEMS transducer in a normal sensitivity mode of operation;
• detecting an overload signal indicative of an excessive sound pressure level at the MEMS transducer;
• in response to detecting the overload signal:
• disabling an output of the MEMS transducer;
• and
• after a delay of a predetermined period of time:
• re-enabling the output of the MEMS transducer;
• operating the MEMS transducer in a reduced-sensitivity mode of operation;
• while operating the MEMS transducer in the reduced-sensitivity mode, estimating a sound pressure level at the MEMS transducer;
• and
• if the sound pressure level at the MEMS transducer is below a safe sound pressure level threshold for a second predetermined period of time, returning the MEMS transducer to the normal sensitivity mode of operation.

A protection system for protecting a MEMS transducer from electrostatic capture, the protection system comprising:

• a charge pump configured to output a bias voltage to bias the MEMS transducer, wherein the charge pump is configured to operate in a first operating mode in which it outputs a first bias voltage and in a second operating mode in which it outputs a second bias voltage, wherein the second bias voltage is higher than the first bias voltage;
• a controller configured to control the operating mode of the charge pump;
• and
• a signal estimator configured to generate an estimate of a sound pressure level of a sound or pressure wave incident on the MEMS transducer,
• wherein the controller is operative to cause the charge pump to operate initially in the first operating mode;
• and
• wherein the controller is operative to cause the charge pump to switch from the first operating mode to the second operating mode if the estimate of the sound pressure level is below a safe sound pressure level threshold.