8.4.1 Hardware Shutdown

The device enters hardware shutdown mode when the SHDNZ pin is asserted low or the AVDD supply voltage is not applied to the device. In hardware shutdown mode, the device consumes the minimum quiescent current from the AVDD supply. All configuration registers and programmable coefficients lose their value in this mode, and I²C or SPI communication to the device is not supported.

If the SHDNZ pin is asserted low when the device is in active mode, the device ramps down volume on the record data, powers down the analog and digital blocks, and puts the device into hardware shutdown mode in 25 ms (typical). The device can also be immediately put into hardware shutdown mode from active mode if the SHDNZ_CFG[1:0], P0_R5_D[3:2], register bits are set to 2'b00. After the SHDNZ pin is asserted low, and after the device enters hardware shutdown mode, keep the SHDNZ pin low for at least 1 ms before releasing SHDNZ for further device operation.

Assert the SHDNZ pin high only when the IOVDD supply settles to a steady voltage level. When the SHDNZ pin goes high, the device sets all configuration registers and programmable coefficients to their default values, and then enters sleep mode.