16-Bit, 16kSPS SD ADC

The L55CSD16B16K IP consists of a 16-bit mono audio ADC with fully differential 1-channel mono audio input, 4-channel general purpose (GP) inputs and a digital microphone input. It also has an analog front end consisting of a microphone bias generator and a wide-range PGA, which offers gains of up to 50dB, allows smaller signals to be measured with high resolution. Analog-to-digital (ADC) employ sigma-delta (SD) modulation with selectable oversampling. ADC includes a digital decimation filter. L55CSD16B16K supports left-justified, I2S compatible and TDM modes. Sampling rates up to 16 kHz are supported.

Figure 1 shows a functional diagram of the L55CSD16B16K. The SD ADC block consists of multiplexers, reference circuits, a fourth-order SD modulator with fully differential architecture and digital decimation filter. The input range of the ADC is limited to between the top-level reference voltage and the bottom-level reference voltage at GP.

Considering the sampling rate of 16kS/s with 1kHz input and full scale input range, the L55CSD16B16K features dynamic performance of the 90dB SNR at Analog Mic path (AMIC).