ZHCSQ26 May 2022 PCM1822
PRODUCTION DATA
The device integrates an ultra-low noise front-end DRE gain amplifier with 117-dB dynamic range performance with a low-noise, low-distortion, multibit delta-sigma (ΔΣ) ADC with a 111-dB dynamic range. The dynamic range enhancer (DRE) is a digitally assisted algorithm to boost the overall channel performance. The DRE monitors the incoming signal amplitude and accordingly adjusts the internal DRE amplifier gain automatically. The DRE achieves a complete-channel dynamic range as high as 117 dB. At a system level, the DRE scheme enables far-field, high-fidelity recording of audio signals in very quiet environments and low-distortion recording in loud environments.
The DRE can be enabled only in slave mode by driving the MD1 pin high. Table 8-20 shows the DRE selection for the record channel.
| MD1 | DRE SELECTION (Supported Only in Slave Mode) |
|---|---|
| Low | The DRE is disabled in slave mode. For master mode, the DRE is always disabled. |
| High | The DRE is enabled with DRE_LVL = –36 dB and DRE_MAXGAIN = 18 dB in slave mode. For master mode, the DRE is always disabled. |
This algorithm is implemented with very low latency and all signal chain blocks are designed to minimize any audible artifacts that may occur resulting from dynamic gain modulation. The target signal threshold level (DRE_LVL), at which the DRE is triggered, is fixed to the –36-dB input signal level. The DRE gain range can be dynamically modulated by using DRE_MAXGAIN, which is fixed to 18 dB to maximize the benefit of the DRE in real-world applications and to minimize any audible artifacts.
Enabling the DRE for processing increases the power consumption of the device because of increased signal processing. Therefore, disable the DRE for low-power critical applications. Furthermore, the DRE is not supported for output sample rates greater than 48 kHz.