ZHCSM31B September 2020 – March 2022 ADC3660
PRODUCTION DATA
The digital output interface utilizes a flexible output bit mapper as shown in Figure 8-37. The bit mapper takes the 16-bit output directly from the ADC or from digital filter block and reformats it to a resolution of 14,16,18 or 20-bit. The output serialization factor gets adjusted accordingly for 2-, 1- and 1/2-wire interface mode. The maximum output data rate can not be exceeded independently of output resolution and serialization factor.
After power up the bit mapper output defaults to 18-bit and manually has to be programmed to 16-bit. See Section 8.3.5.5 for instructions.
For 14-bit the LSBs simply get truncated during the reformatting. With 18 and 20-bit output, bypass or decimation mode has 0s for the two LSBs while only the digital averaging mode utilizes the full 20-bit output.
Table 8-7 provides an overview for the resulting serialization factor depending on output resolution and output modes. Note that the DCLKIN frequency needs to be adjusted accordingly as well. Changing the output resolution to 18-bit, 2-wire mode for example would result in DCLKIN = FS * 4.5 instead of * 4.
OUTPUT RESOLUTION | Interface | SERIALIZATION | FCLK | DCLKIN | DCLK | DA/B5,6 |
---|---|---|---|---|---|---|
14-bit | 2-Wire | 7x | FS/2 | FS* 3.5 | FS* 3.5 | FS* 7 |
1-Wire | 14x | FS | FS* 7 | FS* 7 | FS* 14 | |
1/2-Wire | 28x | FS | FS* 14 | FS* 14 | FS* 28 | |
16-bit | 2-Wire | 8x | FS/2 | FS* 4 | FS* 4 | FS* 8 |
1-Wire | 16x | FS | FS* 8 | FS* 8 | FS* 16 | |
1/2-Wire | 32x | FS | FS* 16 | FS* 16 | FS* 32 | |
18-bit (default) | 2-Wire | 9x | FS/2 | FS* 4.5 | FS* 4.5 | FS* 9 |
1-Wire | 18x | FS | FS* 9 | FS* 9 | FS* 18 | |
1/2-Wire | 36x | FS | FS* 18 | FS* 18 | FS* 36 | |
20-bit | 2-Wire | 10x | FS/2 | FS* 5 | FS* 5 | FS* 10 |
1-Wire | 20x | FS | FS* 10 | FS* 10 | FS* 20 | |
1/2-Wire | 40x | FS | FS* 20 | FS* 20 | FS* 40 |
The programming sequence to change the output interface and/or resolution from default settings is shown in Section 8.3.5.5.