JAJSDU5A August 2017 – February 2020 ADS114S06B , ADS114S08B
PRODUCTION DATA.
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The ADC integrates a precision, low-drift, 2.5-V reference. The internal reference is enabled by setting REFCON[1:0] to 10 (reference is always on) or 01 (reference is on, but powers down in power-down mode) in the reference control register (05h). By default, the internal voltage reference is powered down. To select the internal reference for use with the ADC, set the REFSEL[1:0] bits to 10. The REFOUT pin provides a buffered reference output voltage when the internal reference voltage is enabled. The negative reference output is the REFCOM pin; see Figure 45. Connect a capacitor in the range of 1 μF to 47 μF between REFOUT and REFCOM. Larger capacitor values help filter more noise at the expense of a longer reference start-up time.
The capacitor is not required if the internal reference is not used. However, the internal reference must be powered on if using the IDACs.
The internal reference requires a start-up time, as shown in Table 4, that must be accounted for before starting a conversion.
REFOUT CAPACITOR | SETTLING ERROR | SETTLING TIME (ms) |
---|---|---|
1 µF | 0.01% | 4.5 |
0.001% | 5.9 | |
10 µF | 0.01% | 4.9 |
0.001% | 6.3 | |
47 µF | 0.01% | 5.5 |
0.001% | 7.0 |