ADS7811U/1K datasheet by Texas Instruments

ADS7811U/1K Frequently Asked Questions (FAQs)

• What is the recommended layout and routing for the ADS7811U/1K to minimize noise and ensure accurate conversions?
  Texas Instruments recommends a 4-layer PCB with a dedicated analog ground plane, and to keep the analog and digital signals separate. The analog input traces should be short and direct, and the digital output traces should be routed away from the analog inputs. Additionally, decoupling capacitors should be placed close to the device's power pins.
• How do I handle the device's power-on reset (POR) and what is the recommended power-up sequence?
  The ADS7811U/1K has a built-in POR circuit that resets the device when the power supply voltage rises above 1.5V. To ensure proper operation, the power supply voltage should be ramped up slowly (less than 10ms) and the digital interface should not be accessed until the power supply voltage has reached its nominal value.
• What is the maximum sampling rate that can be achieved with the ADS7811U/1K, and how does it affect the device's power consumption?
  The maximum sampling rate of the ADS7811U/1K is 150kSPS. However, the device's power consumption increases with the sampling rate. At 150kSPS, the device consumes around 15mW, while at lower sampling rates (e.g. 10kSPS), the power consumption is around 5mW.
• How do I calibrate the ADS7811U/1K to achieve the best possible accuracy, and what are the recommended calibration procedures?
  The ADS7811U/1K has an internal calibration circuit that can be used to calibrate the device. The recommended calibration procedure involves applying a known input voltage and adjusting the device's internal calibration registers to achieve the best possible accuracy. Texas Instruments provides a calibration procedure in the device's datasheet and application notes.
• What are the limitations of the ADS7811U/1K's internal reference voltage, and when should an external reference voltage be used?
  The ADS7811U/1K's internal reference voltage has a tolerance of ±1.5% and can be affected by temperature and power supply voltage variations. If a higher accuracy is required, an external reference voltage should be used. The external reference voltage should be connected to the device's REF pin and should be within the range of 2.5V to 5.5V.