SBVS342A February 2019 – March 2019 TPS7A16A-Q1
Use resistors in the order of MΩ to keep the overall quiescent current of the system as low as possible (by making the current used by the resistor divider negligible compared to the quiescent current of the device).
If greater voltage accuracy is required, take into account the voltage offset contributions as a result of feedback current and use 0.1% tolerance resistors.
Table 2 shows the resistor combination to achieve an output for a few of the most common rails using commercially available 0.1% tolerance resistors to maximize nominal voltage accuracy, while adhering to the formula shown in Equation 1.
|VOUT||R1||R2||VOUT/(R1 + R2) « IQ||NOMINAL ACCURACY|
|1.194 V||0 Ω||∞||0 µA||±2%|
|1.8 V||1.18 MΩ||2.32 MΩ||514 nA||±(2% + 0.14%)|
|2..5 V||1.5 MΩ||1.37 MΩ||871 nA||±(2% + 0.16%)|
|3.3 V||2 MΩ||1.13 MΩ||1056 nA||±(2% + 0.35%)|
|5 V||3.4 MΩ||1.07 MΩ||1115 nA||±(2% + 0.39%)|
|10 V||7.87 MΩ||1.07 MΩ||1115 nA||±(2% + 0.42%)|
|12 V||14.3 MΩ||1.58 MΩ||755 nA||±(2% + 0.18%)|
|15 V||42.2 MΩ||3.65 MΩ||327 nA||±(2% + 0.19%)|
|18 V||16.2 MΩ||1.15 MΩ||1038 nA||±(2% + 0.26%)|
Close attention must be paid to board contamination when using high-value resistors; board contaminants can significantly impact voltage accuracy. If board cleaning measures cannot be ensured, consider using a fixed-voltage version of the TPS7A16A-Q1 or using resistors in the order of hundreds or tens of kΩ.