ZHCSLA4E May 2020 – October 2024 TPS61378-Q1
PRODUCTION DATA
The output voltage is determined by the resistor sensed from FB pin before device is enabled.
There are two ways to set the output voltage of the TPS61378-Q1, adjustable output voltage(for TPS61378-Q1 and TPS613783-Q1 only) and fixed output voltage.
Equation 4 shows that the output voltage setting is only influenced by RUP and RDOWN. In normal application, RINSERT can be 0Ω, that is, directly connect FB pin to middle point of feedback voltage divider.
For automotive application that do not prefer to use resistors more than 100 kΩ, RINSERT (>15kΩ) can be used so that calculated RUP and RDOWN feedback resistor value could be less than 100kΩ.When working with adjustable voltage, for the best accuracy, RDOWN is recommended to be smaller than 160 kΩ to ensure that the current flowing through RDOWN is at least 100 times larger than FB pin leakage current. Changing RDOWN towards the lower value increases the robustness against noise injection. Changing RDOWN to higher values reduces the quiescent current to achieve higher efficiency at light load.
Figure 8-3 shows the typical circuit of the FB pin conncetion for fixed output voltage.The FB resistor RFB is defined as Equation 5: