LM5145 datasheet(44/73 Pages) TI2

44 / 73 page

8.2.1.2.7 Feedback Resistors

Configure the dual outputs for fixed 5V and 3.3V voltage setpoints by tying the respective FB pins to VDDA

through 24.9kΩ and 7.5kΩ resistors, respectively.

Alternatively, use feedback resistor dividers values for 5V and 3.3V output voltage setpoints based on the 0.8V

feedback reference of the LM25137. Calculate the upper feedback resistors using Equation 39 assuming a value

of 15kΩ for the lower resistors.

(39)

Equation 40 calculates the resultant output voltage setpoints when using 78.7kΩ, 47kΩ and 15kΩ standard E192

0.5% resistor values.

(40)

In contrast to a fixed output option, installing a feedback resistor divider with a suitable series resistor, typically

50Ω, facilitates measurement of the loop gain characteristic as needed to characterize stability.

8.2.1.2.8 Input Voltage UVLO Resistors

Use Equation 41 and Equation 42 to calculate the input UVLO divider resistors, designated as RUV1 and RUV2

in Figure 7-2, given input turn-on and turn-off voltages specified as 6.5V and 4.5V, respectively. Use a 10kΩ

resistor in series with the applicable EN pin, designated as RUV3, to increase the effective voltage hysteresis

without using higher divider resistances.

(41)

(42)

Selecting standard 1% resistor values of 105kΩ and 19.1kΩ, calculate the actual input voltage turn-on and

turn-off setpoints using Equation 43.

LM25137

SNVSCU4 – OCTOBER 2025

www.ti.com

Submit Document Feedback

Product Folder Links: LM25137

LM5145 Datasheet(PDF) 44 Page - Texas Instruments