SNVSBJ0A December 2019 – June 2020 LM5170
The LM5170 monitors the real time inductor current in each channel at the IOUT1 and IOUT2 pins. The channel current is converted to a small current source scaled by the factors seen in Equation 11 and Equation 12:
The DC offset current is introduced to raise the no-load signal above the possible ground noise floor. Because the monitor signal is in the form of current, an accurate reading can be obtained across a termination resistor even if the resistor is located far from the LM5170 but close to the MCU, thus rejecting potential ground differences between the LM5170 and the MCU. Figure 24 shows a typical channel current monitor through a 9.09-KΩ termination resistor and a 10-nF to 100-nF ceramic capacitor in parallel. The RC network converts the current monitor signal into a DC voltage proportional to the channel DC current. For example, when the current sense voltage DC component is 50 mVdc, namely VCS_dc = 50 mV, the termination RC network will produce a DC voltage of 2.5 V. Note that the maximum IOUT pin voltage is internally clamped to approximately 4 V.