7.3.9 Current Sense

There are two methods to sense the inductor current of the buck converter. The first is using current sense resistor in series with the inductor and the second is to use the DC resistance of the inductor (DCR sensing). Figure 24 illustrates inductor current sensing using a current sense resistor. This configuration continuously monitors the inductor current providing accurate current-limit protection. For the best current-sense accuracy and over current protection, use a low inductance ±1% tolerance current-sense resistor between the inductor and output, with a Kelvin connection to the LM25141-Q1 sense amplifier.

If the peak differential current signal sensed from CS to VOUT exceeds 75 mV, the current limit comparator immediately terminates the HO output for cycle-by-cycle current limiting.

Equation 11.

where

• V_(CS) = 75 mV

I_OUT(MAX) is the overcurrent set-point which is set higher than the maximum load current to avoid tripping the overcurrent comparator during load transients. ΔI is the peak-peak inductor ripple current.

Figure 24. Current Sense