LP3961 datasheet(12/20 Pages) NSC

12 / 20 page

Applications Information (Continued)

Sense Pin

In applications where the regulator output is not very close to

the load, LP3964 can provide better remote load regulation

using the SENSE pin.

Figure 2 depicts the advantage of the

SENSE option. LP3961 regulates the voltage at the output

pin. Hence, the voltage at the remote load will be the regula-

tor output voltage minus the drop across the trace resis-

tance. For example, in the case of a 3.3V output, if the trace

resistance is 100m

Ω, the voltage at the remote load will be

3.22V with 800mAmps of load current, I

LOAD. The LP3964

regulates the voltage at the sense pin. Connecting the sense

pin to the remote load will provide regulation at the remote

load, as shown in

Figure 2. If the sense option pin is not re-

quired, the sense pin must be connected to the V

OUT pin.

Shutdown Operation

A CMOS Logic level signal at the shutdown ( SD) pin will

turn-off the regulator. Pin SD must be actively terminated

through a 10k

Ω pull-up resistor for a proper operation. If this

pin is driven from a source that actively pulls high and low

(such as a CMOS rail to rail comparator), the pull-up resistor

is not required. This pin must be tied to Vin if not used.

DS101129-7

FIGURE 1. Error Flag Operation

DS101129-8

FIGURE 2. Improving remote load regulation using LP3964

LP3961 データシート(PDF) 12 Page - National Semiconductor (TI)