LP3961 Datasheet, PDF (12/20 Pages) National Semiconductor (TI) – 800mA Fast Ultra Low Dropout Linear Regulators

Applications Information (Continued)
FIGURE 1. Error Flag Operation
DS101129-7
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 100mΩ, 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.
FIGURE 2. Improving remote load regulation using LP3964
DS101129-8
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 10kΩ 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.
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