LP3873_15 Datasheet, PDF (13/24 Pages) Texas Instruments – 3A Fast Ultra Low Dropout Linear Regulators

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LP3873, LP3876
SNVS220E – NOVEMBER 2002 – REVISED APRIL 2013
COMPx
low clamp
+
-
+
-
high clamp
0.45V
SS:0.55V
OP:2V
Figure 23. Error Flag Operation
SENSE PIN
In applications where the regulator output is not very close to the load, LP3876 can provide better remote load
regulation using the SENSE pin. Figure 24 depicts the advantage of the SENSE option. LP3873 regulates the
voltage at the output pin. Hence, the voltage at the remote load will be the regulator output voltage minus the
drop across the trace resistance. For example, in the case of a 3.3V output, if the trace resistance is 100mΩ, the
voltage at the remote load will be 3V with 3A of load current, I_LOAD. The LP3876 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 24. If the sense option pin is not required, the sense pin must be connected to the V_OUT pin.
Figure 24. Improving remote load regulation using LP3876
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.
DROPOUT VOLTAGE
The dropout voltage of a regulator is defined as the minimum input-to-output differential required to stay within
2% of the nominal output voltage. For CMOS LDOs, the dropout voltage is the product of the load current and
the Rds(on) of the internal MOSFET.
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Product Folder Links: LP3873 LP3876
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