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SLVS181H − DECEMBER 1998 − REVISED JANUARY 2004
APPLICATION INFORMATION
The TPS763xx low-dropout (LDO) regulators are new families of regulators which have been optimized for use in
battery-operated equipment and feature extremely low dropout voltages, low quiescent current (140 µA), and an enable
input to reduce supply currents to less than 2 µA when the regulator is turned off.
device operation
The TPS763xx uses a PMOS pass element to dramatically reduce both dropout voltage and supply current over more
conventional PNP pass element LDO designs. The PMOS pass element is a voltage-controlled device that, unlike a PNP
transistor, does not require increased drive current as output current increases. Supply current in the TPS763xx is
essentially constant from no-load to maximum load.
Current limiting and thermal protection prevent damage by excessive output current and/or power dissipation. The device
switches into a constant-current mode at approximately 1 A; further load reduces the output voltage instead of increasing
the output current. The thermal protection shuts the regulator off if the junction temperature rises above 165°C. Recovery
is automatic when the junction temperature drops approximately 25°C below the high temperature trip point. The PMOS
pass element includes a back diode that safely conducts reverse current when the input voltage level drops below the output
voltage level.
A logic low on the enable input, EN shuts off the output and reduces the supply current to less than 2 µA. EN should be
tied high in applications where the shutdown feature is not used.
A typical application circuit is shown in Figure 20.
(1)
TPS763xx
1
3
V
IN
I
4
5
NC/FB
OUT
V
O
C1
1 µF
EN
+
4.7 µF
GND
CSR = 1 Ω
2
(1)
TPS76316, TPS76318, TPS76325, TPS76327, TPS76328,
TPS7630 TPS76333, TPS76338, TPS76350 (fixed-voltage options).
Figure 20. Typical Application Circuit
12
TI [ TEXAS INSTRUMENTS ]
