TPS77715PWPG4 Datasheet, PDF (17/26 Pages) Texas Instruments – FAST-TRANSIENT-RESPONSE 750mA LOW-DROPOUT LINEAR REGULATORS

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TPS77701, TPS77715, TPS77718, TPS77725, TPS77733 with RESET OUTPUT
TPS77801, TPS77815, TPS77818, TPS77825, TPS77833 with PG OUTPUT
FASTĆTRANSIENTĆRESPONSE 750ĆmA LOWĆDROPOUT LINEAR REGULATORS
SLVS230G − SEPTEMBER 1999 − REVISED JANUARY 2004
APPLICATION INFORMATION
reset indicator
The TPS777xx features a RESET output that can be used to monitor the status of the regulator. The internal comparator
monitors the output voltage: when the output drops to between 92% and 98% of its nominal regulated value, the RESET
output transistor turns on, taking the signal low. The open-drain output requires a pullup resistor. If not used, it can be left
floating. RESET can be used to drive power-on reset circuitry or as a low-battery indicator. RESET does not assert itself
when the regulated output voltage falls outside the specified 2% tolerance, but instead reports an output voltage low relative
to its nominal regulated value (refer to timing diagram for start-up sequence).
power-good indicator
The TPS778xx features a power-good (PG) output that can be used to monitor the status of the regulator. The internal
comparator monitors the output voltage: when the output drops to between 92% and 98% of its nominal regulated value,
the PG output transistor turns on, taking the signal low. The open-drain output requires a pullup resistor. If not used, it can
be left floating. PG can be used to drive power-on reset circuitry or used as a low-battery indicator.
regulator protection
The TPS777xx and TPS778xx PMOS-pass transistors have a built-in back diode that conducts reverse currents when the
input voltage drops below the output voltage (e.g., during power down). Current is conducted from the output to the input
and is not internally limited. When extended reverse voltage is anticipated, external limiting may be appropriate.
The TPS777xx and TPS778xx also feature internal current limiting and thermal protection. During normal operation, the
TPS777xx and TPS778xx limit output current to approximately 1.7 A. When current limiting engages, the output voltage
scales back linearly until the overcurrent condition ends. While current limiting is designed to prevent gross device failure,
care should be taken not to exceed the power dissipation ratings of the package. If the temperature of the device exceeds
150°C(typ), thermal-protection circuitry shuts it down. Once the device has cooled below 130°C(typ), regulator operation
resumes.
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