Fixed 3V rail at 1A — dropout and noise rejection
The TPS79630KTTRG3 is a fixed 3V output LDO from Texas Instruments, rated for 1A continuous output current. Power supply rejection ratio is 59 dB at 100 Hz, rolling off to 42 dB at 100 kHz. This profile filters low-frequency ripple from a mains-derived supply but passes switching noise above 100 kHz — a post-filter ceramic cap with low ESL ahead of the LDO input cleans up the high-frequency band before the regulator sees it.
Protection set and temperature grade
Built-in protection covers over-current, over-temperature, reverse polarity, and under-voltage lockout (UVLO). The UVLO threshold prevents the pass element from operating in dropout at low input voltage, which keeps the output clean during power-up sequencing. Reverse polarity protection blocks a negative input from damaging the load — useful in battery-powered designs where the connector can be miswired. The TO-263-6 (DDPAK) package with exposed tab carries the thermal dissipation to the PCB copper plane — for 1A at 3V output from a 5V input, the 2W dissipation requires a minimum 1 in² copper pad on the top layer to keep the junction below 125°C at 85°C ambient.
Quiescent current is 385 µA typical, which is moderate for a 1A LDO — not a micropower part, but acceptable in always-on rails where the load current dominates the power budget. The enable pin (active high) lets a system controller shut down the regulator to near-zero Iq when the rail is not needed.