Package and board-fit — SOT-753 footprint
The TCR2EF45,LM(CT comes in a SC-74A / SOT-753 package (supplier device package SMV), a 5-lead surface-mount footprint that fits into a compact board layout without a dedicated thermal pad. The enable pin lets the downstream system shut the regulator off when the load is idle, pulling the quiescent current to near-zero.
4.5 V fixed output — dropout and PSRR
This is a fixed 4.5 V positive-output LDO rated for 200 mA continuous. The maximum dropout is 0.2 V at 150 mA load — meaning the input rail needs to stay above 4.7 V to keep the output in regulation under that load. At lighter loads the dropout is lower, but the headroom budget should be sized for the worst-case 0.2 V figure. PSRR is 73 dB at 1 kHz, which attenuates 1 kHz ripple on the input by a factor of roughly 4500 — useful when the input comes from a switching pre-regulator that switches in the audible range.
Quiescent current and protection
Quiescent current is 60 µA typical — low enough for battery-powered always-on systems but not the lowest in class; the 200 mA output stage draws this overhead continuously. Over-current protection is built in, so a short on the output rail folds back the current without damaging the regulator.
Temp grade and supply range
A 5.0 V ±5% supply is a safer match.