Fixed 3.5V rail with 70dB PSRR — the noise-sensitive supply choice
The Toshiba TAR5S35U(TE85L,F) is a single-output positive fixed linear regulator delivering 3.5V at up to 200mA. Its PSRR of 70dB at 1kHz makes it a strong candidate for powering analog front-ends, reference buffers, or VCO supply rails where keeping supply ripple off the signal path matters. The 0.2V maximum dropout at 50mA means the input rail can sit as low as 3.7V and still hold regulation — useful when the pre-regulator is itself a switching converter with some load-transient droop.
Dropout and headroom — what 0.2V at 50mA buys the BOM
The 0.2V max dropout at 50mA sets the minimum input-to-output differential. For a 3.5V output rail, a 3.7V input is the floor; anything lower and the regulator drops out. At the full 200mA load the dropout will be higher — the 0.2V figure is a 50mA condition — so budget at least 0.5V headroom for the full current range. The 850 µA maximum supply current (quiescent plus dropout) keeps the efficiency penalty small in always-on subsystems.
UFV package — footprint and thermal reality
Housed in a 6-SMD (5 leads) flat-lead package with the UFV supplier designation, this part is a surface-mount device intended for reflow assembly. The five-lead layout with an exposed pad (typical for this class) pulls heat into the PCB copper plane. At 200mA with 0.5V dropout the dissipation is 100mW — well within the package capability with standard 1oz copper pours.
Protection and control — Enable pin and built-in safeguards
An Enable pin allows the output to be gated by a logic signal, useful for sequencing multiple rails or shutting down a peripheral in sleep mode. Over-current and over-temperature protection are integrated — the regulator folds back or shuts off rather than letting the die exceed the SOA. No external pass transistor or protection diode is needed for normal operation.