Fixed 2.9 V rail for noise-sensitive loads
The Toshiba TCR3DF29,LM(CT is a single-output positive linear regulator that delivers a fixed 2.9 V output at up to 300 mA. It belongs to the TCR3DF series, designed for space-constrained, low-noise power rails in battery-powered or industrial equipment. The output is factory-trimmed to 2.9 V, so no external resistor divider is needed — just an input capacitor and an output capacitor for stability. With a maximum dropout voltage of 0.27 V at 300 mA, the input rail needs to stay above 3.17 V to maintain regulation at full load. The PSRR of 70 dB at 1 kHz helps clean up ripple from a switching preregulator, making this part a candidate for powering analog sections like op-amps or ADCs.
Dropout and input headroom
The 0.27 V maximum dropout at 300 mA is the worst-case figure across temperature and load. For a 3.3 V input rail, that leaves 130 mV of headroom at the full load — tight but within spec. If the input rail sags during a transient, the output drops out of regulation. A 3.6 V input gives a comfortable 430 mV margin. The dropout is specified at the full output current, so at lighter loads the actual dropout voltage will be lower, but the 0.27 V max is the number to budget against in the power-tree calculation.
PSRR and output noise
PSRR is listed at 70 dB at 1 kHz, which attenuates a 100 mVpp ripple on the input to about 32 µVpp at the output at that frequency. At lower frequencies (100 Hz to 1 kHz) the PSRR typically stays above 60 dB for this class of LDO, though the datasheet's full curve should be checked for your specific ripple spectrum. This makes the TCR3DF29 suitable for powering a 2.9 V analog rail where switching-regulator noise would otherwise couple into the signal path.
The regulator includes inrush current limiting, overcurrent protection, and overtemperature shutdown. The Enable pin allows the output to be gated by a logic signal, which is useful for sequencing rails or saving power in standby.
Housed in a SC-74A (SOT-753) package with the SMV supplier device code, this is a 5-pin surface-mount package with a 1.6 mm x 2.9 mm body and 0.95 mm pitch. The Enable pin is active-high and is internally pulled down, so leave it floating or tie to ground to keep the output off.
It is RoHS compliant.