3.3 V rail at 250 mA — dropout and PSRR define the fit
The TPS79433DGNR is a single-output positive LDO from Texas Instruments, delivering a fixed 3.3 V at up to 250 mA. PSRR measures 65 dB at 100 Hz, rolling off to 40 dB at 100 kHz — this profile attenuates 100/120 Hz rectifier ripple well but passes higher-frequency switching noise from a preceding DC-DC converter unless additional filtering is placed ahead of the LDO.
Operating range and protection set
The 5.5 V maximum input accommodates 5 V ±10% rails without an external pre-regulator. Integrated protection includes over-current, over-temperature, reverse polarity, and under-voltage lockout (UVLO) — the UVLO threshold prevents the pass FET from operating in dropout, which would otherwise raise output ripple. The enable pin allows external sequencing or shutdown to reduce quiescent current to near zero. Quiescent current is 220 µA typical — this is the load-independent overhead drawn from the input rail. In a battery-powered sensor node that spends most of its time in shutdown, the enable pin pulls Iq to zero; in active mode the 220 µA is a fixed cost against the battery budget.
Package and thermal interface
Supplied in an 8-HVSSOP package (3.00 mm width, exposed pad). Without adequate copper, the 250 mA output at high ambient temperature may trigger the over-temperature protection.