Dual ±3.3V rail with 68dB PSRR — what that means for your noise budget
The LT3032EDE-3.3#PBF is a dual LDO regulator delivering fixed ±3.3V outputs, each rated for 150mA continuous. The positive and negative rails track each other, which matters for analog front-ends where a bipolar supply is needed for op-amps, ADCs, or DACs — the matching between the two outputs keeps the common-mode offset low without an extra trim circuit. PSRR is 68dB at 120Hz on the positive channel, 54dB at 120Hz on the negative. That 68dB figure means the regulator attenuates 120Hz ripple — the fundamental from a full-wave rectifier — by a factor of about 2500×. If your input rail has 100mV of ripple at 120Hz, the output sees roughly 40µV. The negative side's 54dB is still about 500× rejection, adequate for most mixed-signal circuits but worth noting if you are splitting a single noisy supply into a precision bipolar rail.
Dropout headroom and thermal pad layout
Dropout voltage is 0.27V typ on the positive channel and 0.3V typ on the negative at 150mA load. That means each input rail must stay at least about 0.3V above its respective 3.3V output to keep regulation — so a +3.6V rail for the positive side and a -3.6V rail for the negative. If you are running from ±5V, you have 1.7V of headroom, which is comfortable; from ±3.6V you are right at the edge and should check the max dropout over temperature. The part comes in a 14-PowerWFDFN package (4x3mm) with an exposed pad.
Protection features and control — what is built in
Built-in protection covers over-current, over-temperature, and reverse polarity on the input. Reverse polarity protection is a practical feature for field installations where someone might hook up the supply backwards — the part survives it without latching up or blowing. The Enable pin lets you sequence the rails; pulling it low shuts down both outputs simultaneously, which is useful for power-up sequencing in multi-rail designs.