1.1A fixed 1.5V rail with 75dB PSRR — what the noise rejection means for sensitive loads
The LT1965EMS8E-1.5 is a 1.1A low-dropout linear regulator from Analog Devices, delivering a fixed 1.5V output from an input up to 20V. The 75dB PSRR at 120Hz means ripple on the input rail — from a switching preregulator or rectified line — is attenuated by a factor of about 5600 before reaching the output. For a 3.3V input swinging 100 mVpp at 120 Hz, the output sees roughly 18 µVpp of that ripple, clean enough for an ADC reference or a precision analog front-end. Dropout is 0.49V max at the full 1.1A load. That sets the minimum input-to-output headroom: to hold 1.5V regulated at 1.1A, the input must stay above 1.99V. Below that the output tracks the input minus the pass element's drop — the regulator falls out of regulation. On a 3.3V rail that is 1.31V of margin; on a 1.8V rail it is only 0.01V above the dropout ceiling, so the 1.8V rail is not a viable source at full load.
Package and thermal path — the exposed pad is the heat sink
The 8-MSOP-EP (exposed pad) package, supplier device package 8-MSOP-EP, routes the die's heat through the pad to the PCB copper. Without that copper spread, the junction temperature at 1.1A and 2V dropout (2.2W dissipation) would exceed the 125°C absolute maximum junction temperature in still air. That covers industrial enclosures, engine-bay electronics, and outdoor telecom gear. The protection features — over-current, over-temperature, and reverse polarity — mean the regulator survives a miswired input or a shorted output without latching or failing open.
Active lifecycle — still a current production part
That means the part is still in the manufacturer's active portfolio, and new designs can commit to it without a near-term obsolescence risk. The part is not a spot-market surplus item; it is a current-production order code that traces back through the authorized channel.