LM3940ISX-3.3/NOPB

The Texas Instruments LM3940ISX-3.3/NOPB is a 1-A low-dropout (LDO) linear voltage regulator designed for applications requiring a stable 3.3-V output from a 5-V input supply. This device is particularly well-suited for systems that incorporate both 5-V and 3.3-V logic components, drawing primary power from a 5-V bus.

Key electrical specifications include an input voltage range of 4.5 V to 5.5 V and a fixed output voltage of 3.3 V. It can deliver up to 1 A of output current. The regulator features a low quiescent current of typically 0.11 mA and a dropout voltage of 310 mV at maximum load. It also offers good power supply rejection ratio (PSRR) of 32 dB at 100 KHz and low noise of 150 µVrms.

Built-in protection features include over-temperature protection and short-circuit protection, enhancing device reliability. The LM3940 is available in multiple package options, including TO-220, TO-263 (DDPAK/TO-263), and SOT-223, allowing for flexibility in board design and thermal management. The TO-220 package can typically deliver the full 1 A without an additional heatsink, while the surface-mount TO-263 package minimizes board space.