The LM1085 is a series of 3A low dropout positive voltage regulators with a maximum dropout of 1.5V at 3A of load current. It has the same pin-out as National Semiconductor's industry standard LM317. The LM1085 is available in an adjustable version, which can set the output voltage with only two external resistors. It is also available in three fixed voltages: 3.3V, 5.0V and 12.0V. The fixed versions integrate the adjust resistors. The LM1085 circuit includes a zener trimmed bandgap ref- erence, current limiting and thermal shutdown. The LM1085 series is available in TO-220 and TO-263 pack- ages. Refer to the LM1084 for the 5A version, and the LM1086 for the 1.5A version.
The LM1085 series provides low‑dropout positive voltage regulation up to 3 A. It is offered in an adjustable version that uses two external resistors to set the output voltage, as well as fixed‑output versions for 3.3 V, 5.0 V, and 12.0 V. The devices are supplied in TO‑220 and TO‑263 packages and share the same pin‑out as the LM317.
The datasheet lists electrical characteristics such as line and load regulation, dropout voltage, ripple rejection, and thermal resistance, and includes application notes on stability, protection diodes, overload recovery, and recommended external components. Physical dimensions for each package are also provided.
| Maximum Output Current | 3 A |
|---|---|
| Line Regulation (typical) | 0.015 % |
| Load Regulation (typical) | 0.1 % |
| Ripple Rejection (typical) | 75 dB |
| Package Types | TO‑220, TO‑263 |
The LM1085 can deliver up to 3 A of output current.
Fixed‑output versions are available at 3.3 V, 5.0 V, and 12.0 V.
The regulator guarantees a minimum dropout voltage of about 1.5 V over temperature at full load, with typical values around 1.3 V.
The LM1085 is supplied in TO‑220 and TO‑263 (surface‑mount) packages.