L4909 is a multifunction voltage regulator from ST Microelectronics. It has 3 outputs, each of which can be adjusted from 5 to 12V with a maximum current of 1.2A. It also supports short circuit protection, overcurrent warning, external SCR driver and thermal shutdown protection.
The L4909 is a monolithic multifunction voltage regulator containing three independent regulators (REG1, REG2, REG3). Each regulator features an enable input and a feedback input, allowing the output voltage to be set via an external resistive divider. The device is designed for applications requiring multiple regulated voltages with protection features.
| Output voltage range | 5 to 12 V |
|---|---|
| Output current limit | 1.2 A |
| Operating temperature range | 0 to 70 °C |
| Storage temperature | -40 to 150 °C |
| Input DC supply voltage | 40 V |
| Feedback voltage | 1.22 V to 1.32 V |
| Supply voltage rejection | 60 dB |
The L4909 contains three regulators, labeled REG1, REG2, and REG3.
The TRIG pin serves as a trigger for an external SCR used for crowbar protection.
The typical output current limit for any regulator is 1.2 A.