The STMicroelectronics L78M09CDT-TR is a positive fixed linear regulator delivering a regulated 9 V output at up to 500 mA. It takes an unregulated DC input up to 35 V and holds the output steady — no external programming resistors needed, the voltage is fixed. The 56 dB PSRR at 120 Hz tells you it knocks down ripple from a rectified mains supply, so downstream analog or logic circuits see a clean rail. Protection features include overcurrent, overtemperature, and short-circuit — the part shuts itself down before it burns, which matters in a board that might see a load fault. The DPAK surface-mount package (TO-252-3, two leads plus tab) is a common footprint for medium-current linear regulators. The tab is the output, so the PCB copper plane acts as the heatsink — no separate heatsink required at 500 mA if the input-output differential stays moderate.
STMicroelectronics L78M09CDT-TR Linear Regulator, 9V Fixed
MPNL78M09CDT-TR
End of Life
STMicroelectronics L78M09CDT-TR, positive fixed linear regulator, 9V output, 500mA output current, 35V max input, PSRR 56dB at 120Hz, DPAK surface mount package, 0°C to 125°C operating temperature.
$0.71Ref. price · indicative, final on quote
PackagingTO-252-3, DPak (2 Leads + Tab), SC-63
RoHSROHS3 Compliant
Independent supplier — new & surplus stockAuthenticity-screened · ESD-safe packingListing updated Aug 2026
Specifications
| Parameter | Value |
|---|---|
| Output type | Fixed |
| Mounting | Surface Mount |
| Voltage - input | 35V |
| Voltage - output (Min (Fixed)) | 9V |
| Output current | 500mA |
| Current - quiescent | 6 mA |
| Operating temperature | 0°C ~ 125°C |
| PSRR | 56dB (120Hz) |
| Package | Tape & Reel (TR); Cut Tape (CT) |
| Case | TO-252-3, DPak (2 Leads + Tab), SC-63 |
| Protection features | Over Current, Over Temperature, Short Circuit |
| Number of regulators | 1 |
| Output configuration | Positive |
Product details
Frequently asked questions
What is L78M09CDT-TR's listed PSRR?
The power supply rejection ratio is 56 dB at 120 Hz. That means ripple from a full-wave rectified mains supply (100/120 Hz) is attenuated by a factor of roughly 630, giving a clean DC output for sensitive loads.