Voltage regulator 7909

🛠️ Voltage Regulator – 7909 (−9 V, 1 A)

Overview

The LM7909 is part of the LM79XX series of negative voltage regulators, providing a stable −9 V DC output with a maximum current capacity of 1 A. It features internal protections including short-circuit current limiting, thermal shutdown, and safe-area protection, making it reliable and robust for various negative-voltage applications 

Key Features

• Fixed output: −9 V DC

• Maximum output current: 1 A (some versions rated up to 1.5 A)

• Input voltage range: Typically −11 V to −35 V

• Protections: Thermal shutdown, internal current limiting, safe-area protection 

• Dropout voltage: ≈2 V (requires Vin at least −11 V) 

• Package: TO‑220 (pins: Input, Ground, Output) 

Pinout (TO‑220, Leads Down, Front View)

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1 = GND
2 = Input (more negative than −11 V)
3 = Output (−9 V)

Typical Wiring

Vin (e.g. −12 V) → Pin 2 (IN)
GND (common)     → Pin 1
Pin 3 (OUT)      → −9 V rail / load

Applications

• Generating −9 V supply for op-amps, DACs, and analog circuits

• Creating negative rails for audio preamps or power amplifiers

• Dual-voltage supplies alongside positive regulators like 7809

• Reference or bias supplies in measurement and signal-processing systems

✅ Resources

1. 📄 Datasheet: LM79XX series – details for −5 V, −9 V, −12 V, etc. regulators componentsinfo.com+15ti.com+15circuits-diy.com+15diyaudio.com+4mouser.com+4circuitdiagram.org+4

2. 🎥 YouTube Tutorial :https://youtu.be/duKH-9XplCY?si=Hk-RdnMGy_lKHJ1s

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