KEY FEATURES OF 7809 VOLTAGE REGULATOR:
- Fixed voltage linear regulator
- 11-35V input voltage range
- 9V fixed output voltage
- 1A continuous current with 2.2A surge capability
- TO-220 package
The 78xx series of fixed-voltage linear regulators are some of the most popular linear regulators available and have been around for a very long time. They have built-in current limiting and over temperature protection and tend to be fairly robust devices. The prefix may vary depending on the mfr so you may see them listed as LM78xx, MC78xx, L78xx or just 78xx.
The 7809 is a commonly used linear regulator. Input voltage can range from 11 – 35VDC and it outputs a fixed 9V at over 1A of current and up to 2.2A of surge current.
For basic operation, no external components are required. Just hook up the input voltage and ground and you have 9V available on the output.
If you are using it at a fair distance (> 10″) from the supply that is providing the input voltage, then a .33uF or larger input filter capacitor is recommended. The part ideally should be a low ESR part such as a Tantalum or Mylar capacitor, but small electrolytic caps generally work fine. An output capacitor of 0.1uF or larger can also be added to improve output transient response as shown below