Highway - 09 Ic Datasheet

 Unregulated DC    +----->|-----+-----> +9V Regulated DC
 (12V to 25V)      |     7809    |
   + -------------+ Pin1  Pin3  +-------------+
                  |      |                    |
                 Pin2   Pin2                 Pin2
                  |      |                    |
   - -------------+------+--------------------+----- GND

Add two capacitors for stability:

A common stumbling block for beginners is interpreting the thermal limits section of the datasheet. highway 09 ic datasheet

Internally, the Highway 09 integrates the following blocks: Add two capacitors for stability: A common stumbling

A simplified internal diagram would show the input feeding the pass transistor, controlled by the error amplifier comparing a fraction of the output to the 1.25V reference. The current limit and thermal sensors directly pull the error amplifier output low during fault conditions. A simplified internal diagram would show the input

To avoid oscillation and premature failure, follow these layout rules: