# Quick question about the L200 circuit limit

I need some help on how to calculate the output current.. Datasheet:

http://www.zen22142.zen.co.uk/Circuits/Power/l200.pdf

I want to use the (Figure 2. Programmable Current Regulator.) But i don't understand the Io = v5 - 2/R

Is 5 - 2 = PIN 5 minus PIN 2 or something else? Could anyone give me an example? Thank you!

Yes, the term given is the voltage at pin 5 minus the voltage at pin 2 (the datasheet's typesetting does not make this clear). The L200 is measuring the voltage drop across resistor R in Figure 2 to determine the current limit set by the internal comparator. Given in the datasheet is $V_{5-2}$ is a typical value with a temperature dependence given in Figure 18.
The explanation of current limiting given in the ST Designer's Guide on pages 3 and 4 is much more straightforward, using $V_{sc}$: the [short-circuit] current limit starts when the L200 sees about 450mV between pins 5 and 2. This avoids the error in typesetting later repeated in Figure 5 of the guide.