diff --git a/components/pcf8574.rst b/components/pcf8574.rst
index 6cb1cc503..b8f04c17d 100644
--- a/components/pcf8574.rst
+++ b/components/pcf8574.rst
@@ -55,6 +55,9 @@ Configuration variables:
   Defaults to ``0x21``.
 - **pcf8575** (*Optional*, boolean): Whether this is a 16-pin PCF8575. Defaults to ``false``.
 
+.. note::
+
+    If you use PCF8575, pin numbers are from 0 to 15, not 0 to 7 and 10 to 17 as datasheet states!
 
 Pin configuration variables:
 ****************************