ST24FW21 Description
In the text, products are referred as ST24xy21, where "x" is either "L" for VESA 1 or "F" for VESA 2 patible memories and where "y" indicates the Write Control pin connection: "C" means WC on pin 7 and "W" means WC on pin 3. Logic Diagram VCC SCL VCLK WC ST24xy21 SDA Table.