View ds2401 datasheet:

DS2401 Silicon Serial Number www.maxim-ic.com FEATURES PIN ASSIGNMENT Upgrade and drop-in replacement for DS2400 TO-92 TSOC PACKAGE — Extended 2.8 to 6.0 voltage range DALLAS — Multiple DS2401s can reside on a DS2401 common 1-Wire Net Unique, factory-lasered and tested 64-bit TOP VIEW registration number (8-bit family code + 48- 3.7mm x 4.0mm x 1.5mm bit serial number + 8-bit CRC tester); guaranteed no two parts alike Built-in multidrop controller ensures compatibility with other 1-Wire Net products 8-bit family code specifies DS2401 communications requirements to reader 1 2 3 Presence Pulse acknowledges when the reader first applies voltage Low-cost TO-92, SOT-223, and TSOC surface mount packages 1 2 3 TOP VIEW See Mech. Drawings Reduces contr