Para Teensy debes usar DS3231RTC que es la que uso yo pero no tiene soporte EEPROM, asi que algo lógico sería agregarlo.
Mira la página del DS1307RTC que corresponde a www.pjrc.com hay soporte para RTC y para EEPROM y todo para Teensy 3.0
EEPROM Library
EEPROM allows you to permanently store small amounts of data, which is very useful for saving settings, collecting small data sets, or any other use where you need to retain data even if the power is turned off.
Download: EEPROM is included with Arduino
Hardware Requirements
All Teensy boards have EEPROM memory build inside the chip. No extra hardware is required. The demo program reads an analog voltage and stores it into EEPROM, so a trim pot was connected to analog input A0.
