DS1221

DS1221 Nonvolatile Controller x 4 Chip www.dalsemi.com NOT RECOMMENDED FOR NEW DESIGNS, SEE DS1321 DATASHEET INSTEAD. FEATURES Converts CMOS RAMs into nonvolatile memories Data is automatically protected during power loss 2-to-4 decoder provides for up to 4 CMOS RAMs Provides for redundant batteries Test battery condition on power-up Full ±10% operating range Unauthorized access can be prevented with optional security feature 16-pin 0.3-inch DIP saves PC board space Optional 16-pin SOIC surface mount package Optional industrial temperature range of -40°C to +85°C available PIN ASSIGNMENT VCCO VBAT1 *RST A B *RD *WE GND 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 VCCI VBAT2 CE CE0 CE1 CE2 CE3 *D/Q DS1221 16-Pin DIP (300-mil) See Mech. Drawings Section VCCO VBAT1 *RST A B *RD *WE GND 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 VCCI VBAT2 CE CE0 CE1 CE2 CE3 *D/Q PIN DESCRIPTION A, B CE CE0 - CE3 VBAT1 VBAT2 * RST VCCI VCCO * RD * WE *D/Q - Address Inputs - Chip Enable Input - Chip Enable Outputs - + Battery 1 - + Battery 2 - Reset - +5V Supply - RAM Supply - Read Inpu - Write Input - Data Input/Output DS1221 16-Pin SOIC (300-mil) See Mech. Drawings Section *Used with optional security circuit only and must be connected to ground in all other cases. DESCRIPTION The DS1221 Nonvolatile Controller x 4 Chip is a CMOS circuit which solves the application problem of converting CMOS RAMs into nonvolatile memories. Incoming power is monitored for an out-oftolerance condition. When such a ...