DS1222

DS1222 BankSwitch Chip www.dalsemi.com FEATURES Provides bank switching for 16 banks of memory Bank switching is software-controlled by a pattern recognition sequence on four address inputs Automatically sets all 16 banks off on power-up Bank switching logic allows only one bank on at a time Custom recognition patterns are available to prevent unauthorized access Full ±10% operating range Low-power CMOS circuitry Can be used to expand the address range of microprocessors and decoders Optional 16-pin SOIC surface mount package PIN ASSIGNMENT CEI PFI AW AX AY AZ GND 1 2 3 4 5 6 7 14 13 12 11 10 9 8 VCC CEO BS1 BS2 BS3 BS4 NC CEI NC PFI AW AX AY AZ GND 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 VCC CEO NC BS1 BS2 BS3 NC BS4 DS1222 14-Pin DIP (300-mil) See Mech. Drawings Section DS1222S 16-Pin SOIC (300-mil) See Mech. Drawings Section PIN DESCRIPTION AW-AZ CEI CEO NC BS1,BS2, BS3,BS4 PFI VCC GND - Address Inputs - Chip Enable Input - Chip Enable Output - No Connection - Bank Select Outputs - Bank Select Outputs - Power Fail Input - +5 Volts - Ground DESCRIPTION The DS1222 BankSwitch Chip is a CMOS circuit designed to select one of 16 memory banks under software control. Memory bank switching allows for an increase in memory capacity without additional address lines. Continuous blocks of memory are enabled by selecting proper memory bank through a pattern recognition sequence on four address inputs. Custom patterns from Dallas Semiconductor can provide security through unique...