Description
The AT24CS128/256 provides 131,072/262,144 bits of serial electrically erasable and programmable read only memory (EEPROM) organized as 16,384/32,768 words of 8 bits each. The device’s cascadable feature allows up to 4 devices to share a common 2-wire bus. The device also features a one-time programmable 2048 bit array, which once enabled, becomes read-only and cannot be overwritten. If not enabled, the OTP section will function as part of the normal memory array. The device is optimized for use in many industrial and commercial applications where low power and low voltage operation are essential. The devices are available in space-saving 8-pin JEDEC PDIP (AT24CS128/256), 8-pin EIAJ (AT24CS128/256), 8-pin JEDEC SOIC (AT24CS128) packages. In addition, the entire family is available in 5.0V (4.5V to 5.5V), 2.7V (2.7V to 5.5V) and 1.8V (1.8V to 3.6V) versions.

Features
• One-Time Programmable (OTP) Feature
• Low-Voltage and Standard-Voltage Operation
   – 5.0 (VCC = 4.5V to 5.5V)
   – 2.7 (VCC = 2.7V to 5.5V)
   – 1.8 (VCC = 1.8V to 3.6V)
• Internally Organized 16,384 x 8 and 32,768 x 8
• 2-Wire Serial Interface
• Schmitt Trigger, Filtered Inputs for Noise Suppression
• Bidirectional Data Transfer Protocol
• 1 MHz (5V), 400 kHz (2.7V) and 100 kHz (1.8V) Compatibility
• Write Protect Pin for Hardware and Software Data Protection
• 64-Byte Page Write Mode (Partial Page Writes Allowed)
• Self-Timed Write Cycle (5 ms typical)
• High Reliability
   – Endurance: 100,000 Write Cycles
   – Data Retention: 40 Years
   – ESD Protection: >4000V
• Automotive Grade and Extended Temperature Devices Available
• 8-Pin JEDEC PDIP and 8-Pin JEDEC and EIAJ SOIC Packages