The DS1220AB/DS1220AD 16k Nonvolatile SRAMs are 16,384-bit, fully static, nonvolatile SRAMs organized as 2048 words by 8 bits. Each NV SRAM has a self-contained lithium energy source and control circuitry which constantly monitors VCC for an out-of-tolerance condition. When such a condition occurs, the lithium energy source is automatically switched on and write protection is unconditionally enabled to prevent data corruption. The NV SRAMs can be used in place of existing 2k x 8 SRAMs directly conforming to the popular bytewide 24-pin DIP standard. The devices also match the pinout of the 2716 EPROM and the 2816 EEPROM, allowing direct substitution while enhancing performance.
The DS1220AB and DS1220AD are 16‑kbit (16,384‑bit) fully static nonvolatile SRAMs organized as 2048 × 8 bits. Each device contains a self‑contained lithium backup source that automatically protects data during power loss and enables write protection to prevent corruption.
The datasheet provides detailed pin assignments, absolute maximum ratings, recommended operating conditions, DC and AC electrical characteristics, timing diagrams, ordering information, and revision history for both commercial and industrial temperature grades.
| Data retention time | 10 years |
|---|---|
| Operating temperature range (industrial) | -40°C to +85°C |
| Supply voltage (DS1220AB) | 4.75 V – 5.25 V |
| Supply voltage (DS1220AD) | 4.50 V – 5.50 V |
| Read cycle time | 100 ns |
| Write cycle time | 100 ns |
| Package type | 24‑pin EDIP |
| Number of pins | 24 |
The device can retain data for at least 10 years without external power.
The write protection voltage (VTP) for DS1220AD is 4.25 V (typical 4.37 V, max 4.5 V).
DS1220AB operates at 5 V ± 5 % (4.75 V – 5.25 V) and DS1220AD at 5 V ± 10 % (4.5 V – 5.5 V).
The industrial‑grade DS1220AB/AD can operate from –40 °C up to +85 °C.