The TMS27C256 is a 32768-bit (262144-bit) ultraviolet (UV) light erasable, electrically programmable read-only memory (EPROM). The TMS27PC256 is a 32768-bit (262144-bit) one-time programmable (OTP) electrically programmable read-only memory (PROM).
This document describes the TMS27C256 series of ultraviolet (UV) light erasable electrically programmable read-only memories (EPROMs) and the TMS27PC256 series of one-time programmable (OTP) PROMs. Both devices feature a 32,768 x 8-bit organization and are fabricated using power-saving CMOS technology for high-speed operation with simple interfaces to MOS and bipolar circuits.
| Memory Organization | 32,768 by 8-bit (262,144 bits) |
|---|---|
| Operating Voltage | Single 5-V Power Supply |
| Programming Voltage | 13 V |
| Nominal Programming Time | Four seconds |
| Access/Min Cycle Time (10ns) | ’27C/PC256-10 100ns |
| Access/Min Cycle Time (12ns) | '27C/PC256-12 120 ns |
| Access/Min Cycle Time (15ns) | '27C/PC256-15 150 ns |
| Access/Min Cycle Time (17ns) | '27C/PC256-17 170 ns |
| Access/Min Cycle Time (20ns) | '27C/PC256-20 200 ns |
| Access/Min Cycle Time (25ns) | '27C/PC256-25 250ns |
| Active Power Dissipation (Worst Case) | 165 mW |
| Standby Power Dissipation (Worst Case) | 1.4 mW |
The signature code is 9704, where AO selects manufacturer code 97 and A0 high selects device code 04.
A typical 12-mW/cm² filterless UV lamp erases the device in 21 minutes.
The recommended minimum exposure dose (UV intensity x exposure time) is 15-Jes/cm².