Microchip Technology AT27C040-90PU

Overview

AT27C040-90PU from Atmel is a 4 Mb (512K × 8) One-Time Programmable EPROM with 90 ns read access time, 5V ±10% supply, and industrial temperature range (–40°C to +85°C). It features dual-line control (CE/OE), CMOS/TTL-compatible I/O, and rapid programming at 100 μs/byte - used in legacy microprocessor boot memory and firmware storage where non-volatility and long-term data retention are critical.

For engineers reviewing the AT27C040-90PU datasheet, AT27C040-90PU pinout, AT27C040-90PU application, or AT27C040-90PU equivalent, key selection criteria include read timing (tACC = 90 ns), standby current (≤100 μA), JEDEC-standard PDIP-32 packaging, VPP programming voltage (12.0 V ±0.5 V), and integrated product identification code for automated programming equipment compatibility.

Technical Context

The AT27C040-90PU implements a high-reliability CMOS OTP EPROM architecture with a 19-bit address bus (A0–A18) supporting 524,288 byte locations. Its two-line enable logic (CE and OE) enables clean bus interface in high-speed systems without contention, while internal Y-gating and X-decoding ensure deterministic address-to-output delay under specified load conditions.

Programming relies on external VPP = 12.0 V ±0.5 V applied to pin 1, with CE-controlled 100 μs pulses and automatic verify/reprogram loops per byte. The device includes an electrically readable manufacturer ID (0x1E) and device code (0x0B) accessible via A9 high-voltage addressing, enabling standardized programmer recognition and algorithm selection.

Key Specifications

Pinout & Package

AT27C040-90PU is supplied in a 32-lead plastic dual in-line package (PDIP), 0.600" wide (JEDEC MS-001), with 0.100" lead pitch. Pin 1 is VPP (programming voltage), pin 16 is GND, pin 32 is VCC, and pins 17–24 serve as bidirectional data outputs O0–O7.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar OTP EPROM applications.

Compared with AT27C040-70PU, the AT27C040-90PU trades 20 ns slower read timing for broader timing margin tolerance and lower unit cost; compared with AM27C040-90DC, it delivers guaranteed programmer interoperability via electrically readable ID codes and documented rapid programming waveforms.

Availability

AT27C040-90PU is available at Aetrix Electronics and suitable for industrial control firmware storage, legacy microprocessor boot ROM, and embedded instrumentation calibration data requiring stable component supply across extended production lifecycles.

Supply support for AT27C040-90PU includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Atmel Corporation (now part of Microchip Technology) designed high-reliability non-volatile memory and microcontroller solutions for industrial, automotive, and consumer applications before its 2016 acquisition.

The AT27C040 belongs to Atmel's OTP EPROM product line, engineered for firmware and calibration data storage in systems where data immutability, long-term retention (>20 years), and deterministic read timing outweigh reprogrammability needs.

FAQ

What is the maximum read access time specification for AT27C040-90PU?

The AT27C040-90PU has a maximum read access time (tACC) of 90 ns under industrial temperature and voltage conditions (–40°C to +85°C, VCC = 5V ±10%). This value is measured from address valid or CE/OE assertion to valid data on O0–O7, and is guaranteed across the full operating range - critical for integration into 80Cxx and 68000-family microprocessor systems without wait-state insertion.

Does AT27C040-90PU require a separate programming voltage during normal operation?

No, AT27C040-90PU operates from a single 5V supply during read mode. VPP (12.0 V ±0.5 V) is required only during programming and must be disconnected or tied to VCC (5 V) during read operation. The datasheet explicitly states that VPP may be connected directly to VCC except during programming, and doing so increases total supply current to the sum of ICC and IPP - a design consideration confirmed in Section 6.2.

How is the product identification code accessed on AT27C040-90PU?

The AT27C040-90PU integrates a manufacturer ID (0x1E) and device code (0x0B) readable via a dedicated protocol: A9 is driven to VH = 12.0 V ±0.5 V while A0 is toggled (VIL for manufacturer ID, VIH for device code), and all other address lines held low. This electrically readable ID enables automated programming equipment to validate part identity and select correct algorithms - a feature confirmed in Table 6-5 and Section 4 of the datasheet.

What package type is used for AT27C040-90PU?

AT27C040-90PU uses a 32-lead plastic dual in-line package (PDIP), designated as 32P6 in Atmel's ordering nomenclature. Its mechanical dimensions conform to JEDEC MS-001, with 0.600" body width, 0.100" lead pitch, and matte tin lead finish. This package is distinct from the PLCC variant (AT27C040-90JU) and is verified in Section 8 (Ordering Information) and Figure 9.2 of the datasheet.

Can AT27C040-90PU be used in place of AT27C040-70PU without hardware changes?

Yes, AT27C040-90PU is pin-compatible and functionally identical to AT27C040-70PU, differing only in guaranteed read access time (90 ns vs. 70 ns) and corresponding test screening. Both share identical pinout, memory organization, programming algorithm, DC/AC characteristics, and package (32P6 PDIP). System integration requires no PCB or schematic changes - only timing validation to confirm 90 ns meets the host controller's setup/hold window.