Microchip Technology AT27C040-90PI

Overview

AT27C040-90PI from Atmel is a 4-Mbit (512K × 8) one-time programmable EPROM designed for nonvolatile program storage in microprocessor systems. It operates on a single 5V ±10% supply, delivers 90 ns read access time, supports industrial temperature range (–40°C to +85°C), and uses CMOS/TTL-compatible I/O with dual-line control (CE/OE) to prevent bus contention.

For engineers reviewing the AT27C040-90PI datasheet, AT27C040-90PI pinout, AT27C040-90PI application, or AT27C040-90PI equivalent, key selection criteria include its OTP architecture, rapid 100 µs/byte programming algorithm, VPP-dependent programming voltage (12.0 V ±0.5 V), JEDEC-standard 32-lead PDIP package, and integrated product identification code for automated programming equipment compatibility.

Technical Context

The AT27C040-90PI implements a standard OTP EPROM architecture with address decoding for A0–A18 (19-bit addressing), 8-bit parallel data outputs (O0–O7), and two active-low control lines: Chip Enable (CE) and Output Enable (OE). Its read operation requires only VCC = 5V, while programming mandates VPP = 12.0 V ±0.5 V applied simultaneously with elevated VCC = 6.5 V.

It features Rapid™ programming with verified byte-level write cycles, product identification via A9 high-voltage (11.5–12.5 V) and A0 toggling, and robust ESD/latchup protection (2000 V HBM, 200 mA). The device supports both CMOS and TTL input thresholds and guarantees output drive strength of 2.1 mA low and –400 µA high under specified load conditions.

Key Specifications

Pinout & Package

AT27C040-90PI is packaged in a 32-lead, 0.600-inch wide plastic dual-inline package (PDIP), per JEDEC MS-016. Pin 1 is marked by a notch or dot; leads are numbered counter-clockwise from top-left corner.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT27C040-90PI, AM27C040-90DC offers identical timing and voltage specs but diverges in programming reliability margins, while MX27C4001-90PC trades slightly higher active power for lower quiescent draw and requires firmware adaptation for ID verification-both remain viable OTP alternatives when Atmel sourcing is constrained.

Availability

AT27C040-90PI is available at Aetrix Electronics and suitable for industrial control systems, legacy microcontroller platforms, automotive calibration modules, and test equipment requiring stable component supply and long-term obsolescence management.

Supply support for AT27C040-90PI 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 was a U.S.-based semiconductor manufacturer specializing in microcontrollers, nonvolatile memory, and RF solutions before its acquisition by Microchip Technology in 2016.

The AT27C040-90PI belongs to Atmel's OTP EPROM product line, engineered for cost-sensitive, high-reliability firmware storage in industrial and automotive systems where data immutability and long-term retention are mandatory.

FAQ

What is the maximum operating temperature range for the AT27C040-90PI?

The AT27C040-90PI is rated for industrial temperature operation from –40°C to +85°C. This specification is confirmed in the "DC and AC Operating Conditions" table of the official datasheet (0189F–EPROM–4/03), where the "Ind." column explicitly lists this range for all speed grades including the -90 variant. The device undergoes full characterization across this range for parameters including access time, standby current, and output drive capability.

Does the AT27C040-90PI require a separate programming voltage during normal read operation?

No, the AT27C040-90PI does not require VPP during normal read operation. The datasheet specifies that VPP may be connected directly to VCC (5 V) when not programming. VPP = 12.0 V ±0.5 V is required exclusively during programming and verification cycles, and must be applied simultaneously with elevated VCC = 6.5 V. During read mode, only the 5 V ±10% supply is active.

How many address pins does the AT27C040-90PI have, and what is their function?

The AT27C040-90PI has 19 address pins: A0 through A18. These pins collectively decode the full 512K-byte memory space (2¹⁹ = 524,288 addresses). Each unique combination selects one 8-bit byte for read or programming access. The pinout diagrams in the datasheet confirm A0–A18 as dedicated address inputs with no multiplexing or secondary functions in read or program modes.

Can the AT27C040-90PI be used as a direct replacement for the AT27C040-70PI in an existing design?

Yes, the AT27C040-90PI can replace the AT27C040-70PI in most cases, but with a timing trade-off: its 90 ns access time is slower than the 70 ns of the -70 variant. System-level validation is required to ensure the longer tACC and tCE do not violate setup/hold margins in high-speed microprocessor buses. All other electrical, pinout, and functional characteristics-including VPP requirements, ID code, and packaging-are identical.

What is the purpose of the Integrated Product Identification Code in the AT27C040-90PI?

The Integrated Product Identification Code in the AT27C040-90PI provides two electronically readable bytes: Manufacturer ID (0x1E) and Device Code (0x0B). It is accessed by setting A9 to 11.5–12.5 V and toggling A0 while holding all other address lines low. This feature enables automatic device recognition in universal programmers, ensuring correct algorithm selection, voltage application, and verification protocols without manual configuration.