AT49F001NT-90TC Equivalent & Substitute Parts

Part Overview

The AT49F001NT-90TC is a 1Mbit parallel FLASH memory IC manufactured by Microchip Technology, housed in a 32-TSOP package with 90 ns access time. This device operates at 4.5V to 5.5V supply voltage and supports temperatures from 0°C to 70°C. The product is classified as obsolete, making substitute components necessary for new designs and production continuity. The part is RoHS non-compliant and carries an MSL rating of 3 (168 Hours).

Key Parameters

Parameter	Value
Memory Size	1Mbit
Memory Organization	128K x 8
Memory Interface	Parallel
Access Time	90 ns
Write Cycle Time	50µs
Voltage Supply	4.5V ~ 5.5V
Operating Temperature	0°C ~ 70°C
Package Type	32-TFSOP
Mounting Type	Surface Mount
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution of the AT49F001NT-90TC is determined by the following critical parameters:

Memory Interface: Must be parallel to maintain pin-level compatibility
Package Type: Must be 32-TFSOP to ensure PCB footprint compatibility
Voltage Supply Range: Must support 4.5V ~ 5.5V operation
Operating Temperature Range: Must support 0°C ~ 70°C minimum
Mounting Type: Must be surface mount

The SST39SF020A-55-4C-WHE qualifies as a substitute based on these criteria. While it offers increased memory capacity (2Mbit vs 1Mbit) and improved performance (55 ns vs 90 ns access time), these enhancements are backward-compatible with applications designed for the original part. The substitute maintains identical voltage supply requirements, operating temperature range, package form factor, and parallel interface architecture.

Parameter Comparison

Parameter	AT49F001NT-90TC	SST39SF020A-55-4C-WHE
Memory Size	1Mbit	2Mbit
Memory Organization	128K x 8	256K x 8
Memory Interface	Parallel	Parallel
Access Time	90 ns	55 ns
Write Cycle Time	50µs	20µs
Voltage Supply	4.5V ~ 5.5V	4.5V ~ 5.5V
Operating Temperature	0°C ~ 70°C	0°C ~ 70°C
Package Type	32-TFSOP	32-TFSOP
Mounting Type	Surface Mount	Surface Mount
Product Status	Obsolete	Active
RoHS Status	Non-compliant	ROHS3 Compliant
MSL Rating	3 (168 Hours)	3 (168 Hours)

Engineering Selection Recommendations

The SST39SF020A-55-4C-WHE is the qualified substitute for the AT49F001NT-90TC based on the following factors:

Product Status: The original part is obsolete, while the substitute is active and maintains current production availability
Compliance: The substitute achieves ROHS3 compliance, whereas the original is non-compliant
Performance Enhancement: The substitute provides faster access time (55 ns vs 90 ns) and reduced write cycle time (20µs vs 50µs), delivering improved system performance without compromising compatibility
Electrical Compatibility: Both devices operate within identical voltage supply and temperature ranges
Physical Compatibility: Both devices use the 32-TFSOP package with surface mount configuration, ensuring PCB footprint compatibility
Moisture Sensitivity: Both devices share the same MSL rating of 3 (168 Hours)

Frequently Asked Questions (FAQ)

Q: Can the SST39SF020A-55-4C-WHE directly replace the AT49F001NT-90TC in existing designs?

A: Yes. Both devices share identical package geometry (32-TFSOP), voltage supply requirements (4.5V ~ 5.5V), operating temperature range (0°C ~ 70°C), and parallel memory interface. The substitute's increased memory capacity and faster access time are backward-compatible with applications designed for the original part.

Q: What is the primary reason for substitution?

A: The AT49F001NT-90TC is classified as obsolete, making it unavailable for new production. The SST39SF020A-55-4C-WHE is an active product with current manufacturing support and improved compliance status.

Q: Are there any pin-level differences between these devices?

A: Both devices use the 32-TFSOP package. The parallel memory interface architecture is identical, ensuring pin compatibility for standard memory access operations.

Q: Does the substitute offer any performance advantages?

A: Yes. The SST39SF020A-55-4C-WHE provides 55 ns access time compared to the original 90 ns, and reduces write cycle time from 50µs to 20µs. These improvements enhance system performance without requiring design modifications.

Q: What is the compliance difference between these parts?

A: The original AT49F001NT-90TC is RoHS non-compliant. The substitute SST39SF020A-55-4C-WHE is ROHS3 compliant, meeting current environmental and regulatory requirements for electronics manufacturing.

Q: Are moisture sensitivity levels identical?

A: Yes. Both devices carry an MSL rating of 3 (168 Hours), requiring identical handling and storage protocols during manufacturing and assembly.

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