AT25DF021-SSHF-B Equivalent & Substitute Parts

Part Overview

The AT25DF021-SSHF-B is a 2Mbit Serial Peripheral Interface (SPI) FLASH memory IC manufactured by Microchip Technology, packaged in 8-SOIC form factor. This device operates at 50 MHz clock frequency with supply voltage range of 2.3V to 3.6V and is rated for -40°C to 85°C operating temperature. The part is currently listed as obsolete, making identification of functionally equivalent alternatives essential for ongoing system support and new design implementations.

Key Parameters

Parameter	Value
Memory Size	2Mbit
Memory Organization	256K x 8
Memory Interface	SPI
Clock Frequency	50 MHz
Voltage Supply Range	2.3V ~ 3.6V
Operating Temperature	-40°C ~ 85°C
Package / Case	8-SOIC (0.154", 3.90mm Width)
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution eligibility for the AT25DF021-SSHF-B is determined by the following critical parameters:

Memory Capacity: 2Mbit (256K x 8 organization) — substitute parts must match this capacity
Interface Protocol: SPI — substitute parts must support identical serial communication protocol
Supply Voltage: 2.3V ~ 3.6V — substitute parts must operate within this voltage range
Operating Temperature Range: -40°C ~ 85°C — substitute parts must support this thermal envelope
Package Compatibility: 8-SOIC physical form factor with 0.154" (3.90mm) width — mechanical and electrical pin compatibility required

The identified substitute parts meet these core substitution criteria. Variations in clock frequency, write cycle time, and MSL rating represent performance or handling differences that do not preclude functional substitution when system requirements permit.

Parameter Comparison

Parameter	AT25DF021-SSHF-B (Main)	LE25U20AMB-AH (onsemi)	W25X20CLSNIG (Winbond)
Manufacturer	Microchip Technology	onsemi	Winbond Electronics
Memory Size	2Mbit	2Mbit	2Mbit
Memory Organization	256K x 8	256K x 8	256K x 8
Memory Interface	SPI	SPI	SPI
Clock Frequency	50 MHz	30 MHz	104 MHz
Voltage Supply Range	2.3V ~ 3.6V	2.3V ~ 3.6V	2.3V ~ 3.6V
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C
Package / Case	8-SOIC	8-SOIC	8-SOIC
Product Status	Obsolete	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
MSL Rating	1 (Unlimited)	3 (168 Hours)	3 (168 Hours)

Engineering Selection Recommendations

LE25U20AMB-AH (onsemi): This substitute operates at 30 MHz, which is lower than the main part's 50 MHz specification. Selection of this part is appropriate only when system timing requirements permit operation at reduced clock frequency. The part maintains full voltage and temperature compatibility and carries active product status with ROHS3 compliance.

W25X20CLSNIG (Winbond Electronics): This substitute operates at 104 MHz, exceeding the main part's 50 MHz specification. The part is fully compatible across voltage and temperature ranges, maintains ROHS3 compliance, and carries active product status. The higher clock frequency provides performance margin for timing-critical applications. This part is verified as programmable by DiGi-Electronics.

Both substitute parts are currently in active production status, ensuring long-term availability compared to the obsolete AT25DF021-SSHF-B. Selection between substitutes should be based on specific system timing requirements and performance objectives.

Frequently Asked Questions (FAQ)

Q: Can the LE25U20AMB-AH be used as a direct replacement for the AT25DF021-SSHF-B?

A: The LE25U20AMB-AH meets all core substitution criteria: 2Mbit capacity, SPI interface, 2.3V–3.6V supply voltage, and -40°C to 85°C operating range. The 30 MHz clock frequency is lower than the original 50 MHz specification. Substitution is valid when system timing requirements do not mandate the higher clock speed of the original part.

Q: What are the advantages of the W25X20CLSNIG substitute?

A: The W25X20CLSNIG provides 104 MHz clock frequency, which exceeds the original 50 MHz specification and offers performance headroom for timing-sensitive applications. It maintains full compatibility across voltage, temperature, and package specifications. The part is verified as programmable and carries active product status.

Q: Are there package compatibility concerns between substitutes?

A: All three parts use the 8-SOIC package with 0.154" (3.90mm) width. Physical and electrical pin compatibility is maintained across all substitutes. No PCB layout modifications are required for mechanical substitution.

Q: How do MSL ratings affect part selection?

A: The main part carries MSL 1 (unlimited moisture exposure), while both substitutes carry MSL 3 (168-hour limit). MSL rating affects storage and handling procedures. Parts with MSL 3 require controlled humidity storage and have a 168-hour floor life after moisture barrier bag opening. Selection should account for manufacturing environment and storage capabilities.

Q: Are all substitute parts RoHS compliant?

A: Yes. The main part and both substitutes are ROHS3 compliant, ensuring compatibility with RoHS-regulated supply chains and end-use applications.

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