AT45DB321D-MU-SL955 Equivalent & Substitute Parts

Part Overview

The AT45DB321D-MU-SL955 is a 32Mbit Serial Peripheral Interface (SPI) FLASH memory IC manufactured by Renesas Electronics Corporation, packaged in 8-VDFN (6x5) with an exposed pad. This part operates at 66 MHz and is rated for -40°C to 85°C industrial temperature range with a supply voltage range of 2.7V to 3.6V.

The AT45DB321D-MU-SL955 is classified as obsolete. Substitute parts are necessary to maintain design continuity and ensure long-term component availability for new production runs and legacy system support.

Substiute Parts

AT45DB321D-MU-SL955

Renesas Electronics CorporationIn Stock: 693AT45DB321D-MU-SL955 Datasheet

Current PartRFQ

AT45DB321E-MHF2B-T

Renesas Electronics CorporationIn Stock: 811AT45DB321E-MHF2B-T Datasheet

DirectRFQ

AT45DB321E-MWHF2B-T

Renesas Electronics CorporationIn Stock: 2538AT45DB321E-MWHF2B-T Datasheet

MFR RecommendedRFQ

AT45DQ321-MWHF2B-T

Renesas Electronics CorporationIn Stock: 1230AT45DQ321-MWHF2B-T Datasheet

MFR RecommendedRFQ

AT45DQ321-MWHFHJ-T

Renesas Electronics CorporationIn Stock: 747AT45DQ321-MWHFHJ-T Datasheet

MFR RecommendedRFQ

AT45DQ321-MWHFHK-T

Renesas Electronics CorporationIn Stock: 765AT45DQ321-MWHFHK-T Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution for the AT45DB321D-MU-SL955 is determined by the following critical parameters:

• Memory Capacity: 32Mbit (fixed requirement)
• Memory Interface: SPI (fixed requirement)
• Memory Organization: 512 Bytes x 8192 pages (fixed requirement)
• Operating Temperature Range: -40°C ~ 85°C (fixed requirement)
• Package Type: 8-VDFN Exposed Pad (primary mechanical constraint)
• Supply Voltage Compatibility: Substitute parts must operate within or encompass the original 2.7V ~ 3.6V range
• Clock Frequency: Substitute parts operating at higher frequencies (85 MHz, 104 MHz) are acceptable as they maintain backward compatibility
• Product Status: Active status substitutes are preferred over obsolete parts

The substitute parts listed below maintain identical memory capacity, interface protocol, memory organization, and temperature rating. Variations in clock frequency and package dimensions are noted where applicable.

Parameter Comparison

Engineering Selection Recommendations

Primary Substitute (Recommended for PCB Layout Compatibility): AT45DB321E-MWHF2B-T maintains the 8-VDFN package footprint identical to the original AT45DB321D-MU-SL955. This part is active, ROHS3 compliant, and offers improved performance with 85 MHz clock frequency and reduced page write cycle time (4ms vs. 6ms). The expanded supply voltage range (2.3V ~ 3.6V) provides additional design margin. Moisture sensitivity is reduced to MSL 1 (Unlimited), improving handling and storage reliability.

Alternative Substitute (Higher Performance): AT45DQ321-MWHF2B-T, AT45DQ321-MWHFHJ-T, and AT45DQ321-MWHFHK-T offer the highest clock frequency (104 MHz) within the substitute group. These parts maintain 8-VDFN package compatibility and are active with ROHS3 compliance. Selection among these three variants depends on specific procurement and packaging requirements, as all three share identical electrical specifications.

Package Consideration: AT45DB321E-MHF2B-T uses 8-UDFN (5x6) packaging, which differs from the original 8-VDFN footprint. This part is suitable only for new designs where PCB layout can accommodate the different package dimensions. It is not recommended as a direct replacement in existing PCB designs without layout modification.

Frequently Asked Questions (FAQ)

Q: Can AT45DB321E-MWHF2B-T be used as a direct replacement for AT45DB321D-MU-SL955?

A: Yes. Both parts use 8-VDFN Exposed Pad packaging with identical pinout and SPI interface. The AT45DB321E-MWHF2B-T operates at higher clock frequency (85 MHz vs. 66 MHz) and faster page write cycle (4ms vs. 6ms), providing backward compatibility. The expanded supply voltage range (2.3V ~ 3.6V) encompasses the original specification (2.7V ~ 3.6V).

Q: What is the difference between AT45DB321E and AT45DQ321 series?

A: Both series maintain identical 32Mbit capacity, SPI interface, and memory organization. The primary difference is clock frequency: AT45DB321E operates at 85 MHz, while AT45DQ321 operates at 104 MHz. Both are functionally compatible with the original AT45DB321D-MU-SL955 at the SPI protocol level.

Q: Why does AT45DB321E-MHF2B-T use a different package (8-UDFN vs. 8-VDFN)?

A: Package selection depends on manufacturing and performance requirements. The 8-UDFN (5x6) package is smaller than 8-VDFN (6x5 or 6x8). This part is suitable for new designs but requires PCB layout modification and is not recommended for direct board-level replacement of the original part.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All listed substitute parts (AT45DB321E-MHF2B-T, AT45DB321E-MWHF2B-T, AT45DQ321-MWHF2B-T, AT45DQ321-MWHFHJ-T, AT45DQ321-MWHFHK-T) are ROHS3 compliant. The original AT45DB321D-MU-SL955 RoHS status is not specified in available documentation.

Q: What is the significance of Moisture Sensitivity Level (MSL) reduction from 3 to 1?

A: MSL 3 requires storage at controlled humidity (168-hour floor life after moisture exposure). MSL 1 (Unlimited) eliminates moisture sensitivity constraints, reducing handling complexity and improving shelf life. This is an operational advantage of the substitute parts.

Q: Can higher clock frequency substitutes cause compatibility issues?

A: No. Higher clock frequency (85 MHz or 104 MHz) substitutes are backward compatible with designs specified for 66 MHz operation. The SPI interface protocol remains identical. System performance may improve due to faster data transfer rates, but no functional incompatibility exists.

Q: Which substitute part offers the best overall performance?

A: AT45DQ321-MWHF2B-T, AT45DQ321-MWHFHJ-T, and AT45DQ321-MWHFHK-T offer the highest clock frequency (104 MHz) and fastest page write cycle (4ms). For PCB layout compatibility with the original part, AT45DB321E-MWHF2B-T is recommended as it maintains identical 8-VDFN footprint while providing 85 MHz performance.