Equivalent & Substitute Parts for 24LC21AT/SN

Part Overview

The 24LC21AT/SN is a 1Kbit EEPROM memory IC manufactured by Microchip Technology, featuring I2C interface operation at 400 kHz with 8-SOIC surface mount packaging. This device is classified as Active product status and is ROHS3 compliant. The part is supplied in Cut Tape (CT) & Digi-Reel® packaging with 27,040 units currently in stock inventory.

Equivalent and substitute parts are identified based on matching core electrical and mechanical specifications: 1Kbit memory capacity, 128 x 8 memory organization, I2C interface protocol, 8-SOIC package format, and compatible voltage supply ranges. Substitutes may vary in clock frequency, access time, operating temperature range, write cycle time, and packaging format while maintaining functional compatibility for standard I2C EEPROM applications.

Key Parameters

Parameter	24LC21AT/SN
Manufacturer	Microchip Technology
Memory Type	Non-Volatile EEPROM
Memory Size	1Kbit
Memory Organization	128 x 8
Memory Interface	I2C
Clock Frequency	400 kHz
Access Time	900 ns
Write Cycle Time	10 ms
Voltage Supply Range	2.5V ~ 5.5V
Operating Temperature	0°C ~ 70°C
Package / Case	8-SOIC (0.154", 3.90mm Width)
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant
MSL Rating	1 (Unlimited)

Substitute Part Grouping Explanation

Substitute parts for the 24LC21AT/SN are grouped based on the following substitution criteria:

Core Compatibility Parameters (Must Match):

Memory Size: 1Kbit
Memory Organization: 128 x 8
Memory Interface: I2C
Package / Case: 8-SOIC (0.154", 3.90mm Width)
Mounting Type: Surface Mount

Variable Parameters (Allowed to Differ):

Clock Frequency: 400 kHz or higher
Access Time: 900 ns or faster
Write Cycle Time: 5 ms or 10 ms
Voltage Supply Range: 2.5V ~ 5.5V or extended ranges (1.7V ~ 5.5V)
Operating Temperature: 0°C ~ 70°C or extended ranges (-40°C ~ 85°C, -40°C ~ 125°C)
Packaging Format: Cut Tape (CT) & Digi-Reel®, Tape & Reel (TR), or Tube
Manufacturer: Microchip Technology or Rohm Semiconductor

All substitute parts maintain identical memory capacity, organization, interface protocol, and physical package dimensions, ensuring direct functional compatibility in I2C EEPROM applications.

Parameter Comparison

Part Number	Manufacturer	Memory Size	Clock Frequency	Access Time	Write Cycle Time	Voltage Supply	Operating Temperature	Package	Packaging Format	Product Status
24LC21AT/SN	Microchip Technology	1Kbit	400 kHz	900 ns	10 ms	2.5V ~ 5.5V	0°C ~ 70°C	8-SOIC	Cut Tape (CT) & Digi-Reel®	Active
24LC21A/SN	Microchip Technology	1Kbit	400 kHz	900 ns	10 ms	2.5V ~ 5.5V	0°C ~ 70°C	8-SOIC	Tube	Active
24AA014HT-I/SN	Microchip Technology	1Kbit	400 kHz	900 ns	5 ms	1.7V ~ 5.5V	-40°C ~ 85°C	8-SOIC	Tape & Reel (TR)	Active
24AA01T-I/SN	Microchip Technology	1Kbit	400 kHz	3500 ns	5 ms	1.7V ~ 5.5V	-40°C ~ 85°C	8-SOIC	Cut Tape (CT) & Digi-Reel®	Active
24LC014T-I/SN	Microchip Technology	1Kbit	400 kHz	900 ns	5 ms	2.5V ~ 5.5V	-40°C ~ 85°C	8-SOIC	Cut Tape (CT) & Digi-Reel®	Active
24LC01BHT-I/SN	Microchip Technology	1Kbit	400 kHz	900 ns	5 ms	2.5V ~ 5.5V	-40°C ~ 85°C	8-SOIC	Tape & Reel (TR)	Active
24LC01BT-E/SN	Microchip Technology	1Kbit	400 kHz	4.6 µs	5 ms	2.5V ~ 5.5V	-40°C ~ 125°C	8-SOIC	Cut Tape (CT) & Digi-Reel®	Active
24LC01BT-I/SN	Microchip Technology	1Kbit	400 kHz	4.6 µs	5 ms	2.5V ~ 5.5V	-40°C ~ 85°C	8-SOIC	Cut Tape (CT) & Digi-Reel®	Active
24LC01BT/SN	Microchip Technology	1Kbit	400 kHz	4.6 µs	5 ms	2.5V ~ 5.5V	0°C ~ 70°C	8-SOIC	Tape & Reel (TR)	Active
AT24CS01-SSHM-T	Microchip Technology	1Kbit	1 MHz	550 ns	5 ms	1.7V ~ 5.5V	-40°C ~ 85°C	8-SOIC	Cut Tape (CT) & Digi-Reel®	Active
BR24C21FJ-E2	Rohm Semiconductor	1Kbit	400 kHz	Not Specified	10 ms	2.5V ~ 5.5V	-40°C ~ 85°C	8-SOIC	Tape & Reel (TR)	Active

Engineering Selection Recommendations

All listed substitute parts maintain Active product status and ROHS3 compliance, ensuring regulatory alignment with the 24LC21AT/SN. Selection among substitutes depends on application-specific requirements:

For Direct Replacement (Identical Operating Temperature): 24LC21A/SN and 24LC01BT/SN maintain the 0°C ~ 70°C operating temperature range matching the main part. 24LC21A/SN differs only in packaging format (Tube vs. Cut Tape & Digi-Reel®). 24LC01BT/SN offers identical temperature range with Tape & Reel packaging and faster write cycle time (5 ms vs. 10 ms).

For Extended Temperature Range Applications: 24AA014HT-I/SN, 24AA01T-I/SN, 24LC014T-I/SN, 24LC01BHT-I/SN, 24LC01BT-E/SN, and AT24CS01-SSHM-T support -40°C ~ 85°C operating range. 24LC01BT-E/SN extends to -40°C ~ 125°C for high-temperature environments. These parts feature reduced write cycle time (5 ms) compared to the main part (10 ms).

For Extended Voltage Supply Range: 24AA014HT-I/SN, 24AA01T-I/SN, and AT24CS01-SSHM-T support 1.7V ~ 5.5V voltage range, enabling operation in low-power applications. AT24CS01-SSHM-T additionally provides 1 MHz clock frequency and 550 ns access time for higher-speed I2C communication.

For Cross-Manufacturer Compatibility: BR24C21FJ-E2 from Rohm Semiconductor provides equivalent 1Kbit I2C EEPROM functionality with 8-SOIC packaging, -40°C ~ 85°C operating range, and 10 ms write cycle time matching the main part specifications.

Programmability Verification: 24LC21AT/SN, 24LC21A/SN, 24AA01T-I/SN, 24LC014T-I/SN, 24LC01BT-E/SN, and 24LC01BT-I/SN are verified as DiGi-Electronics Programmable. 24AA014HT-I/SN, 24LC01BHT-I/SN, and AT24CS01-SSHM-T are not verified for programmability status.

Frequently Asked Questions (FAQ)

Q: Can 24LC01BT-I/SN directly replace 24LC21AT/SN in existing designs?

A: 24LC01BT-I/SN is functionally compatible as a direct substitute. Both devices feature 1Kbit capacity, 128 x 8 organization, I2C interface at 400 kHz, and 8-SOIC packaging. The main differences are faster write cycle time (5 ms vs. 10 ms), extended access time (4.6 µs vs. 900 ns), and extended operating temperature range (-40°C ~ 85°C vs. 0°C ~ 70°C). Designs operating within 0°C ~ 70°C temperature range will function identically.

Q: What is the difference between Cut Tape (CT) & Digi-Reel® and Tape & Reel (TR) packaging?

A: Both are surface mount packaging formats suitable for automated assembly. Cut Tape (CT) & Digi-Reel® provides individual component strips on carrier tape, while Tape & Reel (TR) supplies components on continuous reel format. Selection depends on production volume and assembly equipment compatibility. Electrical and mechanical specifications remain identical between formats.

Q: Is AT24CS01-SSHM-T compatible with 24LC21AT/SN applications?

A: AT24CS01-SSHM-T is electrically compatible with identical 1Kbit capacity, 128 x 8 organization, and 8-SOIC package. The primary difference is 1 MHz clock frequency versus 400 kHz, enabling faster I2C communication. Extended voltage range (1.7V ~ 5.5V) and operating temperature (-40°C ~ 85°C) provide broader application flexibility. Designs requiring 400 kHz I2C operation will function correctly with AT24CS01-SSHM-T, as the device supports backward compatibility with lower clock frequencies.

Q: Why does 24AA01T-I/SN have slower access time (3500 ns) compared to 24LC21AT/SN (900 ns)?

A: Access time represents the delay from I2C address/command transmission to data availability. 24AA01T-I/SN's 3500 ns access time is within acceptable I2C protocol timing specifications and does not prevent functional compatibility. Applications with strict timing requirements should verify access time specifications against system requirements.

Q: Can BR24C21FJ-E2 from Rohm Semiconductor be used as a substitute?

A: BR24C21FJ-E2 provides equivalent 1Kbit I2C EEPROM functionality with matching 8-SOIC package and 400 kHz clock frequency. Extended operating temperature range (-40°C ~ 85°C) and 10 ms write cycle time match the main part specifications. Cross-manufacturer substitution is supported for applications where component availability or supply chain requirements necessitate alternative sources.

Q: What is the significance of MSL (Moisture Sensitivity Level) rating?

A: All listed parts maintain MSL 1 (Unlimited) or MSL 3 (168 Hours) ratings. MSL 1 indicates unlimited shelf life without moisture exposure precautions. MSL 3 requires storage in controlled humidity environments and has 168-hour floor life after package opening. 24AA01T-I/SN carries MSL 3 rating, requiring adherence to moisture control procedures during storage and assembly.

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