Microchip Serial EEPROM NRND Cross-Reference Guide: 25LC080, 25AA640, 25AA080, 24C08 to Active Equivalents
Cross-reference guide for Microchip NRND serial EEPROMs: 25LC080, 25AA640, 25AA080A (SPI) and 24C08B (I2C) to active A/B-revision drop-in replacements.
Last updated: June 2026
Bottom Line: Several Microchip serial EEPROM order codes — 25LC080-I/SN (8 Kbit SPI), 25AA640-I/SN (64 Kbit SPI), 25AA080A-I/SN (8 Kbit SPI), and 24C08B/SN (8 Kbit I2C) — are Not-Recommended-for-New-Design (NRND). Engineers migrating away from these parts should transition to drop-in active equivalents: the A- and B-suffix die revisions (e.g., 25LC080A, 25LC080B, 25AA080A, 25AA080B, 25AA640A) in the same SOIC-8 or MSOP-8 footprint, operating from 1.8 V–5.5 V on SPI, or the AT24C08C/AT24C08D family on I2C for 24C08B replacements. No board re-spin is needed for same-package substitutions; only firmware page-size handling may require an update when moving from 16-byte (A revision) to 32-byte (B revision) page writes.
Why These Parts Are NRND
Microchip periodically marks mature die revisions as Not-Recommended-for-New-Design once a silicon refresh — offering improved write-endurance, lower standby current, or an expanded voltage range — reaches volume production. NRND status does not mean the parts are counterfeit or defective; it means Microchip prefers new designs to use the latest revision. Supply for NRND parts often thins out over 12–18 months, leading to price volatility and allocation risk. The four affected families are:
- 25LC080-I/SN — original 8 Kbit SPI EEPROM, 16-byte page, 2.5 V–5.5 V, SOIC-8, 1 MHz max clock.
- 25AA640-I/SN — original 64 Kbit SPI EEPROM, 1 MHz max clock, 1.8 V–5.5 V, SOIC-8.
- 25AA080A-I/SN — 8 Kbit SPI EEPROM, A-revision die, 16-byte page, 1.8 V–5.5 V, SOIC-8.
- 24C08B/SN — 8 Kbit I2C EEPROM, 5.0 V operation, 100 kHz clock, SOIC-8.
Decoding the Order-Code Suffix
Understanding the suffix structure saves time when selecting a replacement:
| Field | Example | Meaning |
|---|---|---|
| Base part | 25LC080 | SPI, 8 Kbit, 2.5 V min (LC = 2.5 V); 25AA = 1.8 V min |
| Die revision | A, B, D | Silicon revision; B typically adds 32-byte page, D adds DIP removal |
| Temp grade | -I | Industrial: −40 °C to +85 °C |
| Package code | /SN | SOIC-8 (0.150-inch body); /P = PDIP-8; /MS = MSOP-8; /ST = TSSOP-8 |
The LC prefix (e.g., 25LC080) indicates a 2.5 V minimum supply. The AA prefix (e.g., 25AA080, 25AA640) indicates a 1.8 V minimum supply — important for low-voltage MCU designs. Both operate up to 5.5 V, so an AA-prefix part is a superset of an LC-prefix part at the same density.
SPI vs I2C: Choosing the Right Bus
The 25-series parts (25LC, 25AA) use a 4-wire SPI interface (SCK, SI, SO, /CS). The 24-series (24C08, AT24C08) use a 2-wire I2C interface (SCL, SDA). SPI offers higher throughput — up to 10 MHz for the 25LC080A — while I2C uses fewer GPIO pins and supports multi-device addressing via hardware address pins. For new designs that can spare 4 GPIO pins, the SPI variants offer faster burst reads; for pin-constrained designs, the I2C AT24C08C/D family is the natural 24C08B replacement. Do not substitute a 25-series SPI EEPROM for a 24-series I2C EEPROM without firmware changes.
Density Map: 8 Kbit vs 64 Kbit
| Density | Capacity | Typical page size | Address bytes | NRND example | Active replacement |
|---|---|---|---|---|---|
| 8 Kbit | 1,024 × 8 | 16 bytes (rev A) / 32 bytes (rev B) | 2 | 25LC080-I/SN, 25AA080A-I/SN | 25LC080A-I/SN, 25LC080B-I/SN, 25AA080A-I/SN, 25AA080B-I/SN |
| 64 Kbit | 8,192 × 8 | 32 bytes | 2 | 25AA640-I/SN | 25AA640A-I/SN |
| 8 Kbit I2C | 1,024 × 8 | 16 bytes | 1 | 24C08B/SN | AT24C08C-SSHM-T, AT24C08D-MAHM-E |
Moving from an 8 Kbit to a 64 Kbit part is not a drop-in substitute; address maps and memory layout differ. Always match density when cross-referencing.
Supply Voltage and Temperature Range
All listed parts operate across a wide 2.5 V–5.5 V (LC-prefix) or 1.8 V–5.5 V (AA-prefix) supply range, covering both 3.3 V and 5 V logic systems without level shifters. The -I temperature suffix confirms industrial grade: −40 °C to +85 °C. Consumer-grade parts without the -I suffix are rated 0 °C to +70 °C and should not be used in automotive or outdoor industrial applications unless the datasheet explicitly states otherwise. The AT24C08C and AT24C08D families both carry industrial-grade variants with the same −40 °C to +85 °C rating.
Cross-Reference Table: NRND to Active Replacements
| NRND Order Code | Bus | Density | Package | Active Replacement(s) | Notes |
|---|---|---|---|---|---|
| 25LC080-I/SN | SPI | 8 Kbit | SOIC-8 | 25LC080A-I/SN, 25LC080B-I/SN | B-rev adds 32-byte page |
| 25AA640-I/SN | SPI | 64 Kbit | SOIC-8 | 25AA640A-I/SN | Drop-in; same SOIC-8 footprint |
| 25AA080A-I/SN | SPI | 8 Kbit | SOIC-8 | 25AA080B-I/SN | B-rev; 32-byte page vs 16-byte |
| 24C08B/SN | I2C | 8 Kbit | SOIC-8 | AT24C08C-SSHM-T, AT24C08D-MAHM-E | SOIC-8 or UDFN; 1.7 V min |
For alternative package options — MSOP-8, TSSOP-8, PDIP-8 — additional footprint variants exist in our catalog. Use the FindMyChip part search to filter by package code.
Key Selection Parameters
1. Die Revision (A vs B): Page Write Size Matters
Revision A parts (e.g., 25LC080A, 25AA080A) use a 16-byte page write buffer. Revision B parts (e.g., 25LC080B, 25AA080B) use a 32-byte page write buffer, cutting the number of write cycles needed for large sequential writes by up to 50%. If firmware uses page-aligned writes, moving from an A-rev to a B-rev is firmware-transparent; if code writes partial pages that cross a 16-byte boundary on an A-rev, updating to a 32-byte boundary is required to prevent wrap-around data corruption. Always verify page size in the target datasheet before switching revisions.
2. Minimum Supply Voltage: LC vs AA Prefix
The LC prefix (25LC080) requires a minimum 2.5 V supply, while the AA prefix (25AA080, 25AA640) operates from 1.8 V minimum, making AA-prefix parts compatible with ultra-low-power MCUs such as Cortex-M0+ devices running at 1.8 V I/O. In 3.3 V or 5 V systems, both prefixes behave identically — the AA part is a superset. Choose the AA variant whenever there is any chance of operating below 2.5 V.
3. Clock Speed: 1 MHz vs 10 MHz
Original NRND parts (25LC080-I/SN, 25AA640-I/SN, 25AA080A-I/SN) are rated for 1 MHz maximum SPI clock. Active A- and B-revision replacements are rated for 10 MHz maximum clock at 4.5 V–5.5 V (or 3 MHz at 1.8 V–3.6 V), offering up to a 10× read throughput improvement. Unless the SPI bus is shared with slower peripherals, the active replacements enable faster boot-time configuration loading and reduce firmware latency in real-time systems.
4. Write Endurance and Data Retention
All Microchip 25-series and AT24C08 EEPROM variants specify 1,000,000 write/erase cycles per byte and 200-year data retention at 25 °C (per JEDEC Standard 22, Method A117). These figures are identical across the NRND and active parts, so endurance is not a differentiator when cross-referencing.
5. Package Availability
The SOIC-8 (/SN) is the most common package and the easiest to source globally. MSOP-8 (/MS) is useful for space-constrained designs. TSSOP-8 (/ST) and SOT-23-5 variants exist for the AT24C08C/D for extreme miniaturization. PDIP-8 (/P) is still available for breadboard prototyping but is uncommon in production. Verify that the replacement package matches your PCB land pattern before ordering.
Selection Decision Flowchart
Use this decision tree to select the correct active replacement:
Is the NRND part SPI or I2C?
- I2C (24C08B) → go to step 4.
- SPI (25LC080, 25AA640, 25AA080A) → go to step 2.
What density do you need?
- 8 Kbit → go to step 3.
- 64 Kbit → select 25AA640A-I/SN. Done.
What is your minimum supply voltage?
- ≥ 2.5 V → use 25LC080A-I/SN or 25LC080B-I/SN.
- < 2.5 V (down to 1.8 V) → use 25AA080A-I/SN or 25AA080B-I/SN.
- Prefer 32-byte page writes → choose the B-revision in either case.
For I2C 8 Kbit replacements (24C08B):
- Need SOIC-8 → AT24C08C-SSHM-T.
- Need smallest footprint (UDFN) → AT24C08D-MAHM-E.
- Note: AT24C08C/D operate from 1.7 V minimum — a wider range than 24C08B's 5.0 V-only spec.
Frequently Asked Questions
Are 25LC080-I/SN and 25LC080A-I/SN pin-compatible?
Yes. Both are SOIC-8 parts with the same pinout (VCC, GND, SCK, SI, SO, /CS, /HOLD, /WP). The only functional differences are clock speed (1 MHz vs 10 MHz) and page write size (16 bytes for the original, 16 bytes for the A-revision as well). The 25LC080B-I/SN in the same SOIC-8 footprint extends page write to 32 bytes and should be verified against your firmware's page-boundary assumptions.
Can I replace 24C08B/SN with AT24C08C-SSHM-T directly?
AT24C08C-SSHM-T is electrically compatible in an SOIC-8 footprint and shares the same 8 Kbit I2C protocol. The 24C08B/SN is rated for 5.0 V and 100 kHz; the AT24C08C operates from 1.7 V–5.5 V at up to 400 kHz (Fast Mode I2C), making it a functional superset. No board re-spin is required, but verify that I2C address pins (A0–A2) are wired identically, as AT24C08C uses a 3-bit hardware address.
What is the lead time difference between NRND and active parts?
NRND parts often carry 12–26 week lead times through authorized distributors due to reduced production priority. Active A- and B-revision replacements typically ship within 4–8 weeks from stock at FindMyChip's verified distributor network. For urgent requirements, use the FindMyChip quote form to get competitive pricing and availability from 200+ verified sources within 24 hours.
Do I need to update firmware when switching from 25AA080A to 25AA080B?
Only if your write routine crosses a 16-byte page boundary. The 25AA080A uses a 16-byte page write buffer; the 25AA080B uses a 32-byte buffer. Writes that stay within a single 16-byte page will work identically on the B-revision. If firmware intentionally exploits the 32-byte page of the B-revision, it will cause data corruption on any remaining A-revision parts in field inventory.
Where can I find verified stock of these Microchip EEPROM replacements?
FindMyChip aggregates real-time inventory from 200+ verified distributors. Search by MPN on FindMyChip or submit a BOM request to FindMyChip's quote page for competitive pricing, lead time comparison, and 5-point authenticity verification. All stock is sourced directly from authorized channels to eliminate counterfeit risk.
Conclusion
Migrating away from Microchip's NRND serial EEPROM order codes is straightforward when you match three parameters: bus type (SPI for 25-series, I2C for 24C08B replacements), density (8 Kbit or 64 Kbit), and package (typically SOIC-8 with /SN suffix for industrial -I grade). The active A- and B-revision parts are drop-in hardware replacements in the same footprint, with the B-revision offering a 32-byte page write buffer and 10 MHz clock for improved throughput. For the 24C08B/SN I2C line, the AT24C08C and AT24C08D families extend the voltage range to 1.7 V and support 400 kHz Fast Mode I2C.
Start your cross-reference search on the FindMyChip parts catalog, or contact our sourcing team via /quote to receive competitive pricing from verified distributors within 24 hours.