Part A
25LC1024T-E/SM
Microchip Technology
- Lifecycle
- Active
- Stock
- 6964 PCS
- Package
- SOIC-8
- Series
- Memory
Replacement verdict
Not a drop-in replacement
The 25LC1024T-E/SM and 25LC128T-E/SN are not drop-in replacements for one another. Although both are Microchip SPI serial EEPROM devices sharing the same 8-pin SOIC footprint and similar supply voltage and temperature ratings, they differ fundamentally in memory density (1 Mbit versus 128 Kbit), page size, and command set. The 25LC1024 offers eight times the storage capacity and supports additional instructions such as sector erase and deep power-down, while the 25LC128 provides a smaller, lower-density alternative. Designers must verify firmware addressing, page-write boundaries, and instruction compatibility before considering any substitution.
Different memory density
Different page size
Different command set
Different address width
Parts at a glance
Part B
25LC128T-E/SN
Microchip Technology
- Lifecycle
- Active
- Stock
- 5635 PCS
- Package
- SOIC-8
- Series
- Memory
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | 25LC1024T-E/SM | 25LC128T-E/SN | Why it matters |
|---|---|---|---|
| Memory Density | 1 Mbit (128K x 8) | 128 Kbit (16K x 8) | Determines total storage capacity; the two parts are not drop-in substitutes because the 25LC1024 offers eight times the memory of the 25LC128. |
| Package / Case | 8-SOIC (SOIJ, 5.28mm width) | 8-SOIC (SOIC, 3.90mm width) | Footprint and land pattern differ between SOIJ and narrow SOIC, so PCB layout compatibility must be verified before substitution. |
| Interface Type | SPI (Serial Peripheral Interface) | SPI (Serial Peripheral Interface) | Both use the same SPI protocol, allowing firmware command compatibility at the bus level. |
| Maximum Clock Frequency | 10 MHz | 10 MHz | Clock rate affects read/write throughput; matching rates simplifies timing budget reuse. |
| Operating Voltage Range | 2.5 V to 5.5 V | 2.5 V to 5.5 V | Both support the same supply window, so system power design can be shared. |
| Page Size | 256 bytes | 64 bytes | Page size dictates maximum bytes per write cycle; firmware write routines must be adjusted when swapping parts. |
| Temperature Range | -40°C to +125°C (Extended) | -40°C to +125°C (Extended) | Both meet extended industrial temperature requirements, suitable for harsh environments. |
| Supply Current (Read, max) | 10 mA | 6 mA | Higher read current on the 25LC1024 may affect power budgeting in low-power designs. |
| Endurance | 1,000,000 erase/write cycles | 1,000,000 erase/write cycles | Both offer the same high endurance, ensuring comparable long-term reliability for frequent write applications. |
| Data Retention | >200 years | >200 years | Equivalent retention guarantees non-volatile storage longevity for both devices. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 25LC1024T-E/SM | 25LC128T-E/SN |
|---|---|---|
| Part Status | Active | Active |
| Memory Type | Non-Volatile | Non-Volatile |
| Memory Format | EEPROM | EEPROM |
| Technology | EEPROM | EEPROM |
| Memory Size | 1Mb (128K x 8) | 128Kb (16K x 8) |
| Memory Interface | SPI | SPI |
| Clock Frequency | 20 MHz | 10 MHz |
| Write Cycle Time - Word Page | 6ms | 5ms |
| Voltage - Supply | 2.5V ~ 5.5V | 2.5V ~ 5.5V |
| Operating Temperature | -40°C ~ 125°C (TA) | -40°C ~ 125°C (TA) |
| Mounting Type | Surface Mount | Surface Mount |
Frequently asked questions
What are the key differences between the 25LC1024T-E/SM and the 25LC128T-E/SN?
The primary differences are memory density and package type. The 25LC1024T-E/SM is a 1 Mbit (1024 Kbit) SPI serial EEPROM offered in an 8-lead SOIJ (SM) package, while the 25LC128T-E/SN is a 128 Kbit SPI serial EEPROM offered in an 8-lead SOIC (SN) package. Both operate over the industrial temperature range of -40°C to +125°C and use the standard SPI bus.
Are the 25LC1024T-E/SM and 25LC128T-E/SN pin-compatible?
Both devices use an 8-lead package with the same standard SPI pinout: Chip Select (CS), Serial Clock (SCK), Serial Data In (SI), Serial Data Out (SO), Write Protect (WP), Hold (HOLD), VCC, and VSS. However, the 25LC1024T-E/SM uses the SOIJ (SM) package while the 25LC128T-E/SN uses the SOIC (SN) package. These package types have different body widths and PCB land patterns, so they are not drop-in replacements without verifying footprint compatibility.
Can the 25LC128T-E/SN be used as a direct substitute for the 25LC1024T-E/SM?
No. The 25LC1024T-E/SM provides 1 Mbit of memory while the 25LC128T-E/SN provides only 128 Kbit, which is one-eighth the capacity. A direct substitution would require firmware and address range changes, and the package footprint difference between SOIJ and SOIC must also be resolved. Substitution is only possible after validating all differences against the respective manufacturer datasheets and the target design requirements.
Do both devices support the same SPI modes and clock frequencies?
Both devices support SPI modes 0 (0,0) and 3 (1,1). The 25LC1024T-E/SM supports clock frequencies up to 20 MHz, while the 25LC128T-E/SN supports clock frequencies up to 10 MHz. Designers must ensure the host SPI controller does not exceed the maximum clock rate of the specific device in use.
What are the operating voltage ranges for the 25LC1024T-E/SM and 25LC128T-E/SN?
Both devices operate from a single supply voltage range of 2.5V to 5.5V, making them suitable for mixed 3.3V and 5V system designs. All AC and DC characteristics are specified across this full voltage range per the manufacturer datasheets.
What are the page size and write cycle specifications for these two EEPROMs?
The 25LC1024T-E/SM has a 256-byte page size, while the 25LC128T-E/SN has a 64-byte page size. Both devices support byte and page write operations and are rated for a minimum of 1,000,000 erase/write cycles with a data retention of over 200 years, as specified in the manufacturer datasheets.
Are both devices qualified for automotive or industrial applications?
Both the 25LC1024T-E/SM and 25LC128T-E/SN are offered in the -E temperature grade, which covers the industrial temperature range of -40°C to +125°C. Designers should consult the manufacturer's product qualification data and datasheets to confirm whether specific automotive or other application-specific qualifications apply to each orderable part number.