A 1 Mbit (128 KB) serial SRAM in a SOIC-8, extra read/write memory for microcontrollers that are short on RAM. Unlike flash or EEPROM it has unlimited write endurance and no erase step, so it suits fast-changing data: display frame buffers, audio and sensor buffers, and scratch space. It speaks standard SPI plus faster SDI (dual) and SQI (quad) modes, sharing the six data pins, and offers byte, page, and sequential access. Data is volatile (it clears on power loss). Runs 2.5-5.5 V.

Pinout

Pin	Name	Type	Function
1	CS	input	Chip Select input, active low. Bringing CS low selects the device and begins a transaction; taking CS high terminates the operation and puts the device in standby. Must be held low for the entire operation.
2	SO/SIO1	bidirectional	Serial data output in standard SPI mode; bidirectional data line 1 in SDI (dual) and SQI (quad) modes. Data changes on the falling edge of SCK in SPI mode.
3	SIO2	bidirectional	Bidirectional data line 2, active only in SQI (quad) mode. High-impedance in standard SPI and SDI modes.
4	VSS	power_in	Ground reference for the device (0 V).
5	SI/SIO0	bidirectional	Serial data input in standard SPI mode; bidirectional data line 0 in SDI and SQI modes. Instructions, addresses and write data are shifted in on the rising edge of SCK, MSB first.
6	SCK	input	Serial clock input. Input data is latched on the rising edge; output data changes on the falling edge. Max 20 MHz (I-temp) / 16 MHz (E-temp).
7	HOLD/SIO3	bidirectional	In SPI / SDI mode this is the active-low HOLD input: driving HOLD low with CS low pauses serial communication without deselecting the device (SO goes high-Z, SI is ignored). In SQI (quad) mode this pin becomes bidirectional data line 3.
8	VCC	power_in	Supply voltage input. 23LC1024: 2.5 V to 5.5 V (23A1024 variant: 1.7 V to 2.2 V). Decouple with a 0.1 uF ceramic capacitor close to the pin.

Key specifications

Parameter	Value
Type	Serial SRAM (volatile)
Density	1 Mbit (128 KB)
Interface	SPI / SDI (dual) / SQI (quad)
Endurance	unlimited writes
Access modes	byte / page / sequential
Max clock	20 MHz
Supply voltage	2.5-5.5 V
Package	SOIC-8

Ordering variants

23LC1024-I/SN (SOIC-8)
23LC1024-I/P (PDIP-8)

CAD (KiCad official)

Symbol: 23LC1024 (generated from datasheet; KiCad has no symbol)
Footprint: Package_SO:SOIC-8_3.9x4.9mm_P1.27mm
3D model: SOIC-8 (KiCad packages3D)

Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

Datasheet: Microchip Technology datasheet (32 pp, sha256 b2f1789d475fa761, retrieved 2026-08-17, tier: manufacturer)
Extractor: ds2sf (Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate.
CAD: KiCad official libraries (CC-BY-SA 4.0).

Datasheet PDF