AT28BV256-20SU from Microchip Tech, in a SOIC-28-300mil. Pinout and pin descriptions extracted from the manufacturer datasheet (extract_pins, cross-checked by a second model); symbol, footprint, and 3D from KiCad-official CAD.

Pinout

Pin	Name	Type	Function
1	A14	input	Address input A14; with A6-A13 it selects the 64-byte page during a page write, and all bytes in a page write must share the same A6-A14 state.
2	A12	input	Address input A12; part of the A6-A14 page address that must remain constant during a page write.
3	A7	input	Address input A7; part of the A6-A14 page address that must remain constant during a page write.
4	A6	input	Address input A6; the lowest page-address bit, which must remain constant during a page write.
5	A5	input	Address input A5; one of the A0-A5 inputs that select which byte within the 64-byte page is written.
6	A4	input	Address input A4; selects the byte within the 64-byte page during a page write.
7	A3	input	Address input A3; selects the byte within the 64-byte page during a page write.
8	A2	input	Address input A2; selects the byte within the 64-byte page during a page write.
9	A1	input	Address input A1; selects the byte within the 64-byte page during a page write.
10	A0	input	Address input A0; selects the byte within the 64-byte page during a page write.
11	I/O0	bidirectional	Data input/output bit 0; outputs go to high impedance when CE or OE is high.
12	I/O1	bidirectional	Data input/output bit 1; outputs go to high impedance when CE or OE is high.
13	I/O2	bidirectional	Data input/output bit 2; outputs go to high impedance when CE or OE is high.
14	GND	power_in	Ground reference for the device; all input and output voltages are specified with respect to ground (-0.6V to VCC + 0.6V on outputs).
15	I/O3	bidirectional	Data input/output bit 3; outputs go to high impedance when CE or OE is high.
16	I/O4	bidirectional	Data input/output bit 4; outputs go to high impedance when CE or OE is high.
17	I/O5	bidirectional	Data input/output bit 5; outputs go to high impedance when CE or OE is high.
18	I/O6	bidirectional	Data input/output bit 6; toggles during a write cycle when read as the toggle bit, and stops toggling when the write completes.
19	I/O7	bidirectional	Data input/output bit 7; presents the complement of the last written data during Data Polling to indicate the end of a write cycle.
20	CE	input	Chip enable (active low); CE low with OE low and WE high reads the array, and a high level deselects the device and inhibits writes; pulses shorter than 15 ns (typical) on CE are filtered.
21	A10	input	Address input A10; part of the A6-A14 page address that must remain constant during a page write.
22	OE	input	Output enable (active low); with CE low and WE high it enables the outputs, and OE and A9 are rated from -0.6V to +13.5V with respect to ground.
23	A11	input	Address input A11; part of the A6-A14 page address that must remain constant during a page write.
24	A9	input	Address input A9; rated from -0.6V to +13.5V, and raised to 12V ±0.5V to access the 64-byte device identification block at 7FC0H-7FFFH.
25	A8	input	Address input A8; part of the A6-A14 page address that must remain constant during a page write.
26	A13	input	Address input A13; part of the A6-A14 page address that must remain constant during a page write.
27	WE	input	Write enable (active low); a low pulse on WE with CE low and OE high initiates a write cycle, and WE high inhibits writes.
28	VCC	power_in	Device supply voltage; 2.7V to 3.6V for the AT28BV256-20 operating range.

Key specifications

Parameter	Value
Manufacturer	Microchip Tech
Package	SOIC-28-300mil
Category	Interface ICs
Pins	28

Electrical characteristics

Limits as printed in the datasheet (page.json metadata.characteristics carries them as data).

Parameter	Symbol	Min	Typ	Max	Unit	Conditions	Page
Input Load Current	ILI			10	µA	VIN = 0V to VCC + 1V	6
Output Leakage Current	ILO			10	µA	VI/O = 0V to VCC	6
VCC Standby Current CMOS	ISB			50	µA	CE = VCC - 0.3V to VCC + 1V	6
VCC Active Current	ICC			15	mA	f = 5 MHz; IOUT = 0 mA	6
Input Low Voltage	VIL			0.6	V		6
Input High Voltage	VIH	2			V		6
Output Low Voltage	VOL			0.3	V	IOL = 1.6 mA	6
Output High Voltage	VOH	2			V	IOH = -100 µA	6
Address to Output Delay (AT28BV256-20)	tACC			200	ns		7
CE to Output Delay (AT28BV256-20)	tCE			200	ns		7
OE to Output Delay (AT28BV256-20)	tOE	0		80	ns		7
CE or OE to Output Float (AT28BV256-20)	tDF	0		55	ns	CL = 5 pF	7
Output Hold from OE, CE or Address, whichever occurred first (AT28BV256-20)	tOH	0			ns		7
Input Capacitance	CIN		4	6	pF	f = 1 MHz, T = 25°C; VIN = 0V	8
Output Capacitance	COUT		8	12	pF	f = 1 MHz, T = 25°C; VOUT = 0V	8
Address, OE Set-up Time	tAS, tOES	0			ns		9
Address Hold Time	tAH	50			ns		9
Chip Select Set-up Time	tCS	0			ns		9
Chip Select Hold Time	tCH	0			ns		9
Write Pulse Width (WE or CE)	tWP	200			ns		9
Data Set-up Time	tDS	50			ns		9
Data, OE Hold Time	tDH, tOEH	0			ns		9
Write Cycle Time	tWC			10	ms		10
Address Set-up Time (page mode)	tAS	0			ns		10
Address Hold Time (page mode)	tAH	50			ns		10
Data Set-up Time (page mode)	tDS	50			ns		10
Data Hold Time (page mode)	tDH	0			ns		10
Write Pulse Width (page mode)	tWP	200			ns		10
Byte Load Cycle Time	tBLC			150	µs		10
Write Pulse Width High	tWPH	100			ns		10
Data Hold Time (data polling)	tDH	0			ns		11
OE Hold Time (data polling)	tOEH	0			ns		11
Write Recovery Time (data polling)	tWR	0			ns		11
Data Hold Time (toggle bit)	tDH	10			ns		11
OE Hold Time (toggle bit)	tOEH	10			ns		11
OE High Pulse	tOEHP	150			ns		11
Write Recovery Time (toggle bit)	tWR	0			ns		11
VCC Power Supply	VCC	2.7		3.6	V	DC and AC operating range, AT28BV256-20	6
Operating Temperature (Case)		-40		85	°C	DC and AC operating range, AT28BV256-20	6
Temperature under Bias		-55		125	°C		3
Storage Temperature		-65		150	°C		3
All Input Voltages (including NC Pins) with respect to Ground		-0.6		6.25	V	with respect to ground	3
All Output Voltages with respect to Ground (upper limit is VCC + 0.6 V)		-0.6			V	with respect to ground; upper limit printed as VCC + 0.6V	3
Voltage on OE and A9 with respect to Ground		-0.6		13.5	V	with respect to ground	3

CAD (KiCad official)

Symbol: AT28BV256-20SU
Footprint: Package_SO:SOIC-28W_7.5x17.9mm_P1.27mm
3D model: SOIC-28-300mil (KiCad packages3D, STEP)
3D model files: at28bv256-20su-etched.step / at28bv256-20su-etched.glb carry the MPN laser-etched on the die in a toggleable Adom.LaserEtch group (Fusion-ready); at28bv256-20su.step / at28bv256-20su.glb are the bare package body.

Provenance

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

Datasheet: Microchip Tech datasheet (17 pp, sha256 f00f572c17dec02e, retrieved 2026-10-30, tier: manufacturer)
Extractor: parts-factory 2.0.0 / extract_pins 0.3, primary claude-haiku-5-5 (text), consensus claude-sonnet-5-5 (agreed), guards: pin_guards 0.1: passed. Pins are checked against the footprint pad set and their cited datasheet pages before publish.
CAD: KiCad official libraries (CC-BY-SA 4.0).

Datasheet PDF

AT28BV256-20SU

Verified AT28BV256-20SU

Verification log 1 record

3D Model

Symbol & Footprint

Schematic Symbol

PCB Footprint

Datasheet

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