AT25128B/AT25256B
SPI Serial EEPROM 128 Kbits (16,384 x 8)
and 256 Kbits (32,768 x 8)
Features
• Serial Peripheral Interface (SPI) Compatible
• Supports SPI Modes 0 (0,0) and 3 (1,1):
– Data sheet describes mode 0 operation
• Low-Voltage Operation:
– 1.8V (VCC = 1.8V to 5.5V)
• Industrial Temperature Range: -40°C to +85°C
• 20 MHz Clock Rate (5V)
• 64‑Byte Page Mode
• Block Write Protection:
– Protect 1/4, 1/2 or entire array
• Write-Protect (WP) Pin and Write Disable Instructions for Both Hardware and Software Data
Protection
• Self-Timed Write Cycle within 5 ms Maximum
• ESD Protection > 4,000V
• High Reliability:
– Endurance: 1,000,000 write cycles
– Data retention: 100 years
• Green (Lead-free/Halide-free/RoHS Compliant) Package Options
• Die Sale Options: Wafer Form and Bumped Wafers
Packages
• 8-Lead SOIC, 8-Lead TSSOP, 8-Pad UDFN and 8-Ball VFBGA
© 2019 Microchip Technology Inc.
DS20006193A-page 1
AT25128B/AT25256B
Table of Contents
Features.......................................................................................................................... 1
Packages.........................................................................................................................1
1. Package Types (not to scale).................................................................................... 4
2. Pin Description.......................................................................................................... 5
2.1.
2.2.
2.3.
2.4.
2.5.
2.6.
2.7.
2.8.
Chip Select (CS)...........................................................................................................................5
Serial Data Output (SO)............................................................................................................... 5
Write-Protect (WP)....................................................................................................................... 5
Ground (GND).............................................................................................................................. 5
Serial Data Input (SI)....................................................................................................................6
Serial Data Clock (SCK)...............................................................................................................6
Suspend Serial Input (HOLD).......................................................................................................6
Device Power Supply (VCC)......................................................................................................... 6
3. Description.................................................................................................................7
3.1.
3.2.
SPI Bus Master Connections to Serial EEPROMs.......................................................................7
Block Diagram.............................................................................................................................. 8
4. Electrical Characteristics........................................................................................... 9
4.1.
4.2.
4.3.
4.4.
4.5.
4.6.
Absolute Maximum Ratings..........................................................................................................9
DC and AC Operating Range.......................................................................................................9
DC Characteristics....................................................................................................................... 9
AC Characteristics......................................................................................................................10
SPI Synchronous Data Timimg.................................................................................................. 13
Electrical Specifications..............................................................................................................13
5. Device Operation.....................................................................................................15
5.1.
5.2.
5.3.
5.4.
Interfacing the AT25128B/AT25256B on the SPI Bus................................................................ 15
Device Opcodes......................................................................................................................... 16
Hold Function............................................................................................................................. 16
Write Protection..........................................................................................................................17
6. Device Commands and Addressing........................................................................ 18
6.1.
6.2.
STATUS Register Bit Definition and Function............................................................................ 18
6.3.
Write Enable (WREN) and Write Disable (WRDI)........................................................................19
6.4.
Write STATUS Register (WRSR)................................................................................................. 20
Read STATUS Register (RDSR).................................................................................................19
7. Read Sequence.......................................................................................................23
8. Write Sequence....................................................................................................... 24
8.1.
8.2.
Byte Write...................................................................................................................................24
Page Write..................................................................................................................................25
© 2019 Microchip Technology Inc.
DS20006193A-page 2
AT25128B/AT25256B
8.3.
Polling Routine........................................................................................................................... 25
9. Packaging Information.............................................................................................27
9.1.
Package Marking Information.....................................................................................................27
10. Revision History.......................................................................................................37
The Microchip Web Site................................................................................................ 38
Customer Change Notification Service..........................................................................38
Customer Support......................................................................................................... 38
Product Identification System........................................................................................ 39
Microchip Devices Code Protection Feature................................................................. 39
Legal Notice...................................................................................................................40
Trademarks................................................................................................................... 40
Quality Management System Certified by DNV.............................................................41
Worldwide Sales and Service........................................................................................42
© 2019 Microchip Technology Inc.
DS20006193A-page 3
AT25128B/AT25256B
Package Types (not to scale)
1.
Package Types (not to scale)
8-Lead SOIC/TSSOP
(Top View)
CS
1
8
Vcc
SO
2
7
HOLD
WP
3
6
SCK
GND
4
5
SI
8-Ball VFBGA
(Top View)
8-Pad UDFN
(Top View)
CS
1
8
1
8
Vcc
SO
2
7
HOLD
WP
3
6
SCK
GND
4
5
SI
Vcc
SO
2
7
HOLD
WP
3
6
SCK
GND
4
5
SI
© 2019 Microchip Technology Inc.
CS
DS20006193A-page 4
AT25128B/AT25256B
Pin Description
2.
Pin Description
The descriptions of the pins are listed in Table 2-1.
Table 2-1. Pin Function Table
Name
8-Lead SOIC
8-Lead TSSOP
8-Pad UDFN(1)
CS
1
1
1
1
Chip Select
Serial Data Output
8-Ball VFBGA Function
SO
2
2
2
2
WP(2)
3
3
3
3
Write-Protect
GND
4
4
4
4
Ground
SI
5
5
5
5
Serial Data Input
SCK
HOLD(2)
6
6
6
6
Serial Data Clock
7
7
7
7
Suspends Serial Input
VCC
8
8
8
8
Device Power Supply
Note:
1. The exposed pad on this package can be connected to GND or left floating.
2. The Write-Protect (WP) and Hold (HOLD) pins should be driven high or low as appropriate.
2.1
Chip Select (CS)
The AT25128B/AT25256B is selected when the Chip Select (CS) pin is low. When the device is not
selected, data will not be accepted via the Serial Data Input (SI) pin, and the Serial Output (SO) pin will
remain in a high-impedance state.
To ensure robust operation, the CS pin should follow VCC upon power-up. It is therefore recommended to
connect CS to VCC using a pull-up resistor (less than or equal to 10 kΩ). After power-up, a low level on
CS is required prior to any sequence being initiated.
2.2
Serial Data Output (SO)
The Serial Data Output (SO) pin is used to transfer data out of the AT25128B/AT25256B. During a read
sequence, data is shifted out on this pin after the falling edge of the Serial Data Clock (SCK).
2.3
Write-Protect (WP)
The Write-Protect (WP) pin will allow normal read/write operations when held high. When the WP pin is
brought low and WPEN bit is set to a logic ‘1’, all write operations to the STATUS register are inhibited.
WP going low while CS is still low will interrupt a write operation to the STATUS register. If the internal
write cycle has already been initiated, WP going low will have no effect on any write operation to the
STATUS register. The WP pin function is blocked when the WPEN bit in the STATUS register is set to a
logic ‘0’. This will allow the user to install the AT25128B/AT25256B in a system with the WP pin tied to
ground and still be able to write to the STATUS register. All WP pin functions are enabled when the
WPEN bit is set to a logic ‘1’.
2.4
Ground (GND)
The ground reference for the Device Power Supply (VCC). The Ground (GND) pin should be connected to
the system ground.
© 2019 Microchip Technology Inc.
DS20006193A-page 5
AT25128B/AT25256B
Pin Description
2.5
Serial Data Input (SI)
The Serial Data Input (SI) pin is used to transfer data into the device. It receives instructions, addresses
and data. Data is latched on the rising edge of the Serial Data Clock (SCK).
2.6
Serial Data Clock (SCK)
The Serial Data Clock (SCK) pin is used to synchronize the communication between a master and the
AT25128B/AT25256B. Instructions, addresses or data present on the Serial Data Input (SI) pin is latched
in on the rising edge of SCK, while output on the Serial Data Output (SO) pin is clocked out on the falling
edge of SCK.
2.7
Suspend Serial Input (HOLD)
The Suspend Serial Input (HOLD) pin is used in conjunction with the Chip Select (CS) pin to pause the
AT25128B/AT25256B. When the device is selected and a serial sequence is underway, HOLD can be
used to pause the serial communication with the master device without resetting the serial sequence. To
pause, the HOLD pin must be brought low while the Serial Data Clock (SCK) pin is low. To resume serial
communication, the HOLD pin is brought high while the SCK pin is low (SCK may still toggle during
HOLD). Inputs to the Serial Data Input (SI) pin will be ignored while the Serial Data Output (SO) pin will
be in the high‑impedance state.
2.8
Device Power Supply (VCC)
The Device Power Supply (VCC) pin is used to supply the source voltage to the device. Operations at
invalid VCC voltages may produce spurious results and should not be attempted.
© 2019 Microchip Technology Inc.
DS20006193A-page 6
AT25128B/AT25256B
Description
3.
Description
The AT25128B/AT25256B provides 131,072/262,144 bits of Serial Electrically Erasable and
Programmable Read-Only Memory (EEPROM) organized as 16,384/32,768 words of 8 bits each.
The device is optimized for use in many industrial and commercial applications where low‑power and
low‑voltage operation are essential. The device is available in space-saving 8‑lead SOIC, 8‑lead TSSOP,
8‑pad UDFN and 8‑ball VFBGA packages. All packages operate from 1.8V to 5.5V.
3.1
SPI Bus Master Connections to Serial EEPROMs
SPI Master:
Microcontroller
Data Clock (SCK)
Data Output (SO)
Data Input (SI)
SI
CS3 CS2 CS1 CS0
© 2019 Microchip Technology Inc.
SO SCK
SI
SO SCK
SI
SO SCK
SI
SO SCK
Slave 0
AT25XXX
Slave 1
AT25XXX
Slave 2
AT25XXX
Slave 3
AT25XXX
CS
CS
CS
CS
DS20006193A-page 7
AT25128B/AT25256B
Description
Block Diagram
Memory
System Control
Module
CS
High-Voltage
Generation
Circuit
Power-on
Reset
Generator
VCC
Pause
Operation
Control
HOLD
Register Bank:
STATUS Register
SO
EEPROM Array
1 page
Column Decoder
WP
Data Register
Row Decoder
3.2
Address Register
and Counter
SCK
Data Output
Buffer
GND
Write Protection
Control
© 2019 Microchip Technology Inc.
SI
DS20006193A-page 8
AT25128B/AT25256B
Electrical Characteristics
4.
Electrical Characteristics
4.1
Absolute Maximum Ratings
Operating temperature
-55°C to +125°C
Storage temperature
-65°C to +150°C
Voltage on any pin with respect to ground
-1.0V to +7.0V
VCC
6.25V
DC output current
5.0 mA
ESD protection
> 4 kV
Note: Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to
the device. This is a stress rating only and functional operation of the device at these or any other
conditions above those indicated in the operation listings of this specification is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
4.2
DC and AC Operating Range
Table 4-1. DC and AC Operating Range
AT25128B/AT25256B
4.3
Operating Temperature (Case)
Industrial Temperature Range
-40°C to +85°C
VCC Power Supply
Low-Voltage Grade
1.8V to 5.5V
DC Characteristics
Table 4-2. DC Characteristics(1)
Parameter
Symbol Minimum Typical Maximum Units Conditions
Supply Voltage
VCC1
1.8
—
5.5
V
Supply Voltage
VCC2
2.5
—
5.5
V
Supply Voltage
VCC3
4.5
—
5.5
V
Supply Current
ICC1
—
9.0
10.0
mA
VCC = 5.0V at 20 MHz,
SO = Open, Read
Supply Current
ICC2
—
5.0
7.0
mA
VCC = 5.0V at 10 MHz,
SO = Open, Read, Write
Supply Current
ICC3
—
2.2
3.5
mA
VCC = 5.0V at 1 MHz,
SO = Open, Read, Write
Standby Current
ISB1
—
0.2
3.0
µA
VCC = 1.8V, CS = VCC
© 2019 Microchip Technology Inc.
DS20006193A-page 9
AT25128B/AT25256B
Electrical Characteristics
...........continued
Parameter
Symbol Minimum Typical Maximum Units Conditions
Standby Current
ISB2
—
0.5
3.0
µA
VCC = 2.5V, CS = VCC
Standby Current
ISB3
—
2.0
5.0
µA
VCC = 5.0V, CS = VCC
Input Leakage
IIL
-3.0
—
3.0
µA
VIN = 0V to VCC
Output Leakage
IOL
-3.0
—
3.0
µA
VIN = 0V to VCC,
TAC = 0°C to +70°C
Input
Low-Voltage
VIL(2)
-1.0
—
VCC x 0.3
V
Input
High-Voltage
VIH(2)
VCC x 0.7
—
VCC + 0.5
V
Output
Low-Voltage
VOL1
—
—
0.4
V
3.6V ≤ VCC ≤ 5.5V IOL = 3.0 mA
Output
High-Voltage
VOH1
VCC - 0.8
—
—
V
3.6V ≤ VCC ≤ 5.5V IOH = -1.6 mA
Output
Low-Voltage
VOL2
—
—
0.2
V
1.8V ≤ VCC ≤ 3.6V IOL = 0.15 mA
Output
High-Voltage
VOH2
VCC - 0.2
—
—
V
1.8V ≤ VCC ≤ 3.6V IOH = -100 µA
Note:
1. Applicable over recommended operating range from: TA = -40°C to +85°C, VCC = 1.8V to 5.5V
(unless otherwise noted).
2. VIL min and VIH max are reference only and are not tested.
4.4
AC Characteristics
Table 4-3. AC Characteristics(1)
Parameter
SCK Clock Frequency
Input Rise Time
© 2019 Microchip Technology Inc.
Symbol
fSCK
tRI
Minimum Maximum
Units
Conditions
0
20
MHz
VCC = 4.5V to 5.5V
0
10
MHz
VCC = 2.5V to 5.5V
0
5
MHz
VCC = 1.8V to 5.5V
—
2000
ns
VCC = 4.5V to 5.5V
—
2000
ns
VCC = 2.5V to 5.5V
—
2000
ns
VCC = 1.8V to 5.5V
DS20006193A-page 10
AT25128B/AT25256B
Electrical Characteristics
...........continued
Parameter
Input Fall Time
SCK High Time
SCK Low Time
CS High Time
CS Setup Time
CS Hold Time
Data In Setup Time
Data In Hold Time
HOLD Setup Time
HOLD Hold Time
© 2019 Microchip Technology Inc.
Symbol
tFI
tWH
tWL
tCS
tCSS
tCSH
tSU
tH
tHD
tCD
Minimum Maximum
Units
Conditions
—
2000
ns
VCC = 4.5V to 5.5V
—
2000
ns
VCC = 2.5V to 5.5V
—
2000
ns
VCC = 1.8V to 5.5V
20
—
ns
VCC = 4.5V to 5.5V
40
—
ns
VCC = 2.5V to 5.5V
80
—
ns
VCC = 1.8V to 5.5V
20
—
ns
VCC = 4.5V to 5.5V
40
—
ns
VCC = 2.5V to 5.5V
80
—
ns
VCC = 1.8V to 5.5V
100
—
ns
VCC = 4.5V to 5.5V
100
—
ns
VCC = 2.5V to 5.5V
200
—
ns
VCC = 1.8V to 5.5V
100
—
ns
VCC = 4.5V to 5.5V
100
—
ns
VCC = 2.5V to 5.5V
200
—
ns
VCC = 1.8V to 5.5V
100
—
ns
VCC = 4.5V to 5.5V
100
—
ns
VCC = 2.5V to 5.5V
200
—
ns
VCC = 1.8V to 5.5V
5
—
ns
VCC = 4.5V to 5.5V
10
—
ns
VCC = 2.5V to 5.5V
20
—
ns
VCC = 1.8V to 5.5V
5
—
ns
VCC = 4.5V to 5.5V
10
—
ns
VCC = 2.5V to 5.5V
20
—
ns
VCC = 1.8V to 5.5V
5
—
ns
VCC = 4.5V to 5.5V
10
—
ns
VCC = 2.5V to 5.5V
20
—
ns
VCC = 1.8V to 5.5V
5
—
ns
VCC = 4.5V to 5.5V
10
—
ns
VCC = 2.5V to 5.5V
20
—
ns
VCC = 1.8V to 5.5V
DS20006193A-page 11
AT25128B/AT25256B
Electrical Characteristics
...........continued
Parameter
Symbol
Output Valid
tV
Output Hold Time
HOLD to Output Low Z
HOLD to Output High Z
Output Disable Time
Write Cycle Time
tHO
tLZ
tHZ
tDIS
tWC
Minimum Maximum
Units
Conditions
0
20
ns
VCC = 4.5V to 5.5V
0
40
ns
VCC = 2.5V to 5.5V
0
80
ns
VCC = 1.8V to 5.5V
0
—
ns
VCC = 4.5V to 5.5V
0
—
ns
VCC = 2.5V to 5.5V
0
—
ns
VCC = 1.8V to 5.5V
0
25
ns
VCC = 4.5V to 5.5V
0
50
ns
VCC = 2.5V to 5.5V
0
100
ns
VCC = 1.8V to 5.5V
—
25
ns
VCC = 4.5V to 5.5V
—
50
ns
VCC = 2.5V to 5.5V
—
100
ns
VCC = 1.8V to 5.5V
—
25
ns
VCC = 4.5V to 5.5V
—
50
ns
VCC = 2.5V to 5.5V
—
100
ns
VCC = 1.8V to 5.5V
—
5
ms
VCC = 4.5V to 5.5V
—
5
ms
VCC = 2.5V to 5.5V
—
5
ms
VCC = 1.8V to 5.5V
Note:
1. Applicable over recommended operating range from TA = -40°C to +85°C, VCC = As Specified,
CL = 1 TTL Gate and 30 pF (unless otherwise noted).
© 2019 Microchip Technology Inc.
DS20006193A-page 12
AT25128B/AT25256B
Electrical Characteristics
4.5
SPI Synchronous Data Timimg
tCS
VIH
CS
VIL
tCSS
tCSH
VIH
tWH
SCK
tWL
VIL
tSU
tH
VIH
SI
Valid Data In
VIL
tV
VOH
SO
VOL
tHO
tDIS
High
Impedance
High
Impedance
4.6
Electrical Specifications
4.6.1
Power-Up Requirements and Reset Behavior
During a power-up sequence, the VCC supplied to the AT25128B/AT25256B should monotonically rise
from GND to the minimum VCC level, as specified in Table 4-1, with a slew rate no faster than 0.1 V/µs.
4.6.1.1
Device Reset
To prevent inadvertent write operations or any other spurious events from occurring during a power-up
sequence, the AT25128B/AT25256B includes a Power-on Reset (POR) circuit. Upon power-up, the
device will not respond to any instructions until the VCC level crosses the internal voltage threshold (VPOR)
that brings the device out of Reset and into Standby mode.
The system designer must ensure the instructions are not sent to the device until the VCC supply has
reached a stable value greater than or equal to the minimum VCC level. Additionally, once the VCC is
greater than or equal to the minimum VCC level, the bus master must wait at least tPUP before sending the
first instruction to the device. See Table 4-4 for the values associated with these power-up parameters.
Table 4-4. Power-Up Conditions(1)
Symbol
Parameter
tPUP
Time required after VCC is stable before the device can accept instructions
VPOR
Power-on Reset Threshold Voltage
tPOFF
Minimum time at VCC = 0V between power cycles
Min. Max. Units
100
－
µs
－
1.5
V
0.03
－
ms
Note:
1. These parameters are characterized but they are not 100% tested in production.
If an event occurs in the system where the VCC level supplied to the AT25128B/AT25256B drops below
the maximum VPOR level specified, it is recommended that a full-power cycle sequence be performed by
first driving the VCC pin to GND in less than 1 ms, waiting at least the minimum tPOFF time and then
performing a new power-up sequence in compliance with the requirements defined in this section.
© 2019 Microchip Technology Inc.
DS20006193A-page 13
AT25128B/AT25256B
Electrical Characteristics
4.6.2
Pin Capacitance
Table 4-5. Pin Capacitance(1,2)
Symbol
COUT
CIN
Test Condition
Max.
Units
Conditions
Output Capacitance (SO)
8
pF
VOUT = 0V
Input Capacitance (CS, SCK, SI, WP, HOLD)
6
pF
VIN = 0V
Note:
1. This parameter is characterized but is not 100% tested in production.
2. Applicable over recommended operating range from: TA = 25°C, fSCK = 1.0 MHz, VCC = 5.0V
(unless otherwise noted).
4.6.3
EEPROM Cell Performance Characteristics
Table 4-6. EEPROM Cell Performance Characteristics
Operation
Test Condition
Write Endurance(1)
TA = 25°C, VCC = 3.3V,
Page Write mode
Data Retention(1)
TA = 55°C
Min.
Max.
Units
1,000,000
—
Write Cycles
100
—
Years
Note:
1. Performance is determined through characterization and the qualification process.
4.6.4
Software Reset
The SPI interface of the AT25128B/AT25256B can be reset by toggling the CS input. If the CS line is
already in the active state, it must complete a transition from the inactive state (≥VIH) to the active state
(≤VIL) and then back to the inactive state (≥VIH) without sending clocks on the SCK line. Upon completion
of this sequence, the device will be ready to receive a new opcode on the SI line.
4.6.5
Device Default State at Power-Up
The AT25128B/AT25256B default state upon power-up consists of:
• Standby Power mode
• A high-to-low-level transition on CS is required to enter active state
• Write Enable Latch (WEL) bit in the STATUS register = 0
• Ready/Busy bit in the STATUS register = 0, indicating the device is ready to accept a new command
• Device is not selected
• Not in Hold condition
• WPEN, BP1 and BP0 bits in the STATUS register are unchanged from their previous state due to the
fact that they are nonvolatile values
4.6.6
Device Default Condition
The AT25128B/AT25256B is shipped from Microchip to the customer with the EEPROM array set to an all
FFh data pattern (logic ‘1’ state). The Write-Protect Enable bit in the STATUS register is set to logic ‘0’
(the ability of the EEPROM array to write is dictated by the values of the Block Write‑Protect bits while the
STATUS register’s ability to write is controlled by the WEL bit). The Block Write Protection bits in the
STATUS register are set to logic ‘0’ (no write protection selected).
© 2019 Microchip Technology Inc.
DS20006193A-page 14
AT25128B/AT25256B
Device Operation
5.
Device Operation
The AT25128B/AT25256B is controlled by a set of instructions that are sent from a host controller,
commonly referred to as the SPI Master. The SPI Master communicates with the AT25128B/AT25256B
via the SPI bus which is comprised of four signal lines: Chip Select (CS), Serial Data Clock (SCK), Serial
Data Input (SI), and Serial Data Output (SO).
The SPI protocol defines a total of four modes of operation (Mode 0, 1, 2 or 3) with each mode differing in
respect to the SCK polarity and phase and how the polarity and phase control the flow of data on the SPI
bus. The AT25128B/AT25256B supports the two most common modes, SPI Modes 0 and 3. With SPI
Modes 0 and 3, data is always latched in on the rising edge of SCK and always output on the falling edge
of SCK. The only difference between SPI Modes 0 and 3 is the polarity of the SCK signal when in the
inactive state (when the SPI Master is in Standby mode and not transferring any data). SPI Mode 0 is
defined as a low SCK while CS is not asserted (at VCC) and SPI Mode 3 has SCK high in the inactive
state. The SCK Idle state must match when the CS is deasserted both before and after the
communication sequence in SPI Mode 0 and 3. The figures in this document depict Mode 0 with a solid
line on SCK while CS is inactive and Mode 3 with a dotted line.
Figure 5-1. SPI Mode 0 and Mode 3
CS
SCK
SI
Mode 3
Mode 3
Mode 0
Mode 0
MSB
SO
5.1
LSB
MSB
LSB
Interfacing the AT25128B/AT25256B on the SPI Bus
Communication to and from the AT25128B/AT25256B must be initiated by the SPI Master device, such
as a microcontroller. The SPI Master device must generate the serial clock for the AT25128B/AT25256B
on the Serial Data Clock (SCK) pin. The AT25128B/AT25256B always operates as a slave due to the fact
that the SCK is always an input.
5.1.1
Selecting the Device
The AT25128B/AT25256B is selected when the Chip Select (CS) pin is low. When the device is not
selected, data will not be accepted via the Serial Data Input (SI) pin, and the Serial Data Output (SO) pin
will remain in a high‑impedance state.
5.1.2
Sending Data to the Device
The AT25128B/AT25256B uses the SI pin to receive information. All instructions, addresses and data
input bytes are clocked into the device with the Most Significant bit (MSb) first. The SI pin samples on the
first rising edge of the SCK line after the CS has been asserted.
© 2019 Microchip Technology Inc.
DS20006193A-page 15
AT25128B/AT25256B
Device Operation
5.1.3
Receiving Data from the Device
Data output from the device is transmitted on the SO pin, with the MSb output first. The SO data is
latched on the first falling edge of SCK after the instruction has been clocked into the device, such as the
Read from Memory Array (READ) and Read STATUS Register (RDSR) instructions. See Read Sequence
for more details.
5.2
Device Opcodes
5.2.1
Serial Opcode
After the device is selected by driving CS low, the first byte will be received on the SI pin. This byte
contains the opcode that defines the operation to be performed. Refer to Table 6-1 for a list of all opcodes
that the AT25128B/AT25256B will respond to.
5.2.2
Invalid Opcode
If an invalid opcode is received, no data will be shifted into AT25128B/AT25256B and the SO pin will
remain in a high-impedance state until the falling edge of CS is detected again. This will reinitialize the
serial communication.
5.3
Hold Function
The Suspend Serial Input (HOLD) pin is used to pause the serial communication with the device without
having to stop or reset the clock sequence. The Hold mode, however, does not have an effect on the
internal write cycle. Therefore, if a write cycle is in progress, asserting the HOLD pin will not pause the
operation and the write cycle will continue to completion.
The Hold mode can only be entered while the CS pin is asserted. The Hold mode is activated by
asserting the HOLD pin during the SCK low pulse. If the HOLD pin is asserted during the SCK high pulse,
then the Hold mode will not be started until the beginning of the next SCK low pulse. The device will
remain in the Hold mode as long as the HOLD pin and CS pin are asserted.
While in Hold mode, the SO pin will be in a high-impedance state. In addition, both the SI pin and the
SCK pin will be ignored. The Write-Protect (WP) pin, however, can still be asserted or deasserted while in
the Hold mode.
To end the Hold mode and resume serial communication, the HOLD pin must be deasserted during the
SCK low pulse. If the HOLD pin is deasserted during the SCK high pulse, then the Hold mode will not end
until the beginning of the next SCK low pulse.
If the CS pin is deasserted while the HOLD pin is still asserted, then any operation that may have been
started will be aborted and the device will reset the WEL bit in the STATUS register back to the logic ‘0’
state.
© 2019 Microchip Technology Inc.
DS20006193A-page 16
AT25128B/AT25256B
Device Operation
Figure 5-2. Hold Mode
CS
SCK
HOLD
Hold
Hold
Hold
Figure 5-3. Hold Timing
CS
t CD
t CD
SCK
HOLD
t HD
t HD
t HZ
SO
tLZ
5.4
Write Protection
The Write-Protect (WP) pin will allow normal read and write operations when held high. When the WP pin
is brought low and WPEN bit is a logic ‘1’, all write operations to the STATUS register are inhibited. The
WP pin going low while CS is still low will interrupt a Write STATUS Register (WRSR). If the internal write
cycle has already been initiated, WP going low will have no effect on any write operation to the STATUS
register. The WP pin function is blocked when the WPEN bit in the STATUS register is a logic ‘0’. This will
allow the user to install the AT25128B/AT25256B device in a system with the WP pin tied to ground and
still be able to write to the STATUS register. All WP pin functions are enabled when the WPEN bit is set to
a logic ‘1’.
© 2019 Microchip Technology Inc.
DS20006193A-page 17
AT25128B/AT25256B
Device Commands and Addressing
6.
Device Commands and Addressing
The AT25128B/AT25256B is designed to interface directly with the synchronous Serial Peripheral
Interface (SPI). The AT25128B/AT25256B utilizes an 8‑bit instruction register. The list of instructions and
their operation codes are contained in Table 6-1. All instructions, addresses and data are transferred with
the MSb first and start with a high‑to‑low CS transition.
Table 6-1. Instruction Set for the AT25128B/AT25256B
6.1
Instruction Name
Instruction Format
Operates On
Operation Description
WREN
0000 X110
STATUS Register
Set Write Enable Latch (WEL)
WRDI
0000 X100
STATUS Register
Reset Write Enable Latch (WEL)
RDSR
0000 X101
STATUS Register
Read STATUS Register
WRSR
0000 X001
STATUS Register
Write STATUS Register
READ
0000 X011
Memory Array
Read from Memory Array
WRITE
0000 X010
Memory Array
Write to Memory Array
STATUS Register Bit Definition and Function
The AT25128B/AT25256B includes an 8‑bit STATUS register. The STATUS register bits modulate various
features of the device as shown in Table 6-2 and Table 6-3. These bits can be changed by specific
instructions that are detailed in the following sections.
Table 6-2. STATUS Register Format
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
WPEN
X
X
X
BP1
BP0
WEL
RDY/BSY
Table 6-3. STATUS Register Bit Definition
Bit
7
Name
WPEN
Write-Protect Enable
Type
R/W
Description
0 See Table 6-5 (Factory Default)
1 See Table 6-5 (Factory Default)
6:4
RFU
Reserved for Future Use
R
0 Reads as zeros when the device is not in a write
cycle
1 Reads as ones when the device is in a write cycle
3:2
BP1
BP0
Block Write Protection
R/W 00 No array write protection (Factory Default)
01 Quarter array write protection (see Table 6-4)
10 Half array write protection (see Table 6-4)
11 Entire array write protection (see Table 6-4)
1
WEL
Write Enable Latch
R/W
0 Device is not write enabled (Power-up Default)
1 Device is write enabled
© 2019 Microchip Technology Inc.
DS20006193A-page 18
AT25128B/AT25256B
Device Commands and Addressing
...........continued
Bit
0
Name
Type
RDY/BSY Ready/Busy Status
Description
0 Device is ready for a new sequence
R
1 Device is busy with an internal operation
6.2
Read STATUS Register (RDSR)
The Read STATUS Register (RDSR) instruction provides access to the STATUS register. The ready/busy
and write enable status of the device can be determined by the RDSR instruction. Similarly, the Block
Write Protection (BP) bits indicate the extent of memory array protection employed. The STATUS
register is read by asserting the CS pin, followed by sending in a 05h opcode on the SI pin. Upon
completion of the opcode, the device will return the 8‑bit STATUS register value on the SO pin.
Figure 6-1. RDSR Waveform
CS
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
SCK
RDSR Opcode (05h)
SI
0
0
0
0
0
1
0
1
MSB
STATUS Register Data Out
SO
High-Impedance
D7
D6
D5
D4
D3
D2
D1
D0
MSB
6.3
Write Enable (WREN) and Write Disable (WRDI)
Enabling and disabling writing to the STATUS register and EEPROM array is accomplished through the
Write Enable (WREN) instruction and the Write Disable (WRDI) instruction. These functions change the
status of the WEL bit in the STATUS register.
6.3.1
Write Enable Instruction (WREN)
The Write Enable Latch (WEL) bit of the STATUS register must be set to a logic ‘1’ prior to each Write
STATUS Register (WRSR) and Write to Memory Array (WRITE) instructions. This is accomplished by
sending a WREN (06h) instruction to the AT25128B/AT25256B. First, the CS pin is driven low to select the
device and then a WREN instruction is clocked in on the SI pin. Then the CS pin can be driven high and
the WEL bit will be updated in the STATUS register to a logic ‘1’. The device will power‑up in the write
disable state (WEL = 0).
© 2019 Microchip Technology Inc.
DS20006193A-page 19
AT25128B/AT25256B
Device Commands and Addressing
Figure 6-2. WREN Timing
CS
0
1
2
3
4
5
6
7
SCK
WREN Opcode (06h)
SI
0
0
0
0
0
1
1
0
MSB
High-Impedance
SO
6.3.2
Write Disable Instruction (WRDI)
To protect the device against inadvertent writes, the Write Disable (WRDI) instruction (opcode 04h)
disables all programming modes by setting the WEL bit to a logic ‘0’. The WRDI instruction is independent
of the status of the WP pin.
Figure 6-3. WRDI Timing
CS
0
1
2
3
4
5
6
7
SCK
WRDI Opcode (04h)
SI
0
0
0
0
0
1
0
0
MSB
SO
6.4
High-Impedance
Write STATUS Register (WRSR)
The Write STATUS Register (WRSR) instruction enables the SPI Master to change selected bits of the
STATUS register. Before a WRSR instruction can be initiated, a WREN instruction must be executed to set
the WEL to logic ‘1’. Upon completion of a WREN instruction, a WRSR instruction can be executed.
Note: The WRSR instruction has no effect on bit 6, bit 5, bit 4, bit 1 and bit 0 of the STATUS register. Only
bit 7, bit 3 and bit 2 can be changed via the WRSR instruction. These modifiable bits are the Write Protect
Enable (WPEN) and Block Protect (BP) bits. These three bits are nonvolatile bits that have the
same properties and functions as regular EEPROM cells. Their values are retained while power is
removed from the device.
© 2019 Microchip Technology Inc.
DS20006193A-page 20
AT25128B/AT25256B
Device Commands and Addressing
The AT25128B/AT25256B will not respond to commands other than a RDSR after a WRSR instruction until
the self-timed internal write cycle has completed. When the write cycle is completed, the WEL bit in the
STATUS register is reset to logic ‘0’.
Figure 6-4. WRSR Waveform
CS
tWC(1)
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
SCK
STATUS Register Data In
WRSR Opcode (01h)
SI
0
0
0
0
0
MSB
0
0
1
D7
X
X
X
D3
D2
X
X
MSB
High-Impedance
SO
Note:
1.
6.4.1
This instruction initiates a self-timed internal write cycle (tWC) on the rising edge of CS after a valid
sequence.
Block Write-Protect Function
The WRSR instruction allows the user to select one of four possible combinations as to how the memory
array will be inhibited from writing through changing the Block Write-Protect bits (BP). The four
levels of array protection are:
• None of the memory array is protected.
• Upper quarter (¼) address range is write-protected meaning the highest order address bits are readonly.
• Upper half (½) address range is write-protected meaning the highest order address bits are readonly.
• All of the memory array is write-protected meaning all address bits are read-only.
The Block Write Protection levels and corresponding STATUS register control bits are shown in Table 6-4.
Table 6-4. Block Write-Protect Bits
Level
STATUS Register Bits
Write-Protected/Read‑Only Address Range
BP1
BP0
AT25128B
AT25256B
0
0
0
None
None
1(1/4)
0
1
3000h-3FFFh
6000h-7FFFh
2(1/2)
1
0
2000h-3FFFh
4000h – 7FFFh
3(All)
1
1
0000h-3FFFh
0000h – 7FFFh
© 2019 Microchip Technology Inc.
DS20006193A-page 21
AT25128B/AT25256B
Device Commands and Addressing
6.4.2
Write-Protect Enable Function
The WRSR instruction also allows the user to enable or disable the Write-Protect (WP) pin through the use
of the Write-Protect Enable (WPEN) bit. When the WPEN bit is set to logic ‘0’, the ability to write the
EEPROM array is dictated by the values of the Block Write-Protect (BP) bits. The ability to write the
STATUS register is controlled by the WEL bit. When the WPEN bit is set to logic ‘1’, the STATUS register
is read-only.
Hardware Write Protection is enabled when both the WP pin is low and the WPEN bit has been set to a
logic ‘1’. When the device is Hardware Write‑Protected, writes to the STATUS register, including the Block
Write‑Protect , WEL and WPEN bits, and to the sections in the memory array selected by the Block
Write‑Protect bits are disabled. When Hardware Write Protection is enabled, writes are only allowed to
sections of the memory that are not block‑protected.
Hardware Write Protection is disabled when either the WP pin is high or the WPEN bit is a logic ‘0’. When
Hardware Write Protection is disabled, writes are only allowed to sections of the memory that are not
block‑protected. Refer to Table 6-5 for additional information.
Note: When the WPEN bit is Hardware Write‑Protected, it cannot be set back to a logic ‘0’ as long as
the WP pin is held low.
Table 6-5. WPEN Operation
WPEN
WP
Pin
WEL
Protected Blocks
Unprotected Blocks
STATUS Register
0
x
0
Protected
Protected
Protected
0
x
1
Protected
Writable
Writable
1
Low
0
Protected
Protected
Protected
1
Low
1
Protected
Writable
Protected
x
High
0
Protected
Protected
Protected
x
High
1
Protected
Writable
Writable
© 2019 Microchip Technology Inc.
DS20006193A-page 22
AT25128B/AT25256B
Read Sequence
7.
Read Sequence
Reading the AT25128B/AT25256B via the SO pin requires the following sequence. After the CS line is
pulled low to select a device, the READ (03h) instruction is transmitted via the SI line followed by the
16‑bit address to be read. Refer to Table 7-1 for the address bits for AT25128B/AT25256B.
Table 7-1. AT25128B/AT25256B Address Bits
Address
AT25128B
AT25256B
AN
A13–A0
A14–A0
Don’t Care Bits
A15–A14
A15
Upon completion of the 16‑bit address, any data on the SI line will be ignored. The data (D7‑D0) at the
specified address is then shifted out onto the SO line. If only one byte is to be read, the CS line should be
driven high after the data comes out. The read sequence can be continued since the byte address is
automatically incremented and data will continue to be shifted out. When the highest‑order address bit is
reached, the address counter will rollover to the lowest‑order address bit allowing the entire memory to be
read in one continuous read cycle regardless of the starting address.
Figure 7-1. Read Waveform
CS
0
1
2
3
4
5
6
7
8
9
10 11 12
19 20 21 22 23 24 25 26 27 28 29 30 31
SCK
READ Opcode (03h)
SI
0
0
0
0
0
MSB
0
1
Address Bits A15-A0
1
A
A
A
A
A
A
A
A
A
MSB
Data Byte 1
SO
High-Impedance
D
MSB
© 2019 Microchip Technology Inc.
D
D
D
D
D
D
D
D
D
MSB
DS20006193A-page 23
AT25128B/AT25256B
Write Sequence
8.
Write Sequence
In order to program the AT25128B/AT25256B, two separate instructions must be executed. First, the
device must be write enabled via the Write Enable (WREN) instruction. Then, one of the two possible write
sequences described in this section may be executed.
Note: If the device is not Write Enabled (WREN), the device will ignore the WRITE instruction and will
return to the standby state when CS is brought high. A new CS assertion is required to re‑initiate
communication.
The address of the memory location(s) to be programmed must be outside the protected address field
location selected by the block write protection level. During an internal write cycle, all commands will be
ignored except the RDSR instruction. Refer to Table 8-1 for the address bits for AT25128B/AT25256B.
Table 8-1. AT25128B/AT25256B Address Bits
8.1
Address
AT25128B
AT25256B
AN
A13–A0
A14–A0
Don’t Care Bits
A15–A14
A15
Byte Write
A Byte Write requires the following sequence and is depicted in Figure 8-1. After the CS line is pulled low
to select the device, the WRITE (02h) instruction is transmitted via the SI line followed by the 16‑bit
address and the data (D7‑D0) to be programmed. Programming will start after the CS pin is brought high.
The low‑to‑high transition of the CS pin must occur during the SCK low time (Mode 0) and SCK high time
(Mode 3) immediately after clocking in the D0 (LSB) data bit. The AT25128B/AT25256B is automatically
returned to the Write Disable state (STATUS register bit WEL = 0) at the completion of a write cycle.
Figure 8-1. Byte Write
CS
tWC(1)
0
1
2
3
4
5
6
7
8
9
10 11 12
21 22 23 24 25 26 27 28 29 30 31
SCK
WRITE Opcode (02h)
SI
0
0
0
0
0
MSB
SO
0
1
Address Bits A15-A0
0
A
MSB
A
A
A
A
A
A
Data In
A
A D7 D6 D5 D4 D3 D2 D1 D0
MSB
High-Impedance
Note:
1. This instruction initiates a self-timed internal write cycle (tWC) on the rising edge of CS after a valid
sequence.
© 2019 Microchip Technology Inc.
DS20006193A-page 24
AT25128B/AT25256B
Write Sequence
8.2
Page Write
A Page Write sequence allows up to 64 bytes to be written in the same write cycle, provided that all bytes
are in the same row of the memory array. Partial Page Writes of less than 64 bytes are allowed. After
each byte of data is received, the six lowest order address bits are internally incremented following the
receipt of each data byte. The higher order address bits are not incremented and retain the memory array
page location. If more bytes of data are transmitted that what will fit to the end of that memory row, the
address counter will rollover to the beginning of the same row. Nevertheless, creating a rollover event
should be avoided as previously loaded data in the page could become unintentionally altered. The
AT25128B/AT25256B is automatically returned to the Write Disable state (WEL = 0) at the completion of
a write cycle.
Figure 8-2. Page Write
CS
tWC(1)
0
1
2
3
4
5
6
7
8
9
21 22 23 24 25 26 27 28 29 30 31
SCK
WRITE Opcode (02h)
SI
0
0
0
0
0
MSB
SO
0
1
Address Bits A15-A0
0
A
MSB
A
A
A
A
Data In Byte 1
A
D
MSB
D
D
D
D
D
Data In Byte 64
D
D
D
D
D
D
D
D
D
D
MSB
High-Impedance
Note:
1. This instruction initiates a self‑timed internal write cycle (tWC) on the rising edge of CS after a valid
sequence.
8.3
Polling Routine
A polling routine can be implemented to optimize time‑sensitive applications that would not prefer to wait
the fixed maximum write cycle time (tWC). This method allows the application to know immediately when
the write cycle has completed to start a subsequent operation.
Once the internally-timed write cycle has started, a polling routine can be initiated. This involves
repeatedly sending Read STATUS Register (RDSR) instruction to determine if the device has completed
its self-timed internal write cycle. If the RDY/BSY bit (bit 0 of STATUS register) = 1, the write cycle is still
in progress. If bit 0 = 0, the write cycle has ended. If the RDY/BSY bit = 1, repeated RDSR commands can
be executed until the RDY/BSY bit = 0, signaling that the device is ready to execute a new instruction.
Only the Read STATUS Register (RDSR) instruction is enabled during the write cycle.
© 2019 Microchip Technology Inc.
DS20006193A-page 25
AT25128B/AT25256B
Write Sequence
Figure 8-3. Polling Flowchart
Send Valid
Write
Protocol
Deassert
CS to VCC to
Initiate a
Write Cycle
Send RDSR
Instruction
to the Device
Does
RDY/BSY
= 0?
YES
Continue to
Next Operation
NO
© 2019 Microchip Technology Inc.
DS20006193A-page 26
AT25128B/AT25256B
Packaging Information
9.
Packaging Information
9.1
Package Marking Information
AT25128B and AT25256B: Package Marking Information
8-Lead SOIC
8-Lead TSSOP
ATMLHYWW
###% CO
YYWWNNN
ATHYWW
###%CO
YYWWNNN
8-Pad UDFN
8-Ball VFBGA
2.35 x 3.73 mm Body
2.0 x 3.0 mm Body
###
H%
NNN
Note 1:
###U
WWNNN
designates pin 1
Note 2: Package drawings are not to scale
Catalog Number Truncation
AT25128B
Truncation Code ###: 5DB
AT25256B
Truncation Code ###: 5EB
Date Codes
YY = Year
16: 2016
17: 2017
18: 2018
19: 2019
Voltages
20: 2020
21: 2021
22: 2022
23: 2023
Y = Year
6: 2016
7: 2017
8: 2018
9: 2019
0: 2020
1: 2021
2: 2022
3: 2023
WW = Work Week of Assembly
02: Week 2
04: Week 4
...
52: Week 52
Country of Origin
Device Grade
CO = Country of Origin
H or U: Industrial Grade
% = Minimum Voltage
L: 1.8V min
Atmel Truncation
AT: Atmel
ATM: Atmel
ATML: Atmel
Lot Number or Trace Code
NNN = Alphanumeric Trace Code (2 Characters for Small Packages)
© 2019 Microchip Technology Inc.
DS20006193A-page 27
AT25128B/AT25256B
Packaging Information
8-Lead Plastic Small Outline (SN) - Narrow, 3.90 mm (.150 In.) Body [SOIC]
Note:
For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
2X
0.10 C A–B
D
A
D
NOTE 5
N
E
2
E1
2
E1
E
NOTE 1
2
1
e
B
NOTE 5
NX b
0.25
C A–B D
TOP VIEW
0.10 C
C
A A2
SEATING
PLANE
8X
A1
SIDE VIEW
0.10 C
h
R0.13
h
R0.13
H
SEE VIEW C
VIEW A–A
0.23
L
(L1)
VIEW C
Microchip Technology Drawing No. C04-057-SN Rev E Sheet 1 of 2
© 2017 Microchip Technology Inc.
© 2019 Microchip Technology Inc.
DS20006193A-page 28
AT25128B/AT25256B
Packaging Information
8-Lead Plastic Small Outline (SN) - Narrow, 3.90 mm (.150 In.) Body [SOIC]
Note:
For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
Units
Dimension Limits
Number of Pins
N
e
Pitch
Overall Height
A
Molded Package Thickness
A2
§
Standoff
A1
Overall Width
E
Molded Package Width
E1
Overall Length
D
Chamfer (Optional)
h
Foot Length
L
L1
Footprint
Foot Angle
c
Lead Thickness
b
Lead Width
Mold Draft Angle Top
Mold Draft Angle Bottom
MIN
1.25
0.10
0.25
0.40
0°
0.17
0.31
5°
5°
MILLIMETERS
NOM
8
1.27 BSC
6.00 BSC
3.90 BSC
4.90 BSC
1.04 REF
-
MAX
1.75
0.25
0.50
1.27
8°
0.25
0.51
15°
15°
Notes:
1. Pin 1 visual index feature may vary, but must be located within the hatched area.
2. § Significant Characteristic
3. Dimensions D and E1 do not include mold flash or protrusions. Mold flash or
protrusions shall not exceed 0.15mm per side.
4. Dimensioning and tolerancing per ASME Y14.5M
BSC: Basic Dimension. Theoretically exact value shown without tolerances.
REF: Reference Dimension, usually without tolerance, for information purposes only.
5. Datums A & B to be determined at Datum H.
Microchip Technology Drawing No. C04-057-SN Rev E Sheet 2 of 2
© 2017 Microchip Technology Inc.
© 2019 Microchip Technology Inc.
DS20006193A-page 29
AT25128B/AT25256B
Packaging Information
8-Lead Plastic Small Outline (SN) - Narrow, 3.90 mm Body [SOIC]
Note:
For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
SILK SCREEN
C
Y1
X1
E
RECOMMENDED LAND PATTERN
Units
Dimension Limits
E
Contact Pitch
Contact Pad Spacing
C
Contact Pad Width (X8)
X1
Contact Pad Length (X8)
Y1
MIN
MILLIMETERS
NOM
1.27 BSC
5.40
MAX
0.60
1.55
Notes:
1. Dimensioning and tolerancing per ASME Y14.5M
BSC: Basic Dimension. Theoretically exact value shown without tolerances.
Microchip Technology Drawing C04-2057-SN Rev E
© 2017 Microchip Technology Inc.
© 2019 Microchip Technology Inc.
DS20006193A-page 30
M
AT25128B/AT25256B
Packaging Diagrams and Parameters
Packaging Information
8-Lead Plastic Thin Shrink Small Outline (ST) – 4.4 mm Body [TSSOP]
Note:
For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
D
N
E
E1
NOTE 1
1
2
b
e
c
A
φ
A2
A1
L
L1
Units
Dimension Limits
Number of Pins
MILLIMETERS
MIN
N
NOM
MAX
8
Pitch
e
Overall Height
A
–
0.65 BSC
–
Molded Package Thickness
A2
0.80
1.00
1.05
Standoff
A1
0.05
–
0.15
1.20
Overall Width
E
Molded Package Width
E1
4.30
6.40 BSC
4.40
Molded Package Length
D
2.90
3.00
3.10
Foot Length
L
0.45
0.60
0.75
Footprint
L1
4.50
1.00 REF
Foot Angle
φ
0°
–
8°
Lead Thickness
c
0.09
–
0.20
Lead Width
b
0.19
–
0.30
Notes:
1. Pin 1 visual index feature may vary, but must be located within the hatched area.
2. Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed 0.15 mm per side.
3. Dimensioning and tolerancing per ASME Y14.5M.
BSC: Basic Dimension. Theoretically exact value shown without tolerances.
REF: Reference Dimension, usually without tolerance, for information purposes only.
Microchip Technology Drawing C04-086B
© 2007 Microchip Technology Inc.
© 2019 Microchip Technology Inc.
DS00049AR-page 117
DS20006193A-page 31
M
Note:
AT25128B/AT25256B
Packaging Diagrams and Parameters
Packaging Information
For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
DS00049BC-page 96
© 2019 Microchip Technology Inc.
2009 Microchip Technology Inc.
DS20006193A-page 32
AT25128B/AT25256B
Packaging Information
8-Lead Ultra Thin Plastic Dual Flat, No Lead Package (Q4B) - 2x3 mm Body [UDFN]
Atmel Legacy YNZ Package
Note:
For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
D
A
B
N
(DATUM A)
E
(DATUM B)
NOTE 1
2X
0.10 C
1
2
2X
0.10 C
TOP VIEW
A1
0.10 C
C
SEATING
PLANE
A
8X
(A3)
SIDE VIEW
0.10
0.08 C
C A B
D2
e
2
1 2
0.10
E2
C A B
K
N
L
8X b
e
0.10
0.05
C A B
C
BOTTOM VIEW
Microchip Technology Drawing C04-21355-Q4B Rev A Sheet 1 of 2
© 2017 Microchip Technology Inc.
© 2019 Microchip Technology Inc.
DS20006193A-page 33
AT25128B/AT25256B
Packaging Information
8-Lead Ultra Thin Plastic Dual Flat, No Lead Package (Q4B) - 2x3 mm Body [UDFN]
Atmel Legacy YNZ Package
Note:
For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
Notes:
Units
Dimension Limits
Number of Terminals
N
e
Pitch
A
Overall Height
Standoff
A1
Terminal Thickness
A3
Overall Length
D
Exposed Pad Length
D2
Overall Width
E
Exposed Pad Width
E2
b
Terminal Width
Terminal Length
L
Terminal-to-Exposed-Pad
K
MIN
0.50
0.00
1.40
1.20
0.18
0.35
0.20
MILLIMETERS
NOM
8
0.50 BSC
0.55
0.02
0.152 REF
2.00 BSC
1.50
3.00 BSC
1.30
0.25
0.40
-
MAX
0.60
0.05
1.60
1.40
0.30
0.45
-
1. Pin 1 visual index feature may vary, but must be located within the hatched area.
2. Package is saw singulated
3. Dimensioning and tolerancing per ASME Y14.5M
BSC: Basic Dimension. Theoretically exact value shown without tolerances.
REF: Reference Dimension, usually without tolerance, for information purposes only.
Microchip Technology Drawing C04-21355-Q4B Rev A Sheet 2 of 2
© 2017 Microchip Technology Inc.
© 2019 Microchip Technology Inc.
DS20006193A-page 34
AT25128B/AT25256B
Packaging Information
8-Lead Ultra Thin Plastic Dual Flat, No Lead Package (Q4B) - 2x3 mm Body [UDFN]
Atmel Legacy YNZ Package
Note:
For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
X2
EV
G2
8
ØV
C
Y2
G1
Y1
1
2
SILK SCREEN
X1
E
RECOMMENDED LAND PATTERN
Units
Dimension Limits
E
Contact Pitch
Optional Center Pad Width
X2
Optional Center Pad Length
Y2
Contact Pad Spacing
C
Contact Pad Width (X8)
X1
Contact Pad Length (X8)
Y1
Contact Pad to Center Pad (X8)
G1
Contact Pad to Contact Pad (X6)
G2
Thermal Via Diameter
V
Thermal Via Pitch
EV
MIN
MILLIMETERS
NOM
0.50 BSC
MAX
1.60
1.40
2.90
0.30
0.85
0.20
0.33
0.30
1.00
Notes:
1. Dimensioning and tolerancing per ASME Y14.5M
BSC: Basic Dimension. Theoretically exact value shown without tolerances.
2. For best soldering results, thermal vias, if used, should be filled or tented to avoid solder loss during
reflow process
Microchip Technology Drawing C04-21355-Q4B Rev A
© 2017 Microchip Technology Inc.
© 2019 Microchip Technology Inc.
DS20006193A-page 35
AT25128B/AT25256B
Packaging Information
f
d
A1 BALL
PAD
CORNER
D
0.10
A
(4X)
0.10 C
0.08 C
d
C
A1 BALL PAD CORNER
2
1
Øb
j
j
E
n 0.15 m C A B
n 0.08 m C
A
B
e
C
D
(e1)
B
A1
d
A2
(d1)
A
TOP VIEW
BOTTOM VIEW
SIDE VIEW
8 SOLDER BALLS
COMMON DIMENSIONS
(Unit of Measure = mm)
SYMBOL
Notes:
1. This drawing is for general
2. Dimension 'b' is measured at the maximum solder ball diameter.
3. Solder ball composition shall be 95.5Sn-4.0Ag-.5Cu.
A
A1
A2
b
D
E
e
e1
d
d1
MIN
0.81
0.15
0.40
0.25
MAX
NOM
0.91
0.20
0.45
0.30
2.35 BSC
3.73 BSC
0.75 BSC
0.74 REF
0.75 BSC
0.80 REF
NOTE
1.00
0.25
0.50
0.35
6/11/13
TITLE
8U2-1, 8-ball, 2.35 x 3.73 mm Body, 0.75 mm pitch,
Very Thin, Fine-Pitch Ball Grid Array Package
(VFBGA)
GPC
DRAWING NO.
GWW
8U2-1
REV.
G
Note: For the most current package drawings, please see the Microchip Packaging Specification located
at http://www.microchip.com/packaging.
© 2019 Microchip Technology Inc.
DS20006193A-page 36
AT25128B/AT25256B
Revision History
10.
Revision History
Revision A (May 2019)
Updated to the Microchip template. Microchip DS20006193 replaces Atmel document 8698. Updated Part
Marking Information. Added ESD rating. Removed lead finish designation. Added POR recommendations
section. Updated trace code format in package markings. Updated section content throughout for
clarification. Updated the SOIC, TSSOP, and UDFN package drawings to the Microchip equivalents.
Atmel Document 8698 Revision E (January 2015)
Added the UDFN Expanded Quantity Option and ordering information. Updated the 8MA2 package
outline drawing.
Atmel Document 8698 Revision D (July 2014)
Updated part markings, 8MA2 and 8U2-1 package drawings, package 8A2 to 8X, template, logos, and
disclaimer page. No change to functional specification.
Atmel Document 8698 Revision C (August 2011)
Updated 8A2 and 8S1 package drawings. Corrected page 13, Device Density from 156K to 256K.
Corrected page 9, table headings. Corrected cross references on pages 7, 8, and 9.
Atmel Document 8698 Revision B (March 2010)
Updated Catalog Numbering Scheme. Updated Ordering Information and package types.
Atmel Document 8698 Revision A (December 2009)
Initial document release.
© 2019 Microchip Technology Inc.
DS20006193A-page 37
AT25128B/AT25256B
The Microchip Web Site
Microchip provides online support via our web site at http://www.microchip.com/. This web site is used as
a means to make files and information easily available to customers. Accessible by using your favorite
Internet browser, the web site contains the following information:
• Product Support – Data sheets and errata, application notes and sample programs, design
resources, user’s guides and hardware support documents, latest software releases and archived
software
• General Technical Support – Frequently Asked Questions (FAQ), technical support requests, online
discussion groups, Microchip consultant program member listing
• Business of Microchip – Product selector and ordering guides, latest Microchip press releases,
listing of seminars and events, listings of Microchip sales offices, distributors and factory
representatives
Customer Change Notification Service
Microchip’s customer notification service helps keep customers current on Microchip products.
Subscribers will receive e-mail notification whenever there are changes, updates, revisions or errata
related to a specified product family or development tool of interest.
To register, access the Microchip web site at http://www.microchip.com/. Under “Support”, click on
“Customer Change Notification” and follow the registration instructions.
Customer Support
Users of Microchip products can receive assistance through several channels:
•
•
•
•
Distributor or Representative
Local Sales Office
Field Application Engineer (FAE)
Technical Support
Customers should contact their distributor, representative or Field Application Engineer (FAE) for support.
Local sales offices are also available to help customers. A listing of sales offices and locations is included
in the back of this document.
Technical support is available through the web site at: http://www.microchip.com/support
© 2019 Microchip Technology Inc.
DS20006193A-page 38
AT25128B/AT25256B
Product Identification System
To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office.
AT 2 5 1 2 8 B- SS H L - B
Shipping Carrier Option
B = Bulk (Tubes)
T = Tape and Reel, Standard Quantity Option
E = Tape and Reel, Extended Quantity Option
Product Family
25 = Standard SPI
Serial EEPROM
Operating Voltage
Device Density
Device Grade or
Wafer/Die Thickness
L = 1.8V to 5.5V
128 = 128-Kilobit
256 = 256-Kilobit
H or U = Industrial Temperature Range
(-40°C to +85°C)
11
= 11mil Wafer Thickness
Device Revision
Package Option
SS
X
MA
C
WWU
WDT
= SOIC
= TSSOP
= 2.0mm x 3.0mm UDFN
= VFBGA
= Wafer Unsawn
= Die in Tape and Reel
Examples:
Device
Package
Package
Drawing
Code
Package
Option
Shipping Carrier
Option
Device Grade
AT25128B‑SSHL‑B
SOIC
SN
SS
Bulk (Tubes)
AT25128B‑SSHL‑T
SOIC
SN
SS
Tape and Reel
Industrial
Temperature
(-40°C to 85°C)
AT25256B‑SSHL‑T
SOIC
SN
SS
Tape and Reel
AT25128B‑XHL‑B
TSSOP
ST
X
Bulk (Tubes)
AT25256B‑XHL‑T
TSSOP
ST
X
Tape and Reel
AT25128B‑MAHL‑E
UDFN
Q4B
MA
Tape and Reel
AT25256B‑MAHL‑T
UDFN
Q4B
MA
Tape and Reel
AT25256B‑MAHL‑E
UDFN
Q4B
MA
Tape and Reel
VFBGA
8U2-1
C
Tape and Reel
AT25256B‑CUL‑T
Microchip Devices Code Protection Feature
Note the following details of the code protection feature on Microchip devices:
• Microchip products meet the specification contained in their particular Microchip Data Sheet.
© 2019 Microchip Technology Inc.
DS20006193A-page 39
AT25128B/AT25256B
• Microchip believes that its family of products is one of the most secure families of its kind on the
market today, when used in the intended manner and under normal conditions.
• There are dishonest and possibly illegal methods used to breach the code protection feature. All of
these methods, to our knowledge, require using the Microchip products in a manner outside the
operating specifications contained in Microchip’s Data Sheets. Most likely, the person doing so is
engaged in theft of intellectual property.
• Microchip is willing to work with the customer who is concerned about the integrity of their code.
• Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their
code. Code protection does not mean that we are guaranteeing the product as “unbreakable.”
Code protection is constantly evolving. We at Microchip are committed to continuously improving the
code protection features of our products. Attempts to break Microchip’s code protection feature may be a
violation of the Digital Millennium Copyright Act. If such acts allow unauthorized access to your software
or other copyrighted work, you may have a right to sue for relief under that Act.
Legal Notice
Information contained in this publication regarding device applications and the like is provided only for
your convenience and may be superseded by updates. It is your responsibility to ensure that your
application meets with your specifications. MICROCHIP MAKES NO REPRESENTATIONS OR
WARRANTIES OF ANY KIND WHETHER EXPRESS OR IMPLIED, WRITTEN OR ORAL, STATUTORY
OR OTHERWISE, RELATED TO THE INFORMATION, INCLUDING BUT NOT LIMITED TO ITS
CONDITION, QUALITY, PERFORMANCE, MERCHANTABILITY OR FITNESS FOR PURPOSE.
Microchip disclaims all liability arising from this information and its use. Use of Microchip devices in life
support and/or safety applications is entirely at the buyer’s risk, and the buyer agrees to defend,
indemnify and hold harmless Microchip from any and all damages, claims, suits, or expenses resulting
from such use. No licenses are conveyed, implicitly or otherwise, under any Microchip intellectual
property rights unless otherwise stated.
Trademarks
The Microchip name and logo, the Microchip logo, AnyRate, AVR, AVR logo, AVR Freaks, BitCloud,
chipKIT, chipKIT logo, CryptoMemory, CryptoRF, dsPIC, FlashFlex, flexPWR, Heldo, JukeBlox, KeeLoq,
Kleer, LANCheck, LINK MD, maXStylus, maXTouch, MediaLB, megaAVR, MOST, MOST logo, MPLAB,
OptoLyzer, PIC, picoPower, PICSTART, PIC32 logo, Prochip Designer, QTouch, SAM-BA, SpyNIC, SST,
SST Logo, SuperFlash, tinyAVR, UNI/O, and XMEGA are registered trademarks of Microchip Technology
Incorporated in the U.S.A. and other countries.
ClockWorks, The Embedded Control Solutions Company, EtherSynch, Hyper Speed Control, HyperLight
Load, IntelliMOS, mTouch, Precision Edge, and Quiet-Wire are registered trademarks of Microchip
Technology Incorporated in the U.S.A.
Adjacent Key Suppression, AKS, Analog-for-the-Digital Age, Any Capacitor, AnyIn, AnyOut, BodyCom,
CodeGuard, CryptoAuthentication, CryptoAutomotive, CryptoCompanion, CryptoController, dsPICDEM,
dsPICDEM.net, Dynamic Average Matching, DAM, ECAN, EtherGREEN, In-Circuit Serial Programming,
ICSP, INICnet, Inter-Chip Connectivity, JitterBlocker, KleerNet, KleerNet logo, memBrain, Mindi, MiWi,
motorBench, MPASM, MPF, MPLAB Certified logo, MPLIB, MPLINK, MultiTRAK, NetDetach, Omniscient
Code Generation, PICDEM, PICDEM.net, PICkit, PICtail, PowerSmart, PureSilicon, QMatrix, REAL ICE,
Ripple Blocker, SAM-ICE, Serial Quad I/O, SMART-I.S., SQI, SuperSwitcher, SuperSwitcher II, Total
© 2019 Microchip Technology Inc.
DS20006193A-page 40
AT25128B/AT25256B
Endurance, TSHARC, USBCheck, VariSense, ViewSpan, WiperLock, Wireless DNA, and ZENA are
trademarks of Microchip Technology Incorporated in the U.S.A. and other countries.
SQTP is a service mark of Microchip Technology Incorporated in the U.S.A.
Silicon Storage Technology is a registered trademark of Microchip Technology Inc. in other countries.
GestIC is a registered trademark of Microchip Technology Germany II GmbH & Co. KG, a subsidiary of
Microchip Technology Inc., in other countries.
All other trademarks mentioned herein are property of their respective companies.
©
2019, Microchip Technology Incorporated, Printed in the U.S.A., All Rights Reserved.
ISBN: 978-1-5224-4457-2
Quality Management System Certified by DNV
ISO/TS 16949
Microchip received ISO/TS-16949:2009 certification for its worldwide headquarters, design and wafer
fabrication facilities in Chandler and Tempe, Arizona; Gresham, Oregon and design centers in California
®
®
and India. The Company’s quality system processes and procedures are for its PIC MCUs and dsPIC
®
DSCs, KEELOQ code hopping devices, Serial EEPROMs, microperipherals, nonvolatile memory and
analog products. In addition, Microchip’s quality system for the design and manufacture of development
systems is ISO 9001:2000 certified.
© 2019 Microchip Technology Inc.
DS20006193A-page 41
Worldwide Sales and Service
AMERICAS
ASIA/PACIFIC
ASIA/PACIFIC
EUROPE
Corporate Office
2355 West Chandler Blvd.
Chandler, AZ 85224-6199
Tel: 480-792-7200
Fax: 480-792-7277
Technical Support:
http://www.microchip.com/
support
Web Address:
www.microchip.com
Atlanta
Duluth, GA
Tel: 678-957-9614
Fax: 678-957-1455
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Tel: 512-257-3370
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Tel: 774-760-0087
Fax: 774-760-0088
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Tel: 630-285-0071
Fax: 630-285-0075
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Tel: 972-818-7423
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Tel: 248-848-4000
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Tel: 281-894-5983
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© 2019 Microchip Technology Inc.
DS20006193A-page 42
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