MICROCHIP 25AA256T-IST

25AA256/25LC256
256K SPI™ Bus Serial EEPROM
Device Selection Table
Part Number
VCC Range
Page Size
Temp. Ranges
Packages
25LC256
2.5-5.5V
64 Byte
I, E
P, SN, ST, MF
25AA256
1.8-5.5V
64 Byte
I
P, SN, ST, MF
Features
Description
• Max. clock 10 MHz
• Low-power CMOS technology
- Max. Write Current: 5 mA at 5.5V, 10 MHz
- Read Current: 5 mA at 5.5V, 10 MHz
- Standby Current: 1 µA at 5.5V
• 32,768 x 8-bit organization
• 64 byte page
• Self-timed ERASE and WRITE cycles (5 ms
max.)
• Block write protection
- Protect none, 1/4, 1/2 or all of array
• Built-in write protection
- Power-on/off data protection circuitry
- Write enable latch
- Write-protect pin
• Sequential read
• High reliability
- Endurance: 1,000,000 erase/write cycles
- Data retention: > 200 years
- ESD protection: > 4000V
• Temperature ranges supported;
- Industrial (I):
-40°C to +85°C
- Automotive (E):
-40°C to +125°C
The Microchip Technology Inc. 25AA256/25LC256
(25XX256*) are 256k-bit Serial Electrically Erasable
PROMs. The memory is accessed via a simple Serial
Peripheral Interface™ (SPI™) compatible serial bus.
The bus signals required are a clock input (SCK) plus
separate data in (SI) and data out (SO) lines. Access to
the device is controlled through a Chip Select (CS)
input.
Communication to the device can be paused via the
hold pin (HOLD). While the device is paused,
transitions on its inputs will be ignored, with the
exception of Chip Select, allowing the host to service
higher priority interrupts.
The 25XX256 is available in standard packages
including 8-lead PDIP and SOIC, and advanced
packaging including 8-lead DFN and 8-lead TSSOP.
Pb-free (Pure Sn) finish is also available.
Package Types (not to scale)
TSSOP
PDIP/SOIC
(P, SN)
(ST)
1
2
3
4
8
7
6
5
VCC
HOLD
SCK
SI
• Standard and Pb-free packages available
Pin Function Table
CS
SO
1
2
WP
3
VSS
4
25LC256
CS
SO
WP
VSS
8
7
VCC
HOLD
6
SCK
5
SI
DFN
(MF)
Name
Function
CS 1
Chip Select Input
SO 2
SO
Serial Data Output
WP 3
WP
Write-Protect
VSS 4
VSS
Ground
SI
Serial Data Input
SCK
Serial Clock Input
HOLD
VCC
25LC256
CS
8
VCC
7
HOLD
6
SCK
5
SI
SPI is a registered trademark of Motorola Corporation.
Hold Input
Supply Voltage
* 25XX256 is used in this document as a generic part number for the 25AA256, 25LC256 devices.
 2003 Microchip Technology Inc.
Preliminary
DS21822C-page 1
25AA256/25LC256
1.0
ELECTRICAL CHARACTERISTICS
Absolute Maximum Ratings (†)
VCC .............................................................................................................................................................................6.5V
All inputs and outputs w.r.t. VSS ......................................................................................................... -0.6V to VCC +1.0V
Storage temperature .................................................................................................................................-65°C to 150°C
Ambient temperature under bias ...............................................................................................................-40°C to 125°C
ESD protection on all pins ..........................................................................................................................................4 kV
† NOTICE: 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 those or any other conditions above those
indicated in the operational listings of this specification is not implied. Exposure to maximum rating conditions for an
extended period of time may affect device reliability.
TABLE 1-1:
DC CHARACTERISTICS
DC CHARACTERISTICS
Param.
No.
Sym.
Characteristic
Industrial (I):
TA = -40°C to +85°C
Automotive (E): TA = -40°C to +125°C
Min.
Max.
Units
D001
VIH1
High-level input
voltage
.7 VCC
VCC+1
V
D002
VIL1
-0.3
0.3VCC
V
D003
VIL2
Low-level input
voltage
D004
VOL
VCC = 1.8V to 5.5V
VCC = 2.5V to 5.5V
Test Conditions
VCC ≥ 2.7V
-0.3
0.2VCC
V
VCC < 2.7V
Low-level output
voltage
—
0.4
V
IOL = 2.1 mA
—
0.2
V
IOL = 1.0 mA, VCC < 2.5V
VCC -0.5
—
V
IOH = -400 µA
D005
VOL
D006
VOH
High-level output
voltage
D007
ILI
Input leakage current
—
±1
µA
CS = VCC, VIN = VSS TO VCC
D008
ILO
Output leakage
current
—
±1
µA
CS = VCC, VOUT = VSS TO VCC
D009
CINT
Internal Capacitance
(all inputs and
outputs)
—
7
pF
TA = 25°C, CLK = 1.0 MHz,
VCC = 5.0V (Note)
D010
ICC Read
—
—
5
mA
2.5
mA
VCC = 5.5V; FCLK = 10.0 MHz;
SO = Open
VCC = 2.5V; FCLK = 5.0 MHz;
SO = Open
—
—
5
3
mA
mA
VCC = 5.5V
VCC = 2.5V
—
—
5
µA
1
µA
CS = VCC = 5.5V, Inputs tied to VCC or
VSS, 125°C
CS = VCC = 5.5V, Inputs tied to VCC or
VSS, 85°C
Operating Current
D011
ICC Write
D012
ICCS
Standby Current
Note:
This parameter is periodically sampled and not 100% tested.
DS21822C-page 2
Preliminary
 2003 Microchip Technology Inc.
25AA256/25LC256
TABLE 1-2:
AC CHARACTERISTICS
AC CHARACTERISTICS
Param.
Sym.
No.
Characteristic
Industrial (I):
TA = -40°C to +85°C
Automotive (E): TA = -40°C to +125°C
VCC = 1.8V to 5.5V
VCC = 2.5V to 5.5V
Min.
Max.
Units
Test Conditions
—
—
—
10
5
3
MHz
MHz
MHz
4.5V ≤ Vcc ≤ 5.5V
2.5V ≤ Vcc < 4.5V
1.8V ≤ Vcc < 2.5V
1
FCLK
Clock Frequency
2
TCSS
CS Setup Time
50
100
150
—
—
—
ns
ns
ns
4.5V ≤ Vcc ≤ 5.5V
2.5V ≤ Vcc < 4.5V
1.8V ≤ Vcc < 2.5V
3
TCSH
CS Hold Time
100
200
250
—
—
—
ns
ns
ns
4.5V ≤ Vcc ≤ 5.5V
2.5V ≤ Vcc < 4.5V
1.8V ≤ Vcc < 2.5V
4
TCSD
CS Disable Time
50
—
ns
—
5
Tsu
Data Setup Time
10
20
30
—
—
—
ns
ns
ns
4.5V ≤ Vcc ≤ 5.5V
2.5V ≤ Vcc < 4.5V
1.8V ≤ Vcc < 2.5V
6
THD
Data Hold Time
20
40
50
—
—
—
ns
ns
ns
4.5V ≤ Vcc ≤ 5.5V
2.5V ≤ Vcc < 4.5V
1.8V ≤ Vcc < 2.5V
7
TR
CLK Rise Time
—
2
µs
(Note 1)
8
TF
CLK Fall Time
—
2
µs
(Note 1)
9
THI
Clock High Time
50
100
150
—
—
—
ns
ns
ns
4.5V ≤ Vcc ≤ 5.5V
2.5V ≤ Vcc < 4.5V
1.8V ≤ Vcc < 2.5V
10
TLO
Clock Low Time
50
100
150
—
—
—
ns
ns
ns
4.5V ≤ Vcc ≤ 5.5V
2.5V ≤ Vcc < 4.5V
1.8V ≤ Vcc < 2.5V
11
TCLD
Clock Delay Time
50
—
ns
—
12
TCLE
Clock Enable Time
50
—
ns
—
13
TV
Output Valid from Clock
Low
—
—
—
50
100
160
ns
ns
ns
4.5V ≤ Vcc ≤ 5.5V
2.5V ≤ Vcc < 4.5V
1.8V ≤ Vcc < 2.5V
14
THO
Output Hold Time
0
—
ns
(Note 1)
15
TDIS
Output Disable Time
—
—
—
40
80
160
ns
ns
ns
4.5V ≤ Vcc ≤ 5.5V(Note 1)
2.5V ≤ Vcc ≤ 4.5V(Note 1)
1.8V ≤ Vcc ≤ 2.5V(Note 1)
16
THS
HOLD Setup Time
20
40
80
—
—
—
ns
ns
ns
4.5V ≤ Vcc ≤ 5.5V
2.5V ≤ Vcc < 4.5V
1.8V ≤ Vcc < 2.5V
Note 1: This parameter is periodically sampled and not 100% tested.
2: TWC begins on the rising edge of CS after a valid write sequence and ends when the internal write cycle is
complete.
3: This parameter is not tested but ensured by characterization. For endurance estimates in a specific
application, please consult the Total Endurance™ Model which can be obtained from our web site:
www.microchip.com.
 2003 Microchip Technology Inc.
Preliminary
DS21822C-page 3
25AA256/25LC256
TABLE 1-2:
AC CHARACTERISTICS (CONTINUED)
Industrial (I):
TA = -40°C to +85°C
Automotive (E): TA = -40°C to +125°C
AC CHARACTERISTICS
Param.
Sym.
No.
Characteristic
Min.
Max.
Units
VCC = 1.8V to 5.5V
VCC = 2.5V to 5.5V
Test Conditions
17
THH
HOLD Hold Time
20
40
80
—
—
—
ns
ns
ns
4.5V ≤ Vcc ≤ 5.5V
2.5V ≤ Vcc < 4.5V
1.8V ≤ Vcc < 2.5V
18
THZ
HOLD Low to Output
High-Z
30
60
160
—
—
—
ns
ns
ns
4.5V ≤ Vcc ≤ 5.5V(Note 1)
2.5V ≤ Vcc < 4.5V(Note 1)
1.8V ≤ Vcc < 2.5V(Note 1)
19
THV
HOLD High to Output
Valid
30
60
160
—
—
—
ns
ns
ns
4.5V ≤ Vcc ≤ 5.5V
2.5V ≤ Vcc < 4.5V
1.8V ≤ Vcc < 2.5V
ms
(NOTE 2)
20
TWC
Internal Write Cycle Time
—
5
21
—
Endurance
1M
—
E/W (NOTE 3)
Cycles
Note 1: This parameter is periodically sampled and not 100% tested.
2: TWC begins on the rising edge of CS after a valid write sequence and ends when the internal write cycle is
complete.
3: This parameter is not tested but ensured by characterization. For endurance estimates in a specific
application, please consult the Total Endurance™ Model which can be obtained from our web site:
www.microchip.com.
TABLE 1-3:
AC TEST CONDITIONS
AC Waveform:
VLO = 0.2V
—
VHI = VCC - 0.2V
(Note 1)
VHI = 4.0V
(Note 2)
CL = 100 pF
—
Timing Measurement Reference Level
Input
0.5 VCC
Output
0.5 VCC
Note 1: For VCC ≤ 4.0V
2: For Vcc > 4.0V
DS21822C-page 4
Preliminary
 2003 Microchip Technology Inc.
25AA256/25LC256
FIGURE 1-1:
HOLD TIMING
CS
17
16
17
16
SCK
18
SO
n+2
SI
n+2
n+1
19
high-impedance
n
n
5
don’t care
n+1
n-1
n
n
n-1
HOLD
FIGURE 1-2:
SERIAL INPUT TIMING
4
CS
2
12
11
7
8
Mode 1,1
3
SCK Mode 0,0
5
SI
6
MSB in
LSB in
high-impedance
SO
FIGURE 1-3:
SERIAL OUTPUT TIMING
CS
9
3
10
Mode 1,1
SCK
Mode 0,0
13
14
SO
MSB out
SI
 2003 Microchip Technology Inc.
15
ISB out
don’t care
Preliminary
DS21822C-page 5
25AA256/25LC256
2.0
FUNCTIONAL DESCRIPTION
2.1
Principles of Operation
2.3
The 25XX256 is a 32768 byte Serial EEPROM
designed to interface directly with the Serial Peripheral
Interface (SPI) port of many of today’s popular
microcontroller
families,
including
Microchip’s
PICmicro® microcontrollers. It may also interface with
microcontrollers that do not have a built-in SPI port by
using discrete I/O lines programmed properly in
firmware to match the SPI protocol.
The 25XX256 contains an 8-bit instruction register. The
device is accessed via the SI pin, with data being
clocked in on the rising edge of SCK. The CS pin must
be low and the HOLD pin must be high for the entire
operation.
Table 2-1 contains a list of the possible instruction
bytes and format for device operation. All instructions,
addresses, and data are transferred MSB first, LSB
last.
Data (SI) is sampled on the first rising edge of SCK
after CS goes low. If the clock line is shared with other
peripheral devices on the SPI bus, the user can assert
the HOLD input and place the 25XX256 in ‘HOLD’
mode. After releasing the HOLD pin, operation will
resume from the point when the HOLD was asserted.
2.2
Prior to any attempt to write data to the 25XX256, the
write enable latch must be set by issuing the WREN
instruction (Figure 2-4). This is done by setting CS low
and then clocking out the proper instruction into the
25XX256. After all eight bits of the instruction are
transmitted, the CS must be brought high to set the
write enable latch. If the write operation is initiated
immediately after the WREN instruction without CS
being brought high, the data will not be written to the
array because the write enable latch will not have been
properly set.
Once the write enable latch is set, the user may
proceed by setting the CS low, issuing a WRITE
instruction, followed by the 16-bit address, with the first
MSB of the address being a don’t care bit, and then the
data to be written. Up to 64 bytes of data can be sent to
the device before a write cycle is necessary. The only
restriction is that all of the bytes must reside in the
same page.
Note:
Read Sequence
The device is selected by pulling CS low. The 8-bit read
instruction is transmitted to the 25XX256 followed by
the 16-bit address, with the first MSB of the address
being a don’t care bit. After the correct read instruction
and address are sent, the data stored in the memory at
the selected address is shifted out on the SO pin. The
data stored in the memory at the next address can be
read sequentially by continuing to provide clock pulses.
The internal address pointer is automatically incremented to the next higher address after each byte of
data is shifted out. When the highest address is
reached (7FFFh), the address counter rolls over to
address 0000h allowing the read cycle to be continued
indefinitely. The read operation is terminated by raising
the CS pin (Figure 2-1).
DS21822C-page 6
Write Sequence
Page write operations are limited to writing
bytes within a single physical page,
regardless of the number of bytes
actually being written. Physical page
boundaries start at addresses that are
integer multiples of the page buffer size (or
‘page size’) and, end at addresses that are
integer multiples of page size - 1. If a Page
Write command attempts to write across a
physical page boundary, the result is that
the data wraps around to the beginning of
the current page (overwriting data
previously stored there), instead of being
written to the next page as might be
expected. It is therefore necessary for the
application software to prevent page write
operations that would attempt to cross a
page boundary.
For the data to be actually written to the array, the CS
must be brought high after the Least Significant bit (D0)
of the nth data byte has been clocked in. If CS is
brought high at any other time, the write operation will
not be completed. Refer to Figure 2-2 and Figure 2-3
for more detailed illustrations on the byte write
sequence and the page write sequence respectively.
While the write is in progress, the Status register may
be read to check the status of the WPEN, WIP, WEL,
BP1 and BP0 bits (Figure 2-6). A read attempt of a
memory array location will not be possible during a
write cycle. When the write cycle is completed, the
write enable latch is reset.
Preliminary
 2003 Microchip Technology Inc.
25AA256/25LC256
BLOCK DIAGRAM
Status
Register
HV Generator
Memory
Control
Logic
I/O Control
Logic
EEPROM
Array
X
Dec
Page Latches
SI
SO
Y Decoder
CS
SCK
Sense Amp.
R/W Control
HOLD
WP
VCC
VSS
TABLE 2-1:
INSTRUCTION SET
Instruction Name
Instruction Format
READ
0000 0011
Read data from memory array beginning at selected address
WRITE
0000 0010
Write data to memory array beginning at selected address
WRDI
0000 0100
Reset the write enable latch (disable write operations)
WREN
0000 0110
Set the write enable latch (enable write operations)
RDSR
0000 0101
Read Status register
WRSR
0000 0001
Write Status register
FIGURE 2-1:
Description
READ SEQUENCE
CS
0
1
2
3
4
5
6
7
8
9 10 11
21 22 23 24 25 26 27 28 29 30 31
SCK
instruction
SI
0
0
0
0
0
16-bit address
0
1
1 15 14 13 12
2
1
0
data out
high-impedance
7
SO
 2003 Microchip Technology Inc.
Preliminary
6
5
4
3
2
1
0
DS21822C-page 7
25AA256/25LC256
FIGURE 2-2:
BYTE WRITE SEQUENCE
CS
Twc
0
1
2
3
4
5
6
7
8
9 10 11
21 22 23 24 25 26 27 28 29 30 31
SCK
instruction
SI
0
0
0
0
0
16-bit address
0
1
data byte
2
0 15 14 13 12
1
0
7
6
5
4
3
2
1
0
high-impedance
SO
FIGURE 2-3:
PAGE WRITE SEQUENCE
CS
0
1
2
3
4
5
6
7
8
9 10 11
21 22 23 24 25 26 27 28 29 30 31
SCK
instruction
SI
0
0
0
0
0
16-bit address
0 1
data byte 1
2
0 15 14 13 12
1
0
7
6
5
4
3
2
1
0
CS
32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47
SCK
data byte 2
SI
7
DS21822C-page 8
6
5
4
3
data byte 3
2
1
0
7
6
5
4
3
data byte n (64 max)
2
Preliminary
1
0
7
6
5
4
3
2
1
0
 2003 Microchip Technology Inc.
25AA256/25LC256
2.4
Write Enable (WREN) and Write
Disable (WRDI)
The following is a list of conditions under which the
write enable latch will be reset:
•
•
•
•
The 25XX256 contains a write enable latch.
See
Table 2-4 for the Write-Protect Functionality Matrix.
This latch must be set before any write operation will be
completed internally. The WREN instruction will set the
latch, and the WRDI will reset the latch.
FIGURE 2-4:
Power-up
WRDI instruction successfully executed
WRSR instruction successfully executed
WRITE instruction successfully executed
WRITE ENABLE SEQUENCE (WREN)
CS
0
1
2
3
4
5
6
7
SCK
0
SI
0
0
0
0
1
1
0
high-impedance
SO
FIGURE 2-5:
WRITE DISABLE SEQUENCE (WRDI)
CS
0
1
2
3
4
5
6
7
SCK
SI
0
0
0
0
0
1
10
0
high-impedance
SO
 2003 Microchip Technology Inc.
Preliminary
DS21822C-page 9
25AA256/25LC256
2.5
Read Status Register Instruction
(RDSR)
The Write Enable Latch (WEL) bit indicates the status
of the write enable latch and is read-only. When set to
a ‘1’, the latch allows writes to the array, when set to a
‘0’, the latch prohibits writes to the array. The state of
this bit can always be updated via the WREN or WRDI
commands regardless of the state of write protection
on the Status register. These commands are shown in
Figure 2-4 and Figure 2-5.
The Read Status Register instruction (RDSR) provides
access to the Status register. The Status register may
be read at any time, even during a write cycle. The
Status register is formatted as follows:
TABLE 2-2:
STATUS REGISTER
7
6 5 4
3
2
1
W/R
– – – W/R W/R
R
WPEN X X X BP1 BP0 WEL
W/R = writable/readable. R = read-only.
The Block Protection (BP0 and BP1) bits indicate
which blocks are currently write-protected. These bits
are set by the user issuing the WRSR instruction. These
bits are nonvolatile, and are shown in Table 2-3.
0
R
WIP
See Figure 2-6 for the RDSR timing sequence.
The Write-In-Process (WIP) bit indicates whether the
25XX256 is busy with a write operation. When set to a
‘1’, a write is in progress, when set to a ‘0’, no write is
in progress. This bit is read-only.
FIGURE 2-6:
READ STATUS REGISTER TIMING SEQUENCE (RDSR)
CS
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
1
0
SCK
instruction
SI
0
0
0
0
0
1
0
1
data from Status register
high-impedance
SO
DS21822C-page 10
7
Preliminary
6
5
4
3
2
 2003 Microchip Technology Inc.
25AA256/25LC256
2.6
Write Status Register Instruction
(WRSR)
See Figure 2-7 for the WRSR timing sequence.
TABLE 2-3:
The Write Status Register instruction (WRSR) allows the
user to write to the nonvolatile bits in the Status register
as shown in Table 2-2. The user is able to select one of
four levels of protection for the array by writing to the
appropriate bits in the Status register. The array is
divided up into four segments. The user has the ability
to write-protect none, one, two, or all four of the
segments of the array. The partitioning is controlled as
shown in Table 2-3.
The Write-Protect Enable (WPEN) bit is a nonvolatile
bit that is available as an enable bit for the WP pin. The
Write-Protect (WP) pin and the Write-Protect Enable
(WPEN) bit in the Status register control the
programmable hardware write-protect feature. Hardware write protection is enabled when WP pin is low
and the WPEN bit is high. Hardware write protection is
disabled when either the WP pin is high or the WPEN
bit is low. When the chip is hardware write-protected,
only writes to nonvolatile bits in the Status register are
disabled. See Table 2-4 for a matrix of functionality on
the WPEN bit.
FIGURE 2-7:
ARRAY PROTECTION
BP1
BP0
Array Addresses
Write-Protected
0
0
none
0
1
upper 1/4
(6000h - 7FFFh)
1
0
upper 1/2
(4000h - 7FFFh)
1
1
all
(0000h - 7FFFh)
WRITE STATUS REGISTER TIMING SEQUENCE (WRSR)
CS
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
1
0
SCK
instruction
SI
0
0
0
0
data to Status register
0
0
0
1
7
6
5
4
3
2
high-impedance
SO
Note:
An internal write cycle (TWC) is initiated on the rising edge of CS after a valid write Status Register sequence.
 2003 Microchip Technology Inc.
Preliminary
DS21822C-page 11
25AA256/25LC256
2.7
Data Protection
2.8
The following protection has been implemented to
prevent inadvertent writes to the array:
• The write enable latch is reset on power-up
• A write enable instruction must be issued to set
the write enable latch
• After a byte write, page write or Status register
write, the write enable latch is reset
• CS must be set high after the proper number of
clock cycles to start an internal write cycle
• Access to the array during an internal write cycle
is ignored and programming is continued
TABLE 2-4:
Power-On State
The 25XX256 powers on in the following state:
• The device is in low-power Standby mode
(CS = 1)
• The write enable latch is reset
• SO is in high-impedance state
• A high-to-low-level transition on CS is required to
enter active state
WRITE-PROTECT FUNCTIONALITY MATRIX
WEL
(SR bit 1)
WPEN
(SR bit 7)
WP
(pin 3)
Protected Blocks
Unprotected Blocks
Status Register
0
x
x
Protected
Protected
Protected
1
0
x
Protected
Writable
Writable
1
1
0 (low)
Protected
Writable
Protected
1
1
1 (high)
Protected
Writable
Writable
x = don’t care
DS21822C-page 12
Preliminary
 2003 Microchip Technology Inc.
25AA256/25LC256
3.0
PIN DESCRIPTIONS
The WP pin function is blocked when the WPEN bit in
the Status register is low. This allows the user to install
the 25XX256 in a system with WP pin grounded and
still be able to write to the Status register. The WP pin
functions will be enabled when the WPEN bit is set
high.
The descriptions of the pins are listed in Table 3-1.
TABLE 3-1:
PIN FUNCTION TABLE
Name
Pin Number
CS
1
Chip Select Input
SO
2
Serial Data Output
WP
3
Write-Protect Pin
VSS
4
Ground
3.5
SI
5
Serial Data Input
SCK
6
Serial Clock Input
HOLD
7
Hold Input
VCC
8
Supply Voltage
The SCK is used to synchronize the communication
between a master and the 25XX256. Instructions,
addresses or data present on the SI pin are latched on
the rising edge of the clock input, while data on the SO
pin is updated after the falling edge of the clock input.
3.1
Function
3.4
The 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 clock.
3.6
Chip Select (CS)
A low level on this pin selects the device. A high level
deselects the device and forces it into Standby mode.
However, a programming cycle which is already
initiated or in progress will be completed, regardless of
the CS input signal. If CS is brought high during a
program cycle, the device will go into Standby mode as
soon as the programming cycle is complete. When the
device is deselected, SO goes to the high-impedance
state, allowing multiple parts to share the same SPI
bus. A low-to-high transition on CS after a valid write
sequence initiates an internal write cycle. After powerup, a low level on CS is required prior to any sequence
being initiated.
3.2
Serial Output (SO)
The SO pin is used to transfer data out of the 25XX256.
During a read cycle, data is shifted out on this pin after
the falling edge of the serial clock.
3.3
Serial Input (SI)
Serial Clock (SCK)
Hold (HOLD)
The HOLD pin is used to suspend transmission to the
25XX256 while in the middle of a serial sequence without having to retransmit the entire sequence again. It
must be held high any time this function is not being
used. Once the device is selected and a serial
sequence is underway, the HOLD pin may be pulled
low to pause further serial communication without
resetting the serial sequence. The HOLD pin must be
brought low while SCK is low, otherwise the HOLD
function will not be invoked until the next SCK high-tolow transition. The 25XX256 must remain selected
during this sequence. The SI, SCK and SO pins are in
a high-impedance state during the time the device is
paused and transitions on these pins will be ignored. To
resume serial communication, HOLD must be brought
high while the SCK pin is low, otherwise serial
communication will not resume. Lowering the HOLD
line at any time will tri-state the SO line.
Write-Protect (WP)
This pin is used in conjunction with the WPEN bit in the
Status register to prohibit writes to the nonvolatile bits
in the Status register. When WP is low and WPEN is
high, writing to the nonvolatile bits in the Status register
is disabled. All other operations function normally.
When WP is high, all functions, including writes to the
nonvolatile bits in the Status register, operate normally.
If the WPEN bit is set, WP low during a Status register
write sequence will disable writing to the Status
register. If an internal write cycle has already begun,
WP going low will have no effect on the write.
 2003 Microchip Technology Inc.
Preliminary
DS21822C-page 13
25AA256/25LC256
4.0
PACKAGING INFORMATION
4.1
Package Marking Information
8-Lead DFN
Example:
XXXXXXX
T/XXXXX
YYWW
NNN
25LC256
I/MF
0328
1L7
8-Lead PDIP
Example:
XXXXXXXX
T/XXXNNN
YYWW
25AA256
I/P 1L7
0328
Example:
8-Lead SOIC
XXXXXXXX
T/XXYYWW
NNN
25LC256
I/SN 0328
1L7
8-Lead TSSOP
Example:
5LE
I328
1L7
XXXX
TYWW
NNN
Legend:
XX...X
T
Blank
YY
WW
NNN
Note:
DS21822C-page 14
TSSOP 1st Line Marking Codes
Device
25AA256
25LC256
std mark
5AE
5LE
Pb-free
mark
NAE
NLE
Part number
Temperature (I, E)
Commercial
Year code (last 2 digits of calendar year) except TSSOP
which uses only the last 1 digit
Week code (week of January 1 is week ‘01’)
Alphanumeric traceability code
Custom marking available.
Preliminary
 2003 Microchip Technology Inc.
25AA256/25LC256
8-Lead Plastic Dual Flat No Lead Package (MF) 6x5 mm Body (DFN-S)
E
p
B
E1
n
L
R
D1
1
D
D2
PIN 1
ID
EXPOSED
METAL
PADS
2
E2
TOP VIEW
BOTTOM VIEW
α
A2
A3
A
A1
INCHES
Units
Dimension Limits
Number of Pins
MILLIMETERS*
NOM
MIN
n
MAX
MIN
NOM
MAX
8
8
Pitch
p
Overall Height
A
.033
.039
0.85
1.00
Molded Package Thickness
A2
.026
.031
0.65
0.80
Standoff
A1
.0004
.002
0.01
0.05
Base Thickness
A3
.008 REF.
0.20 REF.
4.92 BSC
.050 BSC
.000
E
.194 BSC
Molded Package Length
E1
.184 BSC
Exposed Pad Length
E2
Overall Length
Overall Width
.152
D
.158
1.27 BSC
0.00
4.67 BSC
.163
3.85
4.00
4.15
5.99 BSC
.236 BSC
.226 BSC
5.74 BSC
Molded Package Width
D1
Exposed Pad Width
D2
.085
.091
.097
2.16
2.31
2.46
Lead Width
B
.014
.016
.019
0.35
0.40
0.47
Lead Length
L
.020
.024
.030
0.50
0.60
0.75
Tie Bar Width
R
α
Mold Draft Angle Top
.356
.014
12
12
*Controlling Parameter
Notes:
Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed .010” (0.254mm) per side.
JEDEC equivalent: pending
Drawing No. C04-113
 2003 Microchip Technology Inc.
Preliminary
DS21822C-page 15
25AA256/25LC256
8-Lead Plastic Dual In-line (P) – 300 mil (PDIP)
E1
D
2
n
1
α
E
A2
A
L
c
A1
β
B1
p
eB
B
Units
Dimension Limits
n
p
Number of Pins
Pitch
Top to Seating Plane
Molded Package Thickness
Base to Seating Plane
Shoulder to Shoulder Width
Molded Package Width
Overall Length
Tip to Seating Plane
Lead Thickness
Upper Lead Width
Lower Lead Width
Overall Row Spacing
Mold Draft Angle Top
Mold Draft Angle Bottom
* Controlling Parameter
§ Significant Characteristic
A
A2
A1
E
E1
D
L
c
§
B1
B
eB
α
β
MIN
.140
.115
.015
.300
.240
.360
.125
.008
.045
.014
.310
5
5
INCHES*
NOM
MAX
8
.100
.155
.130
.170
.145
.313
.250
.373
.130
.012
.058
.018
.370
10
10
.325
.260
.385
.135
.015
.070
.022
.430
15
15
MILLIMETERS
NOM
8
2.54
3.56
3.94
2.92
3.30
0.38
7.62
7.94
6.10
6.35
9.14
9.46
3.18
3.30
0.20
0.29
1.14
1.46
0.36
0.46
7.87
9.40
5
10
5
10
MIN
MAX
4.32
3.68
8.26
6.60
9.78
3.43
0.38
1.78
0.56
10.92
15
15
Notes:
Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed
.010” (0.254mm) per side.
JEDEC Equivalent: MS-001
Drawing No. C04-018
DS21822C-page 16
Preliminary
 2003 Microchip Technology Inc.
25AA256/25LC256
8-Lead Plastic Small Outline (SN) – Narrow, 150 mil (SOIC)
E
E1
p
D
2
B
n
1
α
h
45°
c
A2
A
φ
β
L
Units
Dimension Limits
n
p
Number of Pins
Pitch
Overall Height
Molded Package Thickness
Standoff §
Overall Width
Molded Package Width
Overall Length
Chamfer Distance
Foot Length
Foot Angle
Lead Thickness
Lead Width
Mold Draft Angle Top
Mold Draft Angle Bottom
* Controlling Parameter
§ Significant Characteristic
A
A2
A1
E
E1
D
h
L
φ
c
B
α
β
MIN
.053
.052
.004
.228
.146
.189
.010
.019
0
.008
.013
0
0
A1
INCHES*
NOM
8
.050
.061
.056
.007
.237
.154
.193
.015
.025
4
.009
.017
12
12
MAX
.069
.061
.010
.244
.157
.197
.020
.030
8
.010
.020
15
15
MILLIMETERS
NOM
8
1.27
1.35
1.55
1.32
1.42
0.10
0.18
5.79
6.02
3.71
3.91
4.80
4.90
0.25
0.38
0.48
0.62
0
4
0.20
0.23
0.33
0.42
0
12
0
12
MIN
MAX
1.75
1.55
0.25
6.20
3.99
5.00
0.51
0.76
8
0.25
0.51
15
15
Notes:
Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed
.010” (0.254mm) per side.
JEDEC Equivalent: MS-012
Drawing No. C04-057
 2003 Microchip Technology Inc.
Preliminary
DS21822C-page 17
25AA256/25LC256
8-Lead Plastic Thin Shrink Small Outline (ST) – 4.4 mm (TSSOP)
E
E1
p
D
2
1
n
B
α
A
c
φ
β
A1
A2
L
Units
Dimension Limits
n
p
Number of Pins
Pitch
Overall Height
Molded Package Thickness
Standoff §
Overall Width
Molded Package Width
Molded Package Length
Foot Length
Foot Angle
Lead Thickness
Lead Width
Mold Draft Angle Top
Mold Draft Angle Bottom
* Controlling Parameter
§ Significant Characteristic
A
A2
A1
E
E1
D
L
φ
c
B
α
β
MIN
INCHES
NOM
MAX
8
.026
.033
.002
.246
.169
.114
.020
0
.004
.007
0
0
.035
.004
.251
.173
.118
.024
4
.006
.010
5
5
.043
.037
.006
.256
.177
.122
.028
8
.008
.012
10
10
MILLIMETERS*
NOM
MAX
8
0.65
1.10
0.85
0.90
0.95
0.05
0.10
0.15
6.25
6.38
6.50
4.30
4.40
4.50
2.90
3.00
3.10
0.50
0.60
0.70
0
4
8
0.09
0.15
0.20
0.19
0.25
0.30
0
5
10
0
5
10
MIN
Notes:
Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed
.005” (0.127mm) per side.
JEDEC Equivalent: MO-153
Drawing No. C04-086
DS21822C-page 18
Preliminary
 2003 Microchip Technology Inc.
25AA256/25LC256
APPENDIX A:
REVISION HISTORY
Revision C
Corrections to Section 1.0, Electrical Characteristics.
 2003 Microchip Technology Inc.
Preliminary
DS21822C-page 19
25AA256/25LC256
NOTES:
DS21822C-page 20
Preliminary
 2003 Microchip Technology Inc.
25AA256/25LC256
ON-LINE SUPPORT
Microchip provides on-line support on the Microchip
World Wide Web site.
The web site is used by Microchip as a means to make
files and information easily available to customers. To
view the site, the user must have access to the Internet
and a web browser, such as Netscape® or Microsoft®
Internet Explorer. Files are also available for FTP
download from our FTP site.
SYSTEMS INFORMATION AND
UPGRADE HOT LINE
The Systems Information and Upgrade Line provides
system users a listing of the latest versions of all of
Microchip's development systems software products.
Plus, this line provides information on how customers
can receive the most current upgrade kits.The Hot Line
Numbers are:
1-800-755-2345 for U.S. and most of Canada, and
1-480-792-7302 for the rest of the world.
Connecting to the Microchip Internet
Web Site
042003
The Microchip web site is available at the following
URL:
www.microchip.com
The file transfer site is available by using an FTP
service to connect to:
ftp://ftp.microchip.com
The web site and file transfer site provide a variety of
services. Users may download files for the latest
Development Tools, Data Sheets, Application Notes,
User's Guides, Articles and Sample Programs. A
variety of Microchip specific business information is
also available, including listings of Microchip sales
offices, distributors and factory representatives. Other
data available for consideration is:
• Latest Microchip Press Releases
• Technical Support Section with Frequently Asked
Questions
• Design Tips
• Device Errata
• Job Postings
• Microchip Consultant Program Member Listing
• Links to other useful web sites related to
Microchip Products
• Conferences for products, Development Systems,
technical information and more
• Listing of seminars and events
 2003 Microchip Technology Inc.
Preliminary
DS21822C-page 21
25AA256/25LC256
READER RESPONSE
It is our intention to provide you with the best documentation possible to ensure successful use of your Microchip product. If you wish to provide your comments on organization, clarity, subject matter, and ways in which our documentation
can better serve you, please FAX your comments to the Technical Publications Manager at (480) 792-4150.
Please list the following information, and use this outline to provide us with your comments about this document.
To:
Technical Publications Manager
RE:
Reader Response
Total Pages Sent ________
From: Name
Company
Address
City / State / ZIP / Country
Telephone: (_______) _________ - _________
FAX: (______) _________ - _________
Application (optional):
Would you like a reply?
Y
Device: 25AA256/25LC256
N
Literature Number: DS21822C
Questions:
1. What are the best features of this document?
2. How does this document meet your hardware and software development needs?
3. Do you find the organization of this document easy to follow? If not, why?
4. What additions to the document do you think would enhance the structure and subject?
5. What deletions from the document could be made without affecting the overall usefulness?
6. Is there any incorrect or misleading information (what and where)?
7. How would you improve this document?
DS21822C-page 22
Preliminary
 2003 Microchip Technology Inc.
25AA256/25LC256
PRODUCT IDENTIFICATION SYSTEM
To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office.
PART NO.
X
Device
Tape & Reel
–
X
/XX
X
Temp Range
Package
Lead
Finish
Examples:
a)
b)
Device
25AA256
25LC256
256k-bit, 1.8V, 64-Byte Page, SPI Serial EEPROM
256k-bit, 2.5V, 64-Byte Page, SPI Serial EEPROM
Tape & Reel
Blank
T
=
=
Standard packaging (tube)
Tape & Reel
Temperature Range
I
E
=
=
-40°C to+85°C
-40°C to+125°C
Package
MF
P
SN
ST
=
=
=
=
Micro Lead Frame (6 x 5 mm body), 8-lead
Plastic DIP (300 mil body), 8-lead
Plastic SOIC (150 mil body), 8-lead
TSSOP, 8-lead
Lead Finish
Blank
G
=
=
Standard 63% / 37% Sn/Pb
Matte Tin (Pure Sn)
c)
d)
e)
f)
25AA256-I/STG = 256k-bit, 1.8V Serial
EEPROM, Industrial temp., TSSOP package,
Pb-free
25AA256T-I/SN = 256k-bit, 1.8V Serial
EEPROM, Industrial temp., Tape & Reel, SOIC
package
25AA256T-I/ST = 256k-bit, 1.8V Serial
EEPROM, Industrial temp., Tape & Reel,
TSSOP package
25LC256-I/STG = 256k-bit, 2.5V Serial
EEPROM, Industrial temp., TSSOP package,
Pb-free
25LC256-I/P = 256k-bit, 2.5V Serial EEPROM,
Industrial temp., P-DIP package
25LC256T-E/ST = 256k-bit, 2.5V Serial
EEPROM, Extended temp., Tape & Reel,
TSSOP package
Sales and Support
Data Sheets
Products supported by a preliminary Data Sheet may have an errata sheet describing minor operational differences and
recommended workarounds. To determine if an errata sheet exists for a particular device, please contact one of the following:
1.
2.
3.
Your local Microchip sales office
The Microchip Corporate Literature Center U.S. FAX: (480) 792-7277
The Microchip Worldwide Site (www.microchip.com)
Please specify which device, revision of silicon and Data Sheet (include Literature #) you are using.
New Customer Notification System
Register on our web site (www.microchip.com/cn) to receive the most current information on our products.
 2003 Microchip Technology Inc.
Preliminary
DS21822C-page 23
25AA256/25LC256
NOTES:
DS21822C-page 24
Preliminary
 2003 Microchip Technology Inc.
Note the following details of the code protection feature on Microchip devices:
•
Microchip products meet the specification contained in their particular Microchip Data Sheet.
•
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.
Information contained in this publication regarding device
applications and the like is intended through suggestion only
and may be superseded by updates. It is your responsibility to
ensure that your application meets with your specifications.
No representation or warranty is given and no liability is
assumed by Microchip Technology Incorporated with respect
to the accuracy or use of such information, or infringement of
patents or other intellectual property rights arising from such
use or otherwise. Use of Microchip’s products as critical components in life support systems is not authorized except with
express written approval by Microchip. No licenses are conveyed, implicitly or otherwise, under any intellectual property
rights.
Trademarks
The Microchip name and logo, the Microchip logo, Accuron,
dsPIC, KEELOQ, MPLAB, PIC, PICmicro, PICSTART,
PRO MATE and PowerSmart are registered trademarks of
Microchip Technology Incorporated in the U.S.A. and other
countries.
AmpLab, FilterLab, microID, MXDEV, MXLAB, PICMASTER,
SEEVAL and The Embedded Control Solutions Company are
registered trademarks of Microchip Technology Incorporated
in the U.S.A.
Application Maestro, dsPICDEM, dsPICDEM.net, ECAN,
ECONOMONITOR, FanSense, FlexROM, fuzzyLAB,
In-Circuit Serial Programming, ICSP, ICEPIC, microPort,
Migratable Memory, MPASM, MPLIB, MPLINK, MPSIM,
PICkit, PICDEM, PICDEM.net, PowerCal, PowerInfo,
PowerMate, PowerTool, rfLAB, rfPIC, Select Mode,
SmartSensor, SmartShunt, SmartTel and Total Endurance are
trademarks of Microchip Technology Incorporated in the
U.S.A. and other countries.
Serialized Quick Turn Programming (SQTP) is a service mark
of Microchip Technology Incorporated in the U.S.A.
All other trademarks mentioned herein are property of their
respective companies.
© 2003, Microchip Technology Incorporated, Printed in the
U.S.A., All Rights Reserved.
Printed on recycled paper.
Microchip received QS-9000 quality system
certification for its worldwide headquarters,
design and wafer fabrication facilities in
Chandler and Tempe, Arizona in July 1999
and Mountain View, California in March 2002.
The Company’s quality system processes and
procedures are QS-9000 compliant for its
PICmicro® 8-bit MCUs, KEELOQ® code hopping
devices, Serial EEPROMs, microperipherals,
non-volatile memory and analog products. In
addition, Microchip’s quality system for the
design and manufacture of development
systems is ISO 9001 certified.
 2003 Microchip Technology Inc.
Preliminary
DS21822C-page 25
WORLDWIDE SALES AND SERVICE
AMERICAS
ASIA/PACIFIC
Korea
Corporate Office
Australia
2355 West Chandler Blvd.
Chandler, AZ 85224-6199
Tel: 480-792-7200
Fax: 480-792-7277
Technical Support: 480-792-7627
Web Address: http://www.microchip.com
Suite 22, 41 Rawson Street
Epping 2121, NSW
Australia
Tel: 61-2-9868-6733
Fax: 61-2-9868-6755
168-1, Youngbo Bldg. 3 Floor
Samsung-Dong, Kangnam-Ku
Seoul, Korea 135-882
Tel: 82-2-554-7200 Fax: 82-2-558-5932 or
82-2-558-5934
Atlanta
Unit 915
Bei Hai Wan Tai Bldg.
No. 6 Chaoyangmen Beidajie
Beijing, 100027, No. China
Tel: 86-10-85282100
Fax: 86-10-85282104
3780 Mansell Road, Suite 130
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Tel: 770-640-0034
Fax: 770-640-0307
Boston
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Tel: 978-692-3848
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Tel: 630-285-0071
Fax: 630-285-0075
Dallas
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Tel: 972-818-7423
Fax: 972-818-2924
Detroit
Tri-Atria Office Building
32255 Northwestern Highway, Suite 190
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Tel: 248-538-2250
Fax: 248-538-2260
Kokomo
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Tel: 765-864-8360
Fax: 765-864-8387
Los Angeles
China - Beijing
China - Chengdu
Rm. 2401-2402, 24th Floor,
Ming Xing Financial Tower
No. 88 TIDU Street
Chengdu 610016, China
Tel: 86-28-86766200
Fax: 86-28-86766599
China - Fuzhou
Unit 28F, World Trade Plaza
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Tel: 86-591-7503506
Fax: 86-591-7503521
China - Hong Kong SAR
Unit 901-6, Tower 2, Metroplaza
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Fax: 852-2401-3431
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Room 701, Bldg. B
Far East International Plaza
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San Jose
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San Jose, CA 95131
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Fax: 408-436-7955
Rm. B505A, Fullhope Plaza,
No. 12 Hong Kong Central Rd.
Qingdao 266071, China
Tel: 86-532-5027355 Fax: 86-532-5027205
Toronto
India
6285 Northam Drive, Suite 108
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Tel: 905-673-0699
Fax: 905-673-6509
Divyasree Chambers
1 Floor, Wing A (A3/A4)
No. 11, O’Shaugnessey Road
Bangalore, 560 025, India
Tel: 91-80-2290061 Fax: 91-80-2290062
Japan
Benex S-1 6F
3-18-20, Shinyokohama
Kohoku-Ku, Yokohama-shi
Kanagawa, 222-0033, Japan
Tel: 81-45-471- 6166 Fax: 81-45-471-6122
DS21822C-page 26
Preliminary
Singapore
200 Middle Road
#07-02 Prime Centre
Singapore, 188980
Tel: 65-6334-8870 Fax: 65-6334-8850
Taiwan
Kaohsiung Branch
30F - 1 No. 8
Min Chuan 2nd Road
Kaohsiung 806, Taiwan
Tel: 886-7-536-4818
Fax: 886-7-536-4803
Taiwan
Taiwan Branch
11F-3, No. 207
Tung Hua North Road
Taipei, 105, Taiwan
Tel: 886-2-2717-7175 Fax: 886-2-2545-0139
EUROPE
Austria
Durisolstrasse 2
A-4600 Wels
Austria
Tel: 43-7242-2244-399
Fax: 43-7242-2244-393
Denmark
Regus Business Centre
Lautrup hoj 1-3
Ballerup DK-2750 Denmark
Tel: 45-4420-9895 Fax: 45-4420-9910
France
Parc d’Activite du Moulin de Massy
43 Rue du Saule Trapu
Batiment A - ler Etage
91300 Massy, France
Tel: 33-1-69-53-63-20
Fax: 33-1-69-30-90-79
Germany
Steinheilstrasse 10
D-85737 Ismaning, Germany
Tel: 49-89-627-144-0
Fax: 49-89-627-144-44
Italy
Via Quasimodo, 12
20025 Legnano (MI)
Milan, Italy
Tel: 39-0331-742611
Fax: 39-0331-466781
Netherlands
P. A. De Biesbosch 14
NL-5152 SC Drunen, Netherlands
Tel: 31-416-690399
Fax: 31-416-690340
United Kingdom
505 Eskdale Road
Winnersh Triangle
Wokingham
Berkshire, England RG41 5TU
Tel: 44-118-921-5869
Fax: 44-118-921-5820
07/28/03
 2003 Microchip Technology Inc.