The M95512-A125 and M95512-A145 are 512-Kbitserial EEPROM Automotive grade
devices operating up to 145°C. They are compliant with the very high level of reliability
defined by the Automotive standard AEC-Q100 grade 0.
The devices are accessed by a simple serial SPI compatible interface running up to 20 MHz.
The memory array is based on advanced true EEPROM technology (Electrically Erasable
PROgrammable Memory). The M95512-A125 and M95512-A145 are byte-alterable
memories (65536 × 8 bits) organized as 512 pages of 128 bytes in which the data integrity is
significantly improved with an embedded Error Correction Code logic.
The M95512-A125 and M95512-A145 offer an additional Identification Page (128 bytes) in
which the ST device identification can be read. This page can also be used to store sensitive
application parameters which can be later permanently locked in read-only mode.
Figure 1.Logic diagram
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M95512-A125 M95512-A145 Description
DV
SS
C
HOLDQ
SV
CC
W
AI01790D
M95xxx
1
2
3
4
8
7
6
5
Figure 2.8-pin package connections
1. See Package mechanical data section for package dimensions and how to identify pin-1.
Table 1.Signal names
Signal nameDescription
CSerial Clock
DSerial data input
QSerial data output
SChip Select
W
Write Protect
HOLD
V
CC
V
SS
Hold
Supply voltage
Ground
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Signal descriptionM95512-A125 M95512-A145
2 Signal description
All input signals must be held high or low (according to voltages of VIH or VIL, as specified in
Ta bl e 1 3 and Ta bl e 1 4 )). These signals are described below.
2.1 Serial Data output (Q)
This output signal is used to transfer data serially out of the device during a Read operation.
Data is shifted out on the falling edge of Serial Clock (C), most significant bit (MSB) first. In
all other cases, the Serial Data output is in high impedance.
2.2 Serial Data input (D)
This input signal is used to transfer data serially into the device. D input receives
instructions, addresses, and the data to be written. Values are latched on the rising edge of
Serial Clock (C), most significant bit (MSB) first.
2.3 Serial Clock (C)
This input signal allows to synchronize the timing of the serial interface. Instructions,
addresses, or data present at Serial Data Input (D) are latched on the rising edge of Serial
Clock (C). Data on Serial Data Output (Q) changes after the falling edge of Serial Clock (C).
2.4 Chip Select (S)
Driving Chip Select (S) low selects the device in order to start communication. Driving Chip
Select (S
state.
) high deselects the device and Serial Data output (Q) enters the high impedance
2.5 Hold (HOLD)
The Hold (HOLD) signal is used to pause any serial communications with the device without
deselecting the device.
2.6 Write Protect (W)
This pin is used to write-protect the Status Register.
2.7 VSS ground
VSS is the reference for all signals, including the VCC supply voltage.
2.8 VCC supply voltage
VCC is the supply voltage pin.
Refer to Section 3.1: Active power and Standby power modes and to Section 5.1: Supply
voltage (VCC).
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M95512-A125 M95512-A145 Operating features
AI01438B
C
MSB
CPHA
D
0
1
CPOL
0
1
Q
C
MSB
3 Operating features
3.1 Active power and Standby power modes
When Chip Select (S) is low, the device is selected and in the Active power mode.
When Chip Select (S
progress, the device then goes in to the Standby power mode, and the device consumption
drops to I
, as specified in Ta bl e 1 3 and Ta bl e 1 4 .
CC1
3.2 SPI modes
The device can be driven by a microcontroller with its SPI peripheral running in either of the
two following modes:
●CPOL=0, CPHA=0
●CPOL=1, CPHA=1
For these two modes, input data is latched in on the rising edge of Serial Clock (C), and
output data is available from the falling edge of Serial Clock (C).
The difference between the two modes, as shown in Figure 3, is the clock polarity when the
bus master is in Stand-by mode and not transferring data:
●C remains at 0 for (CPOL=0, CPHA=0)
●C remains at 1 for (CPOL=1, CPHA=1)
Figure 3.SPI modes supported
) is high, the device is deselected. If a Write cycle is not currently in
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Operating featuresM95512-A125 M95512-A145
(/,$
#
(OLD
CONDITION
#
N
(OLD
CONDITION
-36
3.3 Hold mode
The Hold (HOLD) signal is used to pause any serial communications with the device without
resetting the clocking sequence.
The Hold mode starts when the Hold (HOLD
) signal is driven low and the Serial Clock (C) is
low (as shown in Figure 4). During the Hold mode, the Serial Data output (Q) is high
impedance, and the signals present on Serial Data input (D) and Serial Clock (C) are not
decoded. The Hold mode ends when the Hold (HOLD
Clock (C) is or becomes low.
Figure 4.Hold mode activation
Deselecting the device while it is in Hold mode resets the paused communication.
3.4 Protocol control and data protection
) signal is driven high and the Serial
ONDITIO
3.4.1 Protocol control
The Chip Select (S) input offers a built-in safety feature, as the S input is edge-sensitive as
well as level-sensitive: after power-up, the device is not selected until a falling edge has first
been detected on Chip Select (S
prior to going low, in order to start the first operation.
For Write commands (WRITE, WRSR, WRID, LID) to be accepted and executed:
●the Write Enable Latch (WEL) bit must be set by a Write Enable (WREN) instruction
●a falling edge and a low state on Chip Select (S) during the whole command must be
decoded
●instruction, address and input data must be sent as multiple of eight bits
●the command must include at least one data byte
●Chip Select (S) must be driven high exactly after a data byte boundary
Write command can be discarded at any time by a rising edge on Chip Select (S
a byte boundary.
To execute Read commands (READ, RDSR, RDID, RDLS), the device must decode:
●a falling edge and a low level on Chip Select (S) during the whole command
●instruction and address as multiples of eight bits (bytes)
From this step, data bits are shifted out until the rising edge on Chip Select (S
). This ensures that Chip Select (S) must have been high
) outside of
).
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M95512-A125 M95512-A145 Operating features
3.4.2 Status Register and data protection
The Status Register format is shown in Ta b le 2 and the status and control bits of the Status
Register are as follows:
Table 2.Status Register format
b7 b6b5b4b3b2b1b0
SRWD0 0 0 BP1 BP0 WEL WIP
Status Register Write Protect
Block Protect bits
Write Enable Latch bit
Write In Progress bit
Note:Bits b6, b5, b4 are always read as 0.
WIP bit
The WIP bit (Write In Progress) is a read-only flag that indicates the Ready/Busy state of the
device. When a Write command (WRITE, WRSR, WRID, LID) has been decoded and a
Write cycle (t
the device is ready to decode a new command.
) is in progress, the device is busy and the WIP bit is set to 1. When WIP=0,
W
During a Write cycle, reading continuously the WIP bit allows to detect when the device
becomes ready (WIP=0) to decode a new command.
WEL bit
The WEL bit (Write Enable Latch) bit is a flag that indicates the status of the internal Write
Enable Latch. When WEL is set to 1, the Write instructions (WRITE, WRSR, WRID, LID) are
executed; when WEL is set to 0, any decoded Write instruction is not executed.
The WEL bit is set to 1 with the WREN instruction. The WEL bit is reset to 0 after the
following events:
●Write Disable (WRDI) instruction completion
●Write instructions (WRITE, WRSR, WRID, LID) completion including the write cycle
time t
W
Power-up
●
BP1, BP0 bits
The Block Protect bits (BP1, BP0) are non-volatile. BP1,BP0 bits define the size of the
memory block to be protected against write instructions, as defined in Ta bl e 2 . These bits
are written with the Write Status Register (WRSR) instruction, provided that the Status
Register is not protected (refer to SRWD bit and W input signal).
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Operating featuresM95512-A125 M95512-A145
Table 3.Write-protected block size
Status Register bits
Protected blockProtected array addresses
BP1BP0
00NoneNone
01Upper quarterC000h - FFFFh
10Upper half8000h - FFFFh
11Whole memory0000h - FFFFh plus Identification page
SRWD bit and W input signal
The Status Register Write Disable (SRWD) bit is operated in conjunction with the Write
Protect pin (W
Register, regardless of whether the pin Write Protect (W
When the SRWD bit is written to 1, two cases have to be considered, depending on the
state of the W
●Case 1: if pin W is driven high, it is possible to write the Status Register.
●Case 2: if pin W is driven low, it is not possible to write the Status Register (WRSR is
discarded) and therefore SRWD,BP1,BP0 bits cannot be changed (the size of the
protected memory block defined by BP1,BP0 bits is frozen).
) signal. When the SRWD bit is written to 0, it is possible to write the Status
) is driven high or low.
input pin:
Case 2 can be entered in either sequence:
●Writing SRWD bit to 1 after driving pin W low, or
●Driving pin W low after writing SRWD bit to 1.
The only way to exit Case 2 is to pull pin W
Note: if pin W
is permanently tied high, the Status Register cannot be write-protected.
high.
The protection features of the device are summarized in Tab l e 4 .
Table 4.Protection modes
SRWD bitW signalStatus
0X
11
10Status Register is write-protected.
Status Register is writable.
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