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 M95256 M95256-W M95256-R
256 Kbit serial SPI bus EEPROM with high-speed clock
Features

Compatible with SPI bus serial interface (positive clock SPI modes) Single supply voltage: - 4.5 to 5.5 V for M95256 - 2.5 to 5.5 V for M95256-W - 1.8 to 5.5 V for M95256-R High speed - 5 MHz clock rate, 5 ms write time Status Register Hardware protection of the Status Register Byte and Page Write (up to 64 bytes) Self-timed programming cycle Adjustable size read-only EEPROM area Enhanced ESD protection More than 1 000 000 write cycles More than 40-year data retention Packages - ECOPACK(R) (RoHS compliant) TSSOP8 (DW) 169 mil width SO8 (MW) 200 mil width
SO8 (MN) 150 mil width

March 2008
Rev 8
1/43
www.st.com 1
Contents
M95256, M95256-W, M95256-R
Contents
1 2 3 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Memory organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Signal description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 Serial Data output (Q) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Serial Data input (D) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Serial Clock (C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Chip Select (S) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Hold (HOLD) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Write Protect (W) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 VSS ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Supply voltage (VCC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.8.1 3.8.2 3.8.3 3.8.4 Operating supply voltage VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Power-up conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Device Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Power-down . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4
Operating features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.1 4.2 4.3 Hold condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Data protection and protocol control . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5
Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.1 5.2 5.3 Write Enable (WREN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Write Disable (WRDI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Read Status Register (RDSR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
5.3.1 5.3.2 5.3.3 5.3.4 WIP bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 WEL bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 BP1, BP0 bits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 SRWD bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
5.4 5.5
Write Status Register (WRSR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Read from Memory Array (READ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
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M95256, M95256-W, M95256-R
Contents
5.6
Write to Memory Array (WRITE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
5.6.1 ECC (error correction code) and Write cycling . . . . . . . . . . . . . . . . . . . 23
6 7
Delivery state . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Connecting to the SPI bus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
7.1 SPI modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
8 9 10 11 12
Maximum rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 DC and AC parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Part numbering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
3/43
List of tables
M95256, M95256-W, M95256-R
List of tables
Table 1. Table 2. Table 3. Table 4. Table 5. Table 6. Table 7. Table 8. Table 9. Table 10. Table 11. Table 12. Table 13. Table 14. Table 15. Table 16. Table 17. Table 18. Table 19. Table 20. Table 21. Table 22. Table 23. Table 24. Table 25. Signal names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Write-protected block size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Instruction set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Status Register format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Protection modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Operating conditions (M95256) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Operating conditions (M95256-W) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Operating conditions (M95256-R). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 AC measurement conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Capacitance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 DC characteristics (M95256, device grade 3). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 DC characteristics (M95256-W, device grade 6) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 DC characteristics (M95256-W, device grade 3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 DC characteristics (M95256-R) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 AC characteristics (M95256, device grade 3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 AC characteristics (M95256-W, device grade 6) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 AC characteristics (M95256-W, device grade 3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 AC characteristics (M95256-R). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 SO8N - 8 lead plastic small outline, 150 mils body width, package data . . . . . . . . . . . . . . 36 SO8 wide - 8 lead plastic small outline, 200 mils body width, package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 TSSOP8 - 8 lead thin shrink small outline, package mechanical data. . . . . . . . . . . . . . . . 38 Ordering information scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 Available M95256x products (package, voltage range, temperature grade) . . . . . . . . . . . 40 Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
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M95256, M95256-W, M95256-R
List of figures
List of figures
Figure 1. Figure 2. Figure 3. Figure 4. Figure 5. Figure 6. Figure 7. Figure 8. Figure 9. Figure 10. Figure 11. Figure 12. Figure 13. Figure 14. Figure 15. Figure 16. Figure 17. Figure 18. Figure 19. Figure 20. Logic diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 SO and TSSOP connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Hold condition activation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Write Enable (WREN) sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Write Disable (WRDI) sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Read Status Register (RDSR) sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Write Status Register (WRSR) sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Read from Memory Array (READ) sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Byte Write (WRITE) sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Page Write (WRITE) sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Bus master and memory devices on the SPI bus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 SPI modes supported . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 AC measurement I/O waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Serial input timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Hold timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Output timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 SO8N - 8 lead plastic small outline, 150 mils body width, package outline . . . . . . . . . . . . 36 SO8 wide - 8 lead plastic small outline, 200 mils body width, package outline . . . . . . . . . 37 TSSOP8 - 8 lead thin shrink small outline, package outline . . . . . . . . . . . . . . . . . . . . . . . 38
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Description
M95256, M95256-W, M95256-R
1
Description
The M95256, M95256-W and M95256-R are electrically erasable programmable memory (EEPROM) devices. They are accessed by a high speed SPI-compatible bus. Their memory array is organized as 32768 x 8 bits. The device is accessed by a simple serial interface that is SPI-compatible. The bus signals are C, D and Q, as shown in Table 1 and Figure 1. The device is selected when Chip Select (S) is taken low. Communications with the device can be interrupted using Hold (HOLD). Figure 1. Logic diagram
VCC
D C S W HOLD M95256
Q
VSS
AI12361
Figure 2.
SO and TSSOP connections
M95256 S Q W VSS 1 2 3 4 8 7 6 5 VCC HOLD C D
AI12362
1. See Section 10: Package mechanical data for package dimensions, and how to identify pin-1.
6/43
M95256, M95256-W, M95256-R Table 1. Signal names
Function Serial Clock Serial Data input Serial Data output Chip Select Write Protect Hold Supply voltage Ground Input Input Output Input Input Input
Description
Signal name C D Q S W HOLD VCC VSS
Direction
7/43
Memory organization
M95256, M95256-W, M95256-R
2
Memory organization
The memory is organized as shown in Figure 3. Figure 3.
HOLD W S C D Q Control Logic
Block diagram
High Voltage Generator
I/O Shift Register
Address Register and Counter
Data Register Status Register
Size of the Read only EEPROM area
Y Decoder
1 Page
X Decoder
AI01272C
8/43
M95256, M95256-W, M95256-R
Signal description
3
Signal description
See Figure 1: Logic diagram and Table 1: Signal names, for a brief overview of the signals connected to this device.
3.1
Serial Data output (Q)
This output signal is used to transfer data serially out of the device. Data is shifted out on the falling edge of Serial Clock (C).
3.2
Serial Data input (D)
This input signal is used to transfer data serially into the device. It receives instructions, addresses, and the data to be written. Values are latched on the rising edge of Serial Clock (C).
3.3
Serial Clock (C)
This input signal provides 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).
3.4
Chip Select (S)
When this input signal is high, the device is deselected and Serial Data output (Q) is at high impedance. Unless an internal Write cycle is in progress, the device will be in the Standby Power mode. Driving Chip Select (S) low selects the device, placing it in the Active Power mode. After power-up, a falling edge on Chip Select (S) is required prior to the start of any instruction.
3.5
Hold (HOLD)
The Hold (HOLD) signal is used to pause any serial communications with the device without deselecting the device. During the Hold condition, the Serial Data output (Q) is high impedance, and Serial Data input (D) and Serial Clock (C) are Don't Care. To start the Hold condition, the device must be selected, with Chip Select (S) driven low.
9/43
Signal description
M95256, M95256-W, M95256-R
3.6
Write Protect (W)
The main purpose of this input signal is to freeze the size of the area of memory that is protected against Write instructions (as specified by the values in the BP1 and BP0 bits of the Status Register). This pin must be driven either high or low, and must be stable during all write instructions.
3.7
VSS ground
VSS is the reference for the VCC supply voltage.
3.8
3.8.1
Supply voltage (VCC)
Operating supply voltage VCC
Prior to selecting the memory and issuing instructions to it, a valid and stable VCC voltage within the specified [VCC(min), VCC(max)] range must be applied (see Table 7, Table 8 and Table 9.). This voltage must remain stable and valid until the end of the transmission of the instruction and, for a Write instruction, until the completion of the internal write cycle (tW). In order to secure a stable DC supply voltage, it is recommended to decouple the VCC line with a suitable capacitor (usually of the order of 10 nF to 100 nF) close to the VCC/VSS package pins.
3.8.2
Power-up conditions
When the power supply is turned on, VCC continuously rises from VSS to VCC. During this time, the Chip Select (S) line is not allowed to float but should follow the VCC voltage, it is therefore recommended to connect the S line to VCC via a suitable pull-up resistor (see Figure 12). In addition, the Chip Select (S) input offers a built-in safety feature, as the S input is edgesensitive as well as level-sensitive: after power-up, the device does not become selected until a falling edge has first been detected on Chip Select (S). This ensures that Chip Select (S) must have been high, prior to going low to start the first operation. The VCC rise time must not vary faster than 1 V/s. When VCC passes over the POR threshold, the device is reset and enters the Standby Power mode. However, the device must not be accessed until VCC reaches a valid and stable VCC voltage within the specified [VCC(min), VCC(max)] range.
3.8.3
Device Reset
In order to prevent inadvertent write operations during power-up (continuous rise in VCC), a power on reset (POR) circuit is included. At power-up, the device does not respond to any instruction until VCC has reached the power on reset threshold voltage (this threshold is lower than the minimum VCC operating voltage defined in Table 7, Table 8 and Table 9). When VCC passes over the POR threshold, the device is reset and enters the following state:
Standby Power mode
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M95256, M95256-W, M95256-R

Operating features
deselected (at next power-up, a falling edge is required on Chip Select (S) before any instruction can be started). not in the Hold condition Status register: - - - the Write Enable Latch (WEL) is reset to 0 the Write In Progress (WIP) is reset to 0 the SRWD, BP1 and BP0 bits of the Status Register are non-volatile bits and therefore remain unchanged)
Note:
When VCC passes the power on reset threshold voltage and until it reaches the minimum VCC operating voltage, the memory must not be selected/accessed.
3.8.4
Power-down
During power-down (continuous decrease in VCC below the minimum VCC operating voltage), the device must be:

deselected (Chip Select (S) should be allowed to follow the voltage applied on VCC) in Standby Power mode (there should not be any internal Write cycle in progress).
4
4.1
Operating features
Hold condition
The Hold (HOLD) signal is used to pause any serial communications with the device without resetting the clocking sequence. During the Hold condition, the Serial Data output (Q) is high impedance, and Serial Data input (D) and Serial Clock (C) are Don't Care. To enter the Hold condition, the device must be selected, with Chip Select (S) low. Normally, the device is kept selected, for the whole duration of the Hold condition. Deselecting the device while it is in the Hold condition, has the effect of resetting the state of the device, and this mechanism can be used if it is required to reset any processes that had been in progress. The Hold condition starts when the Hold (HOLD) signal is driven low at the same time as Serial Clock (C) already being low (as shown in Figure 4). The Hold condition ends when the Hold (HOLD) signal is driven high at the same time as Serial Clock (C) already being low. Figure 4 also shows what happens if the rising and falling edges are not timed to coincide with Serial Clock (C) being low.
11/43
Operating features Figure 4. Hold condition activation
M95256, M95256-W, M95256-R
C
HOLD
Hold Condition
Hold Condition
AI02029D
12/43
M95256, M95256-W, M95256-R
Operating features
4.2
Status Register
Figure 3 shows the position of the Status Register in the control logic of the device. The Status Register contains a number of status and control bits that can be read or set (as appropriate) by specific instructions. For a detailed description of the Status Register bits, see Section 5.3: Read Status Register (RDSR).
4.3
Data protection and protocol control
Non-volatile memory devices can be used in environments that are particularly noisy, and within applications that could experience problems if memory bytes are corrupted. Consequently, the device features the following data protection mechanisms:

Write and Write Status Register instructions are checked that they consist of a number of clock pulses that is a multiple of eight, before they are accepted for execution. All instructions that modify data must be preceded by a Write Enable (WREN) instruction to set the Write Enable Latch (WEL) bit. This bit is returned to its reset state by the following events: - - - - Power-up Write Disable (WRDI) instruction completion Write Status Register (WRSR) instruction completion Write (WRITE) instruction completion

The Block Protect (BP1, BP0) bits in the Status Register allow part of the memory to be configured as read-only. The Write Protect (W) signal allows the Block Protect (BP1, BP0) bits of the Status Register to be protected.
For any instruction to be accepted, and executed, Chip Select (S) must be driven high after the rising edge of Serial Clock (C) for the last bit of the instruction, and before the next rising edge of Serial Clock (C). Two points need to be noted in the previous sentence:
The `last bit of the instruction' can be the eighth bit of the instruction code, or the eighth bit of a data byte, depending on the instruction (except for Read Status Register (RDSR) and Read (READ) instructions). The `next rising edge of Serial Clock (C)' might (or might not) be the next bus transaction for some other device on the SPI bus. Write-protected block size
Protected array addresse Protected block BP1 0 0 1 1 BP0 0 1 0 1 none Upper quarter Upper half Whole memory M95256, M95256-W, M95256-R none 6000h - 7FFFh 4000h - 7FFFh 0000h - 7FFFh
Table 2.
Status Register bits
13/43
Instructions
M95256, M95256-W, M95256-R
5
Instructions
Each instruction starts with a single-byte code, as summarized in Table 3. If an invalid instruction is sent (one not contained in Table 3), the device automatically deselects itself. Table 3. Instruction set
Description Write Enable Write Disable Read Status Register Write Status Register Read from Memory Array Write to Memory Array Instruction format 0000 0110 0000 0100 0000 0101 0000 0001 0000 0011 0000 0010
Instruction WREN WRDI RDSR WRSR READ WRITE
5.1
Write Enable (WREN)
The Write Enable Latch (WEL) bit must be set prior to each WRITE and WRSR instruction. The only way to do this is to send a Write Enable instruction to the device. As shown in Figure 5, to send this instruction to the device, Chip Select (S) is driven low, and the bits of the instruction byte are shifted in, on Serial Data input (D). The device then enters a wait state. It waits for a the device to be deselected, by Chip Select (S) being driven high. Figure 5. Write Enable (WREN) sequence
S 0 C Instruction D High Impedance Q
AI02281E
1
2
3
4
5
6
7
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M95256, M95256-W, M95256-R
Instructions
5.2
Write Disable (WRDI)
One way of resetting the Write Enable Latch (WEL) bit is to send a Write Disable instruction to the device. As shown in Figure 6, to send this instruction to the device, Chip Select (S) is driven low, and the bits of the instruction byte are shifted in, on Serial Data input (D). The device then enters a wait state. It waits for a the device to be deselected, by Chip Select (S) being driven high. The Write Enable Latch (WEL) bit, in fact, becomes reset by any of the following events:

Power-up WRDI instruction execution WRSR instruction completion WRITE instruction completion. Write Disable (WRDI) sequence
S 0 C Instruction D High Impedance Q
AI03750D
Figure 6.
1
2
3
4
5
6
7
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Instructions
M95256, M95256-W, M95256-R
5.3
Read Status Register (RDSR)
The Read Status Register (RDSR) instruction allows the Status Register to be read. The Status Register may be read at any time, even while a Write or Write Status Register cycle is in progress. When one of these cycles is in progress, it is recommended to check the Write In Progress (WIP) bit before sending a new instruction to the device. It is also possible to read the Status Register continuously, as shown in Figure 7. The status and control bits of the Status Register are as follows:
5.3.1
WIP bit
The Write In Progress (WIP) bit indicates whether the memory is busy with a Write or Write Status Register cycle. When set to 1, such a cycle is in progress, when reset to 0 no such cycle is in progress.
5.3.2
WEL bit
The Write Enable Latch (WEL) bit indicates the status of the internal Write Enable Latch. When set to 1 the internal Write Enable Latch is set, when set to 0 the internal Write Enable Latch is reset and no Write or Write Status Register instruction is accepted.
5.3.3
BP1, BP0 bits
The Block Protect (BP1, BP0) bits are non-volatile. They define the size of the area to be software protected against Write instructions. These bits are written with the Write Status Register (WRSR) instruction. When one or both of the Block Protect (BP1, BP0) bits is set to 1, the relevant memory area (as defined in Table 4) becomes protected against Write (WRITE) instructions. The Block Protect (BP1, BP0) bits can be written provided that the Hardware Protected mode has not been set.
5.3.4
SRWD bit
The Status Register Write Disable (SRWD) bit is operated in conjunction with the Write Protect (W) signal. The Status Register Write Disable (SRWD) bit and Write Protect (W) signal allow the device to be put in the Hardware Protected mode (when the Status Register Write Disable (SRWD) bit is set to 1, and Write Protect (W) is driven low). In this mode, the non-volatile bits of the Status Register (SRWD, BP1, BP0) become read-only bits and the Write Status Register (WRSR) instruction is no longer accepted for execution. Table 4.
b7 SRWD 0 0 0 BP1 BP0 WEL
Status Register format
b0 WIP
Status Register Write Protect Block Protect Bits Write Enable Latch Bit Write In Progress Bit
16/43
M95256, M95256-W, M95256-R Figure 7.
S 0 C Instruction D Status Register Out High Impedance Q 7 MSB 6 5 4 3 2 1 0 7 MSB 6 5 4 3 2 1 Status Register Out 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Instructions
Read Status Register (RDSR) sequence
0
7
AI02031E
17/43
Instructions
M95256, M95256-W, M95256-R
5.4
Write Status Register (WRSR)
The Write Status Register (WRSR) instruction allows new values to be written to the Status Register. Before it can be accepted, a Write Enable (WREN) instruction must have been previously executed. After the Write Enable (WREN) instruction has been decoded and executed, the Status Register is updated with the Write Enable Latch bit (WEL) set to 1. The Write Status Register (WRSR) instruction is entered by driving Chip Select (S) low, followed by the instruction code and the data byte on Serial Data input (D). The instruction is terminated by driving Chip Select (S) high at a byte boundary of the input data. This event triggers the self-timed write cycle, and continues for a period tW (as specified in Table 16, Table 17, Table 18 and Table 19), at the end of which the Write in Progress (WIP) bit is reset to 0. The Write Status Register (WRSR) instruction has no effect on b6, b5, b4, b1 and b0 of the Status Register. b6, b5 and b4 are always read as 0. Chip Select (S) must be driven high after the rising edge of Serial Clock (C) that latches in the eighth bit of the data byte, and before the next rising edge of Serial Clock (C). Otherwise, the Write Status Register (WRSR) instruction is not executed. While the Write Status Register cycle is in progress, the Status Register may still be read to check the value of the Write In Progress (WIP) bit. The Write In Progress (WIP) bit is 1 during the self-timed Write Status Register cycle tW, and is 0 when it is completed. When the cycle is completed, the Write Enable Latch (WEL) is reset. The Write Status Register (WRSR) instruction allows the user to change the values of the Block Protect (BP1, BP0) bits, to define the size of the area that is to be treated as readonly, as defined in Table 4. The Write Status Register (WRSR) instruction also allows the user to set or reset the Status Register Write Disable (SRWD) bit in accordance with the Write Protect (W) signal. The Status Register Write Disable (SRWD) bit and Write Protect (W) signal can be used to put the device in the Hardware-protected mode (HPM, see Table 5). In this mode, the Write Status Register (WRSR) instruction is not executed. The contents of the SRWD and BP1, BP0 bits are updated after the completion of the Write Status Register (WRSR) instruction, including the tW Write cycle. The instruction sequence is shown in Figure 8.
18/43
M95256, M95256-W, M95256-R Table 5.
W signal 1 0
Instructions
Protection modes
SRWD bit 0 0 Mode Write protection of the Status Register Memory content Protected area(1) Unprotected area(1)
1
1
Status Register is Writable (if the WREN Software instruction has set the Protected WEL bit) (SPM) The values in the BP1 and BP0 bits can be changed
Write-protected
Ready to accept Write instructions
0
1
Status Register is Hardware write Hardware protected Protected Write-protected (HPM) The values in the BP1 and BP0 bits cannot be changed
Ready to accept Write instructions
1. As defined by the values in the Block Protect (BP1, BP0) bits of the Status Register, as shown in Table 5.
The protection features of the device are summarized in Table 2. When the Status Register Write Disable (SRWD) bit of the Status Register is 0 (its initial delivery state), it is possible to write to the Status Register provided that the Write Enable Latch (WEL) bit has previously been set by a Write Enable (WREN) instruction, regardless of the whether Write Protect (W) is driven high or low. When the Status Register Write Disable (SRWD) bit of the Status Register is set to 1, two cases need to be considered, depending on the state of Write Protect (W):
If Write Protect (W) is driven high, it is possible to write to the Status Register provided that the Write Enable Latch (WEL) bit has previously been set by a Write Enable (WREN) instruction. If Write Protect (W) is driven low, it is not possible to write to the Status Register even if the Write Enable Latch (WEL) bit has previously been set by a Write Enable (WREN) instruction. (Attempts to write to the Status Register are rejected, and are not accepted for execution). As a consequence, all the data bytes in the memory area that are software protected (SPM) by the Block Protect (BP1, BP0) bits of the Status Register, are also hardware protected against data modification.
Regardless of the order of the two events, the Hardware Protected Mode (HPM) can be entered:

by setting the Status Register Write Disable (SRWD) bit after driving Write Protect (W) low or by driving Write Protect (W) low after setting the Status Register Write Disable (SRWD) bit.
The only way to exit the Hardware Protected Mode (HPM) once entered is to pull Write Protect (W) high. If Write Protect (W) is permanently tied high, the Hardware Protected Mode (HPM) can never be activated, and only the Software Protected Mode (SPM), using the Block Protect (BP1, BP0) bits of the Status Register, can be used.
19/43
Instructions Figure 8. Write Status Register (WRSR) sequence
M95256, M95256-W, M95256-R
S 0 C Instruction Status Register In 7 High Impedance Q
AI02282D
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15
D
6
5
4
3
2
1
0
MSB
20/43
M95256, M95256-W, M95256-R
Instructions
5.5
Read from Memory Array (READ)
As shown in Figure 9, to send this instruction to the device, Chip Select (S) is first driven low. The bits of the instruction byte and address bytes are then shifted in, on Serial Data input (D). The address is loaded into an internal address register, and the byte of data at that address is shifted out, on Serial Data output (Q). If Chip Select (S) continues to be driven low, the internal address register is automatically incremented, and the byte of data at the new address is shifted out. When the highest address is reached, the address counter rolls over to zero, allowing the Read cycle to be continued indefinitely. The whole memory can, therefore, be read with a single READ instruction. The Read cycle is terminated by driving Chip Select (S) high. The rising edge of the Chip Select (S) signal can occur at any time during the cycle. The first byte addressed can be any byte within any page. The instruction is not accepted, and is not executed, if a Write cycle is currently in progress. Figure 9.
S 0 C Instruction 16-Bit Address 1 2 3 4 5 6 7 8 9 10 20 21 22 23 24 25 26 27 28 29 30 31
Read from Memory Array (READ) sequence
D High Impedance Q
15 14 13 MSB
3
2
1
0 Data Out 1 7 6 5 4 3 2 1 0 Data Out 2 7
MSB
AI01793D
1. The most significant address bit (b15) is Don't Care.
21/43
Instructions
M95256, M95256-W, M95256-R
5.6
Write to Memory Array (WRITE)
As shown in Figure 10, to send this instruction to the device, Chip Select (S) is first driven low. The bits of the instruction byte, address bytes, and at least one data byte are then shifted in, on Serial Data input (D). The instruction is terminated by driving Chip Select (S) high at a byte boundary of the input data. The self-timed Write cycle, triggered by the rising edge of Chip Select (S), continues for a period tWC (as specified in Table 16, Table 17, Table 18 and Table 19.), at the end of which the Write in Progress (WIP) bit is reset to 0. In the case of Figure 10, Chip Select (S) is driven high after the eighth bit of the data byte has been latched in, indicating that the instruction is being used to write a single byte. If, though, Chip Select (S) continues to be driven low, as shown in Figure 11, the next byte of input data is shifted in, so that more than a single byte, starting from the given address towards the end of the same page, can be written in a single internal Write cycle. Each time a new data byte is shifted in, the least significant bits of the internal address counter are incremented. If the number of data bytes sent to the device exceeds the page boundary, the internal address counter rolls over to the beginning of the page, and the previous data there are overwritten with the incoming data. (The page size of these devices is 64 bytes). The instruction is not accepted, and is not executed, under the following conditions:

if the Write Enable Latch (WEL) bit has not been set to 1 (by executing a Write Enable instruction just before) if a Write cycle is already in progress if the device has not been deselected, by Chip Select (S) being driven high, at a byte boundary (after the eighth bit, b0, of the last data byte that has been latched in) if the addressed page is in the region protected by the Block Protect (BP1 and BP0) bits.
Figure 10. Byte Write (WRITE) sequence
S 0 C Instruction 16-Bit Address Data Byte 1 2 3 4 5 6 7 8 9 10 20 21 22 23 24 25 26 27 28 29 30 31
D High Impedance Q
15 14 13
3
2
1
0
7
6
5
4
3
2
1
0
AI01795D
1. The most significant address bit (b15) is Don't Care.
22/43
M95256, M95256-W, M95256-R Figure 11. Page Write (WRITE) sequence
S 0 C Instruction 16-Bit Address Data Byte 1 1 2 3 4 5 6 7 8 9 10
Instructions
20 21 22 23 24 25 26 27 28 29 30 31
D
15 14 13
3
2
1
0
7
6
5
4
3
2
1
0
S 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 C Data Byte 2 Data Byte 3 Data Byte N
D
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
6
5
4
3
2
1
0
AI01796D
1. The most significant address bit (b15) is Don't Care.
5.6.1
ECC (error correction code) and Write cycling
The M95256, M95256-W and M95256-R devices offer an ECC (error correction code) logic which compares each 4-byte word with its associated 6 EEPROM bits of ECC. As a result, if a single bit out of 4 bytes of data happens to be erroneous during a Read operation, the ECC detects it and replaces it by the correct value. The read reliability is therefore much improved by the use of this feature. Note however that even if a single byte has to be written, 4 bytes are internally modified (plus the ECC bits), that is, the addressed byte is cycled together with the three other bytes making up the word. It is therefore recommended to write by word (4 bytes) in order to benefit from the larger amount of Write cycles. The M95256-W6 and M95256-R6 devices are qualified at 1 million (1 000 000) Write cycles, using a cycling routine that writes to the device by multiples of 4-byte words.
23/43
Delivery state
M95256, M95256-W, M95256-R
6
Delivery state
The device is delivered with the memory array set at all 1s (FFh). The Status Register Write Disable (SRWD) and Block Protect (BP1 and BP0) bits are initialized to 0.
7
Connecting to the SPI bus
These devices are fully compatible with the SPI protocol. All instructions, addresses and input data bytes are shifted in to the device, most significant bit first. The Serial Data input (D) is sampled on the first rising edge of the Serial Clock (C) after Chip Select (S) goes low. All output data bytes are shifted out of the device, most significant bit first. The Serial Data output (Q) is latched on the first falling edge of the Serial Clock (C) after the instruction (such as the Read from Memory Array and Read Status Register instructions) have been clocked into the device. Figure 12 shows an example of three memory devices connected to an MCU, on an SPI bus. Only one memory device is selected at a time, so only one memory device drives the Serial Data output (Q) line at a time, the other memory devices are high impedance. Figure 12. Bus master and memory devices on the SPI bus
VSS VCC R SDO SPI Interface with (CPOL, CPHA) = (0, 0) or (1, 1) SDI SCK CQD Bus Master (ST6, ST7, ST9, ST10, Others) R CS3 CS2 CS1 S W HOLD S W HOLD S W HOLD SPI Memory Device VCC VSS R SPI Memory Device CQD VCC VSS R SPI Memory Device CQD VCC VSS
AI12304b
1. The Write Protect (W) and Hold (HOLD) signals should be driven, high or low as appropriate.
The pull-up resistor R (represented in Figure 12) ensures that a device is not selected if the bus master leaves the S line in the high-impedance state. In applications where the bus master might enter a state where all SPI bus inputs/outputs would be in high impedance at the same time (for example, if the bus master is reset during
24/43
M95256, M95256-W, M95256-R
Connecting to the SPI bus
the transmission of an instruction), the clock line (C) must be connected to an external pulldown resistor so that, if all inputs/outputs become high impedance, the C line is pulled low (while the S line is pulled high): this ensures that S and C do not become high at the same time, and so, that the tSHCH requirement is met. The typical value of R is 100 k.
7.1
SPI modes
These devices 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 13, 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 13. SPI modes supported
CPOL CPHA C
0
0
1
1
C
D
MSB
Q
MSB
AI01438B
25/43
Maximum rating
M95256, M95256-W, M95256-R
8
Maximum rating
Stressing the device outside the ratings listed in Table 6 may cause permanent damage to the device. These are stress ratings only, and operation of the device at these, or any other conditions outside those indicated in the operating sections of this specification, is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Refer also to the STMicroelectronics SURE Program and other relevant quality documents. Table 6.
Symbol TA TSTG TLEAD VO VI VCC VESD
Absolute maximum ratings
Parameter Ambient operating temperature Storage temperature Lead temperature during soldering Output voltage Input voltage Supply voltage Electrostatic discharge voltage (human body model)(2) Min. -40 -65 Max. 130 150
(1)
Unit C C
see note -0.50 -0.50 -0.50 -4000
VCC+0.6 6.5 6.5 4000
(R)
V V V V
1. Compliant with JEDEC Std J-STD-020C (for small body, Sn-Pb or Pb assembly), the ST ECOPACK 7191395 specification, and the European directive on Restrictions on Hazardous Substances (RoHS) 2002/95/EU. 2. AEC-Q100-002 (compliant with JEDEC Std JESD22-A114, C1 = 100 pF, R1 = 1500 , R2 = 500 ).
26/43
M95256, M95256-W, M95256-R
DC and AC parameters
9
DC and AC parameters
This section summarizes the operating and measurement conditions, and the DC and AC characteristics of the device. The parameters in the DC and AC characteristic tables that follow are derived from tests performed under the measurement conditions summarized in the relevant tables. Designers should check that the operating conditions in their circuit match the measurement conditions when relying on the quoted parameters. Table 7.
Symbol VCC TA Supply voltage Ambient operating temperature (device grade 3)
Operating conditions (M95256)(1)
Parameter Min. 4.5 -40 Max. 5.5 125 Unit V C
1. The 5V M95256 part is offered in "V" process (F6DP26%) only.
Table 8.
Symbol VCC TA
Operating conditions (M95256-W)
Parameter Supply voltage Ambient operating temperature (device grade 6) Ambient operating temperature (device grade 3)
(1)
Min. 2.5 -40 -40
Max. 5.5 85 125
Unit V C C
1. This product is under development. For more information, please contact your nearest ST sales office.
Table 9.
Symbol VCC TA
Operating conditions (M95256-R)
Parameter Supply voltage Ambient operating temperature Min. (1) 1.8 -40 Max. (1) 5.5 85 Unit V C
1. This product is under development. For more information, please contact your nearest ST sales office.
Table 10.
Symbol CL
AC measurement conditions(1)
Parameter Load capacitance Input rise and fall times Input pulse voltages Input and output timing reference voltages Min. 100 50 0.2VCC to 0.8VCC 0.3VCC to 0.7VCC Max. Unit pF ns V V
1. Output Hi-Z is defined as the point where data out is no longer driven.
Figure 14. AC measurement I/O waveform
Input Levels 0.8VCC Input and Output Timing Reference Levels 0.7VCC 0.3VCC
AI00825B
0.2VCC
27/43
DC and AC parameters Table 11.
Symbol COUT CIN
M95256, M95256-W, M95256-R Capacitance(1)
Parameter Test condition VOUT = 0 V VIN = 0 V VIN = 0 V Min. 8 8 6 Max. pF pF pF Unit
Output capacitance (Q) Input capacitance (D) Input capacitance (other pins)
1. Sampled only, not 100% tested, at TA = 25 C and a frequency of 5 MHz.
Table 12.
Symbol ILI ILO ICC ICC1 VIL VIH VOL(1) VOH(1)
DC characteristics (M95256, device grade 3)
Parameter Input leakage current Output leakage current Supply current Supply current (Standby Power mode) Input low voltage Input high voltage Output low voltage Output high voltage IOL = 2 mA, VCC = 5 V IOH = -2 mA, VCC = 5 V 0.8 VCC Test condition VIN = VSS or VCC S = VCC, VOUT = VSS or VCC C = 0.1VCC/0.9VCC at 5 MHz, VCC = 5 V, Q = open S = VCC, VCC = 5 V, VIN = VSS or VCC -0.45 0.7 VCC Min. Max. 2 2 4 5 0.3 VCC VCC+1 0.4 Unit A A mA A V V V V
1. For all 5V range devices, the device meets the output requirements for both TTL and CMOS standards.
Table 13.
Symbol ILI ILO
DC characteristics (M95256-W, device grade 6)
Parameter Input leakage current Output leakage current Test condition VIN = VSS or VCC S = VCC, VOUT = VSS or VCC C = 0.1VCC/0.9VCC at 5 MHz, VCC = 2.5 V, Q = open C = 0.1VCC/0.9VCC at 5 MHz, VCC = 5V, Q = open Supply current (Write) Supply current (Standby Power mode) Input low voltage Input high voltage Output low voltage Output high voltage VCC = 2.5 V and IOL = 1.5 mA or VCC = 5 V and IOL = 2 mA VCC = 2.5 V and IOH = -0.4 mA or 0.8 VCC VCC = 5 V and IOH = -2 mA During tW, S = VCC, 2.5 V < VCC < 5.5 V S = VCC, VIN = VSS or VCC, 2.5 V < VCC < 5.5 V -0.45 0.7 VCC Min. Max. 2 2 3 5 5 5 0.3 VCC VCC+1 0.4 Unit A A mA mA mA A V V V V
ICC
Supply current (Read)
ICC0(1) ICC1 VIL VIH VOL VOH
1. Characterized value, not tested in production.
28/43
M95256, M95256-W, M95256-R Table 14.
Symbol ILI ILO ICC ICC0(1) ICC1 VIL VIH VOL VOH
DC and AC parameters
DC characteristics (M95256-W, device grade 3)
Parameter Input leakage current Output leakage current Supply current (Read) Supply current (Write) Supply current (Standby Power mode) Input low voltage Input high voltage Output low voltage Output high voltage IOL = 1.5 mA, VCC = 2.5 V IOH = -0.4 mA, VCC = 2.5 V 0.8 VCC Test condition VIN = VSS or VCC S = VCC, VOUT = VSS or VCC C = 0.1VCC/0.9VCC at 5 MHz, VCC = 2.5 V, Q = open During tW, S = VCC, 2.5 V < VCC < 5.5 V S = VCC, VIN = VSS or VCC 2.5 V < VCC < 5.5 V, -0.45 0.7 VCC Min. Max. 2 2 3 6 5 0.3 VCC VCC+1 0.4 Unit A A mA mA A V V V V
1. Characterized value, not tested in production.
Table 15.
Symbol ILI ILO ICC ICC0(2) ICC1 VIL
DC characteristics (M95256-R)
Parameter Input leakage current Output leakage current Supply current (Read) Supply current (Write) Supply current (Standby Power mode) Input low voltage Test condition VIN = VSS or VCC S = VCC, VOUT = VSS or VCC C = 0.1VCC/0.9VCC at 2 MHz, VCC = 1.8 V, Q = open During tW, S = VCC, 1.8 V < VCC < 2.5 V S = VCC, VIN = VSS or VCC, 1.8 V < VCC < 2.5 V 1.8 V VCC < 2.5 V 2.5 V VCC < 5.5 V 1.8 V VCC < 2.5 V 2.5 V VCC < 5.5 V IOL = 0.15 mA, VCC = 1.8 V IOH = -0.1 mA, VCC = 1.8 V 0.8 VCC -0.45 -0.45 0.75 VCC 0.7 VCC Min Max 2 2 1 (1) 3 3(1) 0.25 VCC 0.3 VCC VCC+1 VCC+1 0.3 Unit A A mA mA A V V V V V V
VIH VOL VOH
Input high voltage Output low voltage Output high voltage
1. This is preliminary data. 2. Characterized value, not tested in production.
29/43
DC and AC parameters Table 16.
M95256, M95256-W, M95256-R AC characteristics (M95256, device grade 3)
Test conditions specified in Table 10 and Table 7
Symbol fC tSLCH tSHCH tSHSL tCHSH tCHSL tCH (1) tCL
(1) (2) (2)
Alt. fSCK tCSS1 tCSS2 tCS tCSH Clock frequency S active setup time
Parameter
Min. D.C. 90 90 100 90 90 90 90
Max. 5
Unit MHz ns ns ns ns ns ns ns
S not active setup time S deselect time S active hold time S not active hold time
tCLH tCLL tRC tFC tDSU tDH
Clock high time Clock low time Clock rise time Clock fall time Data in setup time Data in hold time Clock low hold time after HOLD not active Clock low hold time after HOLD active Clock low setup time before HOLD active Clock low setup time before HOLD not active
tCLCH tCHCL
1 1 20 30 70 40 0 0 100 60 0 50 50 50 100 5
s s ns ns ns ns ns ns ns ns ns ns ns ns ns ms
tDVCH tCHDX tHHCH tHLCH tCLHL tCLHH tSHQZ
(2)
tDIS tV tHO tRO tFO tLZ tHZ tWC
Output disable time Clock low to output valid Output hold time Output rise time Output fall time HOLD high to output valid HOLD low to output High-Z Write time
tCLQV tCLQX tQLQH tQHQL
(2) (2)
tHHQV tHLQZ (2) tW
1. tCH + tCL must never be less than the shortest possible clock period, 1 / fC(max) 2. Value guaranteed by characterization, not 100% tested in production.
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M95256, M95256-W, M95256-R Table 17. AC characteristics (M95256-W, device grade 6)
DC and AC parameters
Test conditions specified in Table 10 and Table 8 Symbol fC tSLCH tSHCH tSHSL tCHSH tCHSL tCH (1) tCL
(1) (2) (2)
Alt. fSCK tCSS1 tCSS2 tCS tCSH Clock frequency S active setup time
Parameter
Min. D.C. 90 90 100 90 90 90 90
Max. 5
Unit MHz ns ns ns ns ns ns ns
S not active setup time S deselect time S active hold time S not active hold time
tCLH tCLL tRC tFC tDSU tDH
Clock high time Clock low time Clock rise time Clock fall time Data in setup time Data in hold time Clock low hold time after HOLD not active Clock low hold time after HOLD active Clock low setup time before HOLD active Clock low setup time before HOLD not active
tCLCH tCHCL
1 1 20 30 70 40 0 0 100 60 0 50 50 50 100 5
s s ns ns ns ns ns ns ns ns ns ns ns ns ns ms
tDVCH tCHDX tHHCH tHLCH tCLHL tCLHH tSHQZ
(2)
tDIS tV tHO tRO tFO tLZ tHZ tWC
Output disable time Clock low to output valid Output hold time Output rise time Output fall time HOLD high to output valid HOLD low to output High-Z Write time
tCLQV tCLQX tQLQH tQHQL
(2) (2)
tHHQV tHLQZ (2) tW
1. tCH + tCL must never be less than the shortest possible clock period, 1 / fC(max) 2. Value guaranteed by characterization, not 100% tested in production.
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DC and AC parameters Table 18.
M95256, M95256-W, M95256-R AC characteristics (M95256-W, device grade 3)
Test conditions specified in Table 10 and Table 8
Symbol fC tSLCH tSHCH tSHSL tCHSH tCHSL tCH (1) tCL
(1) (2) (2)
Alt. fSCK tCSS1 tCSS2 tCS tCSH Clock frequency S active setup time
Parameter
Min. D.C. 90 90 100 90 90 90 90
Max. 5
Unit MHz ns ns ns ns ns ns ns
S not active setup time S deselect time S active hold time S not active hold time
tCLH tCLL tRC tFC tDSU tDH
Clock high time Clock low time Clock rise time Clock fall time Data in setup time Data in hold time Clock low hold time after HOLD not active Clock low hold time after HOLD active Clock low setup time before HOLD active Clock low setup time before HOLD not active
tCLCH tCHCL
1 1 20 30 70 40 0 0 100 60 0 50 50 50 100 5
s s ns ns ns ns ns ns ns ns ns ns ns ns ns ms
tDVCH tCHDX tHHCH tHLCH tCLHL tCLHH tSHQZ
(2)
tDIS tV tHO tRO tFO tLZ tHZ tWC
Output disable time Clock low to output valid Output hold time Output rise time Output fall time HOLD high to output valid HOLD low to output High-Z Write time
tCLQV tCLQX tQLQH tQHQL
(2) (2)
tHHQV tHLQZ (2) tW
1. tCH + tCL must never be less than the shortest possible clock period, 1 / fC(max) 2. Value guaranteed by characterization, not 100% tested in production.
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M95256, M95256-W, M95256-R Table 19. AC characteristics (M95256-R)
DC and AC parameters
Test conditions specified in Table 10 and Table 9 Symbol fC tSLCH tSHCH tSHSL tCHSH tCHSL tCH (1) tCL
(1) (2) (2)
Alt. fSCK tCSS1 tCSS2 tCS tCSH Clock frequency
Parameter
Min. D.C. 200 200 200 200 200 200 200
Max. 2
Unit MHz ns ns ns ns ns ns ns
S active setup time S not active setup time S deselect time S active hold time S not active hold time
tCLH tCLL tRC tFC tDSU tDH
Clock high time Clock low time Clock rise time Clock fall time Data in setup time Data in hold time Clock low hold time after HOLD not active Clock low hold time after HOLD active Clock low setup time before HOLD active Clock low setup time before HOLD not active
tCLCH tCHCL
1 1 40 50 140 90 0 0 250 150 0 100 100 100 250 5
s s ns ns ns ns ns ns ns ns ns ns ns ns ns ms
tDVCH tCHDX tHHCH tHLCH tCLHL tCLHH tSHQZ
(2)
tDIS tV tHO tRO tFO tLZ tHZ tWC
Output disable time Clock low to output valid Output hold time Output rise time Output fall time HOLD high to output valid HOLD low to output High-Z Write time
tCLQV tCLQX tQLQH tQHQL
(2) (2)
tHHQV tHLQZ (2) tW
1. tCH + tCL must never be less than the shortest possible clock period, 1 / fC(max) 2. Value guaranteed by characterization, not 100% tested in production.
33/43
DC and AC parameters Figure 15. Serial input timing
M95256, M95256-W, M95256-R
tSHSL S tCHSL C tDVCH tCHDX D MSB IN tCLCH LSB IN tCHCL tSLCH tCHSH tSHCH
Q
High Impedance
AI01447C
Figure 16. Hold timing
S tHLCH tCLHL C tCLHH tHLQZ Q tHHQV tHHCH
D
HOLD
AI01448B
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M95256, M95256-W, M95256-R Figure 17. Output timing
S tCH C tCLQV tCLQX Q tQLQH tQHQL D
ADDR.LSB IN
DC and AC parameters
tCLQV tCLQX
tCL
tSHQZ
LSB OUT
AI01449e
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Package mechanical data
M95256, M95256-W, M95256-R
10
Package mechanical data
In order to meet environmental requirements, ST offers the M95256 in ECOPACK(R) packages. These packages have a lead-free second level interconnect. The category of second level interconnect is marked on the package and on the inner box label, in compliance with JEDEC Standard JESD97. The maximum ratings related to soldering conditions are also marked on the inner box label. ECOPACK is an ST trademark. ECOPACK specifications are available at www.st.com. Figure 18. SO8N - 8 lead plastic small outline, 150 mils body width, package outline
h x 45 A2 b e 0.25 mm GAUGE PLANE k
8
A ccc c
D
E1
1
E A1 L L1
SO-A
1. Drawing is not to scale.
Table 20.
Symbol
SO8N - 8 lead plastic small outline, 150 mils body width, package data
millimeters Typ Min Max 1.75 0.1 1.25 0.28 0.17 0.48 0.23 0.1 4.9 6 3.9 1.27 4.8 5.8 3.8 0.25 0 0.4 1.04 5 6.2 4 0.5 8 1.27 0.0409 0.1929 0.2362 0.1535 0.05 0.189 0.2283 0.1496 0.0098 0 0.0157 0.25 0.0039 0.0492 0.011 0.0067 0.0189 0.0091 0.0039 0.1969 0.2441 0.1575 0.0197 8 0.05 Typ inches(1) Min Max 0.0689 0.0098
A A1 A2 b c ccc D E E1 e h k L L1
1. Values in inches are converted from mm and rounded to 4 decimal digits.
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M95256, M95256-W, M95256-R
Package mechanical data
Figure 19. SO8 wide - 8 lead plastic small outline, 200 mils body width, package outline
A2 b e D
A c CP
N
E E1
1
A1
k
L
6L_ME
1. Drawing is not to scale.
Table 21.
SO8 wide - 8 lead plastic small outline, 200 mils body width, package mechanical data
millimeters inches(1) Max 2.5 0 1.51 0.4 0.2 0.35 0.1 0.25 2 0.51 0.35 0.1 6.05 5.02 7.62 1.27 0 0.5 8 6.22 8.89 10 0.8 0.05 0.1976 0.3 0 0.0197 8 0.0157 0.0079 0 0.0594 0.0138 0.0039 Typ Min Max 0.0984 0.0098 0.0787 0.0201 0.0138 0.0039 0.2382 0.2449 0.35 10 0.0315
Symbol Typ A A1 A2 b c CP D E E1 e k L N Min
1. Values in inches are converted from mm and rounded to 4 decimal digits.
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Package mechanical data
M95256, M95256-W, M95256-R
Figure 20. TSSOP8 - 8 lead thin shrink small outline, package outline
D
8
5
c
E1 E
1
4
A1 A CP b e A2
L L1
TSSOP8AM
1. Drawing is not to scale.
Table 22.
Symbol
TSSOP8 - 8 lead thin shrink small outline, package mechanical data
millimeters Typ Min Max 1.200 0.050 1.000 0.800 0.190 0.090 0.150 1.050 0.300 0.200 0.100 3.000 0.650 6.400 4.400 0.600 1.000 0 8 8 2.900 - 6.200 4.300 0.450 3.100 - 6.600 4.500 0.750 0.1181 0.0256 0.2520 0.1732 0.0236 0.0394 0 8 8 0.1142 - 0.2441 0.1693 0.0177 0.0394 0.0020 0.0315 0.0075 0.0035 Typ inches(1) Min Max 0.0472 0.0059 0.0413 0.0118 0.0079 0.0039 0.1220 - 0.2598 0.1772 0.0295
A A1 A2 b c CP D e E E1 L L1 N
1. Values in inches are converted from mm and rounded to 4 decimal digits.
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M95256, M95256-W, M95256-R
Part numbering
11
Part numbering
Table 23.
Example: Device type M95 = SPI serial access EEPROM Device function 256 = 256 Kbit (32768 x 8) Operating voltage blank = VCC = 4.5 to 5.5 V W = VCC = 2.5 to 5.5 V R = VCC = 1.8 to 5.5 V Package MN = SO8 (150 mils width) MW = SO8 (200 mils width) DW = TSSOP8 (169 mils width) Device grade 6 = Industrial temperature range, -40 to 85 C. Device tested with standard test flow 3 = Device tested with High Reliability Certified Flow(1) Automotive temperature range (-40 to 125 C) Option blank = Standard packing T = Tape and reel packing Plating technology P or G = ECOPACK(R) (RoHs compliant) Process A or AB = F8L(2)
1. ST strongly recommends the use of the Automotive Grade devices for use in an automotive environment. The High Reliability Certified Flow (HRCF) is described in the quality note QNEE9801. Please ask your nearest ST sales office for a copy. 2. Used only for device grade 3.
Ordering information scheme
M95256 - W MN 6 T P /A
For a list of available options (speed, package, etc.) or for further information on any aspect of this device, please contact your nearest ST Sales Office. The category of second-level interconnect is marked on the package and on the inner box label, in compliance with JEDEC Standard JESD97. The maximum ratings related to soldering conditions are also marked on the inner box label.
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Part numbering Table 24.
M95256, M95256-W, M95256-R Available M95256x products (package, voltage range, temperature grade)
M95256 (4.5 V to 5.5 V) Range 3 M95256-W (2.5 V to 5.5 V) Range 6, Range 3 Range 6 Range 6, Range 3 M95256-R (1.8 V to 5.5 V) Range 6 Range 6
Package SO8N (MN) SO8W (MW) TSSOP (DW)
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M95256, M95256-W, M95256-R
Revision history
12
Revision history
Table 25.
Date 17-Nov-1999 07-Feb-2000 22-Feb-2000 15-Mar-2000 29-Jan-2001
Document revision history
Revision 2.1 2.2 2.3 2.4 2.5 Changes New -V voltage range added (including the tables for DC characteristics, AC characteristics, and ordering information). New -V voltage range extended to M95256 (including AC characteristics, and ordering information). tCLCH and tCHCL, for the M95xxx-V, changed from 1s to 100ns -V voltage range changed to 2.7-3.6V Lead Soldering Temperature in the Absolute Maximum Ratings table amended Illustrations and Package Mechanical data updated Correction to header of Table 12B TSSOP14 Illustrations and Package Mechanical data updated Document promoted from Preliminary Data to Full Data Sheet Announcement made of planned upgrade to 10 MHz clock for the 5V, -40 to 85C, range. M95128 split off to its own datasheet. Data added for new and forthcoming products, including availability of the SO8 narrow package. Omission of SO8 narrow package mechanical data remedied -V voltage range removed Table of contents, and Pb-free options added. -S voltage range extended to -R. VIL(min) improved to -0.45V Absolute Maximum Ratings for VIO(min) and VCC(min) changed. Soldering temperature information clarified for RoHS compliant devices. Device grade information clarified M95128 datasheet merged back in. Product List summary table added. AEC-Q100-002 compliance. Device Grade information clarified. tHHQX corrected to tHHQV. 10MHz product becomes standard M95128 part numbers removed from document. PDIP8 package removed. ECC (error correction code) and Write cycling paragraph added. Section 3.8: Supply voltage (VCC) added and information removed below Section 4: Operating features. Power up state removed below Section 6: Delivery state. Figure 13: SPI modes supported modified and Note 2 added. Note 1 added to Table 7. ICC1 specified over the whole VCC range and ICC0 added in Table 13, Table 14 and Table 15. ICC specified over the whole VCC range in Table 13. Table 17: AC Characteristics (M95256, Device Grade 6) added. tCHHL and tCHHH replaced by tCLHL and tCLHH, respectively. Figure 16: Hold timing modified. Process added to Table 23: Ordering information scheme. Note 1 added to Table 23. Note 1 removed from Table 19: AC characteristics (M95256-R). TA added to Table 6: Absolute maximum ratings. Order of sections modified.
12-Jun-2001
2.6
08-Feb-2002 09-Aug-2002 24-Feb-2003 26-Jun-2003 21-Nov-2003
2.7 2.8 2.9 2.10 3.0
17-Mar-2004
4.0
21-Oct-2004
5.0
13-Apr-2006
6
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Revision history Table 25.
Date
M95256, M95256-W, M95256-R Document revision history (continued)
Revision Changes M95256 with device grade 6 temperature range removed. Section 3.7: VSS ground added, Section 3.8: Supply voltage (VCC) modified. Small text changes. Section 5.4: Write Status Register (WRSR), Section 5.5: Read from Memory Array (READ) and Section 5.6.1: ECC (error correction code) and Write cycling updated. Note 2 below Figure 12: Bus master and memory devices on the SPI bus removed, replaced by explanatory paragraph. TLEAD added to Table 6: Absolute maximum ratings. Test conditions modified for ICC0 and ICC1, and VIH min modified in Table 16: AC characteristics (M95256, device grade 3). tW modified and "preliminary data" note removed in Table 19: AC characteristics (M95256-R). Blank option removed below Plating technology, process A modified and process V removed in Table 23: Ordering information scheme. Table 24: Available M95256x products (package, voltage range, temperature grade) added. SO8N and SO8W package specifications updated (see Section 10: Package mechanical data). Package mechanical data: inches calculated from mm and rounded to 3 decimal digits. Section 3.8: Supply voltage (VCC) modified. Small text changes. Frequency corrected on page 1. VIL and VIH modified in Table 15: DC characteristics (M95256-R). AB Process added to Table 23: Ordering information scheme.
15-Oct-2007
7
27-Mar-2008
8
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M95256, M95256-W, M95256-R
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