M24512-WDW6TP ,512 Kbit serial I2C bus EEPROMM24512-W M24512-RM24512-DR M24512-DF512-Kbit serial I²C bus EEPROMDatasheet − production data ..
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M24512-WMN6TP ,512 Kbit serial I2C bus EEPROMAbsolute maximum ratings . 23Table 6. Operating conditions (voltage range W) . . . . . . ..
M24512-WMW6 ,512 KBIT SERIAL I²C BUS EEPROMLogic Diagram . . 4Table 2. Signal Names . . 4Power On Reset 4Figure 3. DIP, ..
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M24512-RDW6TP-M24512-RMN6TP-M24512-WDW6TP-M24512-WMN6TP
512Kit Serial I2C bus EEPROM with three Chip Enable Lines
September 2012 Doc ID 16459 Rev 26 1/40
M24512-W M24512-R
M24512-DR M24512-DF512-Kbit serial I²C bus EEPROM
Datasheet − production data
Features Compatible with all I2 C bus modes:
–1 MHz 400 kHz 100 kHz Memory array: 512 Kbit (64 Kbytes) of EEPROM Page size: 128 bytes Additional Write lockable page
(M24512-D order codes) Single supply voltage and high speed: 1 MHz clock from 1.7 V to 5.5V Write: Byte Write within 5 ms Page Write within 5 ms Operating temperature range: from -40 °C up
to +85 °C Random and sequential Read modes Write protect of the whole memory array Enhanced ESD/Latch-Up protection More than 4 million Write cycles More than 200-year data retention Packages: RoHS compliant and halogen-free
(ECOPACK®)
Contents M24512-W M24512-R M24512-DR M24512-DF2/40 Doc ID 16459 Rev 26
Contents Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Signal description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82.1 Serial Clock (SCL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.2 Serial Data (SDA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.3 Chip Enable (E2, E1, E0) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.4 Write Control (WC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.5 VSS (ground) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.6 Supply voltage (VCC ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.6.1 Operating supply voltage VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
2.6.2 Power-up conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.6.3 Device reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.6.4 Power-down conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Memory organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Device operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114.1 Start condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.2 Stop condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.3 Data input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.4 Acknowledge bit (ACK) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.5 Device addressing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145.1 Write operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.1.1 Byte Write . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
5.1.2 Page Write . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
5.1.3 Write Identification Page (M24512-D only) . . . . . . . . . . . . . . . . . . . . . . 17
5.1.4 Lock Identification Page (M24512-D only) . . . . . . . . . . . . . . . . . . . . . . . 17
5.1.5 ECC (Error Correction Code) and Write cycling . . . . . . . . . . . . . . . . . . 18
5.1.6 Minimizing Write delays by polling on ACK . . . . . . . . . . . . . . . . . . . . . . 19
5.2 Read operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
5.2.1 Random Address Read . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
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5.2.2 Current Address Read . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
5.2.3 Sequential Read . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
5.3 Read Identification Page (M24512-D only) . . . . . . . . . . . . . . . . . . . . . . . 21
5.4 Read the lock status (M24512-D only) . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Initial delivery state . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Maximum rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 DC and AC parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Part numbering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
List of tables M24512-W M24512-R M24512-DR M24512-DF
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List of tables
Table 1. Signal names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Table 2. Device select code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Table 3. Most significant address byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Table 4. Least significant address byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Table 5. Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Table 6. Operating conditions (voltage range W) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Table 7. Operating conditions (voltage range R) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Table 8. Operating conditions (voltage range F) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Table 9. AC measurement conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Table 10. Input parameters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Table 11. Cycling performance by groups of four bytes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Table 12. Memory cell data retention . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Table 13. DC characteristics (M24512-W, device grade 6) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Table 14. DC characteristics (M24512-R, M24512-DR, device grade 6) . . . . . . . . . . . . . . . . . . . . . . 27
Table 15. DC characteristics (M24512-DF, device grade 6). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Table 16. 400 kHz AC characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Table 17. 1 MHz AC characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Table 18. TSSOP8 – 8-lead thin shrink small outline, package mechanical data. . . . . . . . . . . . . . . . 33
Table 19. SO8N – 8 lead plastic small outline, 150 mils body width, package data. . . . . . . . . . . . . . 34
Table 20. UFDFPN8 (MLP8) 8-lead ultra thin fine pitch dual flat package no lead
2 x 3 mm, data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Table 21. M24512-DFCS6TP/K, WLCSP 8-bump wafer-level chip scale package mechanical data. 37
Table 22. Ordering information scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Table 23. Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
M24512-W M24512-R M24512-DR M24512-DF List of figures
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List of figures
Figure 1. Logic diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Figure 2. 8-pin package connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Figure 3. WLCSP connections for the M24512-DFCS6TP/K
(top view, marking side, with balls on the underside) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Figure 4. Device select code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Figure 5. Block diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Figure 6. I2 C bus protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Figure 7. Write mode sequences with WC = 0 (data write enabled) . . . . . . . . . . . . . . . . . . . . . . . . . 15
Figure 8. Write mode sequences with WC = 1 (data write inhibited) . . . . . . . . . . . . . . . . . . . . . . . . . 16
Figure 9. Write cycle polling flowchart using ACK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Figure 10. Read mode sequences. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Figure 11. AC measurement I/O waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Figure 12. Maximum Rbus value versus bus parasitic capacitance (Cbus) for
an I2 C bus at maximum frequency fC = 400 kHz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Figure 13. Maximum Rbus value versus bus parasitic capacitance Cbus) for
an I2 C bus at maximum frequency fC = 1MHz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Figure 14. AC waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Figure 15. TSSOP8 – 8-lead thin shrink small outline, package outline . . . . . . . . . . . . . . . . . . . . . . . 33
Figure 16. SO8N – 8 lead plastic small outline, 150 mils body width, package outline . . . . . . . . . . . . 34
Figure 17. UFDFPN8 (MLP8) - 8-lead ultra thin fine pitch dual flat no lead, package outline . . . . . . . 35
Figure 18. M24512-DFCS6TP/K, WLCSP 8-bump wafer-level chip scale package outline . . . . . . . . 36
Description M24512-W M24512-R M24512-DR M24512-DF
6/40 Doc ID 16459 Rev 26
1 Description
The M24512 is a 512-Kbit I2 C-compatible EEPROM (Electrically Erasable PROgrammable
Memory) organized as 64 K × 8 bits.
The M24512-W can operate with a supply voltage from 2.5 V to 5.5 V, the M24512-R and
M24512-DR can operate with a supply voltage from 1.8 V to 5.5 V and the M24512-DF can
operate with a supply voltage from 1.7 V to 5.5V . All these devices operate with a clock
frequency of 1 MHz (or less) over an ambient temperature range of –40°C/ +85 °C.
The M24512-D offers an additional page, named the Identification Page (128 bytes). The
Identification Page can be used to store sensitive application parameters which can be
(later) permanently locked in Read-only mode.
Figure 1. Logic diagram
Figure 2. 8-pin package connections See Section 9: Package mechanical data for package dimensions, and how to identify pin1.
Table 1. Signal names
M24512-W M24512-R M24512-DR M24512-DF Description
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Signal description M24512-W M24512-R M24512-DR M24512-DF
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2 Signal description
2.1 Serial Clock (SCL)
The signal applied on the SCL input is used to strobe the data available on SDA(in) and to
output the data on SDA(out).
2.2 Serial Data (SDA)
SDA is an input/output used to transfer data in or data out of the device. SDA(out) is an open
drain output that may be wire-OR’ed with other open drain or open collector signals on the
bus. A pull-up resistor must be connected from Serial Data (SDA) to VCC (Figure 12
indicates how to calculate the value of the pull-up resistor).
2.3 Chip Enable (E2, E1, E0)
(E2,E1,E0) input signals are used to set the value that is to be looked for on the three least
significant bits (b3, b2, b1) of the 7-bit device select code (see Table 2). These inputs must
be tied to VCC or VSS, as shown in Figure 4. When not connected (left floating), these inputs
are read as low (0).
Figure 4. Device select code
2.4 Write Control (WC)
This input signal is useful for protecting the entire contents of the memory from inadvertent
write operations. Write operations are disabled to the entire memory array when Write
Control (WC) is driven high. Write operations are enabled when Write Control (WC) is either
driven low or left floating.
When Write Control (WC) is driven high, device select and address bytes are
acknowledged, Data bytes are not acknowledged.
2.5 V SS (ground)SS is the reference for the VCC supply voltage.
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2.6 Supply voltage (V CC)
2.6.1 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 Operating conditions
in Section 8: DC and AC parameters). 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 nF to 100 nF) close to the VCC/VSS package pins.
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).
2.6.2 Power-up conditions
The VCC voltage has to rise continuously from 0 V up to the minimum VCC operating voltage
(see Operating conditions in Section 8: DC and AC parameters) and the rise time must not
vary faster than 1 V/µs.
2.6.3 Device reset
In order to prevent inadvertent write operations during power-up, a power-on-reset (POR)
circuit is included.
At power-up, the device does not respond to any instruction until VCC has reached the
internal reset threshold voltage. This threshold is lower than the minimum VCC operating
voltage (see Operating conditions in Section 8: DC and AC parameters). 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 DC voltage within the
specified [VCC(min), VCC(max)] range (see Operating conditions in Section 8: DC and AC
parameters).
In a similar way, during power-down (continuous decrease in VCC), the device must not be
accessed when VCC drops below VCC(min). When VCC drops below the power-on-reset
threshold voltage, the device stops responding to any instruction sent to it.
2.6.4 Power-down conditions
During power-down (continuous decrease in VCC), the device must be in the Standby Power
mode (mode reached after decoding a Stop condition, assuming that there is no internal
write cycle in progress).
Memory organization M24512-W M24512-R M24512-DR M24512-DF
10/40 Doc ID 16459 Rev 26
3 Memory organization
The memory is organized as shown below.
Figure 5. Block diagram
M24512-W M24512-R M24512-DR M24512-DF Device operation
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4 Device operation
The device supports the I2 C protocol. This is summarized in Figure 6. Any device that sends
data on to the bus is defined to be a transmitter, and any device that reads the data to be a
receiver. The device that controls the data transfer is known as the bus master, and the
other as the slave device. A data transfer can only be initiated by the bus master, which will
also provide the serial clock for synchronization. The device is always a slave in all
communications.
2
Device operation M24512-W M24512-R M24512-DR M24512-DF
12/40 Doc ID 16459 Rev 26
4.1 Start condition
Start is identified by a falling edge of Serial Data (SDA) while Serial Clock (SCL) is stable in
the high state. A Start condition must precede any data transfer instruction. The device
continuously monitors (except during a Write cycle) Serial Data (SDA) and Serial Clock
(SCL) for a Start condition.
4.2 Stop condition
Stop is identified by a rising edge of Serial Data (SDA) while Serial Clock (SCL) is stable
and driven high. A Stop condition terminates communication between the device and the
bus master. A Read instruction that is followed by NoAck can be followed by a Stop
condition to force the device into the Standby mode.
A Stop condition at the end of a Write instruction triggers the internal Write cycle.
4.3 Data input
During data input, the device samples Serial Data (SDA) on the rising edge of Serial Clock
(SCL). For correct device operation, Serial Data (SDA) must be stable during the rising edge
of Serial Clock (SCL), and the Serial Data (SDA) signal must change only when Serial Clock
(SCL) is driven low.
4.4 Acknowledge bit (ACK)
The acknowledge bit is used to indicate a successful byte transfer. The bus transmitter,
whether it be bus master or slave device, releases Serial Data (SDA) after sending eight bits
of data. During the 9th clock pulse period, the receiver pulls Serial Data (SDA) low to
acknowledge the receipt of the eight data bits.
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4.5 Device addressing o start communication between the bus master and the slave device, the bus master must
initiate a Start condition. Following this, the bus master sends the device select code, shown
in Table 2(on Serial Data (SDA), most significant bit first).
When the device select code is received, the device only responds if the Chip Enable
Address is the same as the value on the Chip Enable (E2, E1, E0) inputs.
The 8th bit is the Read/Write bit (RW). This bit is set to 1 for Read and 0 for Write operations.
If a match occurs on the device select code, the corresponding device gives an
acknowledgment on Serial Data (SDA) during the 9th bit time. If the device does not match
the device select code, it deselects itself from the bus, and goes into Standby mode.
Table 2. Device select code The most significant bit, b7, is sent first. E0, E1 and E2 are compared with the value read on input pins E0,E1,and E2. For the 5-bump WLCSP package, (E0,E1,E2) inputs are internally connected to (0,0,1)
Instructions M24512-W M24512-R M24512-DR M24512-DF
14/40 Doc ID 16459 Rev 26
5 Instructions
5.1 Write operations
Following a Start condition the bus master sends a device select code with the R/W bit (RW)
reset to 0. The device acknowledges this, as shown in Figure 7, and waits for two address
bytes. The device responds to each address byte with an acknowledge bit, and then waits
for the data byte.
When the bus master generates a Stop condition immediately after a data byte Ack bit (in
the “10th bit” time slot), either at the end of a Byte Write or a Page Write, the internal Write
cycle tW is triggered. A Stop condition at any other time slot does not trigger the internal
Write cycle.
After the Stop condition and the successful completion of an internal Write cycle (tW), the
device internal address counter is automatically incremented to point to the next byte after
the last modified byte.
During the internal Write cycle, Serial Data (SDA) is disabled internally, and the device does
not respond to any requests.
If the Write Control input (WC) is driven High, the Write instruction is not executed and the
accompanying data bytes are not acknowledged, as shown in Figure8.
Table 3. Most significant address byte
Table 4. Least significant address byte
M24512-W M24512-R M24512-DR M24512-DF Instructions
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5.1.1 Byte Write
After the device select code and the address bytes, the bus master sends one data byte. If
the addressed location is Write-protected, by Write Control (WC) being driven high, the
device replies with NoAck, and the location is not modified. If, instead, the addressed
location is not Write-protected, the device replies with Ack. The bus master terminates the
transfer by generating a Stop condition, as shown in Figure7.
Figure 7. Write mode sequences with WC = 0 (data write enabled)
Instructions M24512-W M24512-R M24512-DR M24512-DF
16/40 Doc ID 16459 Rev 26
5.1.2 Page Write
The Page Write mode allows up to 128 bytes to be written in a single Write cycle, provided
that they are all located in the same page in the memory: that is, the most significant
memory address bits, A15/A7, are the same. If more bytes are sent than will fit up to the end
of the page, a “roll-over” occurs, i.e. the bytes exceeding the page end are written on the
same page, from location 0.
The bus master sends from 1 to 128 bytes of data, each of which is acknowledged by the
device if Write Control (WC) is low. If Write Control (WC) is high, the contents of the
addressed memory location are not modified, and each data byte is followed by a NoAck, as
shown in Figure 8. After each transferred byte, the internal page address counter is
incremented.
The transfer is terminated by the bus master generating a Stop condition.
Figure 8. Write mode sequences with WC = 1 (data write inhibited)
M24512-W M24512-R M24512-DR M24512-DF Instructions
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5.1.3 Write Identification Page (M24512-D only)
The Identification Page (128 bytes) is an additional page which can be written and (later)
permanently locked in Read-only mode. It is written by issuing the Write Identification Page
instruction. This instruction uses the same protocol and format as Page Write (into memory
array), except for the following differences: Device type identifier = 1011b MSB address bits A15/A7 are don't care except for address bit A10 which must be ‘0’.
LSB address bits A6/A0 define the byte address inside the Identification page.
If the Identification page is locked, the data bytes transferred during the Write Identification
Page instruction are not acknowledged (NoAck).
5.1.4 Lock Identification Page (M24512-D only)
The Lock Identification Page instruction (Lock ID) permanently locks the Identification page
in Read-only mode. The Lock ID instruction is similar to Byte Write (into memory array) with
the following specific conditions: Device type identifier = 1011b Address bit A10 must be ‘1’; all other address bits are don't care The data byte must be equal to the binary value xxxx xx1x, where x is don't care
Instructions M24512-W M24512-R M24512-DR M24512-DF
18/40 Doc ID 16459 Rev 26
5.1.5 ECC (Error Correction Code) and Write cycling
The Error Correction Code (ECC) is an internal logic function which is transparent for the 2 C communication protocol.
The ECC logic is implemented on each group of four EEPROM bytes(a) . Inside a group, if a
single bit out of the four bytes happens to be erroneous during a Read operation, the ECC
detects this bit and replaces it with the correct value. The read reliability is therefore much
improved.
Even if the ECC function is performed on groups of four bytes, a single byte can be
written/cycled independently. In this case, the ECC function also writes/cycles the three
other bytes located in the same group(a) . As a consequence, the maximum cycling budget is
defined at group level and the cycling can be distributed over the 4 bytes of the group: the
sum of the cycles seen by byte0, byte1, byte2 and byte3 of the same group must remain
below the maximum value defined Table 11: Cycling performance by groups of four bytes. A group of four bytes is located at addresses [4*N, 4*N+1, 4*N+2, 4*N+3], where N is an
integer.
M24512-W M24512-R M24512-DR M24512-DF Instructions
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5.1.6 Minimizing Write delays by polling on ACK
The maximum Write time (tw) is shown in AC characteristics tables in Section 8: DC and AC
parameters, but the typical time is shorter. To make use of this, a polling sequence can be
used by the bus master.
The sequence, as shown in Figure 9, is: Initial condition: a Write cycle is in progress. Step 1: the bus master issues a Start condition followed by a device select code (the
first byte of the new instruction). Step 2: if the device is busy with the internal Write cycle, no Ack will be returned and
the bus master goes back to Step 1. If the device has terminated the internal Write
cycle, it responds with an Ack, indicating that the device is ready to receive the second
part of the instruction (the first byte of this instruction having been sent during Step 1).
Figure 9. Write cycle polling flowchart using ACK The seven most significant bits of the Device Select code of a Random Read (bottom right box in the
figure) must be identical to the seven most significant bits of the Device Select code of the Write (polling
instruction in the figure).
Instructions M24512-W M24512-R M24512-DR M24512-DF
20/40 Doc ID 16459 Rev 26
5.2 Read operations
Read operations are performed independently of the state of the Write Control (WC) signal.
After the successful completion of a Read operation, the device internal address counter is
incremented by one, to point to the next byte address.
For the Read instructions, after each byte read (data out), the device waits for an
acknowledgment (data in) during the 9th bit time. If the bus master does not acknowledge
during this 9th time, the device terminates the data transfer and switches to its Standby
mode.
Figure 10. Read mode sequences
