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参数资料
| 型号： | 24LC256 |
| 厂商： | Microchip Technology Inc. |
| 英文描述： | 256K I 2 C ⑩ CMOS Serial EEPROM |
| 中文描述： | 256K的I 2 C⑩的CMOS串行EEPROM |
| 文件页数： | 12/12页 |
| 文件大小： | 181K |
| 代理商： | 24LC256 |
1998 Microchip Technology Inc.
DS21203C-page 9
24AA256/24LC256
8.0
READ OPERATION
Read operations are initiated in the same way as write
operations with the exception that the R/W bit of the
control byte is set to one. There are three basic types of
read operations: current address read, random read,
and sequential read.
8.1
Current Address Read
The 24xx256 contains an address counter that
maintains the address of the last word accessed, inter-
nally incremented by one. Therefore, if the previous
read access was to address n (n is any legal address),
the next current address read operation would access
data from address n + 1.
Upon receipt of the control byte with R/W bit set to one,
the 24xx256 issues an acknowledge and transmits the
8-bit data word. The master will not acknowledge the
transfer but does generate a stop condition and the
24xx256 discontinues transmission (Figure 8-1).
FIGURE 8-1:
CURRENT ADDRESS READ
8.2
Random Read
Random read operations allow the master to access
any memory location in a random manner. To perform
this type of read operation, rst the word address must
be set. This is done by sending the word address to the
24xx256 as part of a write operation (R/W bit set to 0).
After the word address is sent, the master generates a
start
condition
following
the
acknowledge. This
terminates the write operation, but not before the inter-
nal address pointer is set. Then, the master issues the
control byte again but with the R/W bit set to a one. The
24xx256 will then issue an acknowledge and transmit
the 8-bit data word. The master will not acknowledge
the transfer but does generate a stop condition which
causes the 24xx256 to discontinue transmission
(Figure 8-2). After a random read command, the
internal address counter will point to the address
location following the one that was just read.
8.3
Sequential Read
Sequential reads are initiated in the same way as a
random read except that after the 24xx256 transmits
the rst data byte, the master issues an acknowledge
as opposed to the stop condition used in a random
read. This acknowledge directs the 24xx256 to transmit
the next sequentially addressed 8-bit word (Figure 8-
3). Following the nal byte transmitted to the master,
the master will NOT generate an acknowledge but will
generate a stop condition. To provide sequential reads,
the 24xx256 contains an internal address pointer which
is incremented by one at the completion of each
operation. This address pointer allows the entire
memory contents to be serially read during one
operation. The internal address pointer will automati-
cally roll over from address 7FFF to address 0000 if the
master acknowledges the byte received from the array
address 7FFF.
FIGURE 8-2:
RANDOM READ
FIGURE 8-3:
SEQUENTIAL READ
BUS ACTIVITY
MASTER
SDA LINE
BUS ACTIVITY
P
S
T
O
P
CONTROL
BYTE
S
T
A
R
T
DATA
A
C
K
N
O
A
C
K
11
00 AA A 1
BYTE
21 0
X
BUS ACTIVITY
MASTER
SDA LINE
BUS ACTIVITY
A
C
K
N
O
A
C
K
A
C
K
A
C
K
A
C
K
S
T
O
P
S
T
A
R
T
CONTROL
BYTE
ADDRESS
HIGH BYTE
ADDRESS
LOW BYTE
CONTROL
BYTE
DATA
BYTE
S
T
A
R
T
X = Don’t Care Bit
S 1010
AAA
0
210
S 1010
AAA
1
210
P
BUS ACTIVITY
MASTER
SDA LINE
BUS ACTIVITY
CONTROL
BYTE
DATA n
DATA n + 1
DATA n + 2
DATA n + X
N
O
A
C
K
A
C
K
A
C
K
A
C
K
A
C
K
S
T
O
P
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相关代理商/技术参数 |
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| 24LC256-E/MF | 功能描述:电可擦除可编程只读存储器 32kx8 - 2.5V RoHS:否 制造商:Atmel 存储容量:2 Kbit 组织:256 B x 8 数据保留:100 yr 最大时钟频率:1000 KHz 最大工作电流:6 uA 工作电源电压:1.7 V to 5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8 |
| 24LC256E/MS | 制造商:Microchip Technology 功能描述:EEPROM Serial-I2C 256K-Bit 32K x 8 3.3V/5V 8-Pin MSOP Tube |
| 24LC256-E/MS | 功能描述:电可擦除可编程只读存储器 32kx8 - 2.5V RoHS:否 制造商:Atmel 存储容量:2 Kbit 组织:256 B x 8 数据保留:100 yr 最大时钟频率:1000 KHz 最大工作电流:6 uA 工作电源电压:1.7 V to 5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8 |
| 24LC256-E/P | 功能描述:电可擦除可编程只读存储器 32kx8 - 2.5V RoHS:否 制造商:Atmel 存储容量:2 Kbit 组织:256 B x 8 数据保留:100 yr 最大时钟频率:1000 KHz 最大工作电流:6 uA 工作电源电压:1.7 V to 5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8 |
| 24LC256-E/SM | 功能描述:电可擦除可编程只读存储器 32kx8 - 2.5V RoHS:否 制造商:Atmel 存储容量:2 Kbit 组织:256 B x 8 数据保留:100 yr 最大时钟频率:1000 KHz 最大工作电流:6 uA 工作电源电压:1.7 V to 5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8 |
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