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参数资料
| 型号： | 24LCS21P |
| 英文描述： | I2C Serial EEPROM |
| 中文描述： | I2C串行EEPROM的 |
| 文件页数： | 12/12页 |
| 文件大小： | 159K |
| 代理商： | 24LCS21P |
1999 Microchip Technology Inc.
DS21127D-page 9
24LCS21
6.0
WRITE PROTECTION
When using the 24LCS21 in the bi-directional Mode,
the VCLK pin operates as the write protect control pin.
Setting VCLK high allows normal write operations,
while setting VCLK low prevents writing to any location
in the array. Connecting the VCLK pin to VSS would
allow the 24LCS21 to operate as a serial ROM,
although this conguration would prevent using the
device in the Transmit-Only Mode.
Additionally, Pin 3 performs a exible write protect
function. The 24LCS21 contains a write-protection
control fuse whose factory default state is cleared.
Writing any data to address 7Fh (normally the
checksum in DDC applications) sets the fuse which
enables the WP pin. Until this fuse is set, the 24LCS21
is always write enabled (if VCLK = 1). After the fuse is
set, the write capability of the 24LCS21 is determined
by WP (Figure 6-1).
FIGURE 6-1: WRITE PROTECT TRUTH
TABLE
7.0
READ OPERATION
Read operations are initiated in the same way as write
operations with the exception that the R/W bit of the
slave address is set to one. There are three basic types
of read operations: current address read, random read
and sequential read.
7.1
Current Address Read
The 24LCS21 contains an address counter that
maintains the address of the last word accessed,
internally incremented by one. Therefore, if the
previous access (either a read or write operation) was
to address n, the next current address read operation
would access data from address n + 1. Upon receipt of
the slave address with R/W bit set to one, the 24LCS21
issues an acknowledge and transmits the eight bit data
word. The master will not acknowledge the transfer but
does generate a stop condition and the 24LCS21
discontinues transmission (Figure 7-1).
FIGURE 7-1: CURRENT ADDRESS READ
7.2
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
24LCS21 as part of a write operation. After the word
address is sent, the master generates a start condition
following the acknowledge. This terminates the write
operation, but not before the internal address pointer is
set. Then the master issues the control byte again but
with the R/W bit set to a one. The 24LCS21 will then
issue an acknowledge and transmits the eight bit data
word. The master will not acknowledge the transfer but
does generate a stop condition and the 24LCS21
discontinues transmission (Figure 7-2).
VCLK
WP
Add. 7Fh
Written
Mode
0
X
Read Only
1
X
No
R/W
1
1/open
Yes
R/W
1
0
Yes
Read Only
CONTROL
A
C
K
S
T
A
R
T
S
T
O
P
BYTE
DATA n
BUS ACTIVITY
SDA LINE
BUS ACTIVITY
A
C
K
N
O
MASTER
101 0000 1
FIGURE 7-2: RANDOM READ
BUS ACTIVITY
MASTER
SDA LINE
BUS ACTIVITY
CONTROL
BYTE
WORD
ADDRESS
DATA n
A
C
K
S
T
A
R
T
N
O
S
T
A
R
CONTROL
BYTE
A
C
K
A
C
K
A
C
K
SS
T
P
S
T
O
P
10 1 0 0 0 00
0
01
1
This Material Copyrighted by Its Respective Manufacturer
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| 24LCS22A-I/P | 功能描述:电可擦除可编程只读存储器 VESA E-EDID 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 |
| 24LCS22A-I/PG | 功能描述:电可擦除可编程只读存储器 VESA E-EDID Lead Free Package 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 |
| 24LCS22A-I/SN | 功能描述:电可擦除可编程只读存储器 VESA E-EDID 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 |
| 24LCS22A-I/SNG | 功能描述:电可擦除可编程只读存储器 VESA E-EDID Lead Free Package 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 |
| 24LCS22AT-I/SN | 功能描述:电可擦除可编程只读存储器 VESA E-EDID 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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