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參數(shù)資料
| 型號： | 24LC21-IP |
| 廠商： | Microchip Technology Inc. |
| 英文描述： | 1K 2.5V Dual Mode I 2 C Serial EEPROM |
| 中文描述： | 一千2.5V的雙模式的I 2 C串行EEPROM |
| 文件頁數(shù)： | 9/12頁 |
| 文件大?。?/td> | 81K |
| 代理商： | 24LC21-IP |
1996 Microchip Technology Inc.
DS21095F-page 9
24LC21
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 24LC21 contains an address counter that main-
tains 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 24LC21 issues an acknowl-
edge and transmits the eight bit data word. The master
will not acknowledge the transfer but does generate a
stop condition and the 24LC21 discontinues transmis-
sion (Figure 7-1).
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, first the word address must
be set. This is done by sending the word address to the
24LC21 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 24LC21 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 24LC21 discon-
tinues transmission (Figure 7-2).
7.3
Sequential Read
Sequential reads are initiated in the same way as a ran-
dom read except that after the 24LC21 transmits the
first data byte, the master issues an acknowledge as
opposed to a stop condition in a random read. This
directs the 24LC21 to transmit the next sequentially
addressed 8 bit word (see Figure 7-3).
To provide sequential reads the 24LC21 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.
7.4
Noise Protection
The 24LC21 employs a V
CC
threshold detector circuit
which disables the internal erase/write logic if the V
CC
is below 1.5 volts at nominal conditions.
The SCL and SDA inputs have Schmitt trigger and filter
circuits which suppress noise spikes to assure proper
device operation even on a noisy bus.
FIGURE 7-1:
CURRENT ADDRESS READ
FIGURE 7-2:
RANDOM READ
S
P
BUS ACTIVITY
MASTER
SDA LINE
BUS ACTIVITY
S
T
A
R
T
CONTROL
BYTE
DATA n
A
C
K
N
O
A
C
K
S
T
O
P
S
P
S
BUS ACTIVITY
MASTER
SDA LINE
BUS ACTIVITY
S
T
A
R
T
S
T
O
P
CONTROL
BYTE
WORD
ADDRESS (n)
DATA n
A
C
K
A
C
K
N
O
A
C
K
CONTROL
BYTE
A
C
K
S
T
A
R
T
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| 24LC21-ISN | 1K 2.5V Dual Mode I 2 C Serial EEPROM |
| 24LC21 | 1K 2.5V Dual Mode I 2 C Serial EEPROM |
| 24LC21-P | Connector; Leaded Process Compatible:Yes; Peak Reflow Compatible (260 C):Yes |
| 24LC21-SN | 1K 2.5V Dual Mode I 2 C Serial EEPROM |
| 24LC21A | 1K 2.5V Dual Mode I 2 C Serial EEPROM |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| 24LC21T/SN | 功能描述:電可擦除可編程只讀存儲器 2.5V Dual Mode RoHS:否 制造商:Atmel 存儲容量:2 Kbit 組織:256 B x 8 數(shù)據(jù)保留:100 yr 最大時鐘頻率:1000 KHz 最大工作電流:6 uA 工作電源電壓:1.7 V to 5.5 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 |
| 24LC21T-I/SN | 功能描述:電可擦除可編程只讀存儲器 2.5V Dual Mode RoHS:否 制造商:Atmel 存儲容量:2 Kbit 組織:256 B x 8 數(shù)據(jù)保留:100 yr 最大時鐘頻率:1000 KHz 最大工作電流:6 uA 工作電源電壓:1.7 V to 5.5 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 |
| 24LC22A-I/P | 功能描述:電可擦除可編程只讀存儲器 VESA E-EDID RoHS:否 制造商:Atmel 存儲容量:2 Kbit 組織:256 B x 8 數(shù)據(jù)保留:100 yr 最大時鐘頻率:1000 KHz 最大工作電流:6 uA 工作電源電壓:1.7 V to 5.5 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 |
| 24LC22A-I/PG | 功能描述:電可擦除可編程只讀存儲器 VESA E-EDID Lead Free Package RoHS:否 制造商:Atmel 存儲容量:2 Kbit 組織:256 B x 8 數(shù)據(jù)保留:100 yr 最大時鐘頻率:1000 KHz 最大工作電流:6 uA 工作電源電壓:1.7 V to 5.5 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 |
| 24LC22A-I/SN | 功能描述:電可擦除可編程只讀存儲器 VESA E-EDID RoHS:否 制造商:Atmel 存儲容量:2 Kbit 組織:256 B x 8 數(shù)據(jù)保留:100 yr 最大時鐘頻率:1000 KHz 最大工作電流:6 uA 工作電源電壓:1.7 V to 5.5 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 |
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