25AA640AT-I/SN Microchip Technology, 25AA640AT-I/SN Datasheet - Page 9

• Manufacturer Part Number: 25AA640AT-I/SN
• Description: 64K, 8K X 8, 1.8V SER EE IND 8 SOIC 3.90mm (.150") T/R
• Manufacturer: Microchip Technology

Specifications of 25AA640AT-I/SN

• Format - Memory: EEPROMs - Serial
• Memory Type: EEPROM
• Memory Size: 64K (8K x 8)
• Speed: 10MHz
• Interface: SPI, 3-Wire Serial
• Voltage - Supply: 1.8 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 25AA640AT-I/SNTR

2.4
The 25XX640A contains a write enable latch. See
Table 2-4 for the Write-Protect Functionality Matrix.
This latch must be set before any write operation will be
completed internally. The WREN instruction will set the
latch and the WRDI will reset the latch.
FIGURE 2-4:
FIGURE 2-5:
© 2008 Microchip Technology Inc.
Write Enable (WREN) and Write
Disable (WRDI)
WRITE ENABLE SEQUENCE (WREN)
WRITE DISABLE SEQUENCE (WRDI)
SCK
CS
SO
SCK
SI
CS
SO
SI
0
0
0
0
0
1
0
1
High-Impedance
0
High-Impedance
0
2
2
0
0
3
3
25AA640A/25LC640A
The following is a list of conditions under which the
write enable latch will be reset:
• Power-up
• WRDI instruction successfully executed
• WRSR instruction successfully executed
• WRITE instruction successfully executed
0
0
4
4
1
5
1
5
1
6
0
6
0
7
0
7
DS21830D-page 9