Not recommended for new designs –
Please use 25AA640A or 25LC640A.
25AA640/25LC640
64K SPI Bus Serial EEPROM
Description:
Device Selection Table
Part
Number
VCC
Range
Max Clock
Frequency
Temp
Ranges
The Microchip Technology Inc. 25AA640/25LC640
(25XX640*) is a 64 Kbit Serial Electrically Erasable
PROM [EEPROM]. The memory is accessed via a
simple Serial Peripheral Interface (SPI) compatible
serial bus. The bus signals required are a clock input
(SCK) plus separate data in (SI) and data out (SO)
lines. Access to the device is controlled through a Chip
Select (CS) input.
25AA640
25LC640
25LC640
1.8-5.5V
2.5-5.5V
4.5-5.5V
1 MHz
2 MHz
I
I
3/2.5 MHz
I, E
Features:
Communication to the device can be paused via the
hold pin (HOLD). While the device is paused,
transitions on its inputs will be ignored, with the
exception of Chip Select, allowing the host to service
higher priority interrupts.
• Low-Power CMOS Technology
- Write current: 3 mA, typical
- Read current: 500 μA, typical
- Standby current: 500 nA, typical
• 8192 x 8 Bit Organization
• 32 Byte Page
Block Diagram
• Write Cycle Time: 5 ms max.
• Self-Timed Erase and Write Cycles
• Block Write Protection
STATUS
HV Generator
Register
- Protect none, 1/4, 1/2 or all of array
• Built-in Write Protection
EEPROM
- Power on/off data protection circuitry
- Write enable latch
Memory
Control
Logic
I/O Control
Logic
Array
XDEC
- Write-protect pin
• Sequential Read
Page
Latches
• High Reliability
- Data retention: > 200 years
- ESD protection: > 4000V
• 8-pin PDIP, SOIC and TSSOP Packages
• Temperature Ranges Supported:
- Industrial (I): -40°C to +85°C
- Automotive (E): -40°C to +125°C
SI
SO
Y Decoder
CS
SCK
Sense Amp.
R/W Control
HOLD
WP
VCC
VSS
Package Types
PDIP/SOIC
TSSOP
VCC
HOLD
SCK
SI
CS
SO
1
2
3
4
8
7
6
5
8
7
6
5
1
2
3
4
SCK
SI
VSS
WP
HOLD
VCC
CS
WP
VSS
SO
*25XX640 is used in this document as a generic part number for the 25AA640/25LC640 devices.
© 2008 Microchip Technology Inc.
DS21223H-page 1