© 2008 Microchip Technology Inc. DS21223H-page 1
25AA640/25LC640
Device Selection Table
Features:
• 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
• Write Cycle Time: 5 ms max.
• Self-Timed Erase and Write Cycles
• Block Write Protection
- Protect none, 1/4, 1/2 or all of array
• Built-in Write Protection
- Power on/off data protection circuitry
- Write enable latch
- Write-protect pin
• Sequential Read
• 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
Description:
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.
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.
Block Diagram
Package Types
Part
Number
VCC
Range
Max Clock
Frequency
Temp
Ranges
25AA640 1.8-5.5V 1 MHz I
25LC640 2.5-5.5V 2 MHz I
25LC640 4.5-5.5V 3/2.5 MHz I, E
SI
SO
SCK
CS
HOLD
WP
I/O Control
Memory
Control
Logic
HV Generator
EEPROM
Array
Page
Y Decoder
Sense Amp.
R/W Control
Logic
VCC
VSS
Latches
XDEC
STATUS
Register
25XX640
25XX640
PDIP/SOIC
TSSOP
CS
SO
WP
VSS
VCC
HOLD
SCK
SI
8
7
6
5
1
2
3
4
8
7
6
5
1
2
3
4
HOLD
VCC
CS
SO
SCK
SI
V
SS
WP
64K SPI Bus Serial EEPROM
*25XX640 is used in this document as a generic part number for the 25AA640/25LC640 devices.
Not recommended for new designs –
Please use 25AA640A or 25LC640A.
