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1997 Microchip Technology Inc.

Preliminary

DS21223A-page 1
M

25AA640/25LC640/25C640

DEVICE SELECTION TABLE
FEATURES

• Low power CMOS technology
- Write current: 3 mA typical
- Read current: 500

m

A typical
- Standby current: 500 nA typical
• 8192 x 8 bit organization
• 32 byte page
• Write cycle time: 5ms 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
- Endurance: 1M cycles (guaranteed)
- Data retention: > 200 years
- ESD protection: > 4000 V
• 8-pin PDIP, SOIC, and TSSOP packages
• Temperature ranges supported:

DESCRIPTION

The Microchip Technology Inc. 25AA640/25LC640/
25C640 (25xx640

*

) is a 64K bit serial Electrically Eras-
able PROM. 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, transi-
tions on its inputs will be ignored, with the exception of
chip select, allowing the host to service higher priority
interrupts.

PACKAGE TYPES
BLOCK DIAGRAM

Part
Number
V

CC

Range
Max Clock
Frequency
Temp
Ranges

25AA640 1.8-5.5V 1 MHz C,I
25LC640 2.5-5.5V 2 MHz C,I
25C640 4.5-5.5V 3 MHz C,I,E
- Commercial: (C) 0



C to +70



C
- Industrial: (I) -40



C to +85



C
- Automotive: (E) (25C640) -40



C to +125



C
25xx640
TSSOP
1
2
3
4
8
7
6
5
SCK
SI
VSS
WP
HOLD
VCC
CS
SO
25xx640
PDIP/SOIC
1
2
3
4
8
7
6
5
VCC
HOLD
SCK
SI
CS
SO
WP
VSS
SI
SO
SCK
CS
HOLD
WP
Status
Register
I/O Control
Memory
Control
Logic
X
Dec
HV Generator
EEPROM
Array
Page Latches
Y Decoder
Sense Amp.
R/W Control
Logic
VCC
VSS

64K SPI

™

Bus Serial EEPROM

*25xx640 is used in this document as a generic part number for the 25AA640/25LC640/25C640 devices.
SPI is a trademark of Motorola.