1996 Microchip Technology Inc. DS21127B-page 1

FEATURES

• Completely implements DDC1



/DDC2




interface for monitor identification
• Hardware write-protect pin
• Single supply with operation down to 2.5V
• Low power CMOS technology
- 1 mA active current typical
- 10

m

A standby current typical at 5.5V
• 2-wire serial interface bus, I

2

C



compatible (SCL)
• Self-timed write cycle (including auto-erase)
• Page-write buffer for up to 8 bytes
• 100 kHz (2.5V) and 400 kHz (5V) compatibility
(SCL)
• 10,000,000 erase/write cycles guaranteed
• Data retention > 200 years
• 8-pin PDIP and SOIC package
• Available for extended temperature ranges

DESCRIPTION

The Microchip Technology Inc. 24LCS21 is a
128 x 8-bit dual-mode Electrically Erasable PROM.
This device is designed for use in applications requiring
storage and serial transmission of configuration and
control information. Two modes of operation have been
implemented: Transmit Only Mode and bi-directional
Mode. Upon power-up, the device will be in the Transmit
Only Mode, sending a serial bit stream of the entire
memory array contents, clocked by the VCLK pin. A
valid high to low transition on the SCL pin will cause the
device to enter the bi-directional Mode, with byte select-
able read/write capability of the memory array in stan-
dard I

2

C protocol.
The 24LCS21 also enables the user to write-protect the
entire memory contents using its write-protect pin. The
24LCS21 is available in a standard 8-pin PDIP and
SOIC package in both commercial and industrial
temperature ranges.
- Commercial (C): 0



C to +70



C
- Industrial (I) -40



C to +85



C

PACKAGE TYPES
BLOCK DIAGRAM
24LCS21
SOIC
1
2
3
4
8
7
6
5
VCC
VCLK
SCL
SDA
NC
NC
WP
VSS
24LCS21
PDIP
1
2
3
4
8
7
6
5
VCC
VCLK
SCL
SDA
NC
NC
WP
VSS
I/O
CONTROL
LOGIC
EEPROM
ARRAY
PAGE LATCHES
HV GENERATOR
SENSE AMP
R/W CONTROL
MEMORY
CONTROL
LOGIC
XDEC
YDEC
VCC
VSS
SDA SCL
VCLK
WP

24LCS21

1K 2.5V Dual Mode I

2

C



Serial EEPROM

DDC is a trademark of the Video Electronics Standards Association.
I

2

C is a trademark of Philips Corporation.

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