ATMEL AT24C21-10PI-2.5, AT24C21-10PC-2.5, AT24C21-10SI-2.5, AT24C21-10SC-2.5 Datasheet

Features

•

2-Wire Serial Interface

•

Schmitt Trigger, Filtered Inputs For Noise Suppression

•

DDC1™/ DDC2™ Interface Compliant for Monitor Identification

•

Low Voltage Operatio n

– 2.5 (VCC = 2.5V to 5.5V)

•

Internally Organized 128 x 8

•

100 kHz (2.5V) Compatibility

•

8-Byte Page Write Mode

•

Write Protection Available

•

Self-timed Write Cycle (10 ms max)

•

High Reliability

– Endurance: 1 Million Write Cycles
– Data Retention: 100 Years
– ESD Protection: >3000V

•

8-Pin PDIP and JEDEC SOIC Packages

Description

The AT24C21 provides 1024 bits of serial electrically erasable and programmable
read only memory (EEPROM) organized as 128 words of 8 bits each. The device is
optimized for use in applications requiring data storage and serial transmission of con­figuration and control information. The AT24C21 features two modes of operation:
Transmit-Only Mode and Bi directio nal Mode. Upo n power- up, the AT24C21 will be in
the Transmit-Only Mode, sending a serial-bit stream of the entire m emory contents,
clocked via the VCLK pin. The Bidirect ional Mode is selected by a val id high-to-low
transition on the SCL pi n an d off ers b yte sel ect able read /wri te c apab ility of the enti re
memory array. The A T24C2 1 i s av ailab le in s pac e sa vi ng 8-pi n PDIP a nd 8- pi n S OIC
packages.

2-Wire Serial
EEPROM

1K (128 x 8)

AT24C21

Pin Configurations

Pin Name Function

NC No Connect
SDA Serial Data
SCL Serial Clock Input

(Bidirectional Mode)

VCLK Serial Clock Input

(Transmit-Only Mode)

8-Pin PDIP 8-Pin SOIC

2-Wire, 1K
Serial EEPROM

Rev. 0405E–07/98

1

Absolute Maximum Ratings*

Operating Temperature................................. -55°C to +125°C

Storage Temperature .................................... -65°C to +150°C

Voltage on Any Pin

with Respect to Ground.....................................-1.0V to +7.0V

Maximum Operating Voltage........................................... 6.25V

DC Output Current........................................................5.0 mA

Block Diagram

*NOTICE: Stresses beyond those listed under “Absolute

Maximum Ratings” may cause permanent dam­age to the dev ice . This is a s tress rating only an d
functional oper ation of the device at thes e or any
other conditions beyond those indicated in the
operational sections of this specification is not
implied. Exposure to absolute maximum rating
conditions f or e xtended periods ma y af fect de vice
reliability .

Pin Description

SERIAL CLOCK (SCL):

edge clock data into each EEPROM device and negative
edge clock data out of each device.

SERIAL DATA (SDA):

serial data transfer. This pin is open-drain driven and may
be wire-ORed with any number of other open drain or open
collector devices.

2

The SCL input is used to positive

The SDA pin is bidirectional for

AT24C21

SERIAL CLOCK (VCLK):

the Transmit-Only mode and will transmit the entire mem­ory contents via the SDA pin with positive signals on the
VCLK pin.

Upon power-up, the device is in

Memory Organization

AT24C21, 1K SERIAL EEPROM:

128 pages of one byte each. The 1K requires a 7-bit data
word address for random word addressing.

Internally organized wi th

AT24C21

DC Characteristics

Applicable ov er recommen ded operat ing range from: TAI = -40°C to +85°C, TAC = 0°C to +70°C, VCC = +2.5V to +5.5V
(unless otherwise noted).

Symbol Parameter Test Condition Min Typ Max Units

V

CC

I

CC

I

CC

I

SB

I

LI

I

LO

V

IL

V

IH

V

OL

Supply Voltage 2.5 5.5 V
Supply Current VCC = 5.0V READ at 100 KHz 0.4 1.0 mA
Supply Current VCC = 5.0V WRITE at 100 KHz 2.0 3.0 mA

Standby Current .......VCC = 2.5V

.......VCC = 5.0V

Input Leakage Current VIN = VCC or V
Output Leakage Current V
Input Low Level

(1)

SCL, SDA Pin

Input Low Level VCLK Pin VCC ≥ 2.7V

Input High Level

(1)

SCL, SDA Pin
Input High Level VCLK Pin

VIN = VCC or V
VIN = VCC or V

= VCC or V

OUT

V

< 2.7V

CC

SS
SS

SS

SS

3.0

12.0

0.10 1.0

0.05 1.0

-0.6 V

VCC × 0.7

2.0

4.0

30.0

× 0.3

CC

0.8

0.2 × V

CC

VCC + 0.5 V

Output Low Level VCC = 3.0V IOL = 2.1 mA 0.40 V

Note: 1. VIL min and VIH max are for reference only and not tested.

Pin Capacitance

(1)

Applicable over recommended operating range from TA = 25°C, f = 1.0 MHz, VCC = +1.8V.

Symbol Test Condition Max Units Conditions

C

I/O

C

IN

Note: 1. This parameter is characterized and is not 100% tested.

Input/Out put Capacitance (SDA) 8 pF V

I/O

= 0V

Input Capacitance (A0, A1, A2, SCL, VCLK) 6 pF VIN = 0V

µ

A

µ

A

µ

A

µ

A

V
V
V

V

Transmit-Only Mode

Symbol Parameter 2.5-volt Units

Min Max

T
T
T
T
T

VAA

VHIGH

VLOW

VHZ

VPU

Output valid from VCLK 500 ns
VCLK high-time 4.0
VCLK low-time 4.7
Mode transition time 500 ns
Transmit-Only power-up time 0 ns

µ

s

µ

s

3

AC Characteristics

Applicable over recommended operating range from TA = -40°C to +85°C, VCC = +2.5V to +5.5V CL = 1 TTL Gate and
100 pF (unless otherwise noted).

2.5-volt

Symbol Parameter

f

SCL

t

LOW

t

HIGH

t

I

Clock Frequency, SCL 0 100 KHz
Clock Pulse Width Low 4.7
Clock Pulse Width High 4.0
Noise Suppression Time

(1)

(SDA and SCL pins)

t
t

AA

BUF

Clock Low to Data Out Valid 0.1 3.5
Time the bus must be free before a new

transmission can start

t

HD.STA

t

SU.STA

t

HD.DAT

t

SU.DAT

t

R

t

F

t

SU.STO

t

DH

t

WR

Endurance

(1)

Start Hold Time 4.0
Start Set-up Time 4.7
Data In Hold Time 0
Data In Set-up Time 250 ns
Inputs Rise Time
Inputs Fall Time

(1)

(1)

Stop Set-up Time 4.0
Data Out Hold Time 100 ns
Write Cycle Time 10 ms

5.0V, 25°C, Page Mode 1M Write Cycles

Note: 1. This parameter is characterized and is not 100% tested.

4.7

UnitsMin Max

µ
µ

NA ns

µ
µ

µ
µ
µ

1.0

µ

300 ns

µ

s
s

s
s

s
s
s

s

s

4

AT24C21