HT24LC64
CMOS 64K 2-Wire Serial EEPROM
Features
Block Diagram
• Operating voltage:
1.8V~5.5V for temperature -40°C to +85°C
• Low power consumption
–– Operation: 5mA max.
–– Standby: 3μA max.
• Internal organization: 8192×8
• 2-wire serial interface
• Write cycle time: 5ms max.
• Automatic erase-before-write operation
• Partial page write allowed
• 32-byte Page Write Mode
• Write operation with built-in timer
• Hardware controlled write protection
• 40-year data retention
• 106 rewrite cycles per word
Pin Assignment
• 8-pin DIP/SOP/TSSOP package
General Description
The HT24LC64 is a 64K-bit 2-wire serial read/write
non-volatile memory device using the CMOS floating
gate process. Its 65536 bits of memory are organized
into 8192 words and 8 bits per word. The device is
optimized for use in many industrial and commercial
applications where low power and low voltage
operation are essential. Up to eight HT24LC64
devices may be connected to the same two-wire bus.
The HT24LC64 has high reliability endurance of 1M
erase/write cycles and 40-year data retention.
Pin Description
Pin Name I/O
A0~A2
SDA
SCL
I
Description
Address inputs
I/O Serial data
I
Serial clock input
WP
I
Write protect
VSS
—
Negative power supply, ground
VCC
—
Positive power supply
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HT24LC64
Absolute Maximum Ratings
Supply Voltage .......................... VSS−0.3V to VSS+6.0V
Storage Temperature............................−50°C to 125°C
Input Voltage............................. VSS−0.3V to VCC+0.3V
Operating Temperature..........................−40°C to 85°C
Note: These are stress ratings only. Stresses exceeding the range specified under ″Absolute Maximum Ratings″
may cause substantial damage to the device. Functional operation of this device at other conditions beyond
those listed in the specification is not implied and prolonged exposure to extreme conditions may affect
device reliability.
D.C. Characteristics
Symbol
Parameter
Ta=-40°C~+85°C
Test Conditions
VCC
Conditions
Min.
Typ.
Max.
Unit
VCC
Operating Voltage
—
-40°C to +85°C
1.8
—
5.5
V
ICC1
Operating Current
5V
Read at 400kHz
—
—
2
mA
ICC2
Operating Current
5V
Write at 400kHz
—
—
5
mA
VIL
Input Low Voltage
—
—
-0.45
—
0.3VCC
V
VIH
Input High Voltage
—
—
0.7VCC
—
VCC+0.5
V
VOL
Output Low Voltage
2.4V IOL=2.1mA
—
—
0.4
V
1.8V IOL=0.7mA
—
—
0.2
V
ILI
Input Leakage Current
(A0~A2, SCL, SDA)
5V
VIN=0 or VCC
—
—
1
μA
ILO
Output Leakage Current
5V
VOUT=0 or VCC
—
—
1
μA
VIN=0 or VCC
—
—
3
μA
SDA, SCL=VCC
A0, A1, A2, WP=VSS
—
—
1
μA
—
—
2
μA
—
—
1
μA
5V
ISTB
Standby Current
VIN=0 or VCC
1.8V SDA, SCL=VCC
A0, A1, A2, WP=VSS
CIN
Input Capacitance (See Note)
—
f=1MHz, 25°C
—
—
6
pF
COUT
Output Capacitance (See Note)
—
f=1MHz, 25°C
—
—
8
pF
Note: These parameters are periodically sampled but not 100% tested.
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HT24LC64
A.C. Characteristics
Symbol
Ta=-40°C~+85°C
Parameter
Remark
VCC=1.8V~5.0V VCC=2.5V~5.0V
Min.
Max.
Min.
Max.
Unit
fSK
Clock Frequency
—
—
400
—
1000
kHz
tHIGH
Clock High Time
—
600
—
400
—
ns
tLOW
Clock Low Time
—
1200
—
600
—
ns
tr
SDA and SCL Rise Time
Note
—
300
—
300
ns
tf
SDA and SCL Fall Time
Note
—
300
—
300
ns
tHD:STA
START Condition Hold
Time
After this period the first clock pulse
is generated
600
—
250
—
ns
tSU:STA
START Condition Setup
Time
Only relevant for repeated START
condition
600
—
250
—
ns
tHD:DAT
Data Input Hold Time
—
0
—
0
—
ns
tSU:DAT
Data Input Setup Time
—
150
—
100
—
ns
tSU:STO
STOP Condition Setup
Time
—
600
—
250
—
ns
tAA
Output Valid from Clock
—
—
900
—
600
ns
tBUF
Bus Free Time
Time in which the bus must be free
before a new transmission can start
1200
—
500
—
ns
tSP
Input Filter Time Constant
Noise suppression time
(SDA and SCL Pins)
—
50
—
50
ns
tWR
Write Cycle Time
—
5
—
5
Endurance 25°C, Page Mode
—
5.0V
1,000,000
ms
Write
Cycles
Note: These parameters are periodically sampled but not 100% tested.
For relative timing, refer to timing diagrams.
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HT24LC64
Functional Description
• Stop condition
A low-to-high transition of SDA with SCL high is
a stop condition. After a read sequence, the stop
command will place the EEPROM in a standby
power mode (refer to Start and Stop Definition
Timing Diagram).
• Serial clock – SCL
The SCL input is used for positive edge clock
data into each EEPROM device and negative edge
clock data out of each device.
• Serial data – SDA
The SDA pin is bidirectional for serial data
transfer. The pin is open-drain driven and may be
wired-OR with any number of other open-drain or
open collector devices.
• Acknowledge
All addresses and data words are serially
transmitted to and from the EEPROM in 8-bit
words. The EEPROM sends a zero to acknowledge
that it has received each word. This happens during
the ninth clock cycle.
• Address Inputs – A0, A1, A2
The A2, A1 and A0 pins are device address inputs
that are hard wired or left not connected. When the
pins are hard wired, as many as eight 64K devices
may be addressed on a single bus system (device
addressing is discussed in detail under the Device
Addressing section). The code for the selected
device is setup by connecting these inputs to either
VSS or VCC. If any pin is left unconnected in a
floating state will be internally read as having a
low input, VSS, value.
• Write protect – WP
The HT24LC64 has a write protect pin that
provides hardware data protection. The write
protect pin allows normal read/write operations
when connected to VSS or left floating. When the
write protect pin is connected to VCC, the write
protection feature is enabled and operates as shown
in the following table.
WP Pin Status
Full Array (64K)
VSS or floating
Normal Read/Write Operations
Device Addressing
The 64K EEPROM devices require an 8-bit device
address word following a start condition to enable the
chip for a read or write operation. The device address
word consist of a mandatory one, zero sequence for
the first four most significant bits (refer to the diagram
showing the Device Address). This is common to all
the EEPROM device.
The 64K EEPROM uses the three device address
bits A2, A1, A0 to allow as many as eight devices
on the same bus. These bits must compare to their
corresponding hard wired input pins.
Protect Array
VCC
The 8th bit device address is the read/write operation
select bit. A read operation is initiated if this bit is
high and a write operation is initiated if this bit is low.
Memory Organization
Internally organized with 8192 8-bit words, the 64K
requires a 13-bit data word address for random word
addressing.
If the comparison of the device address succeed the
EEPROM will output a zero at ACK bit. If not, the
chip will return to a standby state.
Device Operations
• Clock and data transition
Data transfer may be initiated only when the bus is
not busy. During data transfer, the data line must
remain stable whenever the clock line is high.
Changes in data line while the clock line is high
will be interpreted as a START or STOP condition.
• Start condition
A high-to-low transition of SDA with SCL high
is a start condition which must precede any other
command (refer to Start and Stop Definition
Timing diagram).
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HT24LC64
Write Operations
• Write protect
The HT24LC64 has a write-protect function and
programming will then be inhibited when the WP
pin is connected to VCC. Under this mode, the
HT24LC64 is used as a serial ROM.
• Byte write
A write operation requires two data word
address following the device address word and
acknowledgment. Upon receipt of this address,
the EEPROM will again respond with a zero
and then clock in the first 8-bit data word. After
receiving the 8-bit data word, the EEPROM will
output a zero and the addressing device, such as a
microcontroller, must terminate the write sequence
with a stop condition. At this time the EEPROM
enters an internally-timed write cycle to the
nonvolatile memory. All inputs are disabled during
this write cycle and EEPROM will not respond
until the write operation is completed (refer to
Byte write timing).
• Read operations
The HT24LC64 supports three read operations,
namely, current address read, random address
read and sequential read. During read operation
execution, the read/write select bit should be set to
"1".
• Page write
The 64K EEPROM is capable of a 32-byte page
write. A page write is initiated in the same way as
a byte write, but the microcontroller does not send
a stop condition after the first data word is clocked
in. Instead, after the EEPROM acknowledges the
receipt of the first data word, the microcontroller
can transmit up to 31 more data words. The
EEPROM will respond with a zero after each data
word received. The microcontroller must terminate
the page write sequence with a stop condition (refer
to Page write timing).
The data word address lower 5 bits are internally
incremented following the receipt of each data
word. The higher data word address bits are not
incremented, retaining the memory page row
location.
Acknowledge Polling Flow
• Current address read
The internal data word address counter maintains
the last address accessed during the last read or
write operation, incremented by one. This address
remains valid between operations as long as the
chip power is maintained. The address will roll
over during read from the last byte of the last
memory page to the first byte of the first page.
The address will roll over during write from the
last byte of the current page to the first byte of
the same page. Once the device address with
the read/write select bit set to one is clocked in
and acknowledged by the EEPROM, the current
address data word is serially clocked out. The
microcontroller does not respond with an input
zero but generates a following stop condition (refer
to Current read timing).
When the word address, internally generated,
reaches the page boundary, the following byte
is placed at the beginning of the same page. If
more than 32 data words are transmitted to the
EEPROM, the data word address will "roll over"
and previous data will be overwritten.
• Acknowledge polling
To maximise bus throughput, one technique is to
allow the master to poll for an acknowledge signal
after the start condition and the control byte for
a write command have been sent. If the device is
still busy implementing its write cycle, then no
ACK will be returned. The master can send the
next read/write command when the ACK signal
has finally been received.
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HT24LC64
• Random read
Arandom read requires a dummy byte write
sequence to load in the data word address which
is then clocked in and acknowledged by the
EEPROM. The microcontroller must then generate
another start condition. The microcontroller
now initiates a current address read by sending
a device address with the read/write select bit
high. The EEPROM acknowledges the device
address and serially clocks out the data word. The
microcontroller should respond with a "no ACK"
signal (high) followed by a stop condition (refer to
Random read timing).
• Sequential read
Sequential reads are initiated by either a current
address read or a random address read. After the
microcontroller receives a data word, it responds
with an acknowledgment. As long as the EEPROM
receives an acknowledgment, it will continue to
increment the data word address and serially clock
out sequential data words. When the memory
address limit is reached, the data word address will
roll over and the sequential read continues. The
sequential read operation is terminated when the
microcontroller does not respond with a zero but
generates a following stop condition.
Byte Write Timing
Page Write Timing
Current Read Timing
Random Read Timing
D a ta (n )
D a ta (n + 1 )
D a ta (n + 2 )
D a ta (n + x )
S to p
R e a d
D e v ic e
A d d re s s
S D A L in e
N o A C K
A C K
A C K
A C K
A C K
R /W
Sequential Read Timing
Rev. 1.50
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January 16, 2014
HT24LC64
Timing Diagrams
Note: The write cycle time tWR is the time from a valid stop condition of a write sequence to the end of the valid
start condition of sequential command.
Rev. 1.50
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January 16, 2014
HT24LC64
Package Information
Note that the package information provided here is for consultation purposes only. As this information may be
updated at regular intervals users are reminded to consult the Holtek website for the latest version of the package
information.
Additional supplementary information with regard to packaging is listed below. Click on the relevant section to be
transferred to the relevant website page.
• Further Package Information (include Outline Dimensions, Product Tape and Reel Specifications)
• Packing Meterials Information
• Carton information
Rev. 1.50
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January 16, 2014
HT24LC64
8-pin DIP (300mil) Outline Dimensions
Symbol
Min.
Nom.
Max.
A
0.355
0.365
0.400
B
0.240
0.250
0.280
C
0.115
0.130
0.195
D
0.115
0.130
0.150
E
0.014
0.018
0.022
F
0.045
0.060
0.070
G
—
0.100 BSC
—
H
0.300
0.310
0.325
I
—
—
0.430
Symbol
Rev. 1.50
Dimensions in inch
Dimensions in mm
Min.
Nom.
Max.
10.16
A
9.02
9.27
B
6.10
6.35
7.11
C
2.92
3.30
4.95
D
2.92
3.30
3.81
E
0.36
0.46
0.56
F
1.14
1.52
1.78
G
—
2.54 BSC
—
H
7.26
7.87
8.26
I
—
—
10.92
9
January 16, 2014
HT24LC64
8-pin SOP (150mil) Outline Dimensions
Symbol
Dimensions in inch
Min.
Nom.
Max.
A
—
0.236 BSC
—
B
—
0.154 BSC
—
0.020
C
0.012
—
C′
—
0.193 BSC
—
D
—
—
0.069
E
—
0.050 BSC
—
F
0.004
—
0.010
G
0.016
—
0.050
H
0.004
—
0.010
α
0°
—
8°
Symbol
Rev. 1.50
Dimensions in mm
Min.
Nom.
Max.
A
—F
6.00 BSC
—
B
—
3.90 BSC
—
C
0.31
—
0.51
C′
—
4.90 BSC
—
D
—
—
1.75
E
—
1.27 BSC
—
F
0.10
—
0.25
G
0.40
—
1.27
H
0.10
—
0.25
α
0°
—
8°
10
January 16, 2014
HT24LC64
8-pin TSSOP Outline Dimensions
Symbol
Dimensions in inch
Min.
Nom.
Max.
A
—
—
0.047
A1
0.002
—
0.006
A2
0.031
0.039
0.041
B
0.007
—
0.012
C
0.004
—
0.006
D
0.114
0.118
0.122
E
—
0.252 BSC
—
E1
0.169
0.173
0.177
e
—
0.026 BSC
—
L
0.018
0.024
0.030
L1
—
0.039 BSC
—
y
—
0.004
—
θ
0°
—
8°
Symbol
Rev. 1.50
Dimensions in mm
Min.
Nom.
Max.
A
—
—
1.20
A1
0.05
—
0.15
A2
0.80
1
1.05
B
0.19
—
0.30
C
0.09
—
0.16
D
2.90
3.00
3.10
E
—
6.40 BSC
—
E1
4.30
4.40
4.50
e
—
0.65 BSC
—
L
0.45
0.60
0.75
L1
—
1.0 BSC
—
y
—
0.10
—
θ
0°
—
8°
11
January 16, 2014
HT24LC64
Copyright© 2014 by HOLTEK SEMICONDUCTOR INC.
The information appearing in this Data Sheet is believed to be accurate at the time
of publication. However, Holtek assumes no responsibility arising from the use of
the specifications described. The applications mentioned herein are used solely
for the purpose of illustration and Holtek makes no warranty or representation that
such applications will be suitable without further modification, nor recommends
the use of its products for application that may present a risk to human life due to
malfunction or otherwise. Holtek's products are not authorized for use as critical
components in life support devices or systems. Holtek reserves the right to alter
its products without prior notification. For the most up-to-date information, please
visit our web site at http://www.holtek.com.tw.
Rev. 1.50
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