LR 24C32/LR 24C64

LESHAN RADIO COMPANY, LTD.
32K bits (4096 X 8) / 64K bits (8192 X 8) Two-wire Serial EEPROM
Two-wire Serial EEPROM
LR 24C32/LR 24C64
Features
Two-wire Serial Interface
VCC = 1.8V to 5.5V
Bi-directional Data Transfer Protocol
Internally Organized
LR24C32, 4096 X 8 (32K bits)
LR24C64, 8192 X 8 (64K bits)
400 kHz (1.8V, 2.7V,5V) Compatibility
32-byte Page (32K/64K) Write Modes
Partial Page Writes Allowed
Self-timed Write Cycle (5 ms max)
High-reliability
1 Million Write Cycles guaranteed
Data Retention > 100 Years
Operating Temperature: -40
to +85
8-lead PDIP, 8-lead SOP and 8-lead TSSOP Packages
Pin Configuration
Ordering Infomation
LR24Cxx:
PDIP8
LR24CxxD: SOP8
LR24CxxT: TSSOP8
Description
LR24C32/LR24C64 provides 32768/65536 bits of serial electrically erasable and
programmable read-only memory (EEPROM) organized as 4096 words of 8 bits each. The
device is optimized for use in many industrial and commercial applications where low-power
and low-voltage operations are essential. The LR24C32/LR24C64 is available in space-saving
8-lead PDIP, 8-lead SOP, and 8-lead TSSOP packages and is accessed via a two-wire serial
interface.
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Pin Descriptions
Pin number
Designation
Type
Name and Functions
Address Inputs
DEVICE/PAGE ADDRESSES (A2, A1, A0): The A2,
A1 and A0 pins are device address inputs that are hardwired or
left not connected for hardware compatibility with other 24Cxx
devices. When the pins are hardwired, as many as eight
A0 - A2
1–3
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32K/64K devices may be addressed on a single bus system
(device addressing is discussed in detail under the Device
Addressing section). If the pins are left floating, the A2, A1 and
A0 pins will be internally pulled down to GND if the capacitive
coupling to the circuit board VCC plane is <3 pF. If coupling is
>3 pF, recommends connecting the address pins to GND.
SDA
5
SCL
6
I/O
&
Open-dr
ain
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Serial Data
SERIAL DATA (SDA): The SDA pin is bi-directional for
serial data transfer. This pin is open-drain driven and may be
wire-ORed with any number of other open-drain or opencollector devices.
Serial Clock Input
SERIAL CLOCK (SCL): The SCL input is used to positive
edge clock data into each EEPROM device and negative edge
clock data out of each device.
Write Protect
WRITE PROTECT (WP): The write protect input, when
connected to GND, allows normal write operations. When WP is
connected high to VCC, all write operations to the memory are
inhibited. If the pin is left floating, the WP pin will be internally
WP
7
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pulled down to GND if the capacitive coupling to the circuit
board VCC plane is <3 pF. If coupling is >3 pF, recommends
connecting the pin to GND. Switching WP to VCC prior to a write
operation creates a software write protect function. The write
protection feature is enabled and operates as shown in the
following
Table 1.
4
GND
P
Ground
8
VCC
P
Power Supply
Table 1:
Write Protect
WP Pin Status:
At VCC
At GND
Part of the Array Protected
24C32
24C64
Full (32K) Array
Full (64K) Array
Normal Read/Write Operations
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Block Diagram
Functional Description
1.
Memory Organization
24C32, 32K SERIAL EEPROM: The 32K is internally organized as 128 pages of 32 bytes each.
Random word addressing requires a 12-bit data word address.
24C64, 64K SERIAL EEPROM: The 64K is internally organized as 256 pages of 32 bytes each.
Random word addressing requires a 13-bit data word address.
2.
Device Operation
CLOCK and DATA TRANSITIONS: The SDA pin is normally pulled high with an external device. Data on the
SDA pin may change only during SCL low time periods (see Figure 1). Data changes during SCL high periods will
indicate a start or stop condition as defined below.
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START CONDITION: A high-to-low transition of SDA with SCL high is a start condition which must precede any
other command (see Figure 2).
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 (see Figure 2)
ACKNOWLEDGE: All addresses and data words are serially transmitted to and from the EEPROM in 8-bit words.
The EEPROM sends a “0” to acknowledge that it has received each word. This happens during the ninth clock cycle.
STANDBY MODE: The 24C32/24C64 features a low-power standby mode which is enabled: (a) upon power-up
and (b) after the receipt of the STOP bit and the completion of any internal operations
MEMORY RESET: After an interruption in protocol, power loss or system reset, any two-wire part can be reset by
following these steps:
1.
Clock up to 9 cycles.
2.
Look for SDA high in each cycle while SCL is high.
3.
Create a start condition.
Figure 1.
Figure 2.
Data Validity
Start and Stop Definition
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Figure 3.
3.
Output Acknowledge
Device Addressing
The 32K/64K EEPROM devices all require an 8-bit device address word following a start condition to
enable the chip for a read or write operation (see Figure 4).
The device address word consists of a mandatory “1”, “0” sequence for the first four most significant bits
as shown. This is common to all the Serial EEPROM devices.
The 32K/64K 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 hardwired input pins. The A2, A1, and A0
pins use an internal proprietary circuit that biases them to a logic low condition if the pins are allowed to
float.
The eighth bit of the 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.
Upon a compare of the device address, the EEPROM will output a “0”. If a compare is not made, the chip
will return to a standby state.
NOISE PROTECTION: Special internal circuitry placed on the SDA and SCL pins prevent small noise
spikes from activating the device.
DATA SECURITY: The 24C32/24C64 has a hardware data protection scheme that allows the user to
write protect the entire memory when the WP pin is at VCC.
4.
Write Operations
BYTE WRITE: A write operation requires an 8-bit data word address following the device address word
and acknowledgment. Upon receipt of this address, the EEPROM will again respond with a “0” and then
clock in the first 8-bit data word. Following receipt of the 8-bit data word, the EEPROM will output a “0”
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, tWR, to the nonvolatile memory.
All inputs are disabled during this write cycle and the EEPROM will not respond until the write is
complete (see Figure 5).
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PAGE WRITE: The 32K/64K devices are capable of 32-byte page writes.
A page write is initiated the same 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 receipt of the first data
word, the microcontroller can transmit up to 31 more data words. The EEPROM will respond with a “0”
after each data word received. The microcontroller must terminate the page write sequence with a stop
condition (see Figure 6).
The data word address lower five (32K/64K) 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. 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: Once the internally timed write cycle has started and the EEPROM inputs
are disabled, acknowledge polling can be initiated. This involves sending a start condition followed by
the device address word. The read/write bit is representative of the operation desired. Only if the internal
write cycle has completed will the EEPROM respond with a “0”, allowing the read or write sequence to
continue.
5.
Read Operations
Read operations are initiated the same way as write operations with the exception that the read/write
select bit in the device address word is set to “1”. There are three read operations: current address read,
random address read and sequential read.
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 stays valid between
operations as long as the chip power is maintained. The address “roll over” during read is from the last
byte of the last memory page to the first byte of the first page. The address “roll over” during write is from
the last byte of the cur- rent page to the first byte of the same page.
Once the device address with the read/write select bit set to “1” 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 “0” but does generate a following stop condition (see Figure 7).
RANDOM READ: A random read requires a “dummy” byte write sequence to load in the data word
address. Once the device address word and data word address are clocked in and acknowledged by the
EEPROM, the microcontroller must 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 does not
respond with a “0” but does generate a following stop condition (see Figure 8).
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 acknowledge. As long
as the EEPROM receives an acknowledge, 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 will continue. The sequential read operation is
terminated when the microcontroller does not respond with a “0” but does generate a following stop
condition (see Figure 9)
Figure 4.
Device Address
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Figure 5.
Byte Write
Figure 6.
Page Write
Figure 7.
Current Address Read
Figure 8.
Random Read
Figure 9.
Sequential Read
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Electrical Characteristics
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AC Electrical Characteristics
Applicable over recommended operating range from TA = –40 C to +85 C, VCC = +1.8V to +5.5V, CL
= 1 TTL Gate and 100 pF (unless otherwise noted)
Parameter
Symbol
1.8, 2.7, 5.0-volt
Min.
Typ.
Max.
Units
Clock Frequency, SCL
fSCL
-
-
400
kHz
Clock Pulse Width Low
tLOW
1.2
-
-
µs
Clock Pulse Width High
tHIGH
0.6
-
-
µs
Noise Suppression Time
tI
-
-
50
ns
tAA
0.1
-
0.9
µs
tBUF
1.2
-
-
µs
Start Hold Time
tHD.STA
0.6
-
-
µs
Start Setup Time
tSU.STA
0.6
-
-
µs
Data In Hold Time
tHD.DAT
0
-
-
µs
Data In Setup Time
tSU.DAT
100
-
-
ns
Inputs Rise Time
tR
-
-
0.3
µs
Inputs Fall Time
tF
-
-
300
ns
Stop Setup Time
tSU.STO
0.6
-
-
µs
Data Out Hold Time
tDH
50
-
-
ns
Write Cycle Time
tWR
-
-
5
ms
1M
-
-
Clock Low to Data Out Valid
Time the bus must be free
before a new transmission
can start
5.0V, 25 C, Byte Mode
Enduran
ce
Write
Cycles
Bus Timing
Figure 10. SCL: Serial Clock, SDA: Serial Data I/O
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Write Cycle Timing
Figure 11. SCL: Serial Clock, SDA: Serial Data I/O
Note:
1. The write cycle time tWR is the time from a valid stop condition of a write sequence to the
end of the internal clear/write cycle.
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Package Information
PDIP Outline Dimensions
Note:
1. This drawing is for general information only; refer to JEDEC Drawing MS-001,
Variation BA for additional information.
2. Dimensions A and L are measured with the package seated in JEDEC seating
plane Gauge GS-3.
3. D, D1 and E1 dimensions do not include mold Flash or protrusions. Mold Flash or
protrusions shall not exceed 0.010 inch.
4. E and eA measured with the leads constrained to be perpendicular to datum.
5. Pointed or rounded lead tips are preferred to ease insertion.
6. b2 and b3 maximum dimensions do not include Dambar protrusions. Dambar
protrusions shall not exceed 0.010 (0.25 mm).
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JEDEC SOIC
Note:
1. These drawings are for general information only. Refer to JEDEC Drawing
MS-012, Variation AA for proper dimensions, tolerances, datums, etc.
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TSSOP
Note:
1. This drawing is for general information only. Refer to JEDEC Drawing
MO-153, Variation AA, for proper dimensions, tolerances, datums, etc.
2. Dimension D does not include mold Flash, protrusions or gate burrs. Mold
Flash, protrusions and gate burrs shall not exceed 0.15 mm (0.006 in) per side.
3. Dimension E1 does not include inter-lead Flash or protrusions. Inter-lead
Flash and protrusions shall not exceed 0.25 mm (0.010 in) per side.
4. Dimension b does not include Dambar protrusion. Allowable Dambar
protrusion shall be 0.08 mm total in excess of the b dimension at maximum
material condition. Dambar cannot be located on the lower radius of the foot.
Minimum space between protrusion and adjacent lead is 0.07 mm.
5. Dimension D and E1 to be determined at Datum Plane H.
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