• Schmitt trigger filtered inputs for noise suppression
• Output slope control to eliminate ground bounce
• 2 ms typical write cycle time, byte or page
• Up to eight devices may be connected to the
same bus for up to 256K bits total memory
• Electrostatic discharge protection > 4000V
• Data retention > 200 years
• 8-pin PDIP and SOIC packages
• Temperature ranges
- Commercial (C):0˚C to70˚C
- Industrial (I):-40˚C to+85˚C
- Automotive (E):-40˚C to +125˚C
2
compatible
DESCRIPTION
P ACKA GE TYPES
PDIP
1
A0
2
A1
3
A2
Vss
SOIC
A0
A1
A2
Vss
4
1
2
3
4
24C32A
24C32A
8
Vcc
7
WP
6
SCL
5
SDA
8
7
6
5
Vcc
WP
SCL
SDA
The Microchip T echnology Inc. 24C32A is a 4K x 8 (32K
bit) Serial Electrically Erasable PROM. It has been
developed for advanced, low power applications such
as personal communications or data acquisition. The
24C32A also has a page-write capability of up to 32
bytes of data. The 24C32A is capable of both random
and sequential reads up to the 32K boundary. Functional address lines allow up to eight 24C32A devices
on the same bus, for up to 256K bits address space.
Advanced CMOS technology and broad voltage range
make this device ideal for low-power/low-voltage, nonvolatile code and data applications. The 24C32A is
available in the standard 8-pin plastic DIP and both 150
mil and 200 mil SOIC packaging.
Storage temperature.....................................-65˚C to +150˚C
Ambient temp. with power applied................-65˚C to +125˚C
Soldering temperature of leads (10 seconds).............+300˚C
ESD protection on all pins ..................................................≥ 4 kV
*Notice: Stresses above those listed under “Maximum Ratings”
may cause permanent damage to the device. This is a stress rating only and functional operation of the device at those or any
other conditions above those indicated in the operational listings
of this specification is not implied. Exposure to maximum rating
conditions for extended periods may affect device reliability.
TABLE 1-2:DC CHARACTERISTICS
Vcc = +4.5V to 5.5V
Commercial (C): Tamb =0 ° C to+70 ° C
Industrial (I): Tamb = -40 ° C to+85 ° C
Automotive(E): Tamb = -40 ° C to +125 ° C
A0, A1, A2, SCL , SDA and WP
pins:
High level input voltageV
Low level input voltageV
Hysteresis of Schmitt Trigger
inputs
Note: This parameter is periodically sampled and not 100% tested.
um Ratings*
SS
............... -0.6V to V
ParameterSymbolMinTypMaxUnitsConditions
C
CC
I
CC
CC
+1.0V
IH
IL
V
HYS
OL
LI
LO
, C
IN
OUT
CC
.7 V
—.3 VccV
.05
V
CC
—.40VI
-1010
-1010
—10pFV
Write—3mAV
Read—0.5mAV
CCS
—15 µ A SCL = SDA = V
NameFunction
A0..A2User Configurable Chip Selects
V
SS
Ground
SDASerial Address/Data I/O
SCLSerial Clock
WPWrite Protect Input
V
CC
+4.5V to 5.5V Power Supply
—V
—V(Note)
OL
= 3.0 mA
IN
AV
AV
= .1V to V
OUT
CC
Tamb = 25˚C, F
CC
CC
= .1V to V
= 5.0V (Note)
= 5.5V, SCL = 400 kHz
= 5.5V, SCL = 400 kHz
CC
CC
= 1 MHz
c
CC
= 5.5V
FIGURE 1-1:BUS TIMING START/STOP
SCL
SU:STA
T
SDA
DS21163B-page 2
STARTSTOP
THD:STA
VHYS
Preliminary
TSU:STO
1996 Microchip Technology Inc.
TABLE 1-3:AC CHARACTERISTICS
≤
24C32A
ParameterSymbol
UnitsRemarks
MinMax
Vcc = 4.5-5.5
Clock frequencyF
Clock high timeT
Clock low timeT
SDA and SCL rise timeT
SDA and SCL fall timeT
START condition hold timeT
HD
CLK
HIGH
LOW
R
F
STA
:
—100kHz
4000—ns
4700—ns
—1000ns(Note 1)
—300ns(Note 1)
4000—nsAfter this period the first clock
pulse is generated
SU
START condition setup timeT
STA
:
4700—nsOnly relevant for repeated
START condition
Data input hold timeT
Data input setup timeT
STOP condition setup timeT
HD
SU
SU
Output valid from clockT
Bus free timeT
:
DAT
DAT
:
:
STO
AA
BUF
0—ns
250—ns
4000—ns
—3500ns(Note 2)
4700—nsTime the bus must be free before
a new transmission can start
min to
Output fall time from V
V
IL
max
IH
Input filter spike suppression
OF
T
T
SP
—250ns(Note 1), C
—50ns(Note 3)
B
100 pF
(SDA and SCL pins)
Write cycle timeT
WR
—5ms
Endurance—1M—cycles25 ° C, Vcc = 5.0V, Block Mode
(Note 4)
B
Note 1: Not 100% tested. C
= Total capacitance of one bus line in pF.
2: As a transmitter, the device must provide an internal minimum delay time to bridge the undefined region
(minimum 300 ns) of the falling edge of SCL to avoid unintended generation of START or STOP conditions.
3: The combined T
and V
SP
specifications are due to Schmitt trigger inputs which provide improved noise
HYS
and spike suppression. This eliminates the need for a Ti specification for standard operation.
4: This parameter is not tested but guaranteed by characterization. For endurance estimates in a specific appli-
cation, please consult the Total Endurance Model which can be obtained on our BBS or website.
FIGURE 1-2:BUS TIMING DATA
TF
TLOW
SCL
TSU:STA
T
SDA
IN
SDA
OUT
1996 Microchip Technology Inc.
TSP
TAA
HD:STA
THD:STA
THIGH
Preliminary
TR
TSU:STOTSU:DATTHD:DAT
TBUFTAA
DS21163B-page 3
24C32A
2.0FUNCTIONAL DESCRIPTION
The 24C32A supports a Bi-directional 2-wire bus and
data transmission protocol. A device that sends data
onto the bus is defined as transmitter, and a device
receiving data as receiver. The bus must be controlled
by a master device which generates the Serial Clock
(SCL), controls the bus access, and generates the
STAR T and ST OP conditions, while the 24C32A works
as slave. Both master and slave can operate as transmitter or receiver but the master device determines
which mode is activated.
3.0BUS CHARACTERISTICS
The following bus protocol has been defined:
• 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 the data line while the clock line is HIGH will be
interpreted as a START or STOP condition.
Accordingly, the following bus conditions have been
defined (Figure 3-1).
3.1Bus not Busy (A)
Both data and clock lines remain HIGH.
3.2Start Data Transfer (B)
A HIGH to LOW transition of the SDA line while the
clock (SCL) is HIGH determines a STAR T condition. All
commands must be preceded by a START condition.
3.3Stop Data Transfer (C)
3.4Data Valid (D)
The state of the data line represents valid data when,
after a START condition, the data line is stable for the
duration of the HIGH period of the clock signal.
The data on the line must be changed during the LOW
period of the clock signal. There is one clock pulse per
bit of data.
Each data transfer is initiated with a START condition
and terminated with a STOP condition. The number of
the data bytes transferred between the START and
STOP conditions is determined by the master device.
3.5Acknowledge
Each receiving device, when addressed, is obliged to
generate an acknowledge signal after the reception of
each byte. The master device must generate an extra
clock pulse which is associated with this acknowledge
bit.
Note:The 24C32A does not generate any
acknowledge bits if an internal programming cycle is in progress.
A device that acknowledges must pull down the SDA
line during the acknowledge clock pulse in such a way
that the SDA line is stable LOW during the HIGH period
of the acknowledge related clock pulse. Of course,
setup and hold times must be taken into account. During reads, a master must signal an end of data to the
slave by NOT generating an acknowledge bit on the last
byte that has been clocked out of the slave. In this case,
the slave (24C32A) will leave the data line HIGH to
enable the master to generate the STOP condition.
A LOW to HIGH transition of the SDA line while the
clock (SCL) is HIGH determines a STOP condition. All
operations must be ended with a STOP condition.
FIGURE 3-1:DATA TRANSFER SEQUENCE ON THE SERIAL BUS
(A)(B)(D)(D)(C)(A)
SCL
SDA
START
CONDITION
ADDRESS OR
ACKNOWLEDGE
VALID
DATA
ALLOWED
TO CHANGE
STOP
CONDITION
DS21163B-page 4
Preliminary
1996 Microchip Technology Inc.
24C32A
3.6Device Addressing
A control byte is the first byte received following the
start condition from the master device. The control byte
consists of a 4-bit control code; for the 24C32A this is
set as 1010 binary for read and write (R/W
) operations.
The next three bits of the control byte are the device
select bits (A2, A1, A0). They are used by the master
device to select which of the eight devices are to be
accessed. These bits are in effect the three most significant bits of the word address. The last bit of the control
byte defines the operation to be performed. When set
to a one a read operation is selected, and when set to
a zero a write operation is selected. The next two bytes
received define the address of the first data byte
(Figure 3-3). Because only A11...A0 are used, the
upper four address bits must be zeros. The most significant bit of the most significant byte of the address is
transferred first.
FIGURE 3-2:CONTROL BYTE
ALLOCATION
START
SLAVE ADDRESS
READ/WRITE
R/W A
Following the start condition, the 24C32A monitors the
SDA bus checking the device type identifier being
transmitted. Upon receiving a 1010 code and appropriate device select bits, the slave device outputs an
acknowledge signal on the SDA line. Depending on the
state of the R/W
Following the start condition from the master, the control code (four bits), the device select (three bits), and
the R/W
by the master transmitter. This indicates to the
addressed slave receiver that a byte with a word
address will follow after it has generated an acknowledge bit during the ninth clock cycle. Therefore, the next
byte transmitted by the master is the high-order byte of
the word address and will be written into the address
pointer of the 24C32A. The next byte is the least significant address byte. After receiving another acknowledge signal from the 24C32A the master device will
transmit the data word to be written into the addressed
memory location.
The 24C32A acknowledges again and the master generates a stop condition. This initiates the internal write
cycle, and during this time the 24C32A will not generate
acknowledge signals (Figure 4-1).
bit which is a logic low are clocked onto the bus
4.2Page Write
The write control byte, word address and the first data
byte are transmitted to the 24C32A in the same way as
in a byte write. But instead of generating a stop condition, the master transmits up to 32 bytes which are temporarily stored in the on-chip page buffer and will be
written into memory after the master has transmitted a
stop condition. After receipt of each word, the five lower
address pointer bits are internally incremented by one.
If the master should transmit more than 32 bytes prior
to generating the stop condition, the address counter
will roll over and the previously received data will be
overwritten. As with the byte write operation, once the
stop condition is received, an internal write cycle will
begin. (Figure 4-2).
FIGURE 4-1:BYTE WRITE
S
BUS ACTIVITY
MASTER
SDA LINE
BUS ACTIVITY
T
A
R
T
FIGURE 4-2:PAGE WRITE
S
BUS ACTIVITY
MASTER
SDA LINE
BUS ACTIVITY
T
A
CONTROL
R
T
BYTE
CONTROL
BYTE
ADDRESS
HIGH BYTE
0000
A
C
K
ADDRESS
HIGH BYTE
0000
A
C
K
A
C
K
A
C
K
ADDRESS
LOW BYTE
ADDRESS
LOW BYTE
DATA BYTE 0
A
C
K
S
DATA
A
C
K
DATA BYTE 31
T
O
P
A
C
K
S
T
O
P
A
C
K
DS21163B-page 6Preliminary 1996 Microchip Technology Inc.
24C32A
5.0ACKNOWLEDGE POLLING
Since the device will not acknowledge during a write
cycle, this can be used to determine when the cycle is
complete (this feature can be used to maximize bus
throughput). Once the stop condition for a write command has been issued from the master, the device initiates the internally timed write cycle. Acknowledge
Polling (ACK) can be initiated immediately. This
involves the master sending a start condition followed
by the control byte for a write command (R/W
device is still busy with the write cycle, then NO ACK
will be returned. If the cycle is complete, then the device
will return the ACK and the master can then proceed
with the next read or write command. See Figure 5-1 for
flow diagram.
FIGURE 5-1:ACKNOWLEDGE POLLING
FLOW
Send
Write Command
Send Stop
Condition to
Initiate Write Cycle
Send Start
Send Control Byte
with R/W = 0
Did Device
Acknowledge
(ACK = 0)?
YES
= 0). If the
NO
6.0READ OPERATION
Read operations are initiated in the same way as write
operations with the exception that the R/W
slave address is set to one. There are three basic types
of read operations: current address read, random read,
and sequential read.
6.1Current Address Read
The 24C32A contains an address counter that maintains the address of the last word accessed, internally
incremented by one. Therefore, if the previous access
(either a read or write operation) was to address n (n is
any legal address), the next current address read operation would access data from address n + 1. Upon
receipt of the slave address with R/W
24C32A issues an acknowledge and transmits the eight
bit data word. The master will not acknowledge the
transfer but does generate a stop condition and the
24C32A discontinues transmission (Figure 6-1).
6.2Random Read
Random read operations allow the master to access
any memory location in a random manner. To perform
this type of read operation, first the word address must
be set. This is done by sending the word address to the
24C32A as part of a write operation (R/W
zero). After the word address is sent, the master generates a start condition following the acknowledge. This
terminates the write operation, but not before the internal address pointer is set. Then the master issues the
control byte again but with the R/W
24C32A will then issue an acknowledge and transmit
the 8-bit data word. The master will not acknowledge
the transfer but does generate a stop condition which
causes the 24C32A to discontinue transmission
(Figure 6-2).
The device select bits A2, A1, A0 can be used to
expand the contiguous address space for up to 256K
bits by adding up to eight 24C32A's on the same bus.
In this case, software can use A0 of the control byte
address bit A12, A1 as address bit A13, and A2 as
address bit A14.
as
6.4Sequential Read
Sequential reads are initiated in the same way as a random read except that after the 24C32A transmits the
first data byte, the master issues an acknowledge as
opposed to the stop condition used in a random read.
This acknowledge directs the 24C32A to transmit the
next sequentially addressed 8-bit word (Figure 6-3).
Following the final byte transmitted to the master, the
master will NOT generate an acknowledge but will generate a stop condition.
To provide sequential reads the 24C32A contains an
internal address pointer which is incremented by one at
the completion of each operation. This address pointer
allows the entire memory contents to be serially read
during one operation. The internal address pointer will
automatically roll over from address 0FFF to address
000 if the master acknowledges the byte received from
the array address 0FFF.
FIGURE 6-2:RANDOM READ
S
BUS ACTIVITY
MASTER
SDA LINE
BUS ACTIVITY
T
A
CONTROL
R
T
BYTE
0000
A
C
K
FIGURE 6-3:SEQUENTIAL READ
BUS ACTIVITY
MASTER
SDA LINE
BUS ACTIVITY
CONTROL
BYTE
DATA nDATA n + 1DATA n + 2DATA n + x
A
C
K
ADDRESS
HIGH BYTE
A
C
K
ADDRESS
LOW BYTE
A
C
K
S
T
A
CONTROL
R
T
A
C
K
A
C
K
BYTE
A
C
K
DATA
BYTE
A
C
K
S
T
O
P
N
O
A
C
K
S
T
O
P
N
O
A
C
K
DS21163B-page 8Preliminary 1996 Microchip Technology Inc.
24C32A
7.0PIN DESCRIPTIONS
7.1A0, A1, A2 Chip Address Inputs
The A0..A2 inputs are used by the 24C32A for multiple
device operation and conform to the 2-wire bus standard. The levels applied to these pins define the
address block occupied by the device in the address
map. A particular device is selected by transmitting the
corresponding bits (A2, A1, A0) in the control byte
(Figure 3-3).
7.2SDA Serial Address/Data Input/Output
This is a Bi-directional pin used to transfer addresses
and data into and data out of the device. It is an open
drain terminal, therefore the SDA bus requires a pullup
resistor to V
kHz)
For normal data transfer SDA is allowed to change only
during SCL low. Changes during SCL HIGH are
reserved for indicating the START and STOP conditions.
7.3SCL Serial Clock
This input is used to synchronize the data transfer from
and to the device.
CC (typical 10KΩ for 100 kHz, 1KΩ for 400
8.0NOISE PROTECTION
The SCL and SDA inputs have filter circuits which suppress noise spikes to ensure proper device operation
even on a noisy bus. All I/O lines incorporate Schmitt
triggers for 400 kHz (Fast Mode) compatibility.
9.0POWER MANAGEMENT
This design incorporates a power standby mode when
the device is not in use and automatically powers off
after the normal termination of any operation when a
stop bit is received and all internal functions are complete. This includes any error conditions, i.e., not receiving an acknowledge or stop condition per the two-wire
bus specification. The device also incorporates V
monitor circuitry to prevent inadvertent writes (data corruption) during low-voltage conditions. The V
circuitry is powered off when the device is in standby
mode in order to further reduce power consumption.
DD monitor
DD
7.4WP
This pin must be connected to either VSS or VCC.
If tied to V
(read/write the entire memory 000-FFF).
If tied to V
entire memory will be write-protected. Read operations
are not affected.
DS21163B-page 10Preliminary 1996 Microchip Technology Inc.
24C32A
24C32A Product Identification System
To order or to obtain information, e.g., on pricing or delivery, please use the listed part numbers, and refer to the factory or the listed
sales offices.
24C32A -/P
Package:P = Plastic DIP (300 mil Body), 8-lead
SN = Plastic SOIC (150 mil Body, EIAJ standard)
SM = Plastic SOIC (207 mil Body, EIAJ standard)
Temperature Blank =0°C to +70°C
Range:I = -40°C to +85°C
Arizona Microchip Technology Ltd.
Unit 6, The Courtyard
Meadow Bank, Furlong Road
Bourne End, Buckinghamshire SL8 5AJ
Tel: 44 1628 850303 Fax: 44 1628 850178
France
Arizona Microchip Technology SARL
Zone Industrielle de la Bonde
2 Rue du Buisson aux Fraises
91300 Massy - France
Tel: 33 1 69 53 63 20 Fax: 33 1 69 30 90 79
Arizona Microchip Technology SRL
Centro Direzionale Colleone Pas Taurus 1
Viale Colleoni 1
20041 Agrate Brianza
Milan Italy
Tel: 39 39 6899939 Fax: 39 39 689 9883
JAPAN
Microchip Technology Intl. Inc.
Benex S-1 6F
3-18-20, Shin Yokohama
Kohoku-Ku, Y okohama
Kanagawa 222 Japan
Tel: 81 45 471 6166 Fax: 81 45 471 6122
9/3/96
All rights reserved. 1996, Microchip Technology Incorporated, USA. 9/96
Printed on recycled paper.
Information contained in this publication regarding device applications and the like is intended through suggestion only and may be superseded by updates. No representation or warranty is given and no liability is assumed by Microchip Technology Incorporated with respect to the accuracy or use of such information, or infringement
of patents or other intellectual property rights arising from such use or otherwise. Use of Microchip’s products as critical components in life support systems is not authorized except with express written approval by Microchip. No licenses are conveyed, implicitly or otherwise, under any intellectual property rights. The Microchip logo and
name are registered trademarks of Microchip Technology Inc. All rights reserved. All other trademarks mentioned herein are the property of their respective companies.
DS21163B-page 12Preliminary 1996 Microchip Technology Inc.
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