ABRIDGED DATA SHEET
DS2432
1Kb Protected 1-Wire EEPROM
with SHA-1 Engine
FEATURES
1128 Bits of 5V EEPROM Memory
Partitioned Into Four Pages of 256 Bits, a
64-Bit Write-Only Secret, and Up to Five
General-Purpose Read/Write Registers
On-Chip 512-Bit ISO/IEC 10118-3 SHA-1
Engine to Compute 160-Bit Message
Authentication Codes (MACs) and to
Generate Secrets
Write Access Requires Knowledge of the
Secret and the Capability of Computing and
Transmitting
a
160-Bit
MAC
as
Authorization
Secret and Data Memory Can Be Write
Protected (All or Page 0 Only) or Put in
EPROM-Emulation Mode (“Write to 0”,
Page 1)
Unique, Factory-Lasered and Tested 64-Bit
Registration Number Assures Absolute
Traceability Because No Two Parts Are Alike
Built-In Multidrop Controller Ensures
Compatibility with Other 1-Wire® Net
Products
Reduces Control, Address, Data, and Power
to a Single Data Pin
Directly Connects to a Single Port Pin of a
Microprocessor and Communicates at Up to
15.3kbps
Overdrive Mode Boosts Communication
Speed to 90.9kbps
Low-Cost 6-Lead TSOC Surface-Mount
Package or Solder-Bumped UCSP™ Package
Reads and Writes Over a Wide Voltage
Range of 2.8V to 5.25V from -40°C to +85°C
PIN CONFIGURATIONS
TOP VIEW
GND 1
6 NC
1-Wire 2
5 NC
NC 3
4 NC
TSOC
(150 mils)
A1 MARK
DS2432
yywwrr
###xx
A
B
C
1
2
3
4
UCSP
(TOP VIEW WITH LASER
MARK, CONTACTS NOT
VISIBLE)
A2 = 1-WIRE
A3 = GND
ALL OTHER BUMPS: NC
yywwrr = DATE/REVISION
###xx = LOT NUMBER
REFER TO THE PACKAGE RELIABILITY REPORT FOR
IMPORTANT GUIDELINES ON QUALIFIED USAGE CONDITIONS.
ORDERING INFORMATION
PART
DS2432P+
DS2432P+T&R
DS2432X-S+
TEMP
RANGE
-40°C to +85°C
-40°C to +85°C
PINPACKAGE
6 TSOC
6 TSOC
8 UCSP (2.5k
-40°C to +85°C
pcs, T&R)
+Denotes a lead(Pb)-free/RoHS-compliant package.
T&R = Tape and reel.
Request Full Data Sheet at:
www.maximintegrated.com/DS2432
1-Wire is a registered trademark and UCSP is a trademark of Maxim Integrated Products, Inc.
1 of 17
219-0003; Rev 9/12
ABRIDGED DATA SHEET
DS2432
DESCRIPTION
The DS2432 combines 1024 bits of EEPROM, a 64-bit secret, an 8-byte register/control page with up to
five user read/write bytes, a 512-bit SHA-1 engine, and a fully-featured 1-Wire interface in a single chip.
Each DS2432 has its own 64-bit ROM registration number that is factory lasered into the chip to provide
a guaranteed unique identity for absolute traceability. Data is transferred serially via the 1-Wire protocol,
which requires only a single data lead and a ground return. The DS2432 has an additional memory area
called the scratchpad that acts as a buffer when writing to the main memory, the register page or when
installing a new secret. Data is first written to the scratchpad from where it can be read back. After the
data has been verified, a copy scratchpad command will transfer the data to its final memory location,
provided that the DS2432 receives a matching 160-Bit MAC. The computation of the MAC involves the
secret and additional data stored in the DS2432 including the device’s registration number. Only a new
secret can be loaded without providing a MAC. The SHA-1 engine can also be activated to compute
160-bit message authentication codes (MAC) when reading a memory page or to compute a new secret,
instead of loading it. Applications of the DS2432 include intellectual property security, after-market
management of consumables, and tamper-proof data carriers.
OVERVIEW
The block diagram in Figure 1 shows the relationships between the major control and memory sections of
the DS2432. The DS2432 has five main data components: 1) 64-bit lasered ROM, 2) 64-bit scratchpad, 3)
four 32-byte pages of EEPROM, 4) 64-bit register page, 5) 64-bit Secrets Memory, and 6) a 512-bit
SHA-1 Engine (SHA = Secure Hash Algorithm). The hierarchical structure of the 1-Wire protocol is
shown in Figure 2. The bus master must first provide one of the seven ROM Function Commands, 1)
Read ROM, 2) Match ROM, 3) Search ROM, 4) Skip ROM, 5) Resume Communication, 6) OverdriveSkip ROM or 7) Overdrive-Match ROM. Upon completion of an Overdrive ROM command byte
executed at regular speed, the device will enter Overdrive mode where all subsequent communication
occurs at a higher speed. The protocol required for these ROM function commands is described in Figure
9. After a ROM function command is successfully executed, the memory and SHA-1 functions become
accessible and the master may provide any one of the seven memory function commands. The protocol
for these memory function commands is described in Figure 7*. All data is read and written least
significant bit first.
*
For Figure 7, refer to the full version of the data sheet.
2 of 17
ABRIDGED DATA SHEET
DS2432
DS2432 BLOCK DIAGRAM Figure 1
PARASITE POWER
1-Wire net
1-Wire
Function Control
Memory and
SHA-1 Function
Control Unit
64-bit
Lasered ROM
512-bit
Secure Hash
Algorithm
Engine
CRC-16
Generator
64-bit
Scratchpad
Data Memory
4 Pages of
256 bits each
Register Page
64 bits
Secrets Memory
64 bits
3 of 17
ABRIDGED DATA SHEET
DS2432
64-BIT LASERED ROM
Each DS2432 contains a unique ROM code that is 64 bits long. The first eight bits are a 1-Wire family
code. The next 48 bits are a unique serial number. The last eight bits are a CRC of the first 56 bits. (See
Figure 3.) The 1-Wire CRC is generated using a polynomial generator consisting of a shift register and
XOR gates as shown in Figure 4. The polynomial is X8 + X5 + X4 + 1. Additional information about the
1-Wire Cyclic Redundancy Check is available in Application Note 27. The shift register bits are
initialized to zero. Then starting with the least significant bit of the family code, one bit at a time is
shifted in. After the 8th bit of the family code has been entered, then the serial number is entered. After the
48th bit of the serial number has been entered, the shift register contains the CRC value. Shifting in the
eight bits of CRC should return the shift register to all zeros.
HIERARCHCAL STRUCTURE FOR 1-Wire PROTOCOL Figure 2
1-Wire net
BUS
Master
Other
Devices
DS2432
Command
Level:
1-Wire ROM Function
Commands (see Figure 9)
Available
Commands:
Data Field
Affected:
Read ROM
Match ROM
Search ROM
Skip ROM
Resume
Overdrive Skip
Overdrive Match
64-bit Reg. #, RC-Flag
64-bit Reg. #, RC-Flag
64-bit Reg. #, RC-Flag
RC-Flag
RC-Flag
RC-Flag, OD-Flag
64-bit Reg. #, RC-Flag, OD-Flag
For details see the full
version of the data sheet.
DS2432-specific
Memory Function
Commands (see Figure 7)
64-BIT LASERED ROM Figure 3
MSB
LSB
8-Bit CRC Code
MSB
*
8-Bit Family Code*
48-Bit Serial Number
LSB
MSB
For the actual Family Code value, refer to the full version of the data sheet.
4 of 17
LSB
MSB
LSB
ABRIDGED DATA SHEET
DS2432
1-Wire CRC GENERATOR Figure 4
8
5
4
Polynomial = X + X + X + 1
st
nd
1
STAGE
X
0
rd
2
STAGE
X
1
th
3
STAGE
X
2
th
4
STAGE
X
th
5
STAGE
3
X
th
6
STAGE
4
X
5
th
7
STAGE
X
6
8
STAGE
X
7
X
8
INPUT DATA
MEMORY MAP
The DS2432 has four memory areas: data memory, secrets memory, register page with special function
registers and user-bytes, and a scratchpad. The data memory is organized in pages of 32 bytes. Secret,
register page and scratchpad are 8 bytes each. The scratchpad acts as a buffer when writing to the data
memory, loading the initial secret or when writing to the register page. For further details (including
Figure 5) refer to the full version of the data sheet.
ADDRESS REGISTERS AND TRANSFER STATUS
The DS2432 employs three address registers: TA1, TA2 and E/S (Figure 6). These registers are common
to many other 1-Wire devices but operate slightly differently with the DS2432. Registers TA1 and TA2
must be loaded with the target address to which the data will be written or from which data will be read.
Register E/S is a read-only transfer-status register, used to verify data integrity with write commands.
Since the scratchpad of the DS2432 is designed to accept data in blocks of eight bytes only, the lower
three bits of TA1 will be forced to 0 and the lower three bits of the E/S register (Ending Offset) will
always read 1. This indicates that all the data in the scratchpad will be used for a subsequent copying into
main memory or secret. Bit 5 of the E/S register, called PF or “partial byte flag”, is a logic-1 if the
number of data bits sent by the master is not an integer multiple of 8 or if the data in the scratchpad is not
valid due to a loss of power. A valid write to the scratchpad will clear the PF bit. Bits 3, 4 and 6 have no
function; they always read 1. The Partial Flag supports the master checking the data integrity after a
Write command. The highest valued bit of the E/S register, called AA or Authorization Accepted, acts as
a flag to indicate that the data stored in the scratchpad has already been copied to the target memory
address. Writing data to the scratchpad clears this flag.
ADDRESS REGISTERS Figure 6
Bit #
7
6
5
4
3
2
1
0
Target Address (TA1)
T7
T6
T5
T4
T3
T2
(0)
T1
(0)
T0
(0)
Target Address (TA2)
T15
T14
T13
T12
T11
T10
T9
T8
Ending Address with
Data Status (E/S)
(Read Only)
AA
1
PF
1
1
E2
(1)
E1
(1)
E0
(1)
5 of 17
ABRIDGED DATA SHEET
DS2432
WRITING WITH VERIFICATION
To write data to the DS2432, the scratchpad has to be used as intermediate storage. First the master issues
the Write Scratchpad command to specify the desired target address, followed by the data to be written to
the scratchpad. Note that writes to data memory must be performed on 8-byte boundaries with the 3 LSBs
of the target address (T2..T0) equal to 000b. If T2..T0 are sent with non-zero values, the device will set
these bits to zero and will write to the modified address upon completion of the command sequence. In
addition, the entire 8-byte scratchpad will be copied to memory when commanded, therefore eight bytes
of data should be written into the scratchpad to ensure that the data to be copied is known. Under certain
conditions (see the Write Scratchpad command) the master will receive an inverted CRC-16 of the
command, address (actual address sent) and data at the end of the write scratchpad command sequence.
Note that the CRC is calculated based on the actual target address sent and not the modified address in the
case of a non-zero T2..T0. Knowing this CRC value, the master can compare it to the value it has
calculated itself to decide if the communication was successful and proceed to the Copy Scratchpad
command. If the master could not receive the CRC-16, it should send the Read Scratchpad command to
verify data integrity. As preamble to the scratchpad data, the DS2432 repeats the target address TA1 and
TA2 and sends the contents of the E/S register. If the PF flag is set, data did not arrive correctly in the
scratchpad or there was a loss of power since data was last written to the scratchpad. The master does not
need to continue reading; it can start a new trial to write data to the scratchpad. Similarly, a set AA flag
together with a cleared PF flag indicates that the device did not recognize the Write command. If
everything went correctly, both flags are cleared. Now the master can continue reading and verifying
every data byte. After the master has verified the data, it can send the Copy Scratchpad command, for
example. This command must be followed exactly by the data of the three address registers TA1, TA2
and E/S. The master should obtain the contents of these registers by reading the scratchpad.
MEMORY AND SHA-1 FUNCTION COMMANDS
This section describes the commands and flow charts to use the memory and SHA-1 engine of the device.
It includes Tables 1 to 4 and Figure 7. Please refer to the full version of the data sheet.
SHA-1 COMPUTATION ALGORITHM
The SHA-1 computation is adapted from the Secure Hash Standard SHA-1 document as it can be
downloaded from the NIST website (http://www.itl.nist.gov/fipspubs/fip180-1.htm). Further details are
found in the full version of the data sheet.
1-Wire BUS SYSTEM
The 1-Wire bus is a system, which has a single bus master and one or more slaves. In all instances the
DS2432 is a slave device. The bus master is typically a microcontroller. The discussion of this bus system
is broken down into three topics: hardware configuration, transaction sequence, and 1-Wire signaling
(signal types and timing). A 1-Wire protocol defines bus transactions in terms of the bus state during
specific time slots that are initiated on the falling edge of sync pulses from the bus master.
6 of 17
ABRIDGED DATA SHEET
DS2432
HARDWARE CONFIGURATION
The 1-Wire bus has only a single line by definition; it is important that each device on the bus be able to
drive it at the appropriate time. To facilitate this, each device attached to the 1-Wire bus must have open
drain or 3-state outputs. The 1-Wire port of the DS2432 is open drain with an internal circuit equivalent
to that shown in Figure 8. A multidrop bus consists of a 1-Wire bus with multiple slaves attached. At
regular speed the 1-Wire bus has a maximum data rate of 15.3kbps. The speed can be boosted to 90.9kbps
by activating the Overdrive Mode. The DS2432 requires a 1-Wire pullup resistor of maximum 2.2 k for
executing any of its memory and SHA-1 function commands at any speed. When communicating with
several DS2432 simultaneously, e.g., to install the same secret in several devices, the resistor should be
bypassed by a low-impedance pullup to VPUP while the device transfers data from the scratchpad to the
EEPROM.
The idle state for the 1-Wire bus is high. If for any reason a transaction needs to be suspended, the bus
MUST be left in the idle state if the transaction is to resume. If this does not occur and the bus is left low
for more than 16 µs (Overdrive Speed) or more than 120 µs (regular speed), one or more devices on the
bus may be reset.
HARDWARE CONFIGURATION Figure 8
BUS MASTER
VPUP
DS2432 1-Wire PORT
RPUP
RX
TX
RX = RECEIVE
Open Drain
Port Pin
DATA
RX
IL
TX
TX = TRANSMIT
100
MOSFET
TRANSACTION SEQUENCE
The protocol for accessing the DS2432 via the 1-Wire port is as follows:
Initialization
ROM Function Command
Memory or SHA-1 Function Command
Transaction/Data
INITIALIZATION
All transactions on the 1-Wire bus begin with an initialization sequence. The initialization sequence
consists of a reset pulse transmitted by the bus master followed by presence pulse(s) transmitted by the
slave(s). The presence pulse lets the bus master know that the DS2432 is on the bus and is ready to
operate. For more details, see the 1-Wire Signaling section.
7 of 17
ABRIDGED DATA SHEET
DS2432
ROM FUNCTION COMMANDS
Once the bus master has detected a presence, it can issue one of the seven ROM function commands that
the DS2432 supports. All ROM function commands are eight bits long. A list of these commands follows
(refer to flowchart in Figure 9):
Read ROM [33h]
This command allows the bus master to read the DS2432’s 8-bit family code, unique 48-bit serial
number, and 8-bit CRC. This command should only be used if there is a single slave on the bus. If more
than one slave is present on the bus, a data collision will occur when all slaves try to transmit at the same
time (open drain will produce a wired-AND result). The resultant family code and 48-bit serial number
read by the master will be invalid.
Match ROM [55h]
The match ROM command, followed by a 64-bit registration number, allows the bus master to address a
specific DS2432 on a multidrop bus. Only the DS2432 that exactly matches the 64-bit registration
number will respond to the following memory function command. All other slaves will wait for a reset
pulse. This command can be used with a single or multiple devices on the bus.
Search ROM [F0h]
When a system is initially brought up, the bus master might not know the number of devices on the
1-Wire bus or their 64-bit registration numbers. The search ROM command allows the bus master to use
a process of elimination to identify the 64-bit numbers of all slave devices on the bus. The search ROM
process is the repetition of a simple 3-step routine: read a bit, read the complement of the bit, then write
the desired value of that bit. The bus master performs this 3-step routine on each bit of the registration
number. After one complete pass, the bus master knows the 64-bit number of one device. Additional
passes will identify the registration numbers of the remaining devices. Refer to Application Note 187 for
a detailed discussion of a search ROM, including an actual example.
Skip ROM [CCh]
This command can save time in a single drop bus system by allowing the bus master to access the
memory and SHA-1 functions without providing the 64-bit registration number. If more than one slave is
present on the bus and, for example, a read command is issued following the Skip ROM command, data
collision will occur on the bus as multiple slaves transmit simultaneously (open-drain pulldowns will
produce a wired-AND result).
Overdrive Skip ROM [3Ch]
On a single-drop bus this command can save time by allowing the bus master to access the memory and
SHA-1 functions without providing the 64-bit registration number. Unlike the normal Skip ROM
command the Overdrive Skip ROM sets the DS2432 in the Overdrive Mode (OD = 1). All
communication following this command code has to occur at Overdrive Speed until a reset pulse of
minimum 480 µs duration resets all devices on the bus to regular speed (OD = 0).
When issued on a multidrop bus this command will set all Overdrive-supporting devices into Overdrive
mode. To subsequently address a specific Overdrive-supporting device, a reset pulse at Overdrive speed
has to be issued followed by a Match ROM or Search ROM command sequence. This will speed up the
search process. If more than one Overdrive-supporting slave is present on the bus and the Overdrive Skip
ROM command is followed by a read command, data collision will occur on the bus as multiple slaves
transmit simultaneously (open drain pulldowns will produce a wired-AND result).
8 of 17
ABRIDGED DATA SHEET
DS2432
ROM FUNCTIONS FLOW CHART Figure 9
Bus Master TX
Reset Pulse
From Memory and SHA-1
Functions Flow Chart
(Figure 7)
From Figure 9, 2
OD
Reset Pulse ?
N
nd
Part
OD = 0
Y
Bus Master TX ROM
Function Command
33h
Read ROM
Command ?
Y
RC = 0
DS2432 TX
Family Code
(1 Byte)
DS2432 TX
Presence Pulse
N
55h
Match ROM
Command ?
F0h
Search ROM
Command ?
N
Y
Y
RC = 0
RC = 0
DS2432 TX Bit 0
Master TX Bit 0
DS2432 TX Bit 0
Master TX Bit 0
N
N
Bit 0
Match ?
Y
Y
DS2432 TX Bit 1
Master TX Bit 1
DS2432 TX Bit 1
Master TX Bit 1
N
Bit 1
Match ?
N
Bit 1
Match ?
Y
DS2432 TX
CRC Byte
To Figure 9
nd
CCh
2 Part
Skip ROM
Command ?
N
Y
RC = 0
Bit 0
Match ?
DS2432 TX
Serial Number
(6 Bytes)
N
Y
DS2432 TX Bit 63
Master TX Bit 63
DS2432 TX Bit 63
Master TX Bit 63
N
Bit 63
Match ?
N
Bit 63
Match ?
Y
Y
RC = 1
RC = 1
To Memory and SHA-1 Functions
Flow Chart (Figure 7)
9 of 17
To Figure 9
nd
2 Part
From Figure 9
nd
2 Part
ABRIDGED DATA SHEET
DS2432
ROM FUNCTIONS FLOW CHART (continued) Figure 9
st
To Figure 9, 1 Part
From Figure 9
st
1 Part
A5h
Resume
Command ?
3Ch
Overdrive
Skip ROM ?
N
Y
N
Y
N
Y
RC = 0 ; OD = 1
RC = 1 ?
69h
Overdrive Match
ROM ?
RC = 0 ; OD = 1
N
Master TX Bit 0
Y
Master
TX Reset ?
N
Y
Bit 0
Match ?
N
Y
Master TX Bit 1
Master
TX Reset ?
Y
Bit 1
Match ?
N
Y
N
Master TX Bit 63
Bit 63
Match ?
Y
RC = 1
From Figure 9
st
1 Part
To Figure 9
st
1 Part
10 of 17
N
ABRIDGED DATA SHEET
DS2432
Overdrive Match ROM [69h]
The Overdrive Match ROM command, followed by a 64-bit registration number transmitted at Overdrive
Speed, allows the bus master to address a specific DS2432 on a multidrop bus and to simultaneously set it
in Overdrive Mode. Only the DS2432 that exactly matches the 64-bit number will respond to the
subsequent memory or SHA-1 function command. Slaves already in Overdrive mode from a previous
Overdrive Skip or a successful Overdrive Match command will remain in Overdrive mode. All Overdrive-capable slaves will return to regular speed at the next Reset Pulse of minimum 480 µs duration. The
Overdrive Match ROM command can be used with a single or multiple devices on the bus.
Resume Command [A5h]
In a typical application the DS2432 needs to be accessed several times to write a full 32-byte page. In a
multidrop environment this means that the 64-bit registration number of a Match ROM command has to
be repeated for every access. To maximize the data throughput in a multidrop environment the Resume
Command function was implemented. This function checks the status of the RC bit and, if it is set,
directly transfers control to the Memory and SHA-1 functions, similar to a Skip ROM command. The
only way to set the RC bit is through successfully executing the Match ROM, Search ROM or Overdrive
Match ROM command. Once the RC bit is set, the device can repeatedly be accessed through the Resume
Command function. Accessing another device on the bus will clear the RC bit, preventing two or more
devices from simultaneously responding to the Resume Command function.
1-Wire SIGNALING
The DS2432 requires strict protocols to ensure data integrity. The protocol consists of four types of signaling on one line: Reset Sequence with Reset Pulse and Presence Pulse, Write 0, Write 1 and Read Data.
Except for the presence pulse the bus master initiates all these signals. The DS2432 can communicate at
two different speeds, regular speed and Overdrive Speed. If not explicitly set into the Overdrive mode,
the DS2432 will communicate at regular speed. While in Overdrive Mode the fast timing applies to all
waveforms.
The initialization sequence required to begin any communication with the DS2432 is shown in Figure 10.
A Reset Pulse followed by a Presence Pulse indicates the DS2432 is ready to send or receive data. The
bus master transmits (TX) a reset pulse (tRSTL, minimum 480 µs at regular speed, 48 µs at Overdrive
Speed). The bus master then releases the line and goes into receive mode (RX). The 1-Wire bus is pulled
to a high state via the pullup resistor. After detecting the rising edge on the data pin, the DS2432 waits
(tPDH, 15-60 µs at regular speed, 2-6 µs at Overdrive speed) and then transmits the Presence Pulse (tPDL,
60-240 µs at regular speed, 8-24 µs at Overdrive Speed). A Reset Pulse of 480 µs or longer will exit the
Overdrive Mode returning the device to regular speed. If the DS2432 is in Overdrive Mode and the Reset
Pulse is no longer than 80 µs the device will remain in Overdrive Mode.
11 of 17
ABRIDGED DATA SHEET
DS2432
INITIALIZATION PROCEDURE “RESET AND PRESENCE PULSES” Figure 10
MASTER TX “RESET PULSE” MASTER RX “PRESENCE PULSE”
tRSTH
VPULLUP
VPULLUP MIN
VIH MIN
VIL MAX
0V
tRSTL
RESISTOR
tR
tPDL
tPDH
MASTER
DS2432
Read/Write Time Slots
The definitions of write and read time slots are illustrated in Figure 11. The master initiates all time slots
by driving the data line low. The falling edge of the data line synchronizes the DS2432 to the master by
triggering an internal delay circuit. During write time slots, the delay circuit determines when the DS2432
will sample the data line. For a read data time slot, if a “0” is to be transmitted, the delay circuit
determines how long the DS2432 will hold the data line low. If the data bit is a “1”, the DS2432 will not
hold the data line low at all.
READ/WRITE TIMING DIAGRAM Figure 11
Write-one Time Slot
tSLOT
VPULLUP
VPULLUP MIN
VIH MIN
VIL MAX
0V
DS2432
Sampling Window
tLOW1
RESISTOR
15 µs
(OD: 2 µs)
60 µs
(OD: 6 µs)
Write-zero Time Slot
tSLOT
VPULLUP
VPULLUP MIN
VIH MIN
VIL MAX
0V
tREC
MASTER
tREC
DS2432
Sampling Window
15 µs
(OD: 2 µs)
tLOW0
60 µs
(OD: 6 µs)
12 of 17
RESISTOR
MASTER
ABRIDGED DATA SHEET
DS2432
READ/WRITE TIMING DIAGRAM Figure 11 (continued)
Read-data Time Slot
tSLOT
VPULLUP
VPULLUP MIN
VIH MIN
tREC
MASTER *
SAMPLING
WINDOW
VIL MAX
0V
tSU
tLOWR
RESISTOR
tRELEASE
tRDV
MASTER
DS2432
*The optimal sampling point for the master is as close as possible to the end time of the tRDV period
without exceeding tRDV. For the case of a Read-one time slot, this maximizes the amount of time for the
pullup resistor to recover the line to a high level. For a Read-zero time slot it ensures that a read will
occur before the fastest 1-Wire device releases the line (tRELEASE = 0).
CRC GENERATION
With the DS2432 there are two different types of CRCs (Cyclic Redundancy Checks). One CRC is an
8-bit type. It is computed at the factory and lasered into the most significant byte of the 64-bit ROM. The
8
5
4
equivalent polynomial function of this CRC is X + X + X + 1. To determine whether the ROM data has
been read without error the bus master can compute the CRC value from the first 56 bits of the 64-bit
ROM and compare it to the value read from the DS2432. This 8-bit CRC is received in the true form
(non-inverted) when reading the ROM.
The other CRC is a 16-bit type, which is used for error detection with Memory and SHA-1 function
commands. For details (including Figure 12), refer to the full version of the data sheet.
13 of 17
ABRIDGED DATA SHEET
DS2432
ABSOLUTE MAXIMUM RATINGS
Voltage Range on Any Pin Relative to Ground
Operating Temperature Range
Storage Temperature Range
Lead Temperature (TSOC only; soldering, 10s)
Soldering Temperature (reflow)
-0.5V to +5.5V
-40C to +85C
-55C to +125C
+300C
+260C
This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operation
sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect
reliability.
DC ELECTRICAL CHARACTERISTICS
PARAMETER
1-Wire Pullup Voltage
1-Wire Input High
1-Wire Input Low
1-Wire Output Low at 4mA
Input Load Current
Programming Current
SHA-1 Computation Current
CAPACITANCE
PARAMETER
1-Wire I/O
EEPROM
PARAMETER
Write/Erase Cycles
Data Retention (at 85°C)
SYMBOL
VPUP
VIH
VIL
VOL
IL
ILPROG
ICSHA
MIN
2.8
2.2
-0.3
TYP
(TA = -40°C to +85°C.)
UNITS
V
V
0.3
V
0.4
V
5
A
500
A
Refer to the full version of data sheet.
SYMBOL
CIN/OUT
MIN
TYP
100
SYMBOL
NCYCLE
tDRET
MIN
50k
10
TYP
MAX
5.25
MAX
800
NOTES
1, 2
1, 3
1
1
4
5, 6
(TA = +25°C.)
UNITS
pF
NOTES
7
(VPUP = 5.0V, TA = +25°C.)
MAX
UNITS
—
years
NOTES
AC ELECTRICAL CHARACTERISTICS: REGULAR SPEED
(VPUP = 2.8V to 5.25V, TA = -40°C to +85°C.)
PARAMETER
Time Slot
Write 1 Low Time
Write 0 Low Time
Read Low Time
Read Data Valid
Release Time
Read Data Setup
Recovery Time
Reset High Time
Reset Low Time
Presence Detect High
Presence Detect Low
Programming Time
SHA-1 Computation Time
SYMBOL
tSLOT
tLOW1
tLOW0
tLOWR
tRDV
tRELEASE
tSU
tREC
tRSTH
tRSTL
tPDHIGH
tPDLOW
tPROG
tCSHA
MIN
60
1
60
1
UNITS
s
s
s
s
15
s
0
15
45
s
1
s
5
s
480
s
480
s
15
60
s
60
240
s
10
ms
Refer to the full version of data sheet.
14 of 17
TYP
MAX
120
15
120
15
NOTES
8
9
10
11
12
12
ABRIDGED DATA SHEET
DS2432
AC ELECTRICAL CHARACTERISTICS: OVERDRIVE SPEED
(VPUP = 2.8V to 5.25V, TA = -40°C to +85°C.)
PARAMETER
Time Slot
Write 1 Low Time
Write 0 Low Time
Read Low Time
Read Data Valid
Release Time
Read Data Setup
Recovery Time
Reset High Time
Reset Low Time
Presence Detect High
Presence Detect Low
Programming Time
SHA-1 Computation Time
SYMBOL
tSLOT
tLOW1
tLOW0
tLOWR
tRDV
tRELEASE
tSU
tREC
tRSTH
tRSTL
tPDHIGH
tPDLOW
tPROG
tCSHA
MIN
6
1
6
1
UNITS
µs
µs
µs
µs
2
µs
0
1.5
4
µs
1
µs
5
µs
48
µs
48
80
µs
2
6
µs
8
24
µs
10
ms
Refer to the full version of data sheet.
NOTES:
1.
2.
3.
4.
5.
6.
7.
TYP
MAX
16
2
16
2
NOTES
8
9
10
All voltages are referenced to ground.
VPUP = external pullup voltage, see Figure 8.
VIH is a function of the external pullup resistor and VPUP.
Input load is to ground.
During write operations to the EEPROM the voltage on the 1-Wire bus must not fall below 2.8V.
Guaranteed by design, not production tested.
Capacitance on the data pin could be 800 pF when power is first applied. Once the parasite
capacitance is charged, it does not affect normal communication.
8. The optimal sampling point for the master is as close as possible to the end time of the tRDV period
without exceeding tRDV. For the case of a Read-one time slot, this maximizes the amount of time for
the pullup resistor to recover the line to a high level. For a Read-zero time slot it ensures that a read
will occur before the fastest 1-Wire device releases the line (tRELEASE = 0).
9. Read data setup time refers to the time the host must pull the 1-Wire bus low to read a bit. Data is
guaranteed to be valid within 1 µs of this falling edge.
10. Applies to a single device attached to a 1-Wire line and a pullup resistor of maximum 2.2k.
11. The reset low time (tRSTL) should be restricted to a maximum of 960µs, to allow interrupt signaling,
otherwise, it could mask or conceal interrupt pulses.
12. The first presence pulse after power-up could be outside the tPDHIGHmax to (tPDHIGHmin + tPDLOWmin)
interval, but will be complete within 2ms after power-up.
15 of 17
ABRIDGED DATA SHEET
DS2432
PACKAGE INFORMATION
For
the
latest
package
outline
information
and
land
patterns
(footprints),
go
to
www.maximintegrated.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status
only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless
of RoHS status.
PACKAGE TYPE
PACKAGE CODE
OUTLINE NO.
LAND PATTERN NO.
6 TSOC
D6+1
21-0382
90-0321
8 UCSP
BR823+1
21-0373
Refer to Application
Note 1891
16 of 17
ABRIDGED DATA SHEET
DS2432
REVISION HISTORY
REVISION
DATE
040907
060608
2/10
DESCRIPTION
Initial release.
Removed the leaded parts from the Ordering Information table and
corrected package name from CSP to UCSPR.
Removed 64-Bit Registration Number from Overdrive Skip ROM in
Figure 2.
Removed reference to tamper detect register (does not exist).
In Figure 8, changed “5A typ” to “IL”.
In the DC Electrical Characteristics table, added the 1-Wire Pullup
Voltage parameter (VPUP) (moved from the headline into the table) and
removed the 1-Wire Output High parameter (VOH). In the EEPROM table,
added (at +85C) to the Data Retention parameter.
Added Package Information section.
Minor nontechnical corrections to the text (various pages).
Electrical characteristics table: tRECMIN changed from 1µs to 5µs (regular
speed) and 2µs (overdrive speed); VILMAX changed from “TBD” to 0.3V;
SHA-1 computation current added.
UCSP package outline deleted; see section Package Information to access
the latest drawing.
Typo- and style corrections
Original Note 8 deleted from EC table notes and remaining notes
renumbered to conform to Style Guide.
3/12
9/12
Deleted DS2432X+ from the Ordering Information table.
Updated the soldering information and added the lead temperature to the Absolute
Maximum Ratings.
Added Note 12 to AC Electrical Characteristics: Regular Speed table parameters
tPDHIGH and tPDLOW.
Revised the electrical characteristics tables Note 7.
Added the land pattern column to the Package Information table.
Changed Overdrive communication speed from 125kbps to 90.9kbps; changed
Overdrive tRECmin from 2µs to 5µs and updated the Overdrive speed accordingly;
reworded Note 10.
PAGES
CHANGED
—
1
4
7
7
14
16
1, 2, 4, 8, 15
14, 15
16
Various
pages
14, 15
1
14
14
15
16
1, 7, 15
17 of 17
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim
reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical
Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000
© 2012 Maxim Integrated
The Maxim logo and Maxim Integrated are trademarks of Maxim Integrated Products, Inc.
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