DALLAS DS1996L-F5

DS1996
64kbit Memory iButtonTM
www.dalsemi.com
F5 MICROCANTM
SPECIAL FEATURES
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65536 bits of read/write nonvolatile memory
Overdrive mode boosts communication
speed to 142k bits per second
256-bit scratchpad ensures integrity of data
transfer
Memory partitioned into 256-bit pages for
packetizing data
Data integrity assured with strict read/write
protocols
Operating temperature range from -40°C to
+70°C
Over 10 years of data retention
5.89
0.36
0.51
c 1993
16.25
YYWW REGISTERED RR
5E
0C
17.35
000000FBC52B
DATA
GROUND
All dimensions are shown in millimeters
COMMON iButton FEATURES
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Unique, factory-lasered and tested 64-bit
registration number (8-bit family code + 48bit serial number 8-bit CRC tester) assures
absolute traceability because no two parts are
alike
Multidrop controller for MicroLAN
Digital identification and information by
momentary contact
Chip-based data carrier compactly stores
information
Data can be accessed while affixed to object
Economically communicates to bus master
with a single digital signal at 16.3k bits per
second
Standard 16 mm diameter and 1-WireTM
protocol ensure compatibility with iButton
family
Button shape is self-aligning with cupshaped probes
Durable stainless steel case engraved with
registration number withstands harsh
environments
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Easily affixed with self-stick adhesive
backing, latched by its flange, or locked with
a ring pressed onto its rim
Presence detector acknowledges when reader
first applies voltage
Meets UL#913 (4th Edit); Intrinsically Safe
Apparatus, Approved under Entity Concept
for use in Class I, Division 1, Group A, B, C
and D Locations (application pending)
ORDERING INFORMATION
DS1996L-F5
F5 MicroCan
EXAMPLES OF ACCESSORIES
DS9096P
DS9101
DS9093RA
DS9093F
DS9092
1 of 18
Self-Stick Adhesive Pad
Multi-Purpose Clip
Mounting Lock Ring
Snap-In Fob
iButton Probe
91099
DS1996
iButton DESCRIPTION
The DS1996 Memory iButton is a rugged read/write data carrier that acts as a localized database that can
be easily accessed with minimal hardware. The nonvolatile memory offers a simple solution to storing
and retrieving vital information pertaining to the object to which the iButton is attached. Data is
transferred serially via the 1-Wire protocol which requires only a single data lead and a ground return.
The scratchpad is an additional page that acts as a buffer when writing to memory. Data is first written to
the scratchpad where it can be read back. After the data has been verified, a copy scratchpad command
will transfer the data to memory. This process ensures data integrity when modifying the memory. A 48bit serial number is factory lasered into each DS1996 to provide a guaranteed unique identity which
allows for absolute traceability. The durable MicroCan package is highly resistant to environmental
hazards such as dirt, moisture, and shock. Its compact button-shaped profile is self-aligning with mating
receptacles, allowing the DS1996 to be easily used by human operators. Accessories permit the DS1996
to be mounted on almost any surface including plastic key fobs, photo-ID badges and printed circuit
boards. Applications include access control, work-in-progress tracking, electronic travelers, storage of
calibration constants, and debit tokens.
OVERVIEW
The block diagram in Figure 1 shows the relationships between the major control and memory sections of
the DS1996. The DS1996 has three main data components: 1) 64-bit lasered ROM, 2) 256-bit scratchpad
and 3) 65536-bit SRAM. The hierarchial structure of the 1-Wire protocol is shown in Figure 2. The bus
master must first provide one of the six ROM Function Commands, 1)Read ROM, 2) Match ROM, 3)
Search ROM, 4) Skip ROM, 5) Overdrive-Skip ROM or Overdrive-Match ROM. Upon completion of an
overdrive ROM command byte executed at standard 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 functions become accessible and the master may provide any one of the four memory function
commands. The protocol for these memory function commands is described in Figure 7. All data read and
written least significant bit first.
PARASITE POWER
The block diagram (Figure 1) shows the parasite-powered circuitry. This circuitry ”steals” power
whenever the data line is high. The data line will provide sufficient power as long as the specified timing
and voltage requirements are met. The advantages of parasite power are two-fold: 1) by parasiting off this
input, lithium is conserved and 2) if the lithium is exhausted for any reason, the ROM may still be read
normally.
64-BIT LASERED ROM
Each DS1996 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.
(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 Dallas 1Wire Cyclic Redundancy Check is available in the Book of DS19xx iButton Standards.
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.
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DS1996
DS1996 BLOCK DIAGRAM Figure 1
3 of 18
DS1996
HIERARCHICAL STRUCTURE FOR 1-WIRE PROTOCOL Figure 2
BUS
MASTER
OTHER
DEVICES
1-WIRE BUS
DS 1996
COMMAND
LEVEL:
1-WIRE ROM FUNCTION
COMMANDS (SEE FIGURE 9)
DS 1996- SPECIFIC
MEMORY FUNCTION
COMMANDS
(SEE FIGURE 7)
AVAILABLE
COMMANDS:
DATA FIELDS
AFFECTED:
READ ROM
MATCH ROM
SEARCH ROM
SKIP ROM
OVERDRIVE SKIP ROM
OVERDRIVE MATCH ROM
64-BIT ROM
64-BIT ROM
64-BIT ROM
N/A
N/A
64-BIT ROM
WRITE SCRATCHPAD
READ SCRATCHPAD
COPY SCRATCHPAD
READ MEMORY
256-BIT SCRATCHPAD
256-BIT SCRATCHPAD
64K-BIT MEMORY
64K-BIT MEMORY
64-BIT LASERED ROM Figure 3
8-Bit CRC Code
MSB
LSB
48-Bit Serial Number
MSB
8-Bit Family Code (0CH)
LSB MSB
1-WIRE CRC GENERATOR Figure 4
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LSB
DS1996
MEMORY
The memory map in Figure 5 shows a 32-byte page called the scratchpad and additional 32-byte pages
called memory. The DS1996 contains 256 pages which comprise the 65536-bit SRAM. The scratchpad is
an additional page that acts as a buffer when writing to memory.
ADDRESS REGISTERS AND TRANSFER STATUS
Because of the serial data transfer, the DS1996 employs three address registers, called TA1, TA2 and E/S
(Figure 6). Registers TA1 and TA2 must be loaded with the target address to which the data will be
written or from which data will be sent to the master upon a Read command. Register E/S acts like a byte
counter and Transfer Status register. It is used to verify data integrity with Write commands. Therefore,
the master only has read access to this register. The lower five bits of the E/S register indicate the address
of the last byte that has been written to the scratchpad. This address is called Ending Offset. Bit 5 of the
E/S register, called PF or ”partial byte flag,” is set if the number of data bits sent by the master is not an
integer multiple of 8. Bit 6, OF or ”Overflow,” is set if more bits are sent by the master than can be stored
in the scratchpad. Note that the lowest five bits of the target address also determine the address within the
scratchpad, where intermediate storage of data will begin. This address is called byte offset. If the target
address for a Write command is 13CH for example, then the scratchpad will store incoming data
beginning at the byte offset 1CH and will be full after only four bytes. The corresponding ending offset in
this example is 1FH. For best economy of speed and efficiency, the target address for writing should
point to the beginning of a new page, i.e., the byte offset will be 0. Thus the full 32-byte capacity of the
scratchpad is available, resulting also in the ending offset of 1FH. However, it is possible to write one or
several contiguous bytes somewhere within a page. The ending offset together with the Partial and
Overflow Flag is mainly a means to support 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.
WRITING WITH VERIFICATION
To write data to the DS1996, 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. In the next step, the master sends the Read Scratchpad command to read the scratchpad
and to verify data integrity. As preamble to the scratchpad data, the DS1996 sends the requested target
address TA1 and TA2 and the contents of the E/S register. If one of the flags OF or PF is set, data did not
arrive correctly in 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 indicates that the Write command was not
recognized by the iButton. If everything went correctly, all three flags are cleared and the ending offset
indicates the address of the last byte written to the scratchpad. Now the master can continue verifying
every data bit. After the master has verified the data, it has to send the Copy Scratchpad command. This
command must be followed exactly by the data of the three address registers TA1, TA2 and E/S as the
master has read them verifying the scratchpad. As soon as the iButton has received these bytes, it will
copy the data to the requested location beginning at the target address.
MEMORY FUNCTION COMMANDS
The “Memory Function Flow Chart” (Figure 7) describes the protocols necessary for accessing the
memory. An example follows the flowchart. The communication between master and DS1996 takes place
either at regular speed (default, OD=0) or at Overdrive Speed (OD=1). If not explicitely set into the
Overdrive Mode the DS1996 assumes regular speed.
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DS1996
Write Scratchpad Command [0FH]
After issuing the write scratchpad command, the master must first provide the 2-byte target address,
followed by the data to be written to the scratchpad. The data will be written to the scratchpad starting at
the byte offset (T4:T0). The ending offset (E4: E0) will be the byte offset at which the bus master has
stopped writing data.
Read Scratchpad Command [AAH]
This command is used to verify scratchpad data and target address. After issuing the read scratchpad
command, the master begins reading. The first two bytes will be the target address. The next byte will be
the ending offset/data status byte (E/S) followed by the scratchpad data beginning at the byte offset (T4:
T0). The master may read data until the end of the scratchpad after which the data read will be all logic
1’s.
DS1996 MEMORY MAP Figure 5
ADDRESS REGISTERS Figure 6
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DS1996
MEMORY FUNCTION FLOW CHART Figure 7
1)
2)
TO BE TRANSMITTED OR RECEIVED AT OVERDRIVE SPEED IF OD=1
RESET PULSE TO BE TRANSMITTED AT OVERDRIVE SPEED IF OD=1;
RESET PULSE TO BE TRANSMITTED AT REGULAR SPEED IF OD=0
OR IF THE DS1996 IS TO BE RESET FROM OVERDRIVE SPEED TO REGULAR SPEED
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DS1996
MEMORY FUNCTION EXAMPLES
Example: Write two data bytes to memory locations 0026h and 0027h (the seventh and eighth bytes of
page 1). Read entire memory.
MASTER MODE
TX
RX
TX
TX
TX
TX
TX
TX
RX
TX
TX
RX
RX
RX
RX
TX
RX
TX
TX
TX
TX
TX
TX
RX
TX
TX
TX
TX
RX
TX
RX
DATA (LSB FIRST)
Reset
Presence
CCh
0Fh
26h
00h
<2 data bytes>
Reset
Presence
CCh
AAh
26h
00h
07h
<2 data bytes>
Reset
Presence
CCh
55h
26h
00h
07h
Reset
Presence
CCh
F0h
00h
00h
<8192 bytes>
Reset
Presence
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COMMENTS
Reset pulse (480-960 µs)
Presence pulse
Issue “skip ROM” command
Issue “write scratchpad” command
TA1, beginning offset=6
TA2, address=0026h
Write 2 bytes of data to scratchpad
Reset pulse
Presence pulse
Issue “skip ROM” command
Issue “read scratchpad” command
Read TA1, beginning offset=6
Read TA2, address=0026h
Read E/S, ending offset=7, flags=0
Read scratchpad data and verify
Reset pulse
Presence pulse
Issue “skip ROM” command
Issue “copy scratchpad” command
TA1
TA2 AUTHORIZATION CODE
E/S
Reset pulse
Presence pulse
Issue “skip ROM” command
Issue “read memory” command
TA1, beginning offset=0
TA2, address=0000h
Read entire memory
Reset pulse
Presence pulse, done
DS1996
Copy Scratchpad [55H]
This command is used to copy data from the scratchpad to memory. After issuing the copy scratchpad
command, the master must provide a 3-byte authorization pattern which is obtained by reading the
scratchpad for verification. This pattern must exactly match the data contained in the three address
registers (TA1, TA2, E/S, in that order). If the pattern matches, the AA (Authorization Accepted) flag
will be set and the copy will begin. A logic 0 will be transmitted after the data has been copied until a
reset pulse is issued by the master. Any attempt to reset the part will be ignored while the copy is in
progress. Copy typically takes 30 µs.
The data to be copied is determined by the three address registers. The scratchpad data from the
beginning offset through the ending offset, will be copied to memory, starting at the target address.
Anywhere from 1 to 32 bytes may be copied to memory with this command. Whole bytes are copied
even if only partially written. The AA flag will be cleared only by executing a write scratchpad
command.
Read Memory [F0H]
The read memory command may be used to read the entire memory. After issuing the command, the
master must provide the 2-byte target address. After the two bytes, the master reads data beginning from
the target address and may continue until the end of memory, at which point logic 1’s will be read. It is
important to realize that the target address registers will contain the address provided. The ending
offset/data status byte is unaffected.
The hardware of the DS1996 provides a means to accomplish error-free writing to the memory section.
To safeguard reading data in the 1-Wire environment and to simultaneously speed up data transfers, it is
recommended to packetize data into data packets of the size of one memory page each. Such a packet
would typically store a 16-bit CRC with each page of data to ensure rapid, error-free data transfers that
eliminate having to read a page multiple times to determine if the received data is correct or not. (See the
Book of DS19xx iButton Standards, Chapter 7 for the recommended file structure to be used with the 1Wire environment.)
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
DS1996 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 specified time slots that are initiated on the falling edge of sync pulses from the bus master. For a
more detailed protocol description, refer to Chapter 4 of the Book of DS19xx iButton Standards.
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 connection or 3-state outputs. The 1-Wire port of the DS1996 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 16.3k bits per second. The speed
can be boosted to 142k bits per second by activating the Overdrive Mode. The 1-Wire bus requires a
pullup resistor of approximately 5 kΩ.
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
9 of 18
DS1996
for more than 16 µs (Overdrive Speed) or more than 120 µs (regular speed), one or more of the devices
on the bus may be reset.
HARDWARE CONFIGURATION Figure 8
Rx= RECEIVE
Tx = TRANSMIT
TRANSACTION SEQUENCE
The protocol for accessing the DS1996 via the 1-Wire port is as follows:
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Initialization
§
ROM Function Command
§
Memory 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 DS1996 is on the bus and is ready to operate. For
more details, see the ”1-Wire Signaling” section.
ROM FUNCTION COMMANDS
Once the bus master has detected a presence, it can issue one of the six ROM function commands. 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 DS1996’s 8-bit family code, unique 48-bit serial
number, and 8-bit CRC. This command can only be used if there is a single DS1996 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
will usually result in a mismatch of the CRC.
10 of 18
DS1996
Match ROM [55H]
The match ROM command, followed by a 64-bit ROM sequence, allows the bus master to address a
specific DS1996 on a multidrop bus. Only the DS1996 that exactly matches the 64-bit ROM sequence
will respond to the subsequent memory function command. All slaves that do not match the 64-bit ROM
sequence will wait for a reset pulse. This command can be used with a single or multiple devices on the
bus.
Skip ROM [CCH]
This command can save time in a single drop bus system by allowing the bus master to access the
memory functions without providing the 64-bit ROM code. If more than one slave is present on the bus
and 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).
Search ROM [F0H]
When a system is initially brought up, the bus master might not know the number of devices on the 1Wire bus or their 64-bit ROM codes. The search ROM command allows the bus master to use a process
of elimination to identify the 64-bit ROM codes 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 simple, 3-step routine on each bit of the ROM.
After one complete pass, the bus master knows the contents of the ROM in one device. The remaining
number of devices and their ROM codes may be identified by additional passes. See Chapter 5 of the
Book of DS19xx iButton Standards for a comprehensive discussion of a search ROM, including an actual
example.
Overdrive Skip ROM [3CH]
On a single-drop bus this command can save time by allowing the bus master to access the memory
functions without providing the 64-bit ROM code. Unlike the normal Skip ROM command the Overdrive
Skip ROM sets the DS1996 in the Overdrive Mode (OD=1). All communication following this command
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-capable devices into Overdrive
mode. To subsequently address a specific Overdrive-capable device, a reset pulse at Overdrive speed has
to be issued followed by a Match ROM or Search ROM command sequence. This will shorten the time
for the search process. If more than one slave supporting Overdrive 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).
Overdrive Match ROM [69H]
The Overdrive Match ROM command, followed by a 64-bit ROM sequence transmitted at Overdrive
Speed, allows the bus master to address a specific DS1996 on a multidrop bus and to simultaneously set it
in Overdrive Mode. Only the DS1996 that exactly matches the 64-bit ROM sequence will respond to the
subsequent memory function command. Slaves already in Overdrive mode from a previous Overdrive
Skip or Match command will remain in Overdrive mode. All other slaves that do not match the 64-bit
ROM sequence or do not support Overdrive will return to or remain at regular speed and wait for a reset
pulse of minimum 480 µs duration. The Overdrive Match ROM command can be used with a single or
multiple devices on the bus.
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DS1996
1-WIRE SIGNALING
The DS1996 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. All these signals except presence pulse are initiated by the bus master. The DS1996 can
communicate at two different speeds, regular speed and Overdrive speed. If not explicitly set into the
overdrive mode, the DS1996 will communicate at regular speed. While in Overdrive Mode the fast timing
applies to all wave forms.
The initialization sequence required to begin any communication with the DS1996 is shown in Figure 10.
A reset pulse followed by a presence pulse indicates the DS1996 is ready to send or receive data given the
correct ROM command and memory function command. 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 contact, the DS1996 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 DS1996 is in Overdrive Mode and the Reset Pulse is no longer than 80 µs the device will remain in
Overdrive Mode.
12 of 18
DS1996
ROM FUNCTIONS FLOW CHART Figure 9
1)
TO BE TRANSMITTED OR RECEIVED AT OVERDRIVE
SPEED IF OD=1
2) THE PRESENCE PULSE WILL BE SHORT IF OD=1
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DS1996
ROM FUNCTIONS FLOW CHART Figure 9 (cont’d)
3) ALWAYS TO BE TRANSMITTED AT OVERDRIVE SPEED
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DS1996
INITIALIZATION PROCEDURE “RESET AND PRESENCE PULSES” Figure 10
RESISTOR
MASTER
DS1996
Regular Speed
480 µs ≤ tRSTL < ∞ *
480 µs ≤ tRSTH < ∞ (includes recovery time)
15 µs ≤ PDH < 60 µs
60 µs ≤ tPDL < 240 µs
Overdrive Speed
48 µs ≤ tRSTL < 80 µs
48 µs ≤ tRSTH < ∞
2 µs ≤ tPDH < 6 µs
8 µs ≤ tPDL < 24 µs
* In order not to mask interrupt signaling by other devices on the 1-Wire bus, tRSTL + tR should always be
less than 960 µs.
READ/WRITE TIME SLOTS
The definitions of write and read time slots are illustrated in Figure 11. All time slots are initiated by the
master driving the data line low. The falling edge of the data line synchronizes the DS1996 to the master
by triggering a delay circuit in the DS1996. During write time slots, the delay circuit determines when the
DS1996 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 DS1996 will hold the data line low overriding the 1 generated by the master. If
the data bit is a ”1”, the iButton will leave the read data time slot unchanged.
READ/WRITE TIMING DIAGRAM Figure 11
Write-One Time Slot
RESISTOR
MASTER
Regular Speed
60 µs ≤ tSLOT < 120 µs
1 µs ≤ tLOW1 < 15 µs
1 µs ≤ tREC < ∞
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Overdrive Speed
6 µs ≤ tSLOT < 16 µs
1 µs ≤ tLOW1 < 2 µs
1 µs ≤ tREC < ∞
DS1996
READ/WRITE TIMING DIAGRAM Figure 11 (cont’d)
Write-Zero Time Slot
Regular Speed
60 µs ≤ tLOW0 < tSLOT < 120 µs
1 µs ≤ tREC < ∞
Overdrive Speed
6 µs ≤ tLOW0 < tSLOT < 16 µs
1 µs ≤ tREC < ∞
Read-Data Time Slot
RESISTOR
MASTER
DS1996
Regular Speed
60 µs ≤ tSLOT < 120 µs
1 µs ≤ tLOWR < 15 µs
0 ≤ tRELEASE < 45 µs
1 µs ≤ tREC < ∞
tRDV = 15 µs
tSU < 1 µs
16 of 18
Overdrive Speed
6 µs ≤ tSLOT < 16 µs
1 µs ≤ tLOWR < 2 µs
0 ≤ tRELEASE < 4 µs
1 µs ≤ tREC < ∞
tRDV = 2 µs
tSU < 1 µs
DS1996
PHYSICAL SPECIFICATIONS
Size
Weight
Humidity
Altitude
Expected Service Life
Safety
See mechanical drawing
3.3 grams (F5 package)
90% RH at 50°C
10,000 feet
10 years at 25°C
Meets UL#913 (4th Edit.); Intrinsically Safe
Apparatus, Approved under Entity Concept
for use in Class I, Division 1, Group A, B, C
and D Locations (application pending)
ABSOLUTE MAXIMUM RATINGS*
Voltage on any Pin Relative to Ground
Operating Temperature
Storage Temperature
∗
-0.5V to +7.0V
-40°C to +70°C
-40°C to +70°C
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
Logic 1
Logic 0
Output Logic Low @ 4 mA
Output Logic High
Input Load Current
SYMBOL
VIH
VIL
VOL
VOH
IL
(VPUP=2.8V to 6.0V, -40°C to +70°C)
MIN
2.2
-0.3
TYP
VPUP
5
MAX
VCC +0.3
+0.8
0.4
6.0
CAPACITANCE
PARAMETER
I/O (1-Wire)
NOTES
1, 8
1
1
1, 2
3
(TA = 25°C)
SYMBOL
CIN/OUT
MIN
TYP
100
MAX
800
AC ELECTRICAL CHARACTERISTICS REGULAR SPEED
PARAMETER
Time Slot
Write 1 Low Time
Write 0 Low Time
Read Data Valid
Release Time
Read Data Setup
Recovery Time
Reset Time High
Reset Time Low
Presence Detect High
Presence Detect Low
UNITS
V
V
V
V
µA
SYMBOL
tSLOT
tLOW1
tLOW0
tRDV
tRELEASE
tSU
tREC
tRSTH
tRSTL
tPDH
tPDL
MIN
60
1
60
0
1
480
480
15
60
17 of 18
TYP
exactly 15
15
MAX
120
15
120
45
1
60
240
UNITS
pF
NOTES
6
(-40°C to 70°C)
UNITS
µs
µs
µs
µs
µs
µs
µs
µs
µs
µs
µs
NOTES
5
4
7
DS1996
AC ELECTRICAL CHARACTERISTICS OVERDRIVE SPEED
PARAMETER
Time Slot
Write 1 Low Time
Write 0 Low Time
Read Data Valid
Release Time
Read Data Setup
Recovery Time
Reset Time High
Reset Time Low
Presence Detect High
Presence Detect Low
SYMBOL
tSLOT
tLOW1
tLOW0
tRDV
tRELEASE
tSU
tREC
tRSTH
tRSTL
tPDH
tPDL
MIN
6
1
6
0
1
48
48
2
8
TYP
exactly 2
1.5
MAX
16
2
16
4
1
80
6
24
(-40°C to 70°C)
UNITS
µs
µs
µs
µs
µs
µs
µs
µs
µs
µs
µs
NOTES
5
4
NOTES:
1. All voltages are referenced to ground.
2. VPUP = external pullup voltage.
3. Input load is to ground.
4. An additional reset or communication sequence cannot begin until the reset high time has expired.
5. 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.
6. Capacitance on the data contact could be 800 pF when power is first applied. If a 5 kΩ resistor is used
to pullup the data line to VCC, 5 ms after power has been applied, the parasite capacitance will not
affect normal communications.
7. The reset low time (tRSTL) should be restricted to a maximum of 960 µs, to allow interrupt signaling,
otherwise, it could mask or conceal interrupt pulses.
8. VIH is a function of the external pullup resistor and the VCC power supply.
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