DS1990A-F5+ [MAXIM]
Serial Number iButton; 序列号iButton
| 型号： | DS1990A-F5+ |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Serial Number iButton |
| 文件： | 总10页 (文件大小：149K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Rev: 10/08
Serial Number iButton
DS190A
General Description
Features
♦ Can Be Read in Less Than 5ms
®
The DS1990A serial number iButton is a rugged data
carrier that serves as an electronic registration number
for automatic identification. Data is transferred serially
♦ Operating Range: 2.8V to 6.0V, -40°C to +85°C
®
through the 1-Wire protocol, which requires only a sin-
Common iButton Features
gle data lead and a ground return. Every DS1990A is
factory lasered with a guaranteed unique 64-bit regis-
tration number that allows for absolute traceability. The
durable stainless-steel iButton package is highly resis-
tant to environmental hazards such as dirt, moisture,
and shock. Its compact coin-shaped profile is self-
aligning with mating receptacles, allowing the DS1990A
to be used easily by human operators. Accessories
enable the DS1990A iButton to be mounted on almost
any object, including containers, pallets, and bags.
♦ Unique Factory-Lasered 64-Bit Registration
Number Ensures Error-Free Device Selection and
Absolute Traceability Because No Two Parts are
Alike
♦ Built-In Multidrop Controller for 1-Wire Net
♦ Digital Identification by Momentary Contact
♦ Data Can Be Accessed While Affixed to Object
♦ Economically Communicates to Bus Master with
Applications
a Single Digital Signal at 16.3kbps
Access Control
♦ Button Shape is Self-Aligning with Cup-Shaped
Work-In-Progress Tracking
Tool Management
Probes
♦ Durable Stainless-Steel Case Engraved with
Registration Number Withstands Harsh
Environments
Inventory Control
Ordering Information
♦ Easily Affixed with Self-Stick Adhesive Backing,
Latched by its Flange, or Locked with a Ring
Pressed Onto its Rim
PART
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
F5 iButton
DS1990A-F5+
DS1990A-F3+
F3 iButton
Pin Configurations
+Denotes a lead-free/RoHS-compliant package.
F3 SIZE
F5 SIZE
Examples of Accessories
3.10mm
5.89mm
0.51mm
0.51mm
BRANDING
PART
DS9096P
DS9101
ACCESSORY
Self-Stick Adhesive Pad
Multipurpose Clip
Mounting Lock Ring
Snap-In Fob
16.25mm
DS9093RA
DS9093A
DS9092
89
01
®
000000FBC52B
®
1-Wire
iButton Probe
17.35mm
D
IO
IO
GND
GND
iButton and 1-Wire are registered trademarks of Maxim
Integrated Products, Inc.
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
Serial Number iButton
ABSOLUTE MAXIMUM RATINGS
IO Voltage Range to GND.....................................-0.5V to +6.0V
IO Sink Current....................................................................20mA
Junction Temperature......................................................+125°C
Storage Temperature Range.............................-55°C to +125°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
DS190A
ELECTRICAL CHARACTERISTICS
(T = -40°C to +85°C.)
A
PARAMETER
IO PIN: GENERAL DATA
1-Wire Pullup Voltage
1-Wire Pullup Resistance
Input Capacitance
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
V
R
(Notes 1, 2)
(Notes 3, 4)
(Notes 5, 6)
(Note 7)
2.8
0.6
6.0
5
V
kꢀ
pF
μA
V
PUP
PUP
C
100
800
IO
L
Input Load Current
I
0.25
Input Low Voltage
V
(Notes 1, 3, 8)
(Notes 1, 9)
(Note 1)
0.3
0.4
IL
Input High Voltage
V
2.2
V
IH
OL
Output Low Voltage at 4mA
Operating Charge
V
V
Q
OP
(Notes 6, 10)
(Note 3)
30
nC
μs
μs
Recovery Time
t
1
REC
Time Slot Duration
t
(Note 3)
61
SLOT
IO PIN: 1-Wire RESET, PRESENCE-DETECT CYCLE
Reset Low Time
t
(Notes 3, 11)
(Notes 3, 12)
480
480
15
μs
μs
μs
μs
μs
RSTL
Reset High Time
t
RSTH
Presence-Detect High Time
Presence-Detect Low Time
Presence-Detect Sample Time
IO PIN: 1-Wire WRITE
Write-Zero Low Time
Write-One Low Time
IO PIN: 1-Wire READ
Read Low Time
t
60
240
75
PDH
t
(Note 13)
(Note 3)
60
PDL
t
60
MSP
t
t
(Notes 3, 14)
(Notes 3, 14)
60
1
120
15
μs
μs
W0L
W1L
t
RL
(Notes 3, 15)
(Notes 3, 15)
1
15 - ꢁ
μs
μs
Read Sample Time
t
t
+ ꢁ
15
MSR
RL
Note 1: All voltages are referenced to ground.
Note 2: External pullup voltage. See Figure 4.
Note 3: System requirement.
Note 4: Full R
range is guaranteed by design and simulation and not production tested. Production testing performed at a
PUP
fixed R
value. Maximum allowable pullup resistance is a function of the number of 1-Wire devices in the system and 1-
PUP
Wire recovery times. The specified value here applies to systems with only one device and with the minimum 1-Wire recov-
ery times. For more heavily loaded systems, an active pullup such as that found in the DS2480B may be required.
Note 5: Capacitance on the IO pin could be 800pF when power is first applied. If a 5kΩ resistor is used to pull up the IO line to
V , 5µs after power has been applied the parasite capacitance will not affect normal communications.
PUP
Note 6: Guaranteed by design, simulation only. Not production tested.
Note 7: Input load is to ground.
2
_______________________________________________________________________________________
Serial Number iButton
DS190A
Note 8: The voltage on IO must be less than or equal to V
whenever the master drives the line low.
ILMAX
Note 9:
V
IH
is a function of the internal supply voltage.
Note 10: 30nC per 72 time slots at 5.0V pullup voltage with a 5kΩ pullup resistor and t
≤ 120µs.
SLOT
Note 11: The reset low time (t
) should be restricted to a maximum of 960µs to allow interrupt signaling. A longer duration could
RSTL
mask or conceal interrupt pulses if this device is used in parallel with a DS1994.
Note 12: An additional reset or communication sequence cannot begin until the reset high time has expired.
Note 13: Presence pulse is guaranteed only after a preceding reset pulse (t
).
RSTL
Note 14: ε in Figure 7 represents the time required for the pullup circuitry to pull the voltage on IO up from V to V . The actual
IL
IH
maximum duration for the master to pull the line low is t
+ t - ε and t
+ t - ε, respectively.
W0LMAX F
W1LMAX
F
Note 15: δ in Figure 7 represents the time required for the pullup circuitry to pull the voltage on IO up from V to the input-high
IL
threshold of the bus master. The actual maximum duration for the master to pull the line low is t
+ t .
RLMAX
F
iButton CAN PHYSICAL SPECIFICATION
SIZE
See the Package Information section.
WEIGHT (DS1990A)
Ca. 2.5 grams
parasite power block. The ROM function control unit
includes the 1-Wire interface and the logic to implement
the ROM function commands, which access 64 bits of
lasered ROM.
Detailed Description
The block diagram in Figure 1 shows the major function
blocks of the device. The DS1990A takes the energy it
needs to operate from the IO line, as indicated by the
PARASITE POWER
DS1990A
ROM
FUNCTION CONTROL
64-BIT
LASERED ROM
IO
Figure 1. Block Diagram
_______________________________________________________________________________________
3
Serial Number iButton
64-Bit Lasered ROM
Each DS1990A contains a unique ROM code that is 64
bits long. The first 8 bits are a 1-Wire family code. The
next 48 bits are a unique serial number. The last 8 bits
are a CRC of the first 56 bits. See Figure 2 for details.
The 1-Wire CRC is generated using a polynomial gen-
erator consisting of a shift register and XOR gates as
shown in Figure 3. The polynomial is X + X + X + 1.
Additional information about the 1-Wire Cyclic
Redundancy Check (CRC) is available in Application
Note 27: Understanding and Using Cyclic Redundancy
Checks with Maxim iButton Products.
1-Wire Bus System
The 1-Wire bus is a system that has a single bus master
and one or more slaves. In all instances, the DS1990A
is a slave device. The bus master is typically a micro-
controller or PC. For small configurations, the 1-Wire
communication signals can be generated under soft-
ware control using a single port pin. Alternatively, the
DS2480B 1-Wire line driver chip or serial-port adapters
based on this chip (DS9097U series) can be used. This
simplifies the hardware design and frees the micro-
processor from responding in real time. The discussion
of this bus system is broken down into three topics:
hardware configuration, transaction sequence, and
1-Wire signaling (signal types and timing). The 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. For a
more detailed protocol description, refer to Chapter 4 of
the Book of iButton Standards.
8
5
4
DS190A
The shift register bits are initialized to 0. 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, 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 8
bits of CRC returns the shift register to all 0s.
MSB
LSB
8-BIT
CRC CODE
8-BIT FAMILY CODE
48-BIT SERIAL NUMBER
(01h)
MSB
LSB MSB
LSB MSB
LSB
Figure 2. 64-Bit Lasered ROM
8
5
4
POLYNOMIAL = X + X + X + 1
1ST
STAGE
2ND
STAGE
3RD
STAGE
4TH
STAGE
5TH
STAGE
6TH
STAGE
7TH
STAGE
8TH
STAGE
0
1
2
3
4
5
6
7
8
X
X
X
X
X
X
X
X
X
INPUT DATA
Figure 3. 1-Wire CRC Generator
4
_______________________________________________________________________________________
Serial Number iButton
DS190A
for more than 120µs, one or more devices on the bus
may be reset.
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
three-state outputs. The 1-Wire port of the DS1990A is
open drain with an internal circuit equivalent to that
shown in Figure 4. A multidrop bus consists of a 1-Wire
bus with multiple slaves attached. At standard speed,
the 1-Wire bus has a maximum data rate of 16.3kbps.
The value of the pullup resistor primarily depends on
the network size and load conditions. For most applica-
tions, the optimal value of the pullup resistor is approxi-
mately 2.2kΩ. 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
Transaction Sequence
The protocol for accessing the DS1990A through the
1-Wire port is as follows:
• Initialization
• ROM Function Command
Initialization
All transactions on the 1-Wire bus begin with an initial-
ization 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
DS1990A is on the bus and is ready to operate. For
more details, see the 1-Wire Signaling section.
V
PUP
SIMPLE BUS MASTER
DS1990A 1-Wire PORT
R
PUP
DATA
Rx
Rx
Tx
Tx
Rx = RECEIVE
Tx = TRANSMIT
100Ω MOSFET
OPEN-DRAIN
PORT PIN
DS2480B BUS MASTER
+5V
V
DD
V
PP
HOST CPU
POL
RXD
TXD
1-W
N.C.
GND
TO 1-Wire DATA
SERIAL IN
SERIAL OUT
SERIAL
PORT
DS2480B
Figure 4. Hardware Configuration
_______________________________________________________________________________________
5
Serial Number iButton
1-Wire ROM Function Commands
Once the bus master has detected a presence, it can
issue one of the ROM function commands the DS1990A
supports. All ROM function commands are 8 bits long.
A list of these commands follows. (See Figure 5 for a
flowchart.)
BUS MASTER Tx
RESET PULSE
BUS MASTER Tx ROM
FUNCTION COMMAND
DS1990A Tx
PRESENCE PULSE
Read ROM [33h]
This command allows the bus master to read the
DS1990A’s 8-bit family code, unique 48-bit serial num-
ber, and 8-bit CRC. This command can only be used if
there is a single slave device on the bus. If more than one
slave is present on the bus, a data collision occurs when
all slaves try to transmit at the same time (open drain pro-
duces a wired-AND result). The resultant family code and
48-bit serial number results in a mismatch of the CRC.
DS190A
33h
READ ROM
COMMAND?
F0h
SEARCH ROM
COMMAND?
N
N
Y
Y
DS1990A Tx
FAMILY CODE
(1 BYTE)
DS1990A Tx BIT 0
DS1990A Tx BIT 0
MASTER Tx BIT 0
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 registration numbers. By taking advantage
of the wired-AND property of the bus, the master can
use a process of elimination to identify the registration
numbers of all slave devices. For each bit of the regis-
tration number, starting with the least significant bit, the
bus master issues a triplet of time slots. On the first slot,
each slave device participating in the search outputs
the true value of its registration number bit. On the sec-
ond slot, each slave device participating in the search
outputs the complemented value of its registration num-
ber bit. On the third slot, the master writes the true
value of the bit to be selected. All slave devices that do
not match the bit written by the master stop participat-
ing in the search. If both of the read bits are zero, the
master knows that slave devices exist with both states
of the bit. By choosing which state to write, the bus
master branches in the ROM code tree. After one com-
plete pass, the bus master knows the registration num-
ber of a single device. Additional passes identify the
registration numbers of the remaining devices. Refer to
Application Note 187: 1-Wire Search Algorithm for a
detailed discussion, including an example.
N
BIT 0 MATCH?
Y
DS1990A Tx
SERIAL NUMBER
(6 BYTES)
DS1990A Tx BIT 1
DS1990A Tx BIT 1
MASTER Tx BIT 1
N
BIT 1 MATCH?
Y
DS1990A Tx
CRC BYTE
DS1990A Tx BIT 63
DS1990A Tx BIT 63
MASTER Tx BIT 63
N
Match ROM [55h]/Skip ROM [CCh]
The minimum set of 1-Wire ROM function commands
includes a Match ROM and a Skip ROM command.
Because the DS1990A contains only the 64-bit ROM
without any additional data fields, Match ROM and Skip
ROM are not applicable. The DS1990A remains silent
(inactive) upon receiving a ROM function command
that it does not support. This allows the DS1990A to
coexist on a multidrop bus with other 1-Wire devices
that do respond to Match ROM or Skip ROM.
BIT 63 MATCH?
Y
Figure 5. ROM Functions Flowchart
6
_______________________________________________________________________________________
Serial Number iButton
DS190A
detect a presence pulse, the master must test the logi-
1-Wire Signaling
cal state of the 1-Wire line at t
.
MSP
The DS1990A requires strict protocols to ensure data
integrity. The protocol consists of four types of signaling
on one line: reset sequence with reset pulse and pres-
ence pulse, write-zero, write-one, and read-data.
Except for the presence pulse, the bus master initiates
all these signals.
Read/Write Time Slots
Data communication with the DS1990A takes place in
time slots that carry a single bit each. Write time slots
transport data from bus master to slave. Read time
slots transfer data from slave to master. The definitions
of the write and read time slots are illustrated in
Figure 7.
To get from idle to active, the voltage on the 1-Wire line
needs to fall from V
to below V
. To get from
ILMAX
PUP
active to idle, the voltage needs to rise from V
to
ILMAX
All communication begins with the master pulling the
data line low. As the voltage on the 1-Wire line falls
above V
. The time it takes for the voltage to make
IHMIN
this rise, referenced as ε in Figure 6, depends on the
below V
, the DS1990A starts its internal timing
ILMAX
value of the pullup resistor (R
the 1-Wire network attached.
) and capacitance of
PUP
generator that determines when the data line is sam-
pled during a write time slot and how long data is valid
during a read time slot.
The initialization sequence required to begin any com-
munication with the DS1990A is shown in Figure 6. A
reset pulse followed by a presence pulse indicates that
the DS1990A is ready to receive a ROM function com-
mand. If the bus master uses slew-rate control on the
Master-to-Slave
For a write-one time slot, the voltage on the data line
must have risen above V
after the write-one low
IHMIN
time t
is expired. For a write-zero time slot, the
W1LMAX
falling edge, it must pull down the line for t
compensate for the edge.
+ t to
F
RSTL
voltage on the data line must stay below V
until
ILMAX
the write-zero low time t
is expired. For most reli-
W0LMIN
After the bus master has released the line, it goes into
receive mode (Rx). Now the 1-Wire bus is pulled to
able communication, the voltage on the data line
should not exceed V
during the entire t
win-
ILMAX
W0L
V
through the pullup resistor or, in the case of a
PUP
dow. After the voltage has risen above V
, the
IHMIN
DS2480B driver, by active circuitry. When the V
is
IHMIN
DS1990A needs a recovery time t
for the next time slot.
before it is ready
REC
crossed, the DS1990A waits for t
a presence pulse by pulling the line low for t
and then transmits
PDH
. To
PDL
MASTER Tx "RESET PULSE"
MASTER Rx "PRESENCE PULSE"
ε
t
MSP
V
PUP
V
IHMIN
V
ILMAX
0V
t
PDH
t
t
t
REC
RSTL
PDL
t
F
t
RSTH
RESISTOR
MASTER
DS1990A
Figure 6. Initialization Procedure: Reset and Presence Pulses
_______________________________________________________________________________________
7
Serial Number iButton
WRITE-ONE TIME SLOT
t
W1L
V
PUP
V
IHMASTER
V
IHMIN
DS190A
V
ILMAX
0V
ε
t
F
t
SLOT
RESISTOR
MASTER
WRITE-ZERO TIME SLOT
t
W0L
V
PUP
V
IHMASTER
V
IHMIN
V
ILMAX
0V
ε
t
F
t
REC
t
SLOT
RESISTOR
MASTER
READ-DATA TIME SLOT
t
MSR
t
RL
V
PUP
V
IHMASTER
V
IHMIN
MASTER
SAMPLING
WINDOW
V
ILMAX
0V
δ
t
t
REC
F
t
SLOT
RESISTOR
MASTER
DS1990A
Figure 7. Read/Write Timing Diagram
8
_______________________________________________________________________________________
Serial Number iButton
DS190A
Slave-to-Master
The sum of t + δ (rise time) on one side and the inter-
RL
A read-data time slot begins like a write-one time slot.
nal timing generator of the DS1990A on the other side
The voltage on the data line must remain below V
define the master sampling window (t
MSRMAX
the data line. For most reliable communication, t
should be as short as permissible and the master should
to
ILMAX
MSRMIN
until the read low time t
is expired. During the t
t
) in which the master must perform a read from
RL
RL
window, when responding with a 0, the DS1990A starts
pulling the data line low; its internal timing generator
determines when this pulldown ends and the voltage
starts rising again. When responding with a 1, the
DS1990A does not hold the data line low at all, and the
RL
read close to but no later than t
. After reading
MSRMAX
from the data line, the master must wait until t
is
SLOT
expired. This guarantees sufficient recovery time t
for the DS1990A to get ready for the next time slot.
REC
voltage starts rising as soon as t is over.
RL
Package Information
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages.
PACKAGE TYPE
F3 iButton
PACKAGE CODE
DOCUMENT NO.
56-G0CAN-F30
56-G0CAN-F50
—
—
F5 iButton
_______________________________________________________________________________________
9
Serial Number iButton
Revision History
REVISION
DATE
PAGES
CHANGED
DESCRIPTION
Redid the formatting based on newer template style. Also deleted the 0F Read ROM
command and added a note about presence pulse criteria.
033005
1–8
Created newer template-style data sheet.
All
1
DS190A
Updated Ordering Information with lead-free part numbers.
Deleted Meets UL 913 (4th Edit); Intrinsically Safe Apparatus: Approved Under Entity
Concept for Use in Class I, Division I, Group A, B, C, and D from the Common iButton
Features and iButton Can Physical Specification sections.
1, 3
Updated Electrical Characteristics table:
10/08
Deleted Output High Voltage parameter.
Moved 1-Wire Pullup voltage parameter from table header to table body.
2
8
Changed V
from 0.8V to 0.3V.
ILMAX
Added Note 14 to the t
specification.
W0L
Changed t
from 15μs – ꢀ to 15μs.
W1LMAX
Added the epsilon timing to the Write-Zero Time Slot in Figure 7.
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.
10 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2008 Maxim Integrated Products
is a registered trademark of Maxim Integrated Products, Inc.
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