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DS2482-800_12 Datasheet

Download or read online Maxim Integrated DS2482-800_12 8-Channel 1-Wire Master pdf datasheet.



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GENERAL DESCRIPTION
2
The DS2482-800 is an I
C-to-1-Wire
that interfaces directly to standard (100kHz max) or
2
fast
(400kHz
max)
I
C
masters
bidirectional protocol conversion between the I
master and any downstream 1-Wire slave devices.
Relative to any attached 1-Wire slave device, the
DS2482-800 is a 1-Wire master. Internal factory-
trimmed timers relieve the system host processor
from generating time-critical 1-Wire waveforms,
supporting both standard and Overdrive 1-Wire
communication
speeds.
To
waveform generation, the DS2482-800 performs
slew-rate control on rising and falling 1-Wire edges
and has a programmable feature to mask the fast
presence pulse edge that some 1-Wire slave devices
can generate. Programmable strong pullup features
support 1-Wire power delivery to 1-Wire devices such
as EEPROMs and sensors. The DS2482-800
combines these features with eight independent
2
1-Wire I/O channels. The I
assignment is controlled by three binary address
inputs, resolving potential conflicts with other I
slave devices in the system.
APPLICATIONS
Wireless Base Stations
Central Office Switches
Functional Diagrams
PBXs
Rack-Based Servers
Medical Clinical Diagnostic Equipment
TYPICAL OPERATING CIRCUIT
1-Wire is a registered trademark of Maxim Integrated Products, Inc.
Pin Configurations appear at end of data sheet.
Functional Diagrams continued at end of data sheet.
UCSP is a trademark of Maxim Integrated Products, Inc.
For pricing, delivery, and ordering information, please contact Maxim Direct
at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.
8-Channel 1-Wire Master
FEATURES
2
I
C Host Interface, Supports 100kHz and 400kHz
bridge device
2
I
C Communication Speeds
1-Wire Master I/O with Selectable Active or
to
perform
2
Passive 1-Wire Pullup
C
Provides Reset/Presence, 8-Bit, Single-Bit, and
Three-Bit 1-Wire I/O Sequences
8 Channels of Independently Operated
1-Wire I/O
Standard and Overdrive 1-Wire Communication
Speeds
Slew Controlled 1-Wire Edges
optimize
1-Wire
Supports Low-Impedance 1-Wire Strong Pullup
for EEPROMs, Temp Sensors, or Other 1-Wire
Slaves That Have Momentary High Current
Modes
Three Address Inputs for I
Assignment
Wide Operating Range: 2.9V to 5.5V, -40°C to
+85°C
16-Pin SO Package (150 mils)
C slave address
ORDERING INFORMATION
2
C
DS2482S-800+
DS2482S-800+T&R
+Denotes a lead(Pb)-free/RoHS-compliant package.
T&R = Tape and reel.
PIN CONFIGURATION
DS2482-800
2
C Address
TEMP
PIN-
PART
RANGE
PACKAGE
-40 to +85C
16 SO
16 SO
-40 to +85C
1
16
IO2
IO3
SCL
2
15
IO1
SDA
3
14
IO0
V
4
13
GND
CC
NC
5
12
IO4
AD2
6
11
IO5
AD1
7
10
IO6
AD0
8
9
IO7
19-4932; Rev 4; 1/12

Summary of Contents

Page 1

... I master and any downstream 1-Wire slave devices. Relative to any attached 1-Wire slave device, the DS2482-800 is a 1-Wire master. Internal factory- trimmed timers relieve the system host processor from generating time-critical 1-Wire waveforms, supporting both standard and Overdrive 1-Wire communication speeds ...

Page 2

ABSOLUTE MAXIMUM RATINGS Voltage on Any Pin Relative to Ground Maximum Current Into Any Pin Operating Temperature Range Junction Temperature Storage Temperature Range Lead Temperature (soldering, 10s) Soldering Temperature (reflow) Stresses beyond those listed under Absolute Maximum Ratings may cause ...

Page 3

PARAMETER Write 0 Low Time Write 0 Recovery Time Reset Low Time Presence-Detect Sample Time Sampling for Short and Interrupt Reset High Time 2 I C-Pins (Note 7) See Figure 9 LOW Level Input Voltage HIGH Level Input Voltage Hysteresis ...

Page 4

... Applies to SDA, SCL, and AD0, AD1, AD2. Note 9: I/O pins of the DS2482 do not obstruct the SDA and SCL lines if V Note 10: The DS2482 provides a hold time of at least 300ns for the SDA signal (referred to the V signal) to bridge the undefined region of the falling edge of SCL. Note 11: The maximum t ...

Page 5

... Data. These registers are addressed by a read pointer. The position of the read pointer, i.e., the register that the host will read in a subsequent read access, is defined by the instruction that the has DS2482 executed last. The host has read and write access to the Channel Selection and Configuration Registers to select one of several 1-Wire channels and to enable certain 1-Wire features ...

Page 6

... The circuit that controls rising edges (Figure 2) operates as follows the pulldown (from DS2482 or 1-Wire slave) ends. From this point on the 1-Wire bus is pulled high through R capacitive load of the 1-Wire line determine the slope ...

Page 7

... If SPU is 1, the DS2482 applies active pullup to the rising edge of the time slot in which the strong pullup starts, regardless of the APU bit setting. However, in contrast to setting APU 1 for active pullup, the low-impedance pullup will not end after t is expired ...

Page 8

... Reset command. Short Detected (SD) The SD bit is updated with every 1-Wire Reset command. If the DS2482 detects a logic 0 on the 1-Wire line at t during the Presence Detect cycle, the SD bit will be set to 1. This bit will return to its default 0 with a subsequent 1-Wire Reset command provided that the short has been removed ...

Page 9

... Triplet command and Application Note 187: 1-Wire Search Algorithm. FUNCTION COMMANDS The DS2482 understands nine function commands, which fall into four categories: device control, I communication, 1-Wire setup and 1-Wire communication. The feedback path to the host is controlled by a read pointer, which is set automatically by each function command for the host to efficiently access relevant information. ...

Page 10

... When read, the upper nibble is always 0h. Defining the features for subsequent 1-Wire communication. 1-Wire activity must have ended before the DS2482 can process this command. Command code and parameter will not be acknowledged if 1WB 1 at the time the command code is received and the command will be ignored. None ...

Page 11

... See the table below for the respective values. Selecting a 1-Wire IO channel other that IO0; randomly selecting one of the available 1-Wire IO channels. 1-Wire activity must have ended before the DS2482 can process this command. Command code and parameter will not be acknowledged if 1WB 1 at the time the command code is received and the command will be ignored ...

Page 12

... To perform single bit writes or reads on a 1-Wire IO channel when single bit communication is necessary (the exception). 1-Wire activity must have ended before the DS2482 can process this command. Command code and bit byte will not be acknowledged if 1WB 1 at the time the command code is received and the command will be ignored ...

Page 13

... NOTE on Figure 7: Depending on its internal state, a 1-Wire slave device will transmit data to its master (e.g., the DS2482). When responding with 1-Wire slave will start pulling the line low during t generator determines when this pulldown ends and the voltage starts rising again. When responding with ...

Page 14

... The direction byte determines the type of write-time slot if both read-time slots are 0 (a typical case). In this case the DS2482 will generate a write-1 time slot and a write-0 time slot the read-time slots are 0 and 1, there will follow a write 0 time slot. ...

Page 15

... Condition Slave Address The slave address to which the DS2482 responds is shown in Figure 8. The logic states at the address pins AD0, AD1 and AD2 determine the value of the address bits A0, A1, and A2. The address pins allow the device to respond to one of eight possible slave addresses. The slave address is part of the slave-address/control byte. The last bit of the slave-address/control byte (R/W) defines the data direction. When set subsequent data will flow from master to slave (write access) ...

Page 16

... Figure 8. DS2482 Slave Address Most Signi- ficant Bit Definitions The following terminology is commonly used to describe I Figure 9. Bus Idle or Not Busy: Both, SDA and SCL, are inactive and in their logic HIGH states. START Condition: To initiate communication with a slave, the master has to generate a START condition. A START condition is defined as a change in state of SDA from HIGH to LOW while SCL remains HIGH ...

Page 17

... NOTE: Timing is referenced to V Writing to the DS2482 To write to the DS2482, the master must access the device in write mode, i.e., the slave address must be sent with the direction bit set to 0. The next byte to be sent is a command code, which, depending on the command, may be followed by a command parameter ...

Page 18

... E5h is an invalid channel selection code. Case C: 1-Wire busy (1WB 1) S AD,0 A CHSL The master should stop and restart as soon as the DS2482 does not acknowledge the command code. Set Read Pointer, e.g., to read from another register Case A: valid read pointer code S AD,0 A SRP C3h is the valid read pointer code for the configuration register ...

Page 19

... In the first cycle, the master sends the command; then the master waits (Idle) for the 1-Wire Reset to complete. In the second cycle the DS2482 is accessed to read the result of the 1-Wire Reset from the Status Register. Case B: 1-Wire idle (1WB 0), busy polling until the 1-Wire Command is completed, then read the result ...

Page 20

... When 1WB has changed from the Status Register holds the valid result of the 1-Wire Single Bit command. Case C: 1-Wire busy (1WB 1) S AD,0 A 1WSB The master should stop and restart as soon as the DS2482 does not acknowledge the command code. 1-Wire Triplet, e.g., to perform a Search ROM function on a 1-Wire IO channel Case A: 1-Wire idle (1WB 0), no busy polling S AD,0 A 1WT The idle time is needed for the 1-Wire function to complete ...

Page 21

... Application Information SDA and SCL Pullup Resistors SDA is an open-drain output on the DS2482 that requires a pullup resistor to realize high logic levels. Because the DS2482 uses SCL only as input (no clock stretching) the master can drive SCL either through an open- drain/collector output with a pullup resistor or a push-pull output. ...

Page 22

Only for pullup voltages of 3V and lower can the maximum permissible bus capacitance of 400pF be maintained. A reduced bus capacitance of 300pF is acceptable for pullup voltages of 4V and lower. For fast speed operation at any pullup ...

Page 23

... Maxim Integrated 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000 © 2012 Maxim Integrated DESCRIPTION and t ) SRC trademark note; added The Maxim logo and Maxim Integrated are trademarks of Maxim Integrated Products, Inc. DS2482-800: 8-Channel 1-Wire Master PAGES CHANGED — 21 10, 11, 12 ...

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