DS1990R Maxim, DS1990R Datasheet
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DS1990R
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DS1990R Summary of contents
Page 1
... Data is transferred serially ® through the 1-Wire protocol, which requires only a sin- gle data lead and a ground return. Every DS1990R 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 ...
Page 2
... IO Sink Current....................................................................20mA 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 ...
Page 3
... SIZE See the Package Information section. WEIGHT (DS1990R) Ca. 2.5 grams Detailed Description The block diagram in Figure 1 shows the major function blocks of the device. The DS1990R takes the energy it needs to operate from the IO line, as indicated by the DS1990R IO Figure 1. Block Diagram _______________________________________________________________________________________ Serial Number iButton whenever the master drives the line low ...
Page 4
... Figure 3. 1-Wire CRC Generator 4 _______________________________________________________________________________________ The 1-Wire bus is a system that has a single bus master and one or more slaves. In all instances, the DS1990R 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 ...
Page 5
... 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 DS1990R is on the bus and is ready to operate. For more details, see the 1-Wire Signaling section. V PUP ...
Page 6
... Match ROM and Skip ROM are not applicable. The DS1990R remains silent (inactive) upon receiving a ROM function command that it does not support. This allows the DS1990R to coexist on a multidrop bus with other 1-Wire devices that do respond to Match ROM or Skip ROM. ...
Page 7
... PUP the 1-Wire network attached. The initialization sequence required to begin any com- munication with the DS1990R is shown in Figure 6. A reset pulse followed by a presence pulse indicates that the DS1990R is ready to receive a ROM function com- mand. If the bus master uses slew-rate control on the falling edge, it must pull down the line for t compensate for the edge ...
Page 8
... WRITE-ZERO TIME SLOT V PUP V IHMASTER V IHMIN V ILMAX RESISTOR READ-DATA TIME SLOT PUP V IHMASTER V IHMIN V ILMAX RESISTOR Figure 7. Read/Write Timing Diagram 8 _______________________________________________________________________________________ ε t SLOT MASTER t W0L t SLOT MASTER t MSR MASTER SAMPLING WINDOW δ t SLOT MASTER ε t REC t REC DS1990R ...
Page 9
... When responding with a 1, the DS1990R does not hold the data line low at all, and the voltage starts rising as soon For the latest package outline information and land patterns www.maxim-ic.com/packages. Note that a “ ...
Page 10
... 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. ...