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PDF DS1822-PAR Data sheet ( Hoja de datos )
| Número de pieza | DS1822-PAR | |
| Descripción | Econo 1-Wire Parasite-Power Digital Thermometer | |
| Fabricantes | Dallas | |
| Logotipo |  |
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DS1822-PAR
Econo 1-Wire® Parasite-Power
Digital Thermometer
www.dalsemi.com
FEATURES
• Unique 1-wire interface requires only one
port pin for communication
• Derives power from data line (“parasite
power”)—does not need a local power supply
• Multi-drop capability simplifies distributed
temperature sensing applications
• Requires no external components
• ±2.0°C accuracy from –10°C to +85°C
• Measures temperatures from –55°C to
+100°C (–67°F to +212°F)
• Thermometer resolution is user-selectable
from 9 to 12 bits
• Converts temperature to 12-bit digital word in
750 ms (max.)
• User–definable temperature alarm settings
• Alarm search command identifies and
addresses devices whose temperature is
outside of programmed limits (temperature
alarm condition)
• Software compatible with the DS18B20-PAR
• Ideal for use in remote sensing applications
(e.g., temperature probes) that do not have a
local power source
PIN ASSIGNMENT
DALLAS
1822P
123
123
(BOTTOM VIEW)
TO-92
(DS1822-PAR)
PIN DESCRIPTION
GND - Ground
DQ - Data In/Out
NC - No Connect
DESCRIPTION
The DS1822-PAR digital thermometer provides 9 to 12–bit centigrade temperature measurements and has
an alarm function with nonvolatile user-programmable upper and lower trigger points. The DS1822-PAR
does not need an external power supply because it derives power directly from the data line (“parasite
power”). The DS1822-PAR communicates over a 1-wire bus, which by definition requires only one data
line (and ground) for communication with a central microprocessor. It has an operating temperature
range of –55°C to +100°C and is accurate to ±2.0°C over a range of –10°C to +85°C.
Each DS1822-PAR has a unique 64-bit identification code, which allows multiple DS1822-PARs to
function on the same 1–wire bus; thus, it is simple to use one microprocessor to control many
DS1822-PARs distributed over a large area. Applications that can benefit from this feature include
HVAC environmental controls, temperature monitoring systems inside buildings, equipment or
machinery, and process monitoring and control systems.
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043001
1 page  
DS1822-PAR
64-BIT LASERED ROM CODE
Each DS1822-PAR contains a unique 64–bit code (see Figure 5) stored in ROM. The least significant 8
bits of the ROM code contain the DS1822-PAR’s 1–wire family code: 22h. The next 48 bits contain a
unique serial number. The most significant 8 bits contain a cyclic redundancy check (CRC) byte that is
calculated from the first 56 bits of the ROM code. A detailed explanation of the CRC bits is provided in
the CRC GENERATION section. The 64–bit ROM code and associated ROM function control logic
allow the DS1822-PAR to operate as a 1–wire device using the protocol detailed in the 1-WIRE BUS
SYSTEM section of this datasheet.
64-BIT LASERED ROM CODE Figure 5
8-BIT CRC
48-BIT SERIAL NUMBER
8-BIT FAMILY CODE (22h)
MSB
LSB MSB
LSB MSB
LSB
MEMORY
The DS1822-PAR’s memory is organized as shown in Figure 6. The memory consists of an SRAM
scratchpad with nonvolatile EEPROM storage for the high and low alarm trigger registers (TH and TL)
and configuration register. Note that if the DS1822-PAR alarm function is not used, the TH and TL
registers can serve as general-purpose memory. All memory commands are described in detail in the
DS1822-PAR FUNCTION COMMANDS section.
DS1822-PAR MEMORY MAP cáÖìêÉ=S
SCRATCHPAD (Power-up State)
byte 0 Temperature LSB (50h)
(85°C)
byte 1 Temperature MSB (05h)
byte 2 TH Register or User Byte 1*
byte 3 TL Register or User Byte 2*
byte 4 Configuration Register*
byte 5 Reserved (FFh)
byte 6 Reserved (0Ch)
byte 7 Reserved (10h)
byte 8 CRC*
*Power-up state depends on value(s) stored
in EEPROM
EEPROM
TH Register or User Byte 1
TL Register or User Byte 2
Configuration Register
Byte 0 and byte 1 of the scratchpad contain the LSB and the MSB of the temperature register,
respectively. These bytes are read-only. Bytes 2 and 3 provide access to TH and TL registers. Byte 4
contains the configuration register data, which is explained in detail in the CONFIGURATION
REGISTER section of this datasheet. Bytes 5, 6 and 7 are reserved for internal use by the device and
cannot be overwritten; these bytes will return all 1s when read.
Byte 8 of the scratchpad is read-only and contains the cyclic redundancy check (CRC) code for bytes 0
through 7 of the scratchpad. The DS1822-PAR generates this CRC using the method described in the
CRC GENERATION section.
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5 Page 
ROM COMMANDS FLOW CHART Figure 9
DS1822-PAR
Initialization
Sequence
MASTER TX
RESET PULSE
DS1822-PAR TX
PRESENCE
PULSE
MASTER TX ROM
COMMAND
33h
READ ROM
COMMAND
N
Y
DS1822-PAR TX
FAMILY CODE
1 BYTE
DS1822-PAR TX
SERIAL NUMBER
6 BYTES
DS1822-PAR TX
CRC BYTE
55h
MATCH ROM
COMMAND
N
Y
MASTER TX
BIT 0
F0h
SEARCH ROM
COMMAND
N
Y
ECh
N
ALARM SEARCH
COMMAND
Y
DS1822-PAR TX BIT 0
DS1822-PAR TX BIT 0
MASTER TX BIT 0
DS1822-PAR TX BIT 0
DS1822-PAR TX BIT 0
MASTER TX BIT 0
CCh
SKIP ROM
COMMAND
N
Y
BIT 0
MATCH?
N
Y
N
BIT 0
MATCH?
Y
MASTER TX
BIT 1
DS1822-PAR TX BIT 1
DS1822-PAR TX BIT 1
MASTER TX BIT 1
DEVICE(S)
WITH ALARM
FLAG SET?
N
Y
BIT 1
MATCH?
N
Y
MASTER TX
BIT 63
BIT 63
MATCH?
N
Y
N
BIT 1
MATCH?
Y
DS1822-PAR TX BIT 63
DS1822-PAR TX BIT 63
MASTER TX BIT 63
N
BIT 63
MATCH?
Y
MASTER TX
FUNCTION
COMMAND
(FIGURE 10)
11 of 19
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| PDF Descargar | [ Datasheet DS1822-PAR.PDF ] | |
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