DS1822-PAR データシートの表示（PDF） - Maxim Integrated

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DS1822-PAR

Econo 1-Wire Parasite-Power Digital Thermometer

Maxim Integrated 

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

eight 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 eight 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 data sheet.

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 NV 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 Figure 6

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

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 data sheet. Bytes 5, 6 and 7 are reserved for internal use by the device and

cannot be overwritten.

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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