Rainbow Electronics DS1822-PAR User Manual
Parasite-power digital thermometer
1 of 19
043001
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
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.
DS1822-PAR
Econo 1-Wire
®
Parasite-Power
Digital Thermometer
www.dalsemi.com
1
(BOTTOM VIEW)
2 3
TO-92
(DS1822-PAR)
DALLAS
1822P
1
GND
DQ
NC
2 3
Document Outline
- FEATURES
- PIN ASSIGNMENT
- PIN DESCRIPTION
- D
- DESCRIPTION
- OVERVIEW
- DS1822-PAR BLOCK DIAGRAM Figure 1
- PARASITE POWER
- SUPPLYING THE DS1822-PAR DURING TEMPERATURE CONVERSIONS Figure 2
- OPERATION – MEASURING TEMPERATURE
- TEMPERATURE REGISTER FORMAT Figure 3
- TEMPERATURE/DATA RELATIONSHIP Table 2
- OPERATION – ALARM SIGNALING
- TH AND TL REGISTER FORMAT Figure 4
- 64-BIT LASERED ROM CODE
- 64-BIT LASERED ROM CODE Figure 5
- MEMORY
- DS1822-PAR MEMORY MAP Figure 6
- CONFIGURATION REGISTER
- Byte 4 of the scratchpad memory contains the configuration register, which is organized as illustrated in Figure 7. The user can set the conversion resolution of the DS1822-PAR using the R0 and R1 bits in this register as shown in Table 3. The power-u
- CONFIGURATION REGISTER Figure 7
- THERMOMETER RESOLUTION CONFIGURATION Table 3
- CRC GENERATION
- CRC GENERATOR Figure 8
- 1-WIRE BUS SYSTEM
- HARDWARE CONFIGURATION
- HARDWARE CONFIGURATION Figure 9
- TRANSACTION SEQUENCE
- INITIALIZATION
- ROM COMMANDS
- SEARCH ROM [F0h]
- READ ROM [33h]
- MATCH ROM [55h]
- SKIP ROM [CCh]
- ALARM SEARCH [ECh]
- DS1822-PAR FUNCTION COMMANDS
- CONVERT T [44h]
- WRITE SCRATCHPAD [4Eh]
- READ SCRATCHPAD [BEh]
- COPY SCRATCHPAD [48h]
- RECALL E2 [B8h]
- DS1822-PAR FUNCTION COMMAND SET Table 4
- NOTES:
- ROM COMMANDS FLOW CHART Figure 9
- DS1822-PAR FUNCTION COMMANDS FLOW CHART Figure 10
- 1-WIRE SIGNALING
- 1-WIRE SIGNALING
- INITIALIZATION PROCEDURE: RESET AND PRESENCE PULSES
- INITIALIZATION TIMING Figure 11
- READ/WRITE TIME SLOTS
- WRITE TIME SLOTS
- READ/WRITE TIME SLOT TIMING DIAGRAM Figure 12
- READ TIME SLOTS
- DETAILED MASTER READ 1 TIMING Figure 13
- RECOMMENDED MASTER READ 1 TIMING Figure 14
- RELATED APPLICATION NOTES
- DS1822-PAR OPERATION EXAMPLE 1
- DS1822-PAR OPERATION EXAMPLE 2
- ABSOLUTE MAXIMUM RATINGS*
- DC ELECTRICAL CHARACTERISTICS (-55˚C to +100˚C; VPU=3.0V to 5.5V)
- NOTES:
- AC ELECTRICAL CHARACTERISTICS: NV MEMORY
- (-55˚C to +100˚C; VPU=3.0V to 5.5V)
- AC ELECTRICAL CHARACTERISTICS: (-55˚C to +100˚C; VPU=3.0V to 5.5V)
- NOTES:
- TYPICAL PERFORMANCE CURVE Figure 15
- TIMING DIAGRAMS Figure 16