DS1721U+T&R Maxim Integrated Products, DS1721U+T&R Datasheet - Page 5
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DS1721U+T&R
Manufacturer Part Number
DS1721U+T&R
Description
IC THERMOMETER/STAT DIG HP 8USOP
Manufacturer
Maxim Integrated Products
Datasheet
1.DS1721STR.pdf
(17 pages)
Specifications of DS1721U+T&R
Function
Thermometer, Thermostat
Topology
ADC, Comparator, Register Bank
Sensor Type
Internal
Sensing Temperature
-55°C ~ 125°C
Output Type
I²C™/SMBus™
Output Alarm
Yes
Output Fan
Yes
Voltage - Supply
2.7 V ~ 5.5 V
Operating Temperature
-55°C ~ 125°C
Mounting Type
Surface Mount
Package / Case
8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
Full Temp Accuracy
+/- 2 C
Digital Output - Bus Interface
Serial (2-Wire)
Digital Output - Number Of Bits
12 bit
Maximum Operating Temperature
+ 125 C
Minimum Operating Temperature
- 55 C
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
DS1721
The active state for the totem-pole output is programmable by the user. The power-up default of the
DS1721 has TH=80°C, TL=75°C, and the output state active high. Refer to the “OPERATION-
Programming” section for instructions in adjusting the thermostat setpoints and T
active state.
COM
THERMOSTAT OUTPUT OPERATION Figure 2
OPERATION-Programming
There are two areas of interest in programming the DS1721: the Configuration/Status register and the
thermostat setpoints. All programming is done via the 2-wire interface using the protocols discussed in
the “Command Set” section.
Configuration/Status Register Programming
The configuration/status register is accessed via the Access Config (ACh) function command. Writing to
or reading from the register is determined by the R/
bit of the 2-wire control byte (See “2-wire Serial
W
Data Bus” section). Data is read from or written to the configuration register MSb first. The format of the
register is illustrated below in Figure 3. The effect each bit has on DS1721 functionality is described
below along with the power-up state of the bit and its ability to be read or written to. The entire register is
volatile and will always power-up in the default state. Therefore, it is recommended that the user issue
any configuration programming commands immediately after power is cycled, before any other
commands are issued.
CONFIGURATION/STATUS REGISTER Figure 3
DONE
X
X
U
R1
R0
POL
1SHOT
MSb
LSb
1SHOT = Temperature Conversion Mode. If 1SHOT is "1", the DS1721 will perform and store one
temperature conversion upon reception of the Start Convert T (51h) command. If 1SHOT is "0", the
DS1721 will continuously perform temperature conversions and store the last completed result in the
Thermometer Register. The user has read/write access to the bit and the power-up default state is "0"
(continuous mode).
POL = TCOM Polarity Bit. If POL is "1", the active state of the TCOM output will be high. A "0" stored
in this location sets the thermostat output to an active low state. The user has read/write access to the
POL bit, and the power-up default state is "1" (active high).
U = Undefined. This bit is used internally by the DS1721. It will be a "0" at power-up and will change to
a "1" once the Start Convert T [51h] command is issued. This is a “Don’t Care” on a write; i.e. The
DS1721 will ignore writes to this location.
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