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DS620 Schematic ( PDF Datasheet ) - Dallas Semiconducotr

Teilenummer DS620
Beschreibung Low-Voltage/ 0.5C Accuracy Digital Thermometer and Thermostat
Hersteller Dallas Semiconducotr
Logo Dallas Semiconducotr Logo 




Gesamt 15 Seiten
DS620 Datasheet, Funktion
www.maxim-ic.com
DS620
Low-Voltage, ±0.5°C Accuracy
Digital Thermometer and Thermostat
GENERAL DESCRIPTION
The DS620 digital thermometer and thermostat
provides low-voltage (1.7V £ VDD £ 3.5V) temperature
measurements with ±0.5°C accuracy from 0°C to
+70°C and an operating temperature range of -55°C
to +125°C. The DS620 communicates over a 2-wire
digital interface. For distributed-sensing applications,
it is multidroppable with three address pins that allow
up to eight DS620s to operate on a single bus.
The DS620 has thermostat functionality with user-
defined thresholds stored in EEPROM registers, and
it can be configured for standalone thermostat
operation. The programmable output (PO) pin serves
as the thermostat output, and this pin can also be
configured to function as an active-low control for
peripheral devices.
APPLICATIONS
Portable Applications
Low-Voltage Temperature-Sensitive Applications
Computers/Servers
Test Equipment
Medical Instruments
Industrial Applications
FEATURES
§ Low-Voltage Operation: 1.7V to 3.5V
§ ±0.5°C Accuracy from 0°C to +70°C
§ Operating Temperature Range: -55°C to +125°C
(-67°F to +257°F)
§ Temperature Measurements Require No
External Components
§ Resolution is User-Selectable to 10-, 11-, 12-, or
13-Bits (0.5°C, 0.25°C, 0.125°C, and 0.0625°C
LSb Weight, Respectively)
§ Multidroppable
§ Fast (200ms max) Temperature-to-Digital
Conversion Time
§ Thermostatic Settings are User-Definable and
Nonvolatile
§ Standalone Thermostat Capability
§ Data is Read/Written Through a 2-Wire Serial
Interface
§ Package: 8-Pin mSOP
ORDERING INFORMATION
PART
TEMP RANGE PIN-PACKAGE
DS620U
-55°C to +125°C
8 µSOP,
Exposed Pad
8 µSOP
DS620U/T&R
-55°C to +125°C Exposed Pad
Tape-and-Reel
TYPICAL OPERATING CIRCUIT
PIN CONFIGURATION
1.7V to 3.5V
1.7V to 3.5V
SDA
SCL
HOST
VDD
SDA
SCL
PO
DS620
A0
A1
A2
GND
Thermostat
DS620
SDA 1
8 VDD
SCL 2
7 A0
PO 3
6 A1
GND 4
5 A2
8-Pin mSOP Package
Exposed Pad
Note: Some revisions of this device may incorporate deviations from published specifications known as errata. Multiple revisions of any device
may be simultaneously available through various sales channels. For information about device errata, click here: www.maxim-ic.com/errata.
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081004






DS620 Datasheet, Funktion
DS620 Digital Thermometer and Thermostat
the device enters a low-power standby state and remains in that state until a temperature conversion is again
initiated by a Start Convert command.
The R0 and R1 bits in the configuration register allow the user to set the conversion resolution to be 10, 11, 12, or
13 bits (0.5°C, 0.25°C, 0.125°C, and 0.0625°C LSb weight, respectively) as shown in Table 6. The default
resolution at power-up is 13-bits. Note that the conversion time doubles for each additional bit of resolution.
After each conversion, the digital temperature is stored as a 16-bit two’s complement number in the 2-byte
temperature register as shown in Figure 3. The temperature register is located in address spaces AAh (MSB) and
ABh (LSB) of the DS620 memory. The sign bit (S) indicates if the temperature is positive (S = 0) or negative (S =
1). Bits 2, 1, and 0 of the temperature register are hardwired to 0. When the device is configured for 13-bit
resolution, the 13 MSbs (bits 15 through 3) of the temperature register will contain temperature data. For 12-bit
resolution, the 12 MSbs (bits 15 through 4) of the temperature register will contain data, and bit 3 will be 0.
Likewise, for 11-bit resolution, the 11 MSbs (bits 15 through 5) will contain data, and for 10-bit the 10 MSbs (bits 15
through 6) will contain data, and all unused LSbs will contain 0s. Table 2 gives examples of 13-bit resolution output
data and the corresponding temperatures.
Figure 3. Temperature, TH, And TL Register Format
MS Byte
bit 15
S
bit 14
27
bit 13
26
Bit 12
25
bit 7 bit 6 bit 5 Bit 4
LS Byte
20
2-1
2-2
2-3
bit 11
24
bit 3
2-4
bit 10
23
bit 2
0
bit 9
22
bit 1
0
bit 8
21
bit 0
0
Table 2. 13-Bit Resolution Temperature/Data Relationship
Temperature (°C)
+125
+25.0625
+10.125
+0.5
0
-0.5
-10.125
-25.0625
-55
Digital Output (binary)
0011 1110 1000 0000
0000 1100 1000 1000
0000 0101 0001 0000
0000 0000 0100 0000
0000 0000 0000 0000
1111 1111 1100 0000
1111 1010 1111 0000
1111 0011 0111 1000
1110 0100 1000 0000
Digital Output (hex)
3E80h
0C88h
0510h
0040h
0000h
FFC0h
FAF0h
F378h
E480h
WRITING TO THE TEMPERATURE REGISTER
The user is given access to write to the DS620 temperature register. This feature can be used for system test and
debugging by allowing the user to force the temperature reading above or below fault thresholds without having to
heat or cool the device.
If data is written to the temperature register while conversions are in progress, the result of the next completed
conversion will overwrite any data that was written to the temperature register. Additionally, no update of the flag
bits in the configuration register, nor an update of the PO pin occur as a result of the temperature being written if a
conversion is taking place. To avoid this from happening, conversions should first be stopped before writing to the
temperature register. When writing to the temperature register, both the MSB and the LSB should be written. An
update of the flag bits and PO pin will only occur after the LSB has been written. See Writing to the DS620 for more
information.
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DS620 pdf, datenblatt
DS620 Digital Thermometer and Thermostat
the DS620 commands. See Writing to the DS620 or Reading from the DS620 for more information on reading from
and writing to the DS620.
WRITING TO THE DS620
The master can write data to the DS620 by issuing an address byte following the control byte. The R/W bit in the
control byte must be a 0 (write). After receiving an ACK from the DS620 in response to the control byte, the master
sends the address of the first register byte to be written, loading the address counter with the desired location. The
DS620 responds with another ACK, after which the master sends the data to be written. After receiving each byte
of data, the DS620 responds with an ACK. The master continues to write data to successive address locations until
it indicates there is no more data to be written by sending a STOP or repeated START condition. The DS620
ignores any data written once the address increments past ADh, the last defined register in the DS620 memory,
and indicates this by sending a NACK after each byte. It also ignores data written to undefined addresses A8h and
A9h. All writes to the DS620 are made to the shadow RAM. Once data is written to the shadow RAM, it is only
stored to EEPROM by issuance of a Copy Data command from the master. At that time all registers are copied to
EEPROM, except the Temperature registers, which are SRAM only, and the undefined registers. The DS620 must
be set to the continuous conversion mode and be actively converting temperature to enable the Copy Data
command to function properly. See Copying to EEPROM Command Sequence for more information.
READING FROM THE DS620
The master can read data from the DS620 by issuing an address byte following the control byte. The R/W bit in the
control byte must be a 0 (write). After receiving an ACK from the DS620 in response to the control byte, the master
writes the address of the first register byte to be read, loading the address counter with the desired location. The
DS620 will respond with another ACK. The master then must issue a repeated START (or a STOP and a START)
followed by a control byte with the same slave address as the first control byte. However, this time the R/W bit must
be a 1 which tells the DS620 that a “read” is being performed. After the DS620 sends an ACK in response to this
control byte, it begins transmitting the requested data on the next clock cycle. The master responds with an ACK
between each byte of data read from the DS620 until no further bytes of data are to be read, at which time the
master responds with a NACK followed by a STOP. The DS620 sends all 1’s (FFh) once the address increments
past ADh, the last defined register in the DS620 memory. There is no guaranteed state of data read from the
undefined registers, A8h and A9h. The Recall Data command should be issued before a read to assure that the
contents of the EEPROM will be in the Shadow RAM when read.
COMMAND SET
The DS620 command set is detailed below:
Start Convert [ 51h ]
0101 0001
Initiates temperature conversions. If the part is in one-shot mode (1SHOT = 1), only one conversion is performed.
In continuous mode (1SHOT = 0), continuous temperature conversions are performed until a Stop Convert
command is issued (even if 1SHOT is changed to a 1).
Stop Convert [ 22h ]
0010 0010
Stops temperature conversions when the device is in continuous conversion mode (1SHOT = 0). This command
has no function if the device is in one-shot mode (1SHOT = 1)
Recall Data [ B8h ]
1011 1000
Refreshes SRAM shadow register with EEPROM data.
Copy Data [ 48h ]
0100 1000
Copies data from all SRAM shadow registers to EEPROM.
NOTE: The DS620 must be set to the continuous conversion mode and be actively converting temperature to
enable the Copy Data command to function properly. See example command sequence in the Copying to
EEPROM Command Sequence section for more information.
Software POR [ 54h ]
0101 0100
Initiates a software power-on-reset (POR), which stops temperature conversions and resets all registers and logic
to their power-up states. The software POR allows the user to simulate cycling the power without actually powering
down the device. This command should not be issued while a Copy Data command is in progress.
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