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PDF DS75LV Data sheet ( Hoja de datos )
| Número de pieza | DS75LV | |
| Descripción | Digital Thermometer and Thermostat | |
| Fabricantes | Maxim Integrated Products | |
| Logotipo |  |
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DESCRIPTION
This low-voltage (1.7V to 3.7V) digital thermometer
and thermostat provides 9-, 10-, 11-, or 12-bit digital
temperature readings over a -55°C to +125°C range
with ±2°C accuracy over a -25°C to +100°C range. At
power-up, the DS75LV defaults to 9-bit resolution for
software compatibility with the LM75. Communication
with the DS75LV is achieved through a simple 2-wire
serial interface. Three address pins allow up to eight
wwwD.SD7a5taLSVhedeet4vUic.ceosmto operate on the same 2-wire bus,
which greatly simplifies distributed temperature-
sensing applications.
The DS75LV thermostat has a dedicated open-drain
output (O.S.) and programmable fault tolerance,
which allows the user to define the number of
consecutive error conditions that must occur before
O.S is activated. There are two thermostatic
operating modes that control thermostat operation
based on user-defined trip-points (TOS and THYST).
A block diagram of the DS75LV is shown in Figure 1
and detailed pin descriptions are given in Table 2.
APPLICATIONS
Personal Computers
Cellular Base Stations
Office Equipment
Any Thermally Sensitive System
PIN CONFIGURATION
SDA 1
8 VDD
SCL 2
7 A0
O.S. 3
6 A1
GND 4
5 A2
DS75LVS—SO (150 mils)
SDA
SCL
O.S.
GND
1
2
3
4
8 VDD
7 A0
6 A1
5 A2
DS75LVU—mSOP/mMAX
DS75LV
Digital Thermometer and Thermostat
FEATURES
§ Operating Range from 1.7V to 3.7V
§ Temperature Measurements Require No
External Components
§ Measures Temperatures from -55°C to +125°C
(-67°F to +257°F)
§ ±2°C Accuracy Over a -25°C to +100°C Range
§ Thermometer Resolution is User-
Configurable from 9 (Default) to 12 Bits (0.5°C
to 0.0625°C Resolution)
§ 9-Bit Conversion Time is 25ms (Max)
§ Thermostatic Settings are User-Definable
§ Data Read/Write Occurs Through a 2-Wire
Serial Interface (SDA and SCL Pins)
§ Data Lines Filtered Internally for Noise
Immunity (50ns Deglitch)
§ Bus Timeout Feature Prevents Lockup
Problems on 2-Wire Interface
§ Multidrop Capability Simplifies Distributed
Temperature-Sensing Applications
§ Pin/Software Compatible with the LM75
§ Available in 8-Pin mSOP (mMAX) and SO
Packages
ORDERING INFORMATION
PART
DS75LVS+
DS75LVS+T&R
DS75LVU+
DS75LVU+T&R
TEMP RANGE
-55°C to +125°C
-55°C to +125°C
-55°C to +125°C
-55°C to +125°C
PIN-PACKAGE
DS75LV
(150-mil) 8-SO
DS75LV
(150-mil) 8-SO,
2500 Piece
Tape-and-Reel
DS75LV
8-µSOP
(µMAX)
DS75LV
8-µSOP
(µMAX), 3000
Piece Tape-
and-Reel
Ordering Information continued at the end of the data sheet.
1 of 13
051106
1 page  
DS75LV: Digital Thermometer and Thermostat
OPERATION¾MEASURING TEMPERATURE
The DS75LV measures temperature using a bandgap temperature sensing architecture. An on-board delta-sigma
analog-to-digital converter (ADC) converts the measured temperature to a digital value that is calibrated in degrees
centigrade; for Fahrenheit applications a lookup table or conversion routine must be used. The DS75LV is factory-
calibrated and requires no external components to measure temperature.
At power-up the DS75LV immediately begins converting temperature to a digital value. The resolution of the digital
output data is user-configurable to 9, 10, 11, or 12 bits, corresponding to temperature increments of 0.5°C, 0.25°C,
0.125°C, and 0.0625°C, respectively, with 9-bit default resolution at power-up. The resolution is controlled via the
R0 and R1 bits in the configuration register as explained in the CONFIGURATION REGISTER section of this data
sheet. Note that the conversion time doubles for each additional bit of resolution.
After each temperature measurement and analog-to-digital conversion, the DS75LV stores the temperature as a
16-bit two’s complement number in the 2-byte temperature register (see Figure 3). The sign bit (S) indicates if the
temperature is positive or negative: for positive numbers S = 0 and for negative numbers S = 1. The most recently
converted digital measurement can be read from the temperature register at any time. Since temperature
conversions are performed in the background, reading the temperature register does not affect the operation in
wwwpr.DoagtraeSshse.et4U.com
Bits 3 through 0 of the temperature register are hardwired to 0. When the DS75LV is configured for 12-bit
resolution, the 12 MSbs (bits 15 through 4) of the temperature register will contain temperature data. For 11-bit
resolution, the 11 MSbs (bits 15 through 5) of the temperature register will contain data, and bit 4 will read out as 0.
Likewise, for 10-bit resolution, the 10 MSbs (bits 15 through 6) will contain data, and for 9-bit the 9 MSbs (bits 15
through 7) will contain data, and all unused LSbs will contain 0s. Table 3 gives examples of 12-bit resolution digital
output data and the corresponding temperatures.
Figure 3. Temperature, TOS, and THYST Register Format
MS Byte
bit 15
S
bit 14
26
bit 13
25
bit 12
24
bit 11
23
bit 7 bit 6 bit 5 bit 4 bit 3
LS Byte
2-1
2-2
2-3
2-4
0
bit 10
22
bit 2
0
bit 9
21
bit 1
0
bit 8
20
bit 0
0
Table 2. 12-Bit Resolution Temperature/Data Relationship
TEMPERATURE (°C)
DIGITAL OUTPUT
(BINARY)
DIGITAL OUTPUT
(HEX)
+125
0111 1101 0000 0000
7D00h
+25.0625
0001 1001 0001 0000
1910h
+10.125
0000 1010 0010 0000
0A20h
+0.5 0000 0000 1000 0000
0080h
0
0000 0000 0000 0000
0000h
-0.5 1111 1111 1000 0000 FF80h
-10.125
1111 0101 1110 0000
F5E0h
-25.0625
1110 0110 1111 0000
E6F0h
-55 1100 1001 0000 0000 C900h
SHUTDOWN MODE
For power-sensitive applications, the DS75LV offers a low-power shutdown mode. The SD bit in the configuration
register controls shutdown mode. When SD is changed to 1, the conversion in progress will be completed and the
result stored in the temperature register after which the DS75LV will go into a low-power standby state. The O.S.
output will be cleared if the thermostat is operating in interrupt mode and O.S will remain unchanged in comparator
mode. The 2-wire interface remains operational in shutdown mode, and writing a 0 to the SD bit returns the
DS75LV to normal operation.
5 of 13
5 Page 
DS75LV: Digital Thermometer and Thermostat
Software POR—The soft power on reset (POR) command is 54h. The master sends a START followed by an
address byte containing the DS75LV bus address. The R/W bit must be a 0. The DS75LV will respond with an
ACK. If the next byte is a 0x54, the DS75LV will reset as if power had been cycled. No ACK will be send by the IC
after the POR command is received.
Reading from the DS75LV—When reading from the DS75LV, if the pointer was already pointed to the desired
register during a previous transaction, the read can be performed immediately without changing the pointer setting.
In this case the master sends a START followed by an address byte containing the DS75LV bus address. The R/W
bit must be a 1, which tells the DS75LV that a read is being performed. After the DS75LV sends an ACK in
response to the address byte, the DS75LV will begin transmitting the requested data on the next clock cycle. When
reading from the configuration register, the DS75LV will transmit one byte of data, after which the master must
respond with a NACK followed by a STOP (see Figure 9e). For two-byte reads (i.e., from the Temperature, TOS or
THYST register), the DS75LV will transmit two bytes of data, and the master must respond to the first data byte with
an ACK and to the second byte with a NACK followed by a STOP (see Figure 9a). If only the most significant byte
of data is needed, the master can issue a NACK followed by a STOP after reading the first data byte in which case
the transaction will be the same as for a read from the configuration register.
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If the pointer is not already pointing to the desired register, the pointer must first be updated as shown in Figure 9d,
which shows a pointer update followed by a single-byte read. The value of the R/W bit in the initial address byte is
a 0 (“write”) since the master is going to write a pointer byte to the DS75LV. After the DS75LV responds to the
address byte with an ACK, the master sends a pointer byte that corresponds to the desired register. The master
must then perform a repeated start followed by a standard one or two byte read sequence (with R/W =1) as
described in the previous paragraph.
Bus Timeout—The DS75LV has a bus timeout feature that prevents communication errors from leaving the IC in a
state where SDA is held low disrupting other devices on the bus. If the DS75LV holds the SDA line low for a period
of tTIMEOUT, its bus interface will automatically reset and release the SDA line. Bus communication frequency must
be fast enough to prevent a reset during normal operation. The bus timeout feature only applies to when the
DS75LV is holding SDA low. Other devices can hold SDA low for an undefined period without causing the interface
to reset.
11 of 13
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| Páginas | Total 13 Páginas | |
| PDF Descargar | [ Datasheet DS75LV.PDF ] | |
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