DS1775R+T&R [MAXIM]
Serial Switch/Digital Sensor, 12 Bit(s), 2Cel, Rectangular, 5 Pin, Surface Mount, SOT-23, 5 PIN;
| 型号： | DS1775R+T&R |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Serial Switch/Digital Sensor, 12 Bit(s), 2Cel, Rectangular, 5 Pin, Surface Mount, SOT-23, 5 PIN PC 输出元件 传感器 换能器 |
| 文件： | 总14页 (文件大小：465K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
DS1775
Digital Thermometer and Thermostat in SOT23
General Description
Benefits and Features
● Temperature Measurements Require No External
The DS1775 digital thermometer and thermostat
provides temperature readings that indicate the device’s
temperature. Thermostat settings and temperature
readings are all communicated to/from the DS1775 over
a simple 2-wire serial interface. No additional components
are required; the device is truly a “temperature-to-digital”
converter.
Components
● Measures Temperatures from -55°C to +125°C
(-67°F to +257°F)
● ±2.0°C Thermometer Accuracy
● Thermometer Resolution is Configurable from 9 Bits
to 12 Bits (0.5°C to 0.0625°C Resolution)
For applications that require greater temperature resolution,
the user can adjust the readout resolution from 9 to 12
bits. This is particularly useful in applications where
thermal runaway conditions must be detected quickly.
● User-Definable Thermostat Settings
● Data is Read From/Written to Through a
● 2-Wire Serial Interface
The open-drain thermal alarm output, O.S., becomes
active when the temperature of the device exceeds a
● 2.7V to 5.5V Wide Power-Supply Range
● Software Compatible with DS75 2-Wire Thermal
user-defined temperature T . The number of consecutive
OS
Watchdog in Thermometer Mode
faults required to set O.S. active is configurable by the
user. The device can also be configured in the interrupt or
comparator mode, to customize the method which clears
the fault condition.
● Space-Conscious 5-Pin SOT23 Package with Low
Thermal Time Constant
As a digital thermometer, the DS1775 is software compatible
with the DS75 2-wire thermal watchdog. The DS1775 is
assembled in a compact 5-pin SOT23 package, allowing
for low-cost thermal monitoring/control in space-
constrained applications. The low thermal mass allows for
time constants previously only possible with thermistors.
Ordering Information appears at end of data sheet.
Applications
● Personal Computers/Servers/Workstations
● Cell Phones
● Office Equipment
● Any Thermally-Sensitive System
19-6687; Rev 1; 11/16
DS1775
Digital Thermometer and Thermostat in SOT23
Absolute Maximum Ratings
(Voltages relative to ground.)
Storage Temperature Range............................ -55°C to +125°C
Voltage Range on V .........................................-0.3V to +7.0V
Voltage Range on Any Other Pin .........................-0.3V to +7.0V
Operating Temperature Range......................... -55°C to +125°C
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow).......................................+260°C
DD
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these
or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect
device reliability.
DC Electrical Characteristics
(2.7V ≤ V
≤ 5.5V, T = -55°C to +125°C, unless otherwise noted.)
DD
A
PARAMETER
SYMBOL
CONDITION
MIN
2.7
TYP
MAX
UNITS
Supply Voltage
Input Logic-High
V
DD
(Note 1)
(Note 1)
5.5
V
0.7 x
V
+
DD
V
V
V
IH
V
0.5
DD
0.3 x
Input Logic-Low
V
IL
(Note 1)
-0.5
V
DD
V
V
3mA sink current (Note 1)
6mA sink current (Note 1)
4mA sink current (Notes 1, 9)
0
0
0.4
0.6
0.8
+10
10
OL1
SDA Output Logic-Low Voltage
V
OL2
O.S. Saturation Voltage
Input Current Each I/O Pin
I/O Capacitance
V
V
OL
0.4 < V < 0.9 x V
I/O
(Note 2)
-10
µA
pF
µA
DD
C
I/O
Standby Current
I
(Notes 3, 4)
1
DD1
Active temp conversions (Notes 3, 4)
Communication only (Notes 3, 4)
1000
100
Active Current
I
µA
DD
DIGITAL THERMOMETER
Thermometer Error
Resolution
-10°C to +85°C (Notes 9, 10)
-55°C to +125°C (Notes 9, 10)
±0.5
±1.0
±2.0
±3.0
12
T
°C
ERR
9
Bits
9-bit conversion
10-bit conversion
11-bit conversion
12-bit conversion
125
250
187.5
375
Conversion Time
t
ms
CONVT
500
750
1000
1500
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DS1775
Digital Thermometer and Thermostat in SOT23
AC Electrical Characteristics-2 Wire Interface
(V
= 2.7V to 5.5V, T = -55°C to +125°C, unless otherwise noted.) (Figure 5)
DD
A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
400
UNITS
Fast mode
SCL Clock Frequency
f
kHz
SCL
Standard mode
100
Fast mode
1.3
4.7
Bus Free Time Between a
STOP and START Condition
t
µs
µs
µs
µs
µs
µs
ns
ns
ns
µs
BUF
Standard mode
Fast mode (Note 5)
Standard mode (Note 5)
Fast mode
0.6
Hold Time (Repeated) START
Condition
t
HD:STA
4.0
1.3
Low Period of SCL
High Period of SCL
t
LOW
Standard mode
4.7
Fast mode
0.6
t
HIGH
Standard mode
4.0
Fast mode
0.6
Setup Time for a
Repeated START
t
SU:STA
HD:DAT
Standard mode
4.7
Fast mode (Note 6)
Standard mode (Note 6)
Fast mode (Note 7)
Standard mode (Note 7)
Fast mode (Note 8)
Standard mode (Note 8)
Fast mode (Note 8)
Standard mode (Note 8)
Fast mode
0
0.9
0.9
Data Hold Time
Data Setup Time
t
0
100
t
SU:DAT
250
20 + 0.1C
20 + 0.1C
20 + 0.1C
20 + 0.1C
0.6
300
1000
300
Rise Time of Both SDA and
SCL Signals
B
B
B
B
t
R
Fall Time of Both SDA and SCL
Signals
t
F
300
Setup Time for STOP
t
SU:STO
Standard mode
4.0
Capacitive Load for Each Bus
Line
C
(Note 8)
400
pF
pF
B
Input Capacitance
C
5
I
Note 1: All voltages are referenced to ground.
Note 2: I/O pins of fast mode devices must not obstruct the SDA and SCL lines if V
is switched off.
DD
Note 3:
Note 4:
I
I
specified with O.S. pin open.
DD
DD
specified with V
at 5.0V and V
, V
= 5.0V, 0°C to +70°C.
DD
SDA SCL
Note 5: After this period, the first clock pulse is generated.
Note 6: The maximum t has only to be met if the device does not stretch the low period (t
) of the SCL signal.
LOW
HD:DAT
Note 7: A fast mode device can be used in a standard mode system, but the requirement t
≥ 250ns must then be met. This is
SU:DAT
automatically the case if the device does not stretch the low period of the SCL signal. If such a device does stretch the low
period of the SCL signal, it must output the next data bit to the SDA line t
SCL line is released.
+ t
= 1000 + 250 = 1250ns before the
R MAX
SU:DAT
Note 8:
C = Total capacitance of one bus line in pF.
B
Note 9: Internal heating caused by O.S. loading causes the DS1775 to read approximately 0.5°C higher if O.S. is sinking the max
rated current.
Note 10: Contact the factory for operation requiring temperature readings greater than +120°C.
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DS1775
Digital Thermometer and Thermostat in SOT23
Pin Configuration
TOP VIEW
+
SCL
1
2
3
5
4
SDA
DS1775
SOT-23
GND
O.S.
V
DD
GND GROUND
SCL
SDA
2-WIRE SERIAL CLOCK
2-WIRE SERIAL DATA INPUT/OUTPUT
POWER-SUPPLY VOLTAGE
V
DD
O.S.
THERMOSTAT OUTPUT SIGNAL
Pin Description
PIN
NAME
FUNCTION
Clock Input/Output for 2-Wire Serial Communication Port. This input should be tied to GND for
stand-alone thermostat operation.
1
SCL
2
GND
O.S.
Ground
Thermostat Output. Open-drain output becomes active when temperature exceeds T
Device configuration defines means to clear overtemperature state.
.
OS
3
4
V
Supply Voltage 2.7V to 5.5V Input Power Pin
DD
Data Input/Output for 2-Wire Serial Communication Port. In the stand-alone thermostat mode,
this input selects hysteresis.
5
SDA
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DS1775
Digital Thermometer and Thermostat in SOT23
doubles the conversion time. This is accomplished by
programming the configuration register. The configuration
register defines the conversion state, thermometer resolu-
tion/conversion time, active state of the thermostat output,
number of consecutive faults to trigger an alarm condition,
and the method to terminate an alarm condition.
Detailed Description
Figure 1 shows a block diagram of the DS1775. The
DS1775 consists of five major components:
1) Precision temperature sensor
2) Analog-to-digital converter
3) 2-wire interface electronics
4) Data registers
The user can also program overtemperature (T ) and
OS
undertemperature (T
) setpoints for thermostatic
HYST
operation. The power-up state of T
is +80°C and that
OS
5) Thermostat comparator
for T
is +75°C. The result of each temperature con-
HYST
The factory-calibrated temperature sensor requires no
external components. Upon power-up, the DS1775 begins
temperature conversions with the default resolution of 9
bits (0.5°C resolution). The host can periodically read the
value in the temperature register, which contains the last
completed conversion. As conversions are performed in
the background, reading the temperature register does
not affect the conversion in progress.
version is compared with the T
and T
setpoints.
OS
HYST
The DS1775 offers two modes for temperature control,
the comparator mode and the interrupt mode. This allows
the user the flexibility to customize the condition that
would generate and clear a fault condition. Regardless of
the mode chosen, the O.S. output becomes active only
after the measured temperature exceeds the respective
trip-point a consecutive number of times; the number of
consecutive conversions beyond the limit to generate an
O.S. is programmable. The power-up state of the DS1775
is in the comparator mode with a single fault generating
an active O.S.
In power-sensitive applications, the user can put the
DS1775 into a shutdown mode, under which the sensor
complete and store the conversion in progress and revert
to a low-power standby state. In applications where small
incremental temperature changes are critical, the user
can change the conversion resolution from 9 bits to 10,
11, or 12. Each additional bit of resolution approximately
Digital data is written to/read from the DS1775 via a
2-wire interface, and all communication is MSb first.
Block Diagram
2.7V - 5.5V
SUPPLY
VDD
PRECISION
OVERSAMPLING
DIGITAL
REFERENCE
MODULATOR
DECIMATOR
DS1775
SDA
SCL
CONFIGURATION
REGISTER
TO
CPU
I/O CONTROL
INPUT SENSE
THERMOMETER
REGISTER
O.S.
THERMOSTAT
REGISTERS
THERMOSTAT
COMPARATOR
GND
Figure 1. Block Diagram
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DS1775
Digital Thermometer and Thermostat in SOT23
assumes the DS1775 is configured for 12-bit resolution; if
the device is configured in a lower resolution mode, those
bits contain zeros. The data is transmitted serially over the
2-wire serial interface, MSb first. The MSb of the tempera-
ture register contains the sign (S) bit, denoting whether the
temperature is positive or negative. For Fahrenheit usage,
a lookup table or conversion routine must be used.
Operation
Measuring Temperature
The core of DS1775 functionality is its direct-to-digital
temperature sensor. The DS1775 measures temperature
through the use of an on-chip temperature measurement
technique with an operating range from -55°C to +125°C.
Temperature conversions are initiated upon power-up, and
the most recent result is stored in the thermometer register.
Conversions are performed continuously unless the user
intervenes by altering the configuration register to put the
DS1775 into a shutdown mode. Regardless of the mode
used, the digital temperature can be retrieved from the
temperature register by setting the pointer to that location
(00h, power-up default). The DS1775 power-up default
has the sensor automatically performing 9-bit conversions
continuously. Details on how to change the settings after
power-up are contained in the Programming section.
Thermostat Control
In its comparator operating mode, the DS1775 functions
as a thermostat with programmable hysteresis, as shown
in Figure 2. When the DS1775’s temperature meets or
exceeds the value stored in the high temperature trip
register (T ) a consecutive number of times, as defined
OS
by the configuration register, the output becomes active
and stays active until the first time that the temperature
falls below the temperature stored in the low temperature
trigger register (T
). In this way, any amount of hys-
HYST
teresis may be obtained. The DS1775 powers up in the
The resolution of the temperature conversion is configu-
rable (9, 10, 11, or 12 bits), with 9-bit readings the default
state. This equates to a temperature resolution of 0.5°C,
0.25°C, 0.125°C, or 0.0625°C. Following each conver-
sion, thermal data is stored in the thermometer register in
two’s complement format; the information can be retrieved
over the 2-wire interface with the device pointer set to the
temperature register. Table 1 describes the exact relation-
ship of output data to measured temperature. The table
comparator mode with T = +80°C and T = +75°C
OS
HYST
and can be used as a stand-alone thermostat (no 2-wire
interface required) with those setpoints.
In the interrupt mode, the O.S. output first becomes active
following the programmed number of consecutive conver-
sions above T . The fault can only be cleared by either
OS
setting the DS1775 in a shutdown mode or by reading any
register (temperature, configuration, T , or T
) on
OS
HYST
Table 1. Temperature/Data Relationships
S
26
25
24
23
0
22
0
21
0
20
LSb
0
MSB
LSB
MSb
2-1
(UNIT = °C)
2-2
2-3
2-4
TEMPERATURE
DIGITAL OUTPUT
(BINARY)
DIGITAL OUTPUT
(°C)
(HEX)
7D00h
1910h
0A20h
0080h
0000h
FF80h
F5E0h
E6F0h
C900h
+125
+25.0625
+10.125
+0.5
0111 1101 0000 0000
0000 1010 0010 0000
0000 1010 0010 0000
0000 0000 1000 0000
0000 0000 0000 0000
1111 1111 1000 0000
1111 0101 1110 0000
1110 0110 1111 0000
1100 1001 0000 0000
0
-0.5
-10.125
-25.0625
-55
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DS1775
Digital Thermometer and Thermostat in SOT23
the device. Following a clear, a subsequent fault can only
occur if consecutive conversions fall below T . This
Programming section for instructions in adjusting the ther-
mostat setpoints, thermostat mode, and O.S. active state.
HYST
interrupt/clear process is thus cyclical (T , clear, T
,
OS
HYST
Programming
There are three areas of interest in programming the
DS1775: the configuration register, the T
clear, T , clear, T
, clear, etc.). Only the first of
OS
HYST
multiple consecutive T
violations activates O.S., even
OS
register, and
OS
if each fault is separated by a clearing function. The same
the T
register. All programming is done via the 2-wire
HYST
situation applies to multiple consecutive T events.
HYST
interface by setting the pointer to the appropriate location.
Table 2 illustrates the pointer settings for the four registers
of the DS1775.
Regardless of the mode chosen, the O.S. output is
open-drain and the active state is set in the configura-
tion register. The power-up default is active low. See the
T
OS
MEASURED
TEMPERATURE
T
HYST
CONVERSIONS
COMPARATOR MODE
INACTIVE
O.S.
OUTPUT
ACTIVE
CONVERSIONS
INTERRUPT MODE
INACTIVE
O.S.
OUTPUT
ACTIVE
ASSUMES A READ
HAS OCCURRED
THIS TRANSFER FUNCTION ASSUMES THE DS1775 IS CONFIGURED SUCH THAT 2
CONSECUTIVE CONVERSIONS OUT OF TOLERANCE CONSTITUTE AND O.S. FAULT
Figure 2. O.S. Output Transfer Function
Table 2. Pointer Register Structure
POINTER
00h
ACTIVE REGISTER
Temperature (default)
Configuration
01h
02h
T
HYST
03h
T
OS
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DS1775
Digital Thermometer and Thermostat in SOT23
The DS1775 powers up with the temperature register
selected. If the host wishes to change the data pointer, it
simply addresses the DS1775 in the write mode (R/W=
0), receives an acknowledge, and writes the 8 bits that
correspond to the new desired location. The last pointer
location is always maintained so that consecutive reads
from the same register do not require the host to always
provide a pointer address. The only exception is at power-
up, in which case the pointer is always set to 00h, the
temperature register. The pointer address must always
precede data in writing to a register, regardless of which
address is currently selected. See the 2-Wire Serial Data
Bus section for details of the 2-wire bus protocol.
and stored; then the device reverts to a low-power stand-
by mode. The O.S. output is cleared if the device is in the
interrupt mode and remains unchanged in the compara-
tor mode. The 2-wire port remains active. The power-up
default state is 0 (continuous conversion mode).
TM = Thermostat mode. If TM = 0, the DS1775 is in the
comparator mode. TM = 1 sets the device to the interrupt
mode. See the Thermostat Control section for a descrip-
tion of the difference between the two modes. The power-
up default state of the TM bit is 0 (comparator mode).
POL = O.S. Polarity Bit. If POL = 1, the active state of
the O.S. output is 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 0 (active low).
Configuration Register Programming
The configuration register is accessed if the DS1775
pointer is currently set to the 01h location. Writing to or
reading from the register is determined by the R/W bit of
the 2-wire control byte (see the 2-Wire Serial Data Bus
section). Data is read from or written to the configuration
register MSb first. The format of the register is illustrated
in Table 3. The effect each bit has on DS1775 functionality
is described below along with the power-up state of the
bit. The user has read/write access to all bits in the con-
figuration register. The entire register is volatile, and thus
it powers up in the default state.
F0, F1 = O.S. Fault Tolerance bits. The fault tolerance
defines the number of consecutive conversions returning
a temperature beyond limits is required to set the O.S.
output in an active state. This may be necessary to add
margin in noisy environments. Table 4 defines the four
settings. The DS1775 powers up with F0 = F1 = 0, such
that a single occurrence triggers a fault.
R0, R1 = Thermometer resolution bits. Table 5 defines
the resolution of the digital thermometer, based on the
settings of these two bits. There is a direct trade-off
between resolution and conversion time, as shown in the
AC Electrical Characteristics. The default state is R0 = 0
and R1 = 0 (9-bit conversions).
SD = Shutdown bit. If SD is 0, the DS1775 continuously
performs temperature conversions and stores the last
completed result in the thermometer register. If SD is
changed to 1, the conversion in progress is completed
Table 3. Configuration/Status Register
0
R1
R0
F1
F0
POL
TM
SD
MSb
LSb
Table 4. Fault Tolerance Configuration
F1
0
F0
0
CONSECUTIVE CONVERSIONS BEYOND LIMITS TO GENERATE FAULT
1
2
4
6
0
1
1
0
1
1
Table 5. Thermometer Resolution Configuration
R1
0
R0
0
THERMOMETER RESOLUTION (BITS)
MAX CONVERSION TIME (SECONDS)
9
0.1875
0.375
0.75
0
1
10
11
12
1
0
1
1
1.5
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DS1775
Digital Thermometer and Thermostat in SOT23
Thermostat Setpoints Programming
2-WIRE Serial Data Bus
The thermostat registers (T
and T
) can be
The DS1775 supports a bidirectional 2-wire bus and data
transmission protocol. A device that sends data onto the
bus is defined as a transmitter, and a device receiving
data as a receiver. The device that controls the message
is called a “master”. The devices that are controlled by
the master are “slaves”. The bus must be controlled by
a master device which generates the serial clock (SCL),
controls the bus access, and generates the START and
STOP conditions. The DS1775 operates as a slave on
the 2-wire bus. Connections to the bus are made via the
open-drain I/O lines SDA and SCL.
OS
HYST
programmed or read via the 2-wire interface. T
is
OS
accessed by setting the DS1775 data pointer to the 03h
location, and to the 02h location for T
.
HYST
The format of the T
and T
registers is identical to
HYST
OS
that of the Thermometer register; that is, 12-bit 2’s com-
plement representation of the temperature in °C. The user
can program the number of bits (9, 10, 11, or 12) for each
T
and T
that corresponds to the thermometer
OS
HYST
resolution mode chosen. For example, if the 9-bit mode is
chosen the three least significant bits of T and T
OS
HYST
are ignored by the thermostat comparator. Table 6 shows
The following bus protocol has been defined
(see Figure 3):
the format for both T and T . The power-up default
OS
HYST
for T
is +80°C and for T
is +75°C.
OS
HYST
● Data transfer may be initiated only when the bus is
If the user does not wish to take advantage of the ther-
mostat capabilities of the DS1775, the 24 bits can be
used for general storage of system data that need not be
maintained following a power loss.
not busy.
● During data transfer, the data line must remain stable
whenever the clock line is HIGH. Changes in the data
line while the clock line is high are interpreted as con-
trol signals.
Table 6. Thermostat Setpoint (T /T
) Format
OS HYST
S
26
25
24
(UNIT = °C)
2-4
0
23
22
0
21
0
20
LSb
0
MSB
LSB
MSb
2-1
2-2
2-3
TEMPERATURE
DIGITAL OUTPUT
(BINARY)
DIGITAL OUTPUT
(°C)
(HEX)
5000h
4B00h
0A20h
0080h
0000h
FF80h
F5E0h
E6F0h
C900h
+80
+75
0101 0000 0000 0000
0100 1011 0000 0000
0000 1010 0010 0000
0000 0000 1000 0000
0000 0000 0000 0000
1111 1111 1000 0000
1111 0101 1110 0000
1110 0110 1111 0000
1100 1001 0000 0000
+10.125
+0.5
0
-0.5
-10.125
-25.0625
-55
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DS1775
Digital Thermometer and Thermostat in SOT23
Accordingly, the following bus conditions have been
defined:
The information is transferred byte-wise and each receiv-
er acknowledges with a ninth bit.
Bus not busy: Both data and clock lines remain HIGH.
Within the bus specifications a standard mode (100kHz
clock rate) and a fast mode (400kHz clock rate) are
defined. The DS1775 works in both modes.
Start data transfer: A change in the state of the data
line, from HIGH to LOW, while the clock is HIGH, defines
a START condition.
Acknowledge: Each receiving device, when addressed,
is obliged to generate an acknowledge after the reception
of each byte. The master device must generate an extra
clock pulse which is associated with this acknowledge bit.
Stop data transfer: A change in the state of the data line,
from LOW to HIGH, while the clock line is HIGH, defines
the STOP condition.
A device that acknowledges must pull down the SDA line
during the acknowledge clock pulse in such a way that
the SDA line is stable LOW during the HIGH period of the
acknowledge related clock pulse. Of course, setup and
hold times must be taken into account. A master must
signal an end of data to the slave by not generating an
acknowledge bit on the last byte that has been clocked
out of the slave. In this case, the slave must leave the
data line HIGH to enable the master to generate the
STOP condition.
Data valid: The state of the data line represents valid
data when, after a START condition, the data line is stable
for the duration of the HIGH period of the clock signal.
The data on the line must be changed during the LOW
period of the clock signal. There is one clock pulse per
bit of data.
Each data transfer is initiated with a START condition and
terminated with a STOP condition. The number of data
bytes transferred between START and STOP conditions
is not limited, and is determined by the master device.
SDA
MSB
SLAVE
ADDRESS
R/W
DIRECTION
BIT
ACKNOWLEDGEMENT
SIGNAL FROM
RECEIVER
ACKNOWLEDGEMENT
SIGNAL FROM
RECEIVER
SCL
1
2
6
7
8
9
1
2
3–8
8
9
ACK
ACK
START
CONDITION
REPEATED IF
MORE BYTES ARE
TRANSFERRED
STOP CONDITION
OR REPEATED
START CONDITION
Figure 3. Data Transfer on 2-Wire Serial Bus
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DS1775
Digital Thermometer and Thermostat in SOT23
Figure 3 details how data transfer is accomplished on the
2-wire bus. Depending upon the state of the R/W bit, two
types of data transfer are possible:
2) Slave transmitter mode: The first byte is received
and handled as in the slave receiver mode. However,
in this mode, the direction bit indicates that the trans-
fer direction is reversed. Serial data is transmitted on
SDA by the DS1775 while the serial clock is input on
SCL. START and STOP conditions are recognized as
the beginning and end of a serial transfer.
1) Data transfer from a master transmitter to a slave
receiver. The first byte transmitted by the master is
the slave address. Next follows a number of data
bytes. The slave returns an acknowledge bit after
each received byte.
Slave Address
2) Data transfer from a slave transmitter to a master
receiver. The first byte (the slave address) is trans-
mitted by the master. The slave then returns an ac-
knowledge bit. Next follows a number of data bytes
transmitted by the slave to the master. The master re-
turns an acknowledge bit after all received bytes other
than the last byte. At the end of the last received byte,
a ‘not acknowledge’ is returned.
A control byte is the first byte received following the
START condition from the master device. The control
byte consists of a 4-bit control code; for the DS1775, this
is set as 1001 binary for read and write operations. The
next three bits of the control byte are the device select bits
(A2, A1, A0). These bits are set to 000 (A2 = 0, A1 = 0, A0
= 0) for the DS1775R and vary according to the device’s
part number as specified in the Ordering Information
table. They are used by the master device to select which
of eight devices are to be accessed. The set bits are in
effect the three least significant bits of the slave address.
The last bit of the control byte (R/W) defines the opera-
tion to be performed. When set to a 1 a read operation is
selected; when set to a 0 a write operation is selected.
Following the START condition, the DS1775 monitors the
SDA bus checking the device type identifier being trans-
mitted. Upon receiving the 1001 code and appropriate
device select bits of 000, the DS1775 outputs an acknowl-
edge signal on the SDA line. See Figure 4.
The master device generates all the serial clock pulses
and the START and STOP conditions. A transfer is ended
with a STOP condition or with a repeated START condi-
tion. Since a repeated START condition is also the begin-
ning of the next serial transfer, the bus is not released.
The DS1775 can operate in the following two modes:
1) Slave receiver mode: Serial data and clock are re-
ceived through SDA and SCL. After each byte is re-
ceived, an acknowledge bit is transmitted. START
and STOP conditions are recognized as the begin-
ning and end of a serial transfer. Address recognition
is performed by hardware after reception of the slave
address and direction bit.
Maxim Integrated
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DS1775
Digital Thermometer and Thermostat in SOT23
WRITE TO POINTER ADDRESS
SCL
SDA
S
0
0
0
0
0
W
A
0
0
0
0
0
0
0
0
P1 P0
A
1
1
P
START
ADDRESS BYTE
DS1775
ACK
POINTER BYTE
DS1775 STOP
ACK
WRITE TO CONFIGURATION REGISTER (SINGLE BYTE)
SCL
SDA
S
0
0
0
0
0
A
0
0
0
0
A
D7 D6 D5 D4 D3 D2 D1 D0
A
W
0
0
1
P
1
1
START
ADDRESS BYTE
DS1775
ACK
POINTER BYTE
DS1775
ACK
DATA BYTE
DS1775 STOP
ACK
WRITE TO T / T
REGISTER (TWO–BYTE)
OS HYST
SCL
SDA
S
A
0
0
0
0
0
W
A
0
0
0
0
0
P1 P0
A
D7 D6 D5 D4 D3 D2 D1 D0
1
1
START
ADDRESS BYTE
DS1775
ACK
POINTER BYTE
DS1775
ACK
MSBYTE
DS1775
ACK
SCL
SDA
A
D7 D6 D5 D4 D3 D2 D1 D0
P
LSBYTE
DS1775 STOP
ACK
READ SINGLE BYTE FROM CURRENT POINTER LOCATION (CONFIGURATION)
SCL
SDA
D7 D6 D5 D4 D3 D2 D1 D0
S
0
0
0
0
0
A
N
P
Rd
1
1
START
ADDRESS BYTE
DS1775
ACK
DATA BYTE
MASTER
NACK
STOP
READ MULTIPLE BYTES FROM CURRENT POINTER LOCATION (TEMPERATURE, T , T
)
OS HYST
SCL
SDA
S
0
0
1
0
0
0
Rd
A
D7 D6 D5 D4 D3 D2 D1 D0
A
D7 D6 D5 D4 D3 D2 D1 D0
N
P
1
START
ADDRESS BYTE
DS1775
ACK
MSBYTE
MASTER
ACK
LSBYTE
MASTER STOP
ACK
READ SINGLE BYTE FROM NEW POINTER ADDRESS REGISTER
SCL
SDA
W
A
0
0
0
0
0
0
P1 P0
A
R
0
0
1
A2 A1 A0 Rd
A
S
0
0
1
0
0
0
1
1
START
ADDRESS BYTE
DS1775
ACK
POINTER BYTE
DS1775 REPEATED
ACK START
ADDRESS BYTE
DS1775
ACK
SCL
SDA
D7 D6 D5 D4 D3 D2 D1 D0
N
P
STOP
DATA BYTE
MASTER
NACK
Figure 4. 2-Wire Serial Communication with DS1775
Maxim Integrated
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DS1775
Digital Thermometer and Thermostat in SOT23
SDA
t
BUF
t
LOW
t
R
t
F
t
HD:STA
SCL
t
HD:STA
t
SU:STO
t
SU:STA
t
t
t
SU:DAT
HD:DAT
HIGH
STOP START
REPEATED
START
Figure 5. Timing Diagram
Ordering Information
PART
ADDRESS
TOP MARK
TEMP RANGE
PIN-PACKAGE
DS1775R+U
000
7750
7751
7752
7753
7754
7755
7756
7757
-55°C to +125°C
5 SOT23
DS1775R+T&R
DS1775R1+U
DS1775R1+T&R
DS1775R2+U
DS1775R2+T&R
DS1775R3+U
DS1775R3+T&R
DS1775R4+U
DS1775R4+T&R
DS1775R5+U
DS1775R5+T&R
DS1775R6+U
DS1775R6+T&R
DS1775R7+U
DS1775R7+T&R
001
010
011
100
101
110
111
-55°C to +125°C
-55°C to +125°C
-55°C to +125°C
-55°C to +125°C
-55°C to +125°C
-55°C to +125°C
-55°C to +125°C
5 SOT23
5 SOT23
5 SOT23
5 SOT23
5 SOT23
5 SOT23
5 SOT23
+Denotes a lead(Pb)-free/RoHS-compliant package.
U = Cut tape.
T&R = Tape and reel.
Package Information
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”,
“#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing
pertains to the package regardless of RoHS status.
PACKAGE TYPE
PACKAGE CODE
OUTLINE NO.
21-0057
LAND PATTERN NO.
90-0174
5 SOT23
U5+1
Maxim Integrated
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DS1775
Digital Thermometer and Thermostat in SOT23
Revision History
REVISION REVISION
PAGES
DESCRIPTION
CHANGED
NUMBER
DATE
Updated the Absolute Maximum Ratings, Ordering Information, Package Information
sections
1
5/13
12, 13
2
Added typical specification to the Thermometer Error parameter in the Electrical
Characteristics table and added Thermometer Error (TERR) typical spec in the
Electrical Characteristics table.
2
11/16
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits)
shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
©
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
2016 Maxim Integrated Products, Inc.
│ 14
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