DS1775R2-TU0026R 查看數據表（PDF） - Maxim Integrated

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DS1775R2-TU0026R

Digital Thermometer and Thermostat in SOT23

Maxim Integrated 

DS1775

Digital Thermometer and Thermostat in SOT23

Thermostat Setpoints Programming

The thermostat registers (TOS and THYST) can be

programmed or read via the 2-wire interface. TOS is

accessed by setting the DS1775 data pointer to the 03h

location, and to the 02h location for THYST.

The format of the TOS and THYST registers is identical to

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

TOS and THYST that corresponds to the thermometer

resolution mode chosen. For example, if the 9-bit mode is

chosen the three least significant bits of TOS and THYST

are ignored by the thermostat comparator. Table 6 shows

the format for both TOS and THYST. The power-up default

for TOS is +80°C and for THYST is +75°C.

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.

2-WIRE Serial Data Bus

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.

The following bus protocol has been defined

(see Figure 3):

●● Data transfer may be initiated only when the bus is

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 (TOS/THYST) Format

S

26

25

24

23

22

21

20

MSb

(UNIT = °C)

LSb

2-1

2-2

2-3

2-4

0

0

0

0

MSB

LSB

TEMPERATURE

(°C)

+80

+75

+10.125

+0.5

0

-0.5

-10.125

-25.0625

-55

DIGITAL OUTPUT

(BINARY)

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

DIGITAL OUTPUT

(HEX)

5000h

4B00h

0A20h

0080h

0000h

FF80h

F5E0h

E6F0h

C900h

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