DS1775R/TR1 DALLAS [Dallas Semiconductor], DS1775R/TR1 Datasheet - Page 7

• Manufacturer Part Number: DS1775R/TR1
• Description: SOT23-5 Digital Thermometer and Thermostat
• Manufacturer: DALLAS [Dallas Semiconductor]

Thermometer Resolution Configuration Table 5
Thermostat Setpoints Programming
The thermostat registers (T
accessed by setting the DS1775 data pointer to the 03h location, and to the 02h location for T
The format of the T
2’ s complement representation of the temperature in C. The user can program the number of bits (9, 10,
11, or 12) for each T
example, if the 9–bit mode is chosen the 3 least significant bits of T
thermostat comparator. The format for both T
for T
Thermostat Setpoint (T
TEMPERATURE/DATA RELATIONSHIPS
If the user does not wish to take advantage of the thermostat 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 bi–directional 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 two–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 4):
R1
0
0
1
1
MSb
2
S
-1
OS
-25.0625 C
+10.125 C
-10.125 C
is 80 C and for T
TEMP
+0.5 C
R0
+80 C
+75 C
-0.5 C
-55 C
0
1
0
1
+0 C
2
2
-2
6
OS
OS
and T
Thermometer Resolution
HYST
and T
2
2
OS
HYST
-3
5
is 75 C.
and T
OS
HYST
10-bit
11-bit
12-bit
registers is identical to that of the Thermometer register; that is, 12–bit
9-bit
/T
DIGITAL OUTPUT
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
HYST
that corresponds to the thermometer resolution mode chosen. For
HYST
2
2
(UNIT = C)
-4
4
) can be programmed or read via the 2–wire interface. T
) Format Table 6
(Binary)
OS
7 of 13
and T
2
0
3
HYST
is shown in Table 6. The power–up default
2
0
2
OS
Max Conversion Time
and T
DIGITAL OUTPUT (Hex)
2
0
1
HYST
0.15s
0.3s
0.6s
1.2s
will be ignored by the
0A20h
4B00h
F5E0h
E6F0h
C900h
FF80h
5000h
0080h
0000h
LSb
102299
2
0
0
HYST
.
MSB
LSB
DS1775
OS
is