DS75_08 Datasheet, PDF (9/14 Pages) Dallas Semiconductor – Digital Thermometer and Thermostat

DS75
CONFIGURATION REGISTER
The configuration register allows the user to program various DS75 options such as conversion
resolution, thermostat fault tolerance, thermostat polarity, thermostat operating mode, and shutdown
mode. The configuration register is arranged as shown in Figure 5 and detailed descriptions of each bit
are provided in Table 4. The user has read/write access to all bits in the configuration register except the
MSb, which is a reserved read-only bit. The entire register is volatile, and thus powers–up in its default
state.
Figure 5. CONFIGURATION REGISTER
MSb
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
LSb
0
R1
R0
F1
F0 POL TM
SD
Table 4. CONFIGURATION REGISTER BIT DESCRIPTIONS
BIT NAME
FUNCTIONAL DESCRIPTION
0
Power-up state = 0
Reserved
The master can write to this bit, but it will always read out as a 0.
R1
Power-up state = 0
Conversion Resolution Bit 1
Sets conversion resolution (see Table 5)
R0
Power-up state = 0
Conversion Resolution Bit 0
Sets conversion resolution (see Table 5)
F1
Power-up state = 0
Thermostat Fault Tolerance Bit 1 Sets the thermostat fault tolerance (see Table 6).
F0
Power-up state = 0
Thermostat Fault Tolerance Bit 0 Sets the thermostat fault tolerance (see Table 6).
POL
Power-up state = 0
Thermostat Output (O.S.) Polarity POL = 0 — O.S. is active low.
POL = 1 — O.S. is active high.
TM
Power-up state = 0
Thermostat Operating Mode
TM = 0 — Comparator mode.
TM = 1 — Interrupt mode.
See the OPERATION–Thermostat section for a detailed description
of these modes.
SD
Power-up state = 0
Shutdown
SD = 0 — Active conversion and thermostat operation.
SD = 1 — Shutdown mode.
See the SHUTDOWN MODE section for a detailed description of
this mode.
Table 5. RESOLUTION CONFIGURATION
R1 R0 THERMOMETER MAX CONVERSION
RESOLUTION
TIME
00
9–bit
150 ms
01
10–bit
300 ms
10
11–bit
600 ms
11
12–bit
1200 ms
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