Rainbow Electronics LM75 - Manual (Page 11)

1.0 Functional Description
(Continued)
1.11 POINTER REGISTER
(Selects which registers will be read from or written to):
P7 P6 P5 P4 P3 P2 P1 P0
0 0 0 0 0 0 Register
Select
P0-P1: Register Select:
P1 P0 Register
0 0 Temperature (Read only) (Power-up default)
0 1 Configuration (Read/Write)
1 0 T
HYST
(Read/Write)
1 1 T
OS
(Read/Write)
P2–P7: Must be kept zero. 1.12 TEMPERATURE REGISTER
(Read Only):
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
MSB Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 LSB X X X X X X X
D0–D6: Undefined
D7–D15: Temperature Data. One LSB = 0.5˚C. Two’s
complement format.
1.13 CONFIGURATION REGISTER
(Read/Write):
D7 D6 D5 D4 D3 D2 D1 D0
0 0 0 Fault Queue O.S. Cmp/Int Shutdown
Polarity
Power up default is with all bits “0” (zero).
D0: Shutdown: When set to 1 the LM75 goes to low power
shutdown mode.
D1: Comparator/Interrupt mode: 0 is Comparator mode, 1 is
Interrupt mode.
D2: O.S. Polarity: 0 is active low, 1 is active high. O.S. is an
open-drain output under all conditions.
D3–D4: Fault Queue: Number of faults necessary to detect
before setting O.S. output to avoid false tripping due to
noise. Faults are determind at the end of a conversion.
Conversions take about 100 ms, typically, to complete.
D4 D3 Number of Faults
0 0 1 (Power-up default)
0 1 2
1 0 4
1 1 6
D5–D7: These bits are used for production testing and must
be kept zero for normal operation. 1.14 T
HYST
AND T
OS
REGISTER
(Read/Write):
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
MSB Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 LSB X X X X X X X
D0–D6: Undefined
D7–D15: T
HYST
Or T
OS
Trip Temperature Data. Power up
default is T
OS
= 80˚C, T
HYST
= 75˚C.
LM75
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