LM75B, LM75C

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SNIS153B – JULY 2009 – REVISED MARCH 2013

An inadvertent 8-bit read from a 16-bit register, with the D7 bit low, can cause the LM75 to stop in a state where

the SDA line is held low as shown in Figure 11. This can prevent any further bus communication until at least 9

additional clock cycles have occurred. Alternatively, the master can issue clock cycles until SDA goes high, at

which time issuing a “Stop” condition will reset the LM75.

Figure 11. Inadvertent 8-Bit Read from 16-Bit Register where D7 is Zero (“0”)

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

Register Select

P0-P1: Register Select:

P2

P1

P0

Register

0

0

0

Temperature (Read only) (Power-up default)

0

0

1

Configuration (Read/Write)

0

1

0

0

1

1

P3–P7: Must be kept zero.

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.

CONFIGURATION REGISTER (Read/Write):

D7

D6

D5

D4

D3

D2

D1

D0

0

0

0

Fault Queue

O.S. Polarity

Cmp/Int

Shutdown

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. See specified temperature conversion time in the

Temperature-to-Digital Converter Characteristics table.

D4

D3

Number of Faults

0

0

1 (Power-up default)

0

1

2

1

0

4

1

1

6

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