LM76

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SNIS109E – JANUARY 2000 – REVISED MARCH 2013

The first data byte is the most significant byte with most significant bit first, permitting only as much data as

necessary to be read to determine the temperature condition. For instance, if the first four bits of the temperature

data indicates a critical condition, the host processor could immediately take action to remedy the excessive

temperature. At the end of a read, the LM76 can accept either Acknowledge or No Acknowledge from the Master

(No Acknowledge is typically used as a signal for the slave that the Master has read its last byte).

An inadvertent 8-bit read from a 16-bit register, with the D7 bit low, can cause the LM76 to stop in a state where

the SDA line is held low as shown in Figure 7. 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 LM76.

Figure 7. 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–P2: 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

T_CRIT (Read/Write)

1

0

0

1

0

1

P3–P7: Must be kept zero.

TEMPERATURE REGISTER

Table 1. (Read Only):

D15

D14

D13

D12

D11

D10

D9

D8

D7

D6

D5

D4

D3

D2

D1

D0

Sign

MSB

Bit 10

Bit 9

Bit 8

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

CRIT

HIGH

LOW

Status Bits

D0–D2: Status Bits

D3–D15: Temperature Data. One LSB = 0.0625°C. Two's complement format.

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