1.9 POINTER REGISTER

(Selects which registers will be read from or written to):

P7

P6

P5

P4

P3

P2

P1

P0

00000

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)

010

T

0

1

1

T_CRIT (Read/Write)

100

T

101

T

P3–P7: Must be kept zero.

1.10 TEMPERATURE REGISTER

(Read Only):

D15

D14

D13

D12

D11

D10

D9

D8

D7

D6

D5

D4

D3

D2

D1

D0

Sign

Sign

Sign

Sign

MSB

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 = 0.5˚C. Two’s complement format.

1.11 CONFIGURATION REGISTER

(Read/Write):

D7

D6

D5

D4

D3

D2

D1

D0

0

0

0

Fault Queue

INT Polarity

T_CRIT_A

Polarity

INT Mode

Shutdown

D0: Shutdown - When set to 1 the LM77 goes to low power shutdown mode. Power up default of “0”.

D1: Interrupt mode-0is Comparator Interrupt mode, 1 is Event Interrupt mode. Power up default of “0”.

D2, D3: T_CRIT_A and INT Polarity-0is active low, 1 is active high. Outputs are open-drain. Power up default of “0”

D4: Fault Queue - When set to 1 the Fault Queu is enabled,

see

Section 1.7. Power up default of “0”.

D5–D7: These bits are used for production testing and must be kept zero for normal operation.

1.12 T

(Read/Write):

D15

D14

D13

D12

D11

D10

D9

D8

D7

D6

D5

D4

D3

D2

D1

D0

Sign

Sign

Sign

Sign

MSB

Bit7

Bit6

Bit5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

X

X

X

D0–D2: Undefined

D3–D15: T

T

T

Avoid programming setpoints so close that their hysteresis values overlap. See

Section 1.1.

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