2.2 TEMPERATURE DATA REGISTER

Pointer Address 00h (Read Only)

Reset State: 7FFCh (+255.96875˚C)

One-Shot State: 8000h (-256˚C)

D15

D14

D13

D12

D11

D10

D9

D8

SIGN

128˚C

64˚C

32˚C

16˚C

8˚C

4˚C

2˚C

D7

D6

D5

D4

D3

D2

D1

D0

1˚C

0.5˚C

0.25˚C

0.125˚C

0.0625˚C

0.03125˚C

reserved

reserved

Bits

Name

Description

15:2

Temperature Data

Represents the temperature that was measured by the most recent temperature conversion.

On Power-up, this data is invalid until the Data Available (DAV) bit in the Control/Status

register is high (after the completion of the first temperature conversion). The resolution is

user-progammable from 11-bit resolution (0.25˚C/LSB) through 14-bit resolution

(0.03125˚C/LSB). The desired resolution is programmed with bits 5 and 6 of the

Control/Status register.

1:0

Not Used

Return zeros upon read.

2.3 CONFIGURATION REGISTER

Pointer Address 01h (R/W)

Reset State: 40h

D7

D6

D5

D4

D3

D2

D1

D0

PD

reserved

ALRT EN

ALRT POL

ALRT RST

ONE SHOT

reserved

Bits

Name

Description

7

Full Power Down

Writinga1to this bit puts the LM73 in shutdown mode for power conservation. Writing a 0

puts the LM73 into normal mode.

6

reserved

User must write onlya1to this bit

5

ALERT Enable

A 0 in this location enables the ALERT output. A 1 disables it. This bit also controls the

ALERT Status bit (the Control/Status Register, Bit 3) since that bit reflects the state of the

Alert pin.

4

ALERT Polarity

When set to 1, the ALERT pin and ALERT Status bit are active-high. When 0, it is

active-low.

3

ALERT Reset

Writinga1to this bit resets the ALERT pin and the ALERT Status bit. It will always be 0

when read.

2

One Shot

When in shutdown mode (Bit 7 is 1), initiates a single temperature conversion and update of

the temperature register with new temperature data. Has no effect when in continuous

conversion mode (i.e., when Bit 7 is 0). Always returns a 0 when read.

1:0

Reserved

User must write onlya0to these bits.

2.4 T

Pointer Address 02h (R/W)

Reset State: 7FE0h (+255.75˚C)

D15

D14

D13

D12

D11

D10

D9

D8

SIGN

128˚C

64˚C

32˚C

16˚C

8˚C

4˚C

2˚C

D7

D6

D5

D4

D3

D2

D1

D0

1˚C

0.5˚C

0.25˚C

reserved

Bits

Name

Description

15:5

Upper-Limit

Temperature

If the measured temperature that is stored in this register exceeds this user-programmable

upper temperature limit, the ALERT pin will go active and the THIGH flag in the

Control/Status register will be set to 1. Two’s complement format.

4:0

Reserved

Returns zeros upon read. Recommend writing zeros only in these bits.

www.national.com

14