7.

Status Register: busy, diode fault

8.

Configuration Register: resolution control, conversion

rate control, standby control

9.

1-shot Register

10. Manufacturer ID

11. Revision ID

1.1 CONVERSION SEQUENCE

The LM95221 takes approximately 66 ms to convert the

Local Temperature, Remote Temperature 1 and 2, and to

update all of its registers. Only during the conversion pro-

cess the busy bit (D7) in the Status register (02h) is high.

These conversions are addressed in a round robin se-

quence. The conversion rate may be modified by the Con-

version Rate bits found in the Configuration Register (03h).

When the conversion rate is modified a delay is inserted

between conversions, the actual conversion time remains at

66ms (26 ms for each remote and 14 ms for local). Different

conversion rates will cause the LM95221 to draw different

amounts of supply current as shown in Figure 2.

1.2 POWER-ON-DEFAULT STATES

LM95221 always powers up to these known default states.

The LM95221 remains in these states until after the first

conversion.

1.

Command Register set to 00h

2.

Local Temperature set to 0˚C

3.

Remote Diode Temperature set to 0˚C until the end of

the first conversion

4.

Status Register depends on state of thermal diode in-

puts

5.

Configuration register set to 00h; continuous conversion,

time = 66ms

1.3 SMBus INTERFACE

The LM95221 operates as a slave on the SMBus, so the

SMBCLK line is an input and the SMBDAT line is bidirec-

tional. The LM95221 never drives the SMBCLK line and it

does not support clock stretching. According to SMBus

specifications, the LM95221 has a 7-bit slave address. All

bits A6 through A0 are internally programmed and can not be

changed by software or hardware. The LM95221 has the

following SMBus slave address:

Version

A6

A5

A4

A3

A2

A1

A0

LM95221

0

1

0

1

0

1

1

1.4 TEMPERATURE DATA FORMAT

Temperature data can only be read from the Local and

Remote Temperature registers .

Remote temperature data is represented by an 11-bit, two’s

complement word or unsigned binary word with an LSb

(Least Significant Bit) equal to 0.125˚C. The data format is a

left justified 16-bit word available in two 8-bit registers. Un-

used bits will always report "0".

11-bit, 2’s complement (10-bit plus sign)

Temperature

Digital Output

Binary

Hex

+125˚C

0111 1101 0000 0000

7D00h

+25˚C

0001 1001 0000 0000

1900h

+1˚C

0000 0001 0000 0000

0100h

+0.125˚C

0000 0000 0010 0000

0020h

0˚C

0000 0000 0000 0000

0000h

−0.125˚C

1111 1111 1110 0000

FFE0h

−1˚C

1111 1111 0000 0000

FF00h

−25˚C

1110 0111 0000 0000

E700h

−55˚C

1100 1001 0000 0000

C900h

11-bit, unsigned binary

Temperature

Digital Output

Binary

Hex

+255.875˚C

1111 1111 1110 0000

FFE0h

+255˚C

1111 1111 0000 0000

FF00h

+201˚C

1100 1001 0000 0000

C900h

+125˚C

0111 1101 0000 0000

7D00h

+25˚C

0001 1001 0000 0000

1900h

+1˚C

0000 0001 0000 0000

0100h

+0.125˚C

0000 0000 0010 0000

0020h

0˚C

0000 0000 0000 0000

0000h

Local Temperature data is represented by a 10-bit, two’s

complement word with an LSb (Least Significant Bit) equal to

0.25˚C. The data format is a left justified 16-bit word avail-

able in two 8-bit registers. Unused bits will always report "0".

Local temperature readings greater than +127.875˚C are not

clamped to +127.875˚C, they will roll-over to negative tem-

perature readings.

Temperature

Digital Output

Binary

Hex

+125˚C

0111 1101 0000 0000

7D00h

+25˚C

0001 1001 0000 0000

1900h

+1˚C

0000 0001 0000 0000

0100h

+0.125˚C

0000 0000 0010 0000

0020h

0˚C

0000 0000 0000 0000

0000h

20094306

FIGURE 2. Conversion Rate Effect on Power Supply

Current

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