1.5 INTERNAL REGISTER STRUCTURE

The LM70 has three registers, the temperature register, the

configuration register and the manufacturer’s/device identifi-

cation register. The temperature and manufacturer’s/device

identification registers are read only. The configuration reg-

ister is write only.

1.5.1 CONFIGURATION REGISTER

(Selects shutdown or continuous conversion modes):

(Write Only):

D15

D14

D13

D12

D11

D10

D9

D8

D7

D6

D5

D4

D3

D2

D1

D0

X

XXXXXXX

Shutdown

D0-D15 set to XX FF hex enables shutdown mode.

D0-D15 set to XX 00 hex enables continuous conversion

mode.

Note: setting D0-D15 to any other values may place the

LM70 into a manufacturer’s test mode, upon which the LM70

will stop responding as described. These test modes are to

be used for National Semiconductor production testing only.

See Section 1.2 Serial Bus Interface for a complete discus-

sion.

1.5.2 TEMPERATURE REGISTER

(Read Only):

D15

D14

D13

D12

D11

D10

D9

D8

D7

D6

D5

D4

D3

D2

D1

D0

MSB

Bit 9

Bit 8

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

LSB

1

1

1

X

X

D0–D1: Undefined. TRI-STATE will be output on SI/0.

D2–D4: Always set high.

D5–D15: Temperature Data. One LSB = 0.25˚C. Two’s

complement format.

1.5.3 MANUFACTURER’S/DEVICE ID REGISTER

(Read Only):

D15

D14

D13

D12

D11

D10

D9

D8

D7

D6

D5

D4

D3

D2

D1

D0

1

0000001000000

X

X

D0–D1: Undefined. TRI-STATE will be output on SI/0.

D2-D4: Always set LOW.

D5–D15: Manufacturer’s ID Data. This register is accessed

whenever the LM70 is in shutdown mode.

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