LM74-3EVAL National Semiconductor, LM74-3EVAL Datasheet - Page 10

LM74-3EVAL

Manufacturer Part Number

LM74-3EVAL

Description

Manufacturer

National Semiconductor

Datasheet

1.LM74-3EVAL.pdf (15 pages)

Specifications of LM74-3EVAL

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1.0 Functional Description

1.5 INTERNAL REGISTER STRUCTURE

The LM74 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):

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

D0–D15 set to 00 00 hex sets Continuous conversion mode.

Note: setting D0-D15 to any other values may place the LM74 into a manufacturer’s test mode, upon which the LM74 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 discussion.

1.5.2 Temperature Register (after power-up, before first complete temperature conversion)

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

D2–D15: Power-on Reset (POR) values.

1.5.3 Temperature Register (after completion of first temperature conversion)

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

D2: High.

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

1.5.4 Manufacturer’s Device ID Register

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

D2–D15: Manufacturer’s/Device ID Data. This register is accessed whenever the LM74 is in shutdown mode.

(Write Only):

(Read Only):

MSB

D15

Bit 11 Bit 10

D14

D13

Bit 9

D12

Bit 8

D11

Bit 7

D10

(Continued)

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Shutdown

LSB