1.8.6 LOCAL AND REMOTE T_CRIT REGISTERS

(Read/Write):

D7

D6

D5

D4

D3

D2

D1

D0

MSB

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

LSB

D7–D0: RT_CRIT and LT_CRIT setpoint temperature data. Power up default is LT_CRIT =127˚C and RT_CRIT = 95˚C.

2.0 SMBus Timing Diagrams

3.0 Application Hints

The LM91 can be applied easily in the same way as other

integrated-circuit temperature sensors, and its remote diode

sensing capability allows it to be used in new ways as well.

It can be soldered to a printed circuit board, and because the

path of best thermal conductivity is between the die and the

pins, its temperature will effectively be that of the printed

circuit board lands and traces soldered to the LM91’s pins.

This presumes that the ambient air temperature is almost the

same as the surface temperature of the printed circuit board;

if the air temperature is much higher or lower than the

20034310

(a) Serial Bus Write to the internal Command Register followed by a the Data Byte

20034311

(b) Serial Bus Write to the internal Command Register

20034312

(c) Serial Bus Read from a Register with the internal Command Register preset to desired value.

FIGURE 4. Serial Bus Timing Diagrams

www.national.com

11