LM99

SNIS129D – JANUARY 2003 – REVISED MARCH 2013

www.ti.com

D7–D0: T_CRIT Hysteresis temperature. Power-on default is TH = 10°C. 1 LSB = 1°C, maximum value = 31.

FILTER and ALERT CONFIGURE REGISTER

Table 16. (Read and Write Address BFh):

BIT

D7

D6

D5

D4

D3

D2

D1

D0

Value

0

0

0

0

0

Filter Level

ALERT Configure

D7-D3: is not defined defaults to "0".

D2-D1: input filter setting as defined the table below:

D2

D1

Filter Level

0

0

No Filter

0

1

Level 1

1

0

Level 1

1

1

Level 2

Level 2 sets maximum filtering.

D0: when set to "1" comparator mode is enabled.

MANUFACTURERS ID REGISTER

(Read Address FEh) Default value 01h.

DIE REVISION CODE REGISTER

(Read Address FFh) The LM99 version has a default value 31h or 49 decimal. The LM99-1 version has a default

value of 34h or 52 decimal. This register will increment by 1 every time there is a revision to the die by Texas

Instruments.

Application Hints

The LM99 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 LM99'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 surface temperature, the actual temperature of the of the LM99 die will be at an

intermediate temperature between the surface and air temperatures. Again, the primary thermal conduction path

is through the leads, so the circuit board temperature will contribute to the die temperature much more strongly

than will the air temperature.

To measure temperature external to the LM99's die, use a remote diode. This diode can be located on the die of

a target IC, allowing measurement of the IC's temperature, independent of the LM99's temperature. The LM99

has been optimized to measure the NVIDIA GeForceFX family thermal diode. Remember that a discrete diode's

temperature will be affected, and often dominated, by the temperature of its leads.

20

Submit Documentation Feedback

Copyright © 2003–2013, Texas Instruments Incorporated

Product Folder Links: LM99