LM62 datasheet(4/7 Pages) NSC

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Typical Performance Characteristics To generate these curves the LM62 was mounted to a

printed circuit board as shown in

Figure 2. (Continued)

1.0 Mounting

The LM62 can be applied easily in the same way as other

integrated-circuit temperature sensors. It can be glued or ce-

mented to a surface. The temperature that the LM62 is sens-

ing will be within about +0.2˚C of the surface temperature

that LM62’s leads are attached to.

This presumes that the ambient air temperature is almost the

same as the surface temperature; if the air temperature were

much higher or lower than the surface temperature, the ac-

tual temperature measured would be at an intermediate tem-

perature between the surface temperature and the air tem-

perature.

To ensure good thermal conductivity the backside of the

LM62 die is directly attached to the GND pin. The lands and

traces to the LM62 will, of course, be part of the printed cir-

cuit board, which is the object whose temperature is being

measured. These printed circuit board lands and traces will

not cause the LM62’s temperature to deviate from the de-

sired temperature.

Alternatively, the LM62 can be mounted inside a sealed-end

metal tube, and can then be dipped into a bath or screwed

into a threaded hole in a tank. As with any IC, the LM62 and

accompanying wiring and circuits must be kept insulated and

dry, to avoid leakage and corrosion. This is especially true if

the circuit may operate at cold temperatures where conden-

sation can occur. Printed-circuit coatings and varnishes such

as Humiseal and epoxy paints or dips are often used to en-

sure that moisture cannot corrode the LM62 or its connec-

tions.

The thermal resistance junction to ambient (

JA) is the pa-

rameter used to calculate the rise of a device junction tem-

perature due to its power dissipation. For the LM62 the

equation used to calculate the rise in the die temperature is

as follows:

J = TA + θJA [(+VS IQ) + (+VS −VO)IL]

where I

Q is the quiescent current and ILis the load current on

the output. Since the LM62’s junction temperature is the ac-

tual temperature being measured care should be taken to

minimize the load current that the LM62 is required to drive.

Supply Voltage

vs Supply Current

DS100893-12

Start-Up Response

DS100893-22

DS100893-14

FIGURE 2. Printed Circuit Board Used

for Heat Sink to Generate All Curves.

⁄2" Square Printed Circuit Board

with 2 oz. Copper Foil or Similar.

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