GND

OS, OS,

US, US

V

+

VIA to ground plane

VIA to power plane

0.1 µ F

R is optional maybe directly

connected to GND or V

+

R only required

for open-drain

HYST

LM26

SNIS115S – MAY 2001 – REVISED SEPTEMBER 2015

www.ti.com

10 Power Supply Recommendations

The LM26 has excellent power supply noise rejection. Listed below is a variety of signals used to test the LM26

power supply rejection. False triggering of the output was not observed when these signals where coupled into

the V+ pin of the LM26.

•

square wave 400 kHz, 1 Vp-p

•

square wave 2 kHz, 200 mVp-p

•

sine wave 100 Hz to 1 MHz, 200 mVp-p

Testing was done while maintaining the temperature of the LM26 one degree centigrade way from the trip point

with the output not activated.

11 Layout

11.1 Layout Guidelines

The LM26 can be applied easily in the same way as other integrated-circuit temperature sensors. It can be glued

or cemented to a surface. The temperature that the LM26 is sensing will be within about +0.06°C of the surface

temperature to which the LM26'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 actual temperature measured would

be at an intermediate temperature between the surface temperature and the air temperature.

To ensure good thermal conductivity, the backside of the LM26 die is directly attached to the GND pin (pin 2).

The temperatures of the lands and traces to the other leads of the LM26 will also affect the temperature that is

being sensed.

Alternatively, the LM26 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 LM26 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 condensation can occur. Printed-circuit coatings and varnishes such as Humiseal and epoxy

paints or dips are often used to ensure that moisture cannot corrode the LM26 or its connections.

11.2 Layout Example

Figure 14. LM26 Typical Layout

12

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