VDD Supply

(+2.4V to +5.5V)

GND

VDD

TOVER

VTEMP

TRIP TEST

Microcontroller

LM57

TOVER

Digital In

SENSE1

SENSE2

LM57-Q1

SNIS191A – JULY 2015 – REVISED JULY 2015

www.ti.com

Typical Application (continued)

8.2.4 Grounding of the TRIP TEST Pin

The circuit in Figure 24 shows the TRIP TEST pin grounded. This allows the LM57-Q1 to function autonomously

without microcontroller intervention. In all other respects this circuit functions similarly to the circuit shown in

Figure 21.

Figure 24. Typical Application Schematic without Microcontroller TRIP TEST Control

9 Power Supply Recommendations

Power supply bypass capacitors are optional and may be required if the supply line is noisy. TI recommends that

a local supply decoupling capacitor be used to reduce noise. For noisy environments, TI recommends a 100-nF

supply decoupling capacitor placed closed across VDD and GND pins of LM57-Q1.

10 Layout

10.1 Layout Guidelines

The LM57-Q1 can be applied easily in the same way as other integrated-circuit temperature sensors. It can be

glued or cemented to a surface. The temperatures of the lands and traces to the other leads of the LM57-Q1 will

also affect the temperature reading.

Alternatively, the LM57-Q1 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 LM57-Q1 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. If moisture creates a short circuit from the VTEMP output to

ground or VDD, the VTEMP output from the LM57-Q1 will not be correct. Printed-circuit coatings are often used to

ensure that moisture cannot corrode the leads or circuit traces.

28

Submit Documentation Feedback

Copyright © 2015, Texas Instruments Incorporated

Product Folder Links: LM57-Q1