0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

±50

0

50

100

150

TEMPERATURE (

ƒC)

C001

GND

OUT

VDD

CBP

RMUX

Input

Pin

CFILTER

LMT87

CSAMPLE

Reset

Sample

CMUX

Simplified Input Circuit of

SAR Analog-to-Digital Converter

RSS

+2.7V to +5.5V

13

LMT87

www.ti.com

SNIS170E – JANUARY 2014 – REVISED OCTOBER 2017

Product Folder Links: LMT87

Submit Documentation Feedback

Copyright © 2014–2017, Texas Instruments Incorporated

9 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component

specification, and TI does not warrant its accuracy or completeness. TI’s customers are

responsible for determining suitability of components for their purposes. Customers should

validate and test their design implementation to confirm system functionality.

9.1 Application Information

The LMT87 features make it suitable for many general temperature-sensing applications. It can operate down to

2.7-V supply with 5.4-µA power consumption. Package options like the through-hole TO-92 package also allow

the LMT87 to be mounted onboard, off-board, to a heat sink, or on multiple unique locations in the same

application.

9.2 Typical Applications

9.2.1 Connection to ADC

Figure 13. Suggested Connection to a Sampling Analog-to-Digital Converter Input Stage

9.2.1.1 Design Requirements

Most CMOS ADCs found in microcontrollers and ASICs have a sampled data comparator input structure. When

the ADC charges the sampling cap, it requires instantaneous charge from the output of the analog source such

as the LMT87 temperature sensor and many op amps. This requirement is easily accommodated by the addition

of a capacitor (CFILTER).

9.2.1.2 Detailed Design Procedure

The size of CFILTER depends on the size of the sampling capacitor and the sampling frequency. Because not all

ADCs have identical input stages, the charge requirements will vary. This general ADC application is shown as

an example only.

9.2.1.3 Application Curve

Figure 14. Analog Output Transfer Function