+1.8V to +5.5V

GND

OUT

VDD

CBP

RMUX

Input

Pin

CFILTER

LMT85

CSAMPLE

Reset

Sample

CMUX

Simplified Input Circuit of

SAR Analog-to-Digital Converter

RSS

13

LMT85

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SNIS168E – MARCH 2013 – REVISED OCTOBER 2017

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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 LMT85 features make it suitable for many general temperature-sensing applications. It can operate down to

1.8-V supply with 5.4-µA power consumption, making it ideal for battery powered devices. Package options like

the through-hole TO-92 package allow the LMT85 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 an 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 LMT85 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