+2.7V to +5.5V

GND

OUT

Input

Pin

LMT84

Reset

Sample

Simplified Input Circuit of

SAR Analog-to-Digital Converter

LMT84

SHUTDOWN

Any logic

device output

R1

4.1V

R3

R2

0.1 PF

U3

LM4040

R4

V+

+

-

U1

LMT84

U2

(High = overtemp alarm)

R1 + R2||R3

(4.1)R2

R2 + R1||R3

(4.1)R2

LMT84, LMT84-Q1

SNIS167A – MARCH 2013 – REVISED JUNE 2013

www.ti.com

APPLICATION CIRCUITS

Figure 13. Celsius Thermostat

Figure 14. Conserving Power Dissipation with Shutdown

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

LMT84/LMT84-Q1 temperature sensor and many op amps. This requirement is easily accommodated by the addition

frequency. Since not all ADCs have identical input stages, the charge requirements will vary. This general ADC

application is shown as an example only.

Figure 15. Suggested Connection to a Sampling Analog-to-Digital Converter Input Stage

10

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