+

-

INP

INN

HYSTP

HYSTN

OUT

LMP7300

C1

2.32 k:

1%

205 k:

1%

0.1 PF

46.4 k:

1%

15.4 k:

1%

19.6 k:

1%

+

-

INP

INN

HYSTP

HYSTN

OUT

C2

2.32 k:

1%

205 k:

1%

USB POWER SOURCE

4.3V to 5.5V

0.1 PF

V

+

* NTC Thermistor

Such as: OMEGA #44008

30 k: @ 25°C

19.74 k: @ 35°C

46.67 k: @ 15°C

61.9 k:

1%

TEMPERATUE

FAULT

1 M:

1 M:

TEMPERATURE

FAULT

LMP7300

LMP7300

SNOSAT7F – AUGUST 2007 – REVISED MARCH 2013

www.ti.com

EVALUATION BOARDS

Texas Instruments provides the following PCB boards as an aid in evaluating the LMP7300 performance.

Evaluation Board

Device

Package

Ordering ID

LMP7300MA

8-Pin SOIC

LMP7300MA-EVAL

WINDOW COMPARATOR

Figure 25 shows two LMP7300s configured as a micropower window detector in a temperature level detection

application. The circuit shown monitors the ambient temperature change. If the temperature rises outside the

15°C to 35°C window, either comparator 1 for high temp, or comparator 2 for low temp, will set low, indicating a

fault condition has occurred. The open collector outputs are pulled up separately but can be wire-OR’d for a

single fault indication. If the temperature returns inside the window it must overcome the 22 mV asymmetric

hysteresis band established on either comparator. For the high side the temperature must drop below 34°C and

for the low side the temperature must rise above 16°C for the outputs to reset high and remove the fault

indication. The temperature is sensed by a 30 k

Ω @ 25°C Omega Precision NTC Thermistor #44008 (±0.2% tol).

Figure 24. Temperature Controlled Window Detector to Monitor Ambient Temperature

PRECISION HIGH TEMPERATURE SWITCH

The LMP7300 brings accuracy and stability to simple sensor switch applications. Figure 26 shows the LMP7300

setup in a high temperature switch configuration. The input bridge establishes the trip point at 85°C and the reset

temperature at 80°C. The comparator is set up with positive hysteresis of 14.3 mV and no negative hysteresis.

When the temperature is rising it trips at 85°C. The 14.3 mV hysteresis allows the temperature to drop to 80°C

before reset.

14

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