INA+

GND

INB–

V

DD

OUTA

OUTB

Reference

TPS3700

www.ti.com

SBVS187D – FEBRUARY 2012 – REVISED JANUARY 2015

8 Detailed Description

8.1 Overview

The TPS3700 device combines two comparators for overvoltage and undervoltage detection. The TPS3700

device is a wide-supply voltage range (1.8 V to 18 V) device with a high-accuracy rising input threshold of

400 mV (1% over temperature) and built-in hysteresis. The outputs are also rated to 18 V and can sink up to 40

mA.

The TPS3700 device is designed to assert the output signals, as shown in Table 1. Each input terminal can be

set to monitor any voltage above 0.4 V using an external resistor divider network. With the use of two input

terminals of different polarities, the TPS3700 device forms a window comparator. Broad voltage thresholds can

be supported that allow the device to be used in a wide array of applications.

Table 1. TPS3700 Truth Table

CONDITION

OUTPUT

STATUS

OUTA high

Output A not asserted

OUTA low

Output A asserted

OUTB low

Output B asserted

OUTB high

Output B not asserted

8.2 Functional Block Diagram

8.3 Feature Description

8.3.1 Inputs (INA+, INB–)

The TPS3700 device combines two comparators. Each comparator has one external input (inverting and

noninverting); the other input is connected to the internal reference. The comparator rising threshold is designed

and trimmed to be equal to the reference voltage (400 mV). Both comparators also have a built-in falling

hysteresis that makes the device less sensitive to supply rail noise and ensures stable operation.

The comparator inputs can swing from ground to 6.5 V, regardless of the device supply voltage used. Although

not required in most cases, good analog design practice is to place a 1-nF to 10-nF bypass capacitor at the

comparator input for extremely noisy applications to reduce sensitivity to transients and layout parasitics.

For comparator A, the corresponding output (OUTA) is driven to logic low when the input INA+ voltage drops

Figure 1.

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