Data Sheet

ADCMP361

APPLICATION INFORMATION

The ADCMP361 is a low power comparator and reference

circuit featuring a 400 mV reference that operates from 1.7 V

to 5.5 V. The comparator is 0.275% accurate with a built-in

hysteresis of 9.3 mV. There are two outputs, one the inverse

of the other. This enables the ADCMP361 to be used as an

inverting or a noninverting comparator circuit. These open-

drain outputs are capable of sinking 40 mA.

COMPARATORS AND INTERNAL REFERENCE

The comparator has one input available externally; the other

comparator input is connected internally to the 400 mV reference.

The rising input threshold voltage of the comparators is designed

to be equal to that of the reference.

POWER SUPPLY

The ADCMP361 is designed to operate from 1.7 V to 5.5 V. A 100 nF

INPUTS

string to the input, take care when choosing resistor values. This

is due to the fact that the input bias current will be in parallel

with the bottom resistor, R2, of the input resistor divider string.

This bottom resistor must therefore be chosen carefully in order

to reduce the error introduced by this bias current (see Figure 30).

OUT

IN

ADCMP361

400mV

GND

OUT

R1

R2

Figure 30. Input Bias Current Effect on Input Resistor String

OUTPUTS

The open-drain comparator outputs are limited to the

ADDING HYSTERESIS

To prevent oscillations at the output caused by noise or slowly

moving signals passing the switching threshold, each compara-

tor has built-in hysteresis of approximately 9.3 mV. Positive

feedback can be used to increase hysteresis.

For the configuration shown in Figure 31, two resistors are used

to create different switching thresholds, depending on whether

the input signal is increasing or decreasing in magnitude. When

high input threshold used to trigger the output low to high

the output high to low transmission.

The upper input threshold level is given by

(

)

R2

R2

R1+

IN_HI

V

V

The lower input threshold level is given by

(

)

PULLUP

CC

PULLUP

R

R2

R1

V

R

R2

R1

+

−

+

+

IN_LO

V

V

The hysteresis is the difference between these voltage levels and

is given by

PULLUP

R

R2

R1

+

=

∆

CC

IN

V

V

ADCMP361

OUT

OUT

R1

R2

Figure 31. Comparator Configuration with Added Hysteresis

ADCMP361

R2 = 1MΩ

R1 = 200kΩ

IN+

IN–

OUT

Figure 32. Noninverting Comparator Configuration with Hysteresis

Rev. B | Page 11 of 12