Single/Dual/Quad, Micropower,

Ultra-Low-Voltage, Rail-to-Rail I/O Comparators

______________________________________________________________________________________

11

in the values for this example, R1 = (2.2M

Ω + 10k) x

(50mV / 5.0V) = 22.1k

Ω.

threshold voltage where the comparator output tran-

point. For this example, choose 3.0V.

5) Calculate R2 as follows:

Choose a standard value of 15k

Ω.

6) Verify trip voltages and hysteresis as follows:

is the falling-voltage trip point.

Circuit Layout and Bypassing

Power-supply bypass capacitors are not needed if sup-

ply impedance is low, but 100nF bypass capacitors

should be used when supply impedance is high or

when supply leads are long. Minimize signal lead

lengths to reduce stray capacitance between the input

and output that might cause instability.

IR Receiver

Figure 5 shows an application using the MAX965 as an

infrared receiver. The infrared photodiode creates a

current relative to the amount of infrared light present.

This current creates a voltage across R1. When this

voltage level crosses the reference voltage applied to

the inverting input, the output transitions. Optional R3

provides additional hysteresis for noise immunity.

2-Cell to TTL Logic-Level Shifter

Figure 6 shows an application using the MAX965

to convert a 2-cell voltage-level signal into a TTL-

compatible signal. The supply voltage for the compara-

tor comes from the 2-cell supply. The output is pulled

up to a 5V supply.

V

ri

g

V

V

x R x

R

R

R

R

V

falling

V

V

R x V

R

R

Hysteresis

V

V

IN

THR

REF

IN

THF

THR

CC

THR

THF

sin :

:

=

+

+

+









=

−

+









=

−

1

1

1

1

2

1

3

4

1

3

4

R

V

V

x R

R

R

R

R

V

x

k

k

M

k

k

THR

REF

2

1

1

1

1

1

3

4

2

1

3 0

1 2

22

1

22

1

2 2

10

14 76

=









−

−

+

=









−

−

+

=

.

.

.

.

GND

0.1

µF

OUT

R3

REF

MAX965

HYST

Figure 5. IR Receiver

GND

+5V

2 CELLS

0.1

µF

OUT

INPUT

REF

MAX965

HYST

Figure 6. 2-Cell to TTL Logic-Level Translator