MB3771

3

s

s

s

s FUNCTIONAL DESCRIPTIONS

Comparators Comp.A and Comp.B apply a hysteresis to the detected voltage, so that when the voltage at either

Comp. B may be used to detect any given voltage(Sample Application 3), and can also be used as a forced

reset pin (with reset hold time) with TTL input (Sample Application 6).

Instantaneous breaks or drops in the power supply can be detected as abnormal conditions by the MB3771

within a 2

µs interval. However because momentary breaks or drops of this duration do not cause problems in

Because the RESET output has built-in pull-up resistance, there is no need to connect to external pull-up

resistance when connected to a high impedance load such as a CMOS logic IC.

Comparator Comp. C is an open-collector output comparator without hysteresis, in which the polarity of input/

output characteristics is reversed. Thus Comp. C is useful for over-voltage detection (Sample Application 11)

and positive logic RESET signal output (Sample Application 7), as well as for creating a reference voltage

(Sample Application 10).

s

s

s

s FUNCTION EXPLANATION

(3) RESET goes high when CT begins charging.

successively.

(7) Same as Point 4.

RESET

1

2

3

4

8

7

6

5

RESET

0.8 V

(1)

(2)

(3)

(4) (5) (6)

(7)

(8)

t

t