HIGH-PRECISION VOLTAGE DETECTOR

S-807 Series

38

Seiko Instruments Inc.

2. Power-on reset circuit

The Nch open-drain output products of the S-807 Series can be used to construct a power-on reset circuit. Following is an

example

.

Di

(Nch open-drain products)

R

OUT

S-807XX

AN/SN

C

+

-

Figure 28

(V)

t (s)

OUT

(V)

t (s)

Note 1: R should be 7.5k

Ω or less for purpose of protection against oscillation.

Note 2: “Di” momentarily discharges the charge received via “C” at the falling edge of power off. There

is no need to insert a diode, when there is no conflict with application circuit even if there is a

delay in the falling edge of OUT at the falling edge of power off.

Note 3: When there is a sharp rise in power, the output voltage may go “H” momentarily in unstable range of

the output voltage (the output voltage is unstable below the minimum operating voltage) .

(V)

t (s)

OUT

(V)

t (s)

Figure 27

(R

≤7.5kΩ)