S1002 datasheet(16/39 Pages) SII

16 / 39 page

VOLTAGE DETECTOR WITH SENSE PIN

S-1002 Series

Rev.1.1_00

Seiko Instruments Inc.



Operation

1. Basic operation

1. 1 S-1002 Series NA / NB type

(1) When the power supply voltage (VDD) is the minimum operation voltage or higher, and the SENSE pin voltage

(VSENSE) is the release voltage (

+VDET) or higher, the Nch transistor is turned off to output VDD ("H") when the

output is pulled up. Since the Nch transistor (N1) is turned off, the input voltage to the comparator is

(RB

+ RC ) • VSENSE

+ RB + RC

(2) Even if VSENSE decreases to

+VDET or lower, VDD is output when VSENSE is higher than the detection voltage

(

−VDET).

When VSENSE decreases to

−VDET or lower (point A in Figure 22), the Nch transistor is turned on. And then VSS

("L") is output from the OUT pin after the elapse of the detection delay time (tDET).

At this time, N1 is turned on, and the input voltage to the comparator is

• VSENSE

+ RB

(3) Even if VSENSE further decreases to the IC's minimum operation voltage or lower, the output from the OUT pin is

stable when VDD is minimum operation voltage or higher.

(4) Even if VSENSE exceeds

−VDET, VSS is output when VSENSE is lower than +VDET.

(5) When VSENSE increases to

+VDET or higher (point B in Figure 22), the Nch transistor is turned off. And then VDD

is output from the OUT pin after the elapse of the release delay time (tRESET) when the output is pulled up.

VSS

VREF

−

OUT

VDD

SENSE

VDD

100 k

VSENSE

Nch

*1.

Parasitic diode

Figure 21 Operation of S-1002 Series NA / NB Type

VSENSE

VSS

VDD

VSS

(1)

(2) (3)

(5)

(4)

tDET

tRESET

Hysteresis width

(VHYS)

Minimum operation voltage

Output from OUT pin

Release voltage (

+VDET)

Detection voltage (

−VDET)

Figure 22 Timing Chart of S-1002 Series NA / NB Type

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