BUILT-IN DELAY CIRCUIT (EXTERNAL DELAY TIME SETTING) VOLTAGE DETECTOR WITH SENSE PIN
Rev.2.1_01
S-1004 Series
2. 3 Power on sequence
Apply power in the order, the VDD pin then the SENSE pin.
As seen in Figure 27, when VSENSE ≥ +VDET, the OUT pin output (VOUT) rises and the S-1004 Series becomes the
release status (normal operation).
VDD
+VDET
VSENSE
tRESET
VOUT
Figure 27
Caution If power is applied in the order the SENSE pin then the VDD pin, an erroneous release may occur
even if VSENSE < +VDET
.
2. 4 Precautions when shorting between the VDD pin and the SENSE pin
2. 4. 1 Input resistor
Do not connect the input resistor (RA) when shorting between the VDD pin and the SENSE pin.
A feed-through current flows through the VDD pin at the time of release. When connecting the circuit shown as
Figure 28, the feed-through current of the VDD pin flowing through RA will cause a drop in VSENSE at the time of
release.
At that time, oscillation may occur if VSENSE ≤ −VDET
.
RA
VDD
VSS
OUT
CD
SENSE
VDD
Figure 28
2. 4. 2 Parasitic resistance and parasitic capacitance
Due to the difference in parasitic resistance and parasitic capacitance of the VDD pin and the SENSE pin,
power may be applied to the SENSE pin first.
Note that an erroneous release may occur if this happens (refer to "2. 3 Power on sequence").
Caution In CMOS output product, make sure that the VDD pin input impedance does not become too
high, regardless of the above. Since a feed-through current is large, a malfunction may occur if
the VDD pin voltage changes greatly at the time of release.
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