HIGH-PRECISION VOLTAGE DETECTOR
S-807 Series
Technical Terms
1. Detection voltage (-V
DET
)
Detection voltage -V
DET
is the voltage at which the detector’s output goes active. In products with
“Nch
open-drain” and
“CMOS
active low output” configurations the output goes low on detection. It goes high in products with CMOS active high
output configurations. This detection voltage varies slightly among products of the same type. The variation of voltages
between the specified minimum [(-V
DET
)min.] and maximum [(-V
DET
)max.] values is called the detection voltage range. (See
Figure 9.)
Example : For the S-80745AN, detection voltage lies in the range
4.392≤(-V
DET
)≤4.608.
2. Release voltage (+V
DET
)
Release voltage +V
DET
is the voltage at which a unit’s output returns (is
“released”)
to its inactive state (high for Nch and
CMOS active low output configurations, and low for CMOS active high output configurations). The value of this voltage for
any single unit lies in a range determined from the value of that unit’s detection voltage (see Figure 10):
(-V
DET
)×1.02≤(+V
DET
)≤(-V
DET
)×1.08.
Example : For an S-80745AN with -V
DET
=4.608, release voltage lies in the range 4.700≤(+V
DET
)≤4.997.
For an S-80745AN with -V
DET
=4.392, release voltage lies in the range 4.480≤(+V
DET
)≤4.743.
When calculating the overall release voltage range for S-807 Series products, care must be taken to consider the variation in
the series’ detection voltage values. The minimum and maximum values for release voltage [(+V
DET
)min. and (+V
DET
)max.)]
must be determined using (-V
DET
)min. and (-V
DET
)max.:
(+V
DET
)min.=[(-V
DET
)min.]×1.02;
(+V
DET
)max.=[(-V
DET
)max.]×1.08.
Example : For S-80745AN voltage detectors, release voltage lies in the range 4.480≤(+V
DET
)≤4.977.
Note :
Detection voltage(-V
DET
) and Release voltage(+V
DET
) range equally from 4.480V to 4.608V, however, (+V
DET
) >
(-V
DET
).
V
DD
V
DD
Detection voltage
(-V
DET
)max.
(-V
DET
)min.
Detection voltage range
(+V
DET
)min.
Release voltage
(+V
DET
)max.
Release voltage range
OUT
OUT
Figure 9
Figure 10
3. Hysteresis width (V
HYS
)
Hysteresis width is the voltage difference between a device’s detection voltage and its release voltage (see Figure 14.
V
HYS
=B-A). By giving a device hysteresis, erroneous toggling of the output due to noise at the input is avoided.
4. Through-type current
Through-type current refers to the instantaneous current flow which occurs at the moment a voltage detector output toggles.
This current is quite large in devices with CMOS configured outputs, and also occurs to some extent in Nch open-drain
configured devices. S-807 Series voltage detectors are specially designed to limit through-type currents and are superior to
S-805 Series devices in this respect. (See current consumption characteristics.)
24
Seiko Instruments Inc.
SII [ SEIKO INSTRUMENTS INC ]
