ULTRA-SMALL PACKAGE HIGH-PRECISION VOLTAGE DETECTOR
Detection voltage range
Release voltage range
Figure 18 Detection voltage (CMOS output products)
Figure 19 Release voltage (CMOS output products)
2. Hysteresis width (VHYS)
The hysteresis width is the voltage difference between the detection voltage and the release voltage (The voltage at point
B − The voltage at point A = VHYS in Figure 15). The existence of the hysteresis width prevents malfunction caused by
noise on input signal.
3. Through-type current
The through-type current refers to the current that flows instantaneously at the time of detection and release of a voltage
detector. The through-type current is large in CMOS output products, small in Nch open-drain output products.
In applications where a resistor is connected to the voltage detector input (Figure 20), taking a CMOS active “L” product
for example, the through-type current which is generated when the output goes from “L” to “H” (release) causes a voltage
drop equal to [through-type current] × [input resistance] across the resistor. When the input voltage drops below the
detection voltage (−VDET) as a result, the output voltage goes to low level. In this state, the through-type current stops
and its resultant voltage drop disappears, and the output goes from “L” to “H”. The through-type current is then
generated again, a voltage drop appears, and repeating the process finally induces oscillation.
Figure 20 An example for bad implementation of input voltage divider
Seiko Instruments Inc.