S-19101C25H-M5T2U Datasheet, PDF (14/31 Pages) Seiko Instruments Inc – BUILT-IN DELAY CIRCUIT

FOR AUTOMOTIVE 105°C OPERATION VOLTAGE DETECTOR BUILT-IN DELAY CIRCUIT (EXTERNAL DELAY TIME SETTING)
S-19101xxxH Series
Rev.1.0_01
3. Delay time (tD)
The delay time in the S-19101xxxH Series is a period from the input voltage to the VDD pin exceeding the release
voltage (+VDET) until the output from the OUT pin inverts. The delay time changes according to the delay capacitor
(CD).
V_DD
+V_DET
OUT
t_D
Figure 20 Delay Time
4. Feed-through current
Feed-through current is a current that flows instantaneously at the time of detection and release of a voltage
detector. The feed-through current is large in CMOS output product, small in Nch open-drain output product.
5. Oscillation
In applications where a resistor is connected to the voltage detector input (Figure 21), taking a CMOS output
(active "L") product for example, the feed-through current which is generated when the output goes from "L" to "H"
(release) causes a voltage drop equal to [feed-through 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 feed-through current stops and its resultant voltage drop disappears, and the output goes from "L" to "H". The
feed-through current is then generated again, a voltage drop appears, and repeating the process finally induces
oscillation.
VDD
R_A
V_IN
S-19101C
OUT
R_B
VSS
Figure 21 Example for Bad Implementation Due to Detection Voltage Change
Caution
The release voltage is set to the same value as the detection voltage, since there is no hysteresis
width in the S-19101xxxH Series. Therefore, the output goes from "H" to "L" if the power
supply voltage (VDD) reaches the detection voltage. The voltage which once became to "L" goes
from "L" to "H" again. This repeating process may induce oscillation as well. Perform thorough
evaluation using the actual application.
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