S-19500A03A-E8T1U4 Datasheet, PDF (31/52 Pages) Seiko Instruments Inc – CMOS VOLTAGE REGULATOR WITH WATCHDOG TIMER AND RESET FUNCTION

FOR AUTOMOTIVE 125°C OPERATION HIGH-WITHSTAND VOLTAGE CMOS VOLTAGE REGULATOR WITH WATCHDOG TIMER AND RESET FUNCTION
Rev.1.2_01
S-19500/19501 Series
The time period from when the watchdog timer detects a trigger to when it detects a time-out (tWD,TO) is indicated
as the following expression. Figure 43 shows a timing chart of the watchdog timer.
tWI,tr ≤ tWD,TO ≤ tWD,p
V_DLY
(1)
V_DU
(2), (5)
(3)
(4)
V_DWL
t
V_WI
t_WD,TO
t
t_WI,tr
V_WO
t
Figure 43
Regardless of the status of the watchdog timer, the capacitance of CDLY could be discharged by the detector
operation. Even if watchdog timer detects a trigger of signal input to the WI pin, the WO pin outputs "L" when VDLY
reaches VDWL. After that, the watchdog timer restarts the monitoring operation if the WO pin outputs "H" when VDLY
reaches VDU.
3. 2 Output current detection circuit
Since the S-19500/19501 Series has a built-in output current detection circuit, the watchdog timer operates
autonomously. When using the autonomous watchdog operation function, the current flows in the load is detected
by the output current of the regulator, the watchdog timer initiates the activation when the output current is the
watchdog activation threshold current (IO,WDact) or more, the watchdog timer is deactivated when the output current
is the watchdog deactivation threshold current (IO,WDdeact) or less
When not using the autonomous watchdog operation function, select a connection of the WADJ pin from Table 6
in " Pin Functions ".
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