S-19400 Datasheet, PDF (24/36 Pages) Seiko Instruments Inc – Watchdog operation voltage range

FOR AUTOMOTIVE 125°C OPERATION LOW CURRENT CONSUMPTION WATCHDOG TIMER WITH RESET FUNCTION
S-19400/19401 Series
Rev.2.1_00
 Precautions
• It will take time for the discharge operation to be performed if the capacitance of C_POR is extremely large at the low
voltage detection, so the discharge operation may not be completed by the time the power supply voltage exceeds
the detection voltage. In that case, since the charge-discharge operation of the CPOR pin is performed after the
discharge operation is completed, the delay time of the same time length as the discharge operation occurs in reset
time-out period (t_RST).
• Select a capacitor which satisfies the following equation for C_POR and C_WDT. If this condition is not satisfied, the
delay time of the same time length as the discharge operation occurs in t_RST since the discharge operation of an
external capacitor connected to the CWDT pin is not completed by the time the CWDT pin initiates the next
charge-discharge operation.
C_WDT / C_POR ≤ 600
• When the power supply voltage falls to 0.9 V or lower, set a time interval of 20 μs or longer by the time the power
supply is raised again. If the appropriate time length is not secured, the time-out period after raising the power
supply voltage may get delayed.
• When the time that the power supply voltage falls below the detection voltage is short, the S-19400/19401 Series
may not detect a voltage. In that case, the time-out period after raising the power supply voltage may get delayed.
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• Since input pins (the WEN pin, the WDI pin and the W / T pin) in the S-19400/19401 Series are CMOS
configurations, make sure that an intermediate potential is not input when the S-19400/19401 Series operates.
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• Since the WDO pin and the RST pin are affected by external resistance and external capacitance, use the
S-19400/19401 Series after performing thorough evaluation with the actual application.
• Do not apply an electrostatic discharge to this IC that exceeds the performance ratings of the built-in electrostatic
protection circuit.
• SII Semiconductor Corporation claims no responsibility for any disputes arising out of or in connection with any
infringement by products including this IC of patents owned by a third party.
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