S-19400 Datasheet, PDF (15/36 Pages) Seiko Instruments Inc – Watchdog operation voltage range

FOR AUTOMOTIVE 125°C OPERATION LOW CURRENT CONSUMPTION WATCHDOG TIMER WITH RESET FUNCTION
Rev.2.1_00
S-19400/19401 Series
 Operation
1. From power-on to reset release
The S-19400/19401 Series initiates the initialization if the VDD pin voltage exceeds the release voltage (+V_DET).
The _{_}c_{__}h_{_}a_{__}r_{_}g_{_} e-discharge operatio_{__}n_{___}t_{_}o_{_} the CPOR pin is initiated after the passage of the initialization time (t_INIT), and
the WDO pin output and the RST pin output change from "L" to "H" after the operation is performed 4 times.
VDD
CPOR
WDO
RST
(S-19401 only)
tINIT
tRST
+VDET
VCPU
VCPL
Output "L" → "H"
Output "L" → "H"
Remark V_CPU: CPOR charge upper limit threshold (1.25 V typ.)
V_CPL: CPOR charge lower limit threshold (0.20 V typ.)
Figure 23
t_INIT changes according to the power supply rising time. Refer to Figure 24 for the relation between t_INIT and the
power supply rising time.
0.1
0.01
0.001
0.0001
0.000001 0.00001 0.0001 0.001 0.01 0.1
Power supply rising time [s]
Figure 24 Power Supply Rising Time Dependency of Initialization Time
Power supply rising time
VDD
CPOR
Initialization time^*1
*1. The initialization time is the time period from when the VDD pin voltage reaches V_DD / 2 to when C_POR rises.
Figure 25 Initialization Time
15