S-77100 Datasheet, PDF (20/40 Pages) Seiko Instruments Inc – POWER SEQUENCER

POWER SEQUENCER
S-77100/77101 Series
Rev.1.0_01
3. 2 S-77101 Series special operation
The Operation when the sequence operation is not co_{_}m_{___}p_{__}l_{_}eted normally, the power supply voltage drops
significantly or connecting the VDD pin, the ON pin and the OFF pin is a special operation.
3. 2. 1 Special operations during on-sequence period and off-sequence period
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Do not change the ON pin and the OFF pin during on-sequence period and off-sequence period in order to
perform the sequence operation normally.
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(1) When ON pin or OFF pin changes from "H" to "L" during on-sequence period
Since the ENBL_x pins all change to "L" when the ON pin changes from "H" to "L" during on-sequence period,
the off-sequence operation timing is not guaranteed._{__}I_{_}n_{___}a_{_}ddition, CDLY charge operation is stopped and the
automatic discharge operation is started. When the OFF pin changes from "H" to "L" during on-sequence
period, the off-sequence operation is performed after the on-sequence operation is completed. The operation
example is shown in Figure 21.
Original on-sequence period
On-sequence period Off-sequence period
ON
OFF
CDLY
ENBL_A
ENBL_B
ENBL_C
Figure 21
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(2) When OFF pin or ON pin changes from "L" to "H" during off-sequence period
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Since the ENBL_x pins all change to "L" when the OFF pin changes from "L" to "H" during off-sequence
period, the off-sequence operation timing is not guaranteed. In addition, CDLY charge operation is stopped and
the automatic discharge operation is started. When the ON pin changes from "L" to "H" during off-sequence
period, the on-sequence operation is performed after the off-sequence operation is completed. The operation
example is shown in Figure 22.
Original off-sequence period On-sequence period Off-sequence period On-sequence period
ON
OFF
CDLY
ENBL_A
ENBL_B
ENBL_C
Figure 22
Remark Refer to "3. Automatic discharge time (tDCHG) approximate calculation formula" in " Relation
between Delay Time and External Capacitor" for the automatic discharge operation.
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