LM3880_14 Datasheet, PDF (10/20 Pages) Texas Instruments – Power Sequencer

LM3880, LM3880Q
SNVS451H – AUGUST 2006 – REVISED JULY 2011
www.ti.com
The sequencing order for power up is always controlled by layout. The flag number translates directly into the
sequence order during power up (ie FLAG1 will always be first). However, for some systems a different power
down order could be required. To allow flexibility for this aspect in a design, the Power Sequencer incorporates
six different options for controlling the power down sequence. These options can be seen in the timing diagrams
on the next page. This ability can be programmed in addition to the custom timers.
Input
EN
Output
FLAG1
FLAG2
FLAG3
FLAG1
FLAG2
FLAG3
delay1 delay2 delay3
(t_d1) (t_d2) (t_d3)
delay4 delay5 delay6
(t_d4) (t_d5) (t_d6)
Sequence 1
Sequence 2
FLAG1
FLAG2
FLAG3
Sequence 3
FLAG1
FLAG2
FLAG3
Sequence 4
FLAG1
FLAG2
FLAG3
Sequence 5
FLAG1
FLAG2
FLAG3
Figure 8. Power Down Sequence Options
Sequence 6
10
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