DM385, DM388
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SPRS821D –MARCH 2013–REVISED DECEMBER 2013
1.8 V Supplies
(DVDD, DVDD_x, VDDA_x_1P8,
VDDA_1P8)
3.3 V Supplies
(DVDD, DVDD_x, DVDD_C, VDDA_x_3P3)
1.35 V/1.5 V/1.8 V DVDD_DDR[0]
CVDD, CVDD_x
7
6
5
Figure 7-2. Power-Down Sequence
3.3 V Supplies
V Delta(A)
1.8 V Supplies
(Excluding DVDD_DDR[x])
A. V Delta Max = 2 V.
Figure 7-3. 3.3 V Supplies Falling After 1.8 V Supplies Delta
CVDD_x
CVDD
8
Figure 7-4. CVDD and CVDD_x Power-Down Sequence
7.2.9 Power-Supply Decoupling
7.2.9.1 Analog and PLL
PLL and Analog supplies benefit from filters or ferrite beads to keep the noise from causing problems. The
minimum recommendation is a ferrite bead along with at least one capacitor on the device side of the
bead. An additional recommendation is to add one capacitor just before the bead to form a Pi filter. The
filter needs to be as close as possible to the device pin, with the device side capacitor being the most
important component to be close to the device pin. PLL pins close together can be combined on the same
supply, but analog pins should all have their own filters. PLL pins farther away from each other may need
their own filtered supply.
Copyright © 2013, Texas Instruments Incorporated
Power, Reset, Clocking, and Interrupts
135
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