SM320DM642-HIREL Datasheet, PDF (73/170 Pages) Texas Instruments – SM320DM642-HiRel Video/Imaging Fixed Point Digital Signal Processor

SM320DM642-HiRel
www.ti.com
SGUS063A – JUNE 2009 – REVISED OCTOBER 2010
5.3 Power Supplies
For more information regarding TI's power management products and suggested devices to power TI
DSPs, visit www.ti.com/dsppower.
5.3.1 Power-Supply Sequencing
TI DSPs do not require specific power sequencing between the core supply and the I/O supply. However,
systems should be designed to ensure that neither supply is powered up for extended periods of time
(>1 second) if the other supply is below the proper operating voltage.
5.3.2 Power-Supply Design Considerations
A dual-power supply with simultaneous sequencing can be used to eliminate the delay between core and
I/O power up. A Schottky diode can also be used to tie the core rail to the I/O rail (see Figure 5-5).
I/O Supply
Core Supply
Schottky
Diode
DV_DD
C6000
DSP
CV_DD
V_SS
GND
Figure 5-5. Schottky Diode Diagram
Core and I/O supply voltage regulators should be located close to the DSP (or DSP array) to minimize
inductance and resistance in the power delivery path. Additionally, when designing for high-performance
applications utilizing the C6000™ platform of DSPs, the PC board should include separate power planes
for core, I/O, and ground, all bypassed with high-quality low-ESL/ESR capacitors.
5.3.3 Power-Supply Decoupling
In order to properly decouple the supply planes from system noise, place as many capacitors (caps) as
possible close to the DSP. Assuming 0603 caps, the user should be able to fit a total of 60 caps, 30 for
the core supply and 30 for the I/O supply. These caps need to be close to the DSP power pins, no more
than 1.25 cm maximum distance to be effective. Physically smaller caps, such as 0402, are better
because of their lower parasitic inductance. Proper capacitance values are also important. Small bypass
caps (near 560 pF) should be closest to the power pins. Medium bypass caps (220 nF or as large as can
be obtained in a small package) should be next closest. TI recommends no less than 8 small and
8 medium caps per supply (32 total) be placed immediately next to the BGA vias, using the "interior" BGA
space and at least the corners of the "exterior".
Eight larger caps (four for each supply) can be placed further away for bulk decoupling. Large bulk caps
(on the order of 100 °F) should be furthest away (but still as close as possible). No less than four large
caps per supply (eight total) should be placed outside of the BGA.
Any cap selection needs to be evaluated from a yield/manufacturing point-of-view. As with the selection of
any component, verification of capacitor availability over the product’s production lifetime should be
considered.
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DM642 Peripheral Information and Electrical Specifications
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