Recommended Clock And Control Signal Transition Behavior; Power Supplies - Texas Instruments TMS320C6474 Manual

TMS320C6474
SPRS552F – OCTOBER 2008 – REVISED JULY 2010
7.2

Recommended Clock and Control Signal Transition Behavior

All clocks and control signals must transition between V
manner.
7.3

Power Supplies

7.3.1 Power-Supply Sequencing
Power supply sequencing must be followed as seen in
Table 7-1. Timing Requirements for Power Supply Ramping
(see Figure 7-4)
NO.
3 t
su(DVDD18-DVDD11)
4 t
h(DVDD11-POR)
(1) Stable means that the voltage is valid as per
For more information on power-supply sequencing, see the TMS320C6474 Hardware Design Guide
application report (literature number SPRAAW7)
7.3.2 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. These caps need to be close to the DSP, no more than 1.25 cm maximum
distance to be effective. Physically smaller caps are better, such as 0402, but need to be evaluated from a
yield/manufacturing point-of-view. Parasitic inductance limits the effectiveness of the decoupling
capacitors, therefore physically smaller capacitors should be used while maintaining the largest available
capacitance value. As with the selection of any component, verification of capacitor availability over the
product's production lifetime should be considered.
7.3.3 Power-Down Operation
One of the power goals for the C6474 device is to reduce power dissipation due to unused peripherals.
There are different ways to power down peripherals on the C6474 device.
76 Peripheral Information and Electrical Specifications
PARAMETERS
Setup Time, DV and VREFSSTL supply stable before
DD18
DV and CV supplies stable
DD11 DD11
Hold time, POR low after CV
DD11
Section 6.2, Recommended Operating Conditions.
DV
DD18
V
REFSSTL
DV
DD11
CV
DD11
POR
Figure 7-4. Power-Supply Timing
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and V (or between V
IH IL
Figure 7-4.
(1)
(1)
and DV supplies stable
DD11
3
4
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and V ) in a monotonic
IL IH
MIN MAX UNIT
0.5 200 ms
100
ms