OMAP3530-HiRel datasheet(121/239 Pages) TI

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4.3.4

DPLL and DLL Noise Isolation

OMAP Device

DPLL_MPU

DPLL_IVA

DPLL_CORE

DLL

DPLL5

DPLL4

vdds_dpll_dll

vdds_dpll_per

NoiseFilter

030-017

OMAP3525-HiRel and OMAP3530-HiRel Applications Processors

www.ti.com

SPRS599 – JUNE 2009

The DPLL and DLL require dedicated power supply pins to isolate the core analog circuit from the

switching noise generated by the core logic that can cause jitter on the clock output signal. Guard rings

are added to the cell to isolate it from substrate noise injection.

The vdd supplies are the most sensitive to noise; decoupling capacitance is recommended below the

supply rails. The maximum input noise level allowed is 30 mVPP for frequencies below 1 MHz.

Figure 4-11= illustrates an example of a noise filter.

Figure 4-11. DPLL and DLL Noise Filter

Table 4-21 specifies the noise filter requirements.

Table 4-21. DPLL and DLL Noise Filter Requirements

NAME

MIN

TYP

MAX

UNIT

Filtering capacitor

100

(1) The capacitors must be inserted between power and ground as close as possible.

(2) This circuit is provided only as an example.

(3) The filter must be located as close as possible to the device.

(4) No filtering required if noise is below 10 mVPP.

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OMAP3530-HiRel Datasheet(PDF) 121 Page - Texas Instruments