PNX1501E NXP Semiconductors, PNX1501E Datasheet - Page 69

• Manufacturer Part Number: PNX1501E
• Description: Digital Signal Processors & Controllers (DSP, DSC) MEDIA PROCESSOR PNX15XX/266MHZ
• Manufacturer: NXP Semiconductors

Specifications of PNX1501E

• Product: DSPs
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Package / Case: SOT-795
• Minimum Operating Temperature: 0 C
• Lead Free Status / Rohs Status: Details
• Other names: PNX1501E,557

Philips Semiconductors
Volume 1 of 1
10. Board Design Guidelines
12NC 9397 750 14321
Product data sheet
10.1 Power Supplies Decoupling
The following sections discuss the fundamentals of board design for the PNX1500
system. The intent is to give general guidelines on the subject, not the complete in
depth coverage.
A minimum of four layers board is recommended.
Power supply regulators require large smoothing capacitors to deliver the current until
the regulator can follow the load conditions. These smoothing capacitors are typically
large electrolytic capacitors with considerable parasitic inductance, typically in the
order of 10 nH. This high inductance does not allow for rapid supply of varying
currents required in high speed processors as the PNX1500. The following
recommendations assume a load transient of up to 1 A within 2 ns which is
considered conservative for the PNX1500. However, this does guarantee adequate
decoupling.
In “high frequency” applications, each power plane VCCP, VCCM and VDD should be
decoupled with at least 10 capacitor of 0.1 F. Capacitors should be chosen such that
the total series inductance is approximately within the order of 0.2 nH (i.e. 2 nH per
capacitor). The parasitic series resistance per capacitor should be in the order of 0.1
placed as closely as possible to the power pins of the PNX1500.
For “medium frequency”, each power plane VCCP, VCCM and VDD should be
decoupled with at least 10 capacitors of 47 F. Capacitors should be chosen such
that the total series inductance is approximately with the order of 0.5 nH. The
parasitic series resistance per capacitor should be in the order of 0.1 . Aluminum or
wet “wound foil” tantalum capacitors should not be used. Instead, dry tantalum
capacitors or equivalent total series resistor and inductance capacitors like the new
ceramic or polymer tantalum can be used. Despite the larger footprint these surface
mount “medium frequency” decoupling capacitors should still be placed as closely as
physically possible to the PNX1500 power pins.
Last step before the power regulator itself is the bulk decoupling. The bulk decoupling
can be achieved with five 100 F or 220 F capacitors. These capacitors usually have
an inductance of 10 nH and internal equivalent series resistance (ESR) of 0.1 . The
amount and size are dependant on how fast the regulator operates.
The VIA connection to the power planes should be as wide as the capacitor soldering
lead which is different from a VIA of a regular signal. The routing and VIA inductance
and resistance must be included when computing the total series inductance and
resistance.
Other devices like the memories also require local decoupling capacitors. Three 0.1
device.
Additional global decoupling can also be distributed across the board.
F capacitors combined with one 22 F or 47 F are recommended for each memory
. Ceramic capacitors may be used. These surface mount capacitors should be
Rev. 2 — 1 December 2004
© Koninklijke Philips Electronics N.V. 2002-2003-2004. All rights reserved.
Chapter 1: Integrated Circuit Data
PNX15xx Series
1-43