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Renesas VersaClock7 PCB Manuallines

Renesas VersaClock7 PCB Manuallines

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VersaClock7 PCB Layout Guidelines
PCB layout is a physical realization of the circuit designs. Good board layout practices will improve the electrical
performance by controlling crosstalk and ensuring signal integrity. In addition, layout plays a fundamental role in
meeting EMC emissions and immunity requirements.
This document provides information and recommendations to aid in the design and layout of PCB circuitry using
VersaClock7 (VC7) devices. It contains information for generic PCB layout and some particular considerations
for VC7 devices.
Contents
1.
Layer Stack-Up ............................................................................................................................................... 2
2.
Placement ....................................................................................................................................................... 4
3.
Crystal Placement and Handling .................................................................................................................. 4
4.
VC7 Device Electrical and Thermal Pad Handling...................................................................................... 5
4.1
4.2
4.3
5.
Trace Routing ................................................................................................................................................. 9
5.1
Single-Ended Routing ............................................................................................................................ 9
5.2
Differential (Clock) Pair Routing ............................................................................................................ 9
6.
Power Supply Trace and Power Filtering Layout ..................................................................................... 12
7.
References .................................................................................................................................................... 13
8.
Revision History .......................................................................................................................................... 13
R31UH0017EU0100 Rev.1.00
Aug 4, 2022
[3]
...................................................................................................... 5
[4]
...................................................................................................... 7
[5]
.................................................................................................... 8
Manual
Page 1
© 2022 Renesas Electronics

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  • Page 1: Table Of Contents

    Manual VersaClock7 PCB Layout Guidelines PCB layout is a physical realization of the circuit designs. Good board layout practices will improve the electrical performance by controlling crosstalk and ensuring signal integrity. In addition, layout plays a fundamental role in meeting EMC emissions and immunity requirements.

  • Page 2: Layer Stack-Up

    VC7 PCB Layout Guidelines Manual 1. Layer Stack-Up A PCB consists of multiple layers of copper (foil) and isolation materials laminated together. PCB layer stack-up design refers to the layer arrangement of copper and dielectric material layers with the total number of layers and the thickness of each layer taking into considerations.
  • Page 3 VC7 PCB Layout Guidelines Manual It is worth noting that stripline signals are in between two GND plane layers. This minimizes crosstalk between the stripline signals and signals outside this layer. This is why an optimal stack-up design will enhance EMC performance of a PCB design.

  • Page 4: Placement

    VC7 PCB Layout Guidelines Manual Figure 4. Copper Weight (Foil Thickness) 2. Placement The optimal placement of the VC7 device and its neighboring components is specific to each design. The following general recommendations are provided for the designer to consider: ■...

  • Page 5: Vc7 Device Electrical And Thermal Pad Handling

    VC7 PCB Layout Guidelines Manual Figure 5. XIN Overdrive with an LVCMOS or an LVPECL Clock Source 4. VC7 Device Electrical and Thermal Pad Handling VC7 devices come with an ePad – a ground island directly beneath the device on the same layer the IC is soldered on the PCB.
  • Page 6 VC7 PCB Layout Guidelines Manual Figure 6. 40-LGA Land Pattern Dimensions Figure 7. Layout Land Pattern Recommendations for RC21008AQ R31UH0017EU0100 Rev.1.00 Page 6 Aug 4, 2022...

  • Page 7: Rc21012A/Rc21012A - Qfn-48

    VC7 PCB Layout Guidelines Manual RC21012A/RC21012A – QFN-48 ■ Device land pattern is shown below ● PCB pad width: 0.20mm ● PCB pad length: 0.55mm ○ Toe extension (beyond package edge): 0.05mm ○ Heel extension (toward package center): 0mm ■ Stencil recommendations (Unit: mm) ●...

  • Page 8: Rc21005A/Rc21005Aq - 32-Lga [5]

    VC7 PCB Layout Guidelines Manual RC21005A/RC21005AQ – 32-LGA ■ Device land pattern is shown below. ■ Stencil recommendations (Unit: mm) ● Thickness: 0.125 ● Aperture for thermal pads: 0.60 × 0.55 (x4, each aperture vertex closes to the aggregate center of the pattern.

  • Page 9: Trace Routing

    VC7 PCB Layout Guidelines Manual 5. Trace Routing Routing a PCB board with VC7 devices should follow the generic engineering practice of PCB routing rules. Routing recommendations are summarized in the following sections. Single-Ended Routing ■ Keep clock traces as straight as possible. Use arc-shaped (or 45 degree) traces instead of right-angle or even sharp-angle bending.
  • Page 10 VC7 PCB Layout Guidelines Manual ■ Keep both leads of a differential pair the same length so that signals arrive at the receiver at the same time. Use “phase matching bumps” to the lead that is shorter than the other lead to make both signal leads the same length.
  • Page 11 VC7 PCB Layout Guidelines Manual ■ Changing layers when routing differential pairs is not uncommon. When that happens, place a pair of ground vias close to the signal vias, respectively, to provide a return current path. Figure 15. Ground Vias Added Close to Signal Vias when Signal Changes Layers ■...

  • Page 12: Power Supply Trace And Power Filtering Layout

    VC7 PCB Layout Guidelines Manual 6. Power Supply Trace and Power Filtering Layout Power filtering is one of the most important measures to prevent power supply noises from coupling to the device outputs, adversely affecting performance, especially when using switched power supplies. Usually we recommend power supply filtering with a parallel combination of bulk, decoupling, and bypass capacitors as displayed in the following figure.

  • Page 13: References

    VC7 PCB Layout Guidelines Manual 7. References 1. IPC-D-317A 2. RC21008A/RC31008A-EVK Layout 3. REN_PSC-4864-01_20201208 4. REN_PSC-4212-05_20190510 5. REN_PSC-4889-02_20220114 6. AN-909 PCB Layout Considerations for Designing IDT VersaClock 3S, 5 and 6 Clock Products 7. AN-376 LIU PCB Layout Guide 8. Revision History Revision Date Description...
  • Page 14 Renesas' products are provided only subject to Renesas' Terms and Conditions of Sale or other applicable terms agreed to in writing. No use of any Renesas resources expands or otherwise alters any applicable warranties or warranty disclaimers for these products.

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