Contents
4.1 Reference Schematic Diagram...........................................................................................................................44
4.2 PCB Layout Reference Design............................................................................................................................48
4.2.1 Four-layer PCBs in QFN56 Package...........................................................................................................48
4.2.2 Two-layer PCBs in QFN Packages..............................................................................................................51
4.2.3 External Flash Connection for GR5515I0ND.............................................................................................52
4.2.4 Four-layer PCBs in BGA68 Package(NRND)...............................................................................................53
5.1 Can the Voltages of All GR551x I/O Pins Be Set to 3.3 V?................................................................................56
5.2 Why Is the Power Consumption in GR551x Sleep Modes High?...................................................................... 56
5.3 Can the RF PI Circuits Be Simplified or Removed?........................................................................................... 57
7.1.1 GR5515IGND/GR5515I0ND QFN56...........................................................................................................60
7.1.2 GR5515RGBD BGA68 (NRND)................................................................................................................... 62
7.1.3 GR5515GGBD BGA55................................................................................................................................ 64
7.1.4 GR5513BEND QFN40................................................................................................................................ 66
7.2.1 Stencil Design for Perimeter Pads............................................................................................................ 68
7.2.2 Via Types and Solder Voiding................................................................................................................... 69
7.3 SMT Reflow Process.......................................................................................................................................... 70
7.4 Rework Guideline.............................................................................................................................................. 72
7.4.1 Component Removal................................................................................................................................ 73
7.4.2 Site Redress...............................................................................................................................................73
7.4.3 Solder Paste Printing.................................................................................................................................73
7.4.4 Component Placement............................................................................................................................. 74
7.4.5 Component Attachment........................................................................................................................... 74
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