RL78/G14 Recommended PCB Layout for Reducing Noise
R01AN1876EC0100 Rev. 1.00 Page 2 of 14
Feb. 28, 2014
Contents
1. Preface .............................................................................................................................. 3
2. Recommended PCB Layout ............................................................................................ 4
2.1 Wiring of VDD and VSS .............................................................................................................. 4
2.2 Oscillator Concerns .................................................................................................................... 4
2.3 Bypass Capacitor........................................................................................................................ 4
2.4 Wiring of RESET Pin ................................................................................................................... 4
2.5 Wiring of REGC Pin..................................................................................................................... 4
2.6 Wiring of TOOL0 Pin ................................................................................................................... 4
3. Description of the Test Board......................................................................................... 5
3.1 Schematics of the Test Board ................................................................................................... 5
3.2 PCB Layout of the Two Test Boards......................................................................................... 5
3.3 Differences between Recommended Layout and Non-recommended Layout..................... 6
3.3.1 Wiring of VDD and VSS..........................................................................................................6
3.3.2 Oscillator Concerns.................................................................................................................6
3.3.3 Bypass Capacitor....................................................................................................................6
3.3.4 Wiring of RESET Pin...............................................................................................................7
3.3.5 Wiring of REGC Pin................................................................................................................7
3.3.6 Wiring of TOOL0 Pin...............................................................................................................7
3.4 Block Diagram of the Test Board .............................................................................................. 7
4. Reducing Noise Test of Different Layout....................................................................... 9
4.1 Test Description .......................................................................................................................... 9
4.2 Test Conditions ........................................................................................................................... 9
4.3 Test Results............................................................................................................................... 10
4.4 Test Conclusions ...................................................................................................................... 11
5. Improve the Non-recommended Board........................................................................ 12
5.1 Modification of the Non-recommended Board....................................................................... 12
5.2 Test Results of the Modified Board......................................................................................... 13
5.3 Recommendations for PCB Board Improvement .................................................................. 13
6. Documents for Reference ............................................................................................. 14
