文档介绍：AND8326/D
PCB Design Guidelines for
Dual Power Supply Voltage
Translators
Jim Lepkowski
ON Semiconductor
Introduction Figure 1 provides an example of the mended
The design of the PCB is an important factor in locations of the VL and VCC decoupling capacitors. Ceramic
maximizing the performance of a dual power supply voltage capacitors with a magnitude of mF to mF are a good
translator. The PCB design guidelines presented in this choice because they are inexpensive, small and have
document offer the following benefits: excellent high frequency attenuation specifications. Ground
• Effective power supply decoupling is provided by and power planes are one monly used to provide
placing ceramic capacitors next to the IC with short, low impedance trace connections.
minimum length connection traces
Minimizing the Loop Area
• Short PCB traces and ground planes reduce RF
Figure 2 shows that the translator's I/O and I/O traces
susceptibility and radiated emissions 1 2
• form a loop with the ground trace. The loop area functions
Robust ESD and EMI protection is achieved by placing as an antenna that allows high frequency noise to enter
Transient Voltage Suppressors (TVS) diodes next to the (susceptibility) and leave (emissions) the PCB.
I/O connector Furthermore, RF susceptibility and emissions are
proportional to the size of the loop and the frequ