Placement on the printed circuit board pcb the

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Placement on the Printed Circuit Board (PCB): The decoupling capacitors should be placed as close to the pins as possible. It is recommended to place the capacitors on the same side of the board as the device. If space is constricted, the capacitor can be placed on another layer on the PCB using a via; however, ensure that the trace length from the pin to the capacitor is within one-quarter inch (6 mm) in length. Handling high-frequency noise: If the board is experiencing high-frequency noise, above tens of MHz, add a second ceramic-type capacitor in parallel to the above described decoupling capacitor. The value of the second capacitor can be in the range of 0.01 μF to 0.001 μF. Place this second capacitor next to the primary decoupling capacitor. In high-speed circuit designs, consider implementing a decade pair of capacitances as close to the power and ground pins as possible. For example, 0.1 μF in parallel with 0.001 μF. Maximizing performance: On the board layout from the power supply circuit, run the power and return traces to the decoupling capacitors first, and then to the device pins. This ensures that the decoupling capacitors are first in the power chain. Equally important is to keep the trace length between the capacitor and the power pins to a minimum, thereby reducing the PCB track inductance. Note 1: This data sheet summarizes the features of the dsPIC33EVXXXGM00X/10X family of devices. It is not intended to be a comprehensive reference source. To complement the information in this data sheet, refer to the related section in the “dsPIC33/PIC24 Family Reference Man- ual” , which is available from the Microchip web site ( www.microchip.com ). 2: Some registers and associated bits described in this section may not be available on all devices. Refer to Section 4.0 “Memory Organization” in this data sheet for device-specific register and bit information. Note: The AV DD and AV SS pins must be connected, regardless of the ADC voltage reference source.
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