2015 Microchip Technology Inc. DS00001885A-page 11
SSC7150
3.0 GUIDELINES FOR GETTING STARTED
3.1 Basic Connection Requirements
Getting started with the SSC7150 requires attention to a minimal set of device pin connections before proceeding with
development. The following is a list of pin names, which must always be connected:
• All V
DD and VSS pins (see Section 3.2 “Decoupling Capacitors”)
• All AV
DD and AVSS pins, even if the ADC module is not used (see Section 3.2 “Decoupling Capacitors”). Note
that there is no ADC support in this device. See Note below.
•V
CAP pin (see Section 3.3 “Capacitor on Internal Voltage Regulator (Vcap)”)
• MCLR# pin (see Section 3.4 “Master Clear (MCLR#) Pin”)
Refer to the following schematic for connection information:
SSC7150 Sensor Hub Module, Assy. 6753, Schematic Revision 1.4.
3.2 Decoupling Capacitors
The use of decoupling capacitors on power supply pins, such as VDD, VSS, AVDD and AVSS is required. See Figure 3-1.
Consider the following criteria when using decoupling capacitors:
• Value and type of capacitor: A value of 0.1 µF (100 nF), 10-20V is recommended. The capacitor should be a low
Equivalent Series Resistance (low-ESR) capacitor and have resonance frequency in the range of 20 MHz and
higher. It is further recommended that ceramic capacitors be used.
• Placement on the printed circuit board: The decoupling capacitors should be placed as close to the pins as
possible. It is recommended that the capacitors be placed 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, upward of 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 min-
imum thereby reducing PCB track inductance.
Note: The AV
DD and AVSS pins must be connected, regardless of ADC use and the ADC voltage reference
source.
