Motus Reference Manual
Page 82 of 146
Version 1.1
29/11/2019
13.4
OEM Power Supply
A high level of power supply filtering has been built into Motus OEM, however it is still
recommended that the power supply be free of significant noise. The unit is only rated
for inputs from 4.5 V to 5.5 V, exceeding 6 V can cause permanent damage to the unit.
On start-up of the Motus OEM the device will initially draw an increased impulse
current (~400mA for 2 microseconds) whilst it charges on board capacitors. It is
important that the user's circuit is tolerant to these small impulses on start-up to avoid
unsuccessful power up. It is recommended that a supply is selected that can provide a
maximum current of 0.5A. Switch-mode supplies are suitable as Motus OEM has on-
board filters to remove any supply noise and ripple.
13.5
OEM Pin Protection
Users should ensure that any signals that are connected externally from the PCB,
including GPIO and UART pins, are adequately protected. The use of a 5V zener diode
and 1k resistor should provide enough protection for the majority of use cases, see
Illustration 62.
External interface pins on Motus have on board pull-up/pull-down resistors enabled to
avoid signals oscillating when not connected. The user shouldn't need to place any
pull-up or pull-down resistors on their PCB.
Illustration 62: Motus OEM external signal protection example
