Vansco VMM3120, User Manual

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User Guide 15
Inputs

The VMM3120 has a maximum allowable wetting current of
approximately 10 mA. Wetting currents greater than 10 mA must be
incorporated using resistors embedded in the system wire harness.
Note : A digital switch (typically connected to a digital input) usually requires
wetting current. The amount of wetting current required is based on battery
voltage and on the value of the pull-down resistor.
The following diagram shows the configuration for the power control inputs:
Figure 5: Power Control Digital Input Configuration
3.1.3.3. Power Control Digital Input Installation Connections
You must be aware of the following when connecting the power control digital
input:

The power control digital input is usually connected to the vehicle ignition,
but it can be connected to any power source in a system.

To protect the harness that connects the VMM3120 to the ignition, place a
fuse of 200 mA or higher in the circuit that feeds the VMM3120.

If your VMM3120 must always be powered, the power control digital input
can be directly connected to a fused battery power input (called VBATT),
which will provide constant power.

When battery power (VBATT) is connected, and the power control digital
input is inactive, the VMM3120 will go into sleep mode.