Vansco VMM3120, User Manual, Page: 43 / 92

User Guide 33
Outputs
4.1.4.3. Short-to-Battery
Short-to-battery faults occur when a high-side output pin is connected to battery
voltage.
The high-side output circuit uses voltage on the output pin to determine if a short-
to-battery condition exists.
Note: To detect a short-to-battery fault, high-side outputs must be off.
The output must be configured correctly for high-side outputs to be able to detect
short-to-battery.
4.2. Low-Side Outputs with Current Sense
The VMM3120 has 4 low-side outputs:

OUTPUT1_2A5_LS to OUTPUT4_2A5_LS
4.2.1. Low-Side Outputs with Current Sense Capabilities
Low-side outputs with current sense are used for switching grounds to loads using
either a pulse width modulated (PWM) signal, or an on/off signal. They also have
the ability to sense current that is provided to loads, through an amplifier circuit.
When a low-side output is used as a PWM signal, a pulsed output signal is
provided by the VMM3120, where the percentage of time that the output is on vs.
off is determined by the duty cycle of the signal, and the duty cycle is determined
by the application software.
Note: Current flow gets interrupted when using low-side outputs as a PWM
signal, because the outputs are not on continuously. Therefore, current
feedback control systems should use a high-side output for PWM signals, and
a low-side output (turned on at 100%) for sensing current.

When low-side outputs are used as an on/off signal, the output provides
ground when in the on state (the application software is responsible for
switching low-side outputs on and off).

When low-side outputs are used to sense current, the application software will
monitor the current flowing into the low-side output, and based on the amount
of current, will turn the output either on or off.