User Manual

Single Channel Operation
Advanced Digital Motor Controller User Manual 27
Single Channel Operation
Dual channel Brushed DC controllers may be ordered with the -S (Single Channel) suffix.
The two channel outputs must be paralleled as shown in the datasheet so that they can
drive a single load with twice the power. To perform in this manner, the controller’s Power
Transistors that are switching in each channel must be perfectly synchronized. Without
this synchronization, the current will flow from one channel to the other and cause the
destruction of the controller.
The single channel version of the controller incorporates a hardware setting inside the
controller which ensures that both channels switch in a synchronized manner and respond
to commands sent to channel 1.
Important Warning
Before pairing the outputs, attach the motor to one channel and then the other. Veri-
fy that the motor responds the same way to command changes.
Power Fuses
For low Amperage applications (below 30A per motor), it is recommended that a fuse be
inserted in series with the main battery circuit as shown in Figure 1-2 on page 24.
The fuse will be shared by the two output stages and therefore must be placed before the
Y connection to the two power wires. Fuse rating should be the sum of the expected cur-
rent on both channels. Note that automotive fuses above 40A are generally slow, will be
of limited effectiveness in protecting the controller and may be omitted in the high current
application. The fuse will mostly protect the wiring and battery against after the controller
has failed.
Important Warning
Fuses are typically slow to blow and will thus allow temporary excess current to
flow through them for a time (the higher the excess current, the faster the fuse will
blow). This characteristic is desirable in most cases, as it will allow motors to draw
surges during acceleration and braking. However, it also means that the fuse may
not be able to protect the controller.
Wire Length Limits
The controller regulates the output power by switching the power to the motors On and
Off at high frequencies. At such frequencies, the wires’ inductance produces undesirable
effects such as parasitic RF emissions, ringing, and overvoltage peaks. The controller has
built-in capacitors and voltage limiters that will reduce these effects. However, should the
wire inductance be increased, for example by extended wire length, these effects will be
amplified beyond the controller’s capability to correct them. This is particularly the case for
the main battery power wires.