Version 1.6 - May 28, 2012
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Current Sensor Jumpers:
The Infineon BTN7960B power chips used in the MegaMoto
provide a current mirror output that reflects the current passing through the high side of the
half-bridge inside each chip. This current is passed through a 634
Ω
resistor to provide a
voltage that can be read by the Arduino CPU. Since the low side of the half-bridge provides
no output on the current sensor pin it is possible to connect the sensor outputs from both
power chips in parallel. When the MegaMoto is configured as an H-bridge the current sense
output of the connected sensor outputs properly reflects the current through the bridge in
either direction. A close up of the SENSOR jumper block is shown in Figure 3.
Figure 3. Current sensor jumper block
When operating in H-bridge mode the jumper shown in red above may be placed to link the
current sense outputs of both chips. A second jumper chooses which Arduino analog pin to
connect to this combined signal. If operating sensing of the individual half-bridge current
outputs is desired the red jumper above is not placed and two jumpers are used to connect
each power chip current sense output to a different analog input pin. See the application
examples section for more details. The current sense output is optional and need not be
connected if monitoring of the load current is not desired.
Note, when the bridging jumper shown above is installed the current reading will be ½
the normal separate reading.
That is if the jumper is not installed the current reading will be
as in the specifications table above. The bridging jumper connects the two sensing resistors
from the two BTN7960s in parallel giving ½ the reading.
Power Connections
Motor Outputs:
The MegaMoto circuit is two independent half-bridge circuits mounted on a
single PCB. The two motor outputs may work together to form a full H-bridge for bi-directional
drive of a motor or other load or each half-bridge may be used independently. The MA output
is controlled by the PWMA input and the MB output is controlled by the PWMB input.
The
MegaMoto does not function with a PWM and Direction input.
The screw terminal and the
solder pads on each side are tied together and either or both may be used to power the load.
Battery Inputs:
The MegaMoto requires an external battery connected to the BAT + and –
inputs. This battery is not connected to the Arduino positive supply and cannot be used to
power the Arduino. There is no voltage regulator on the MegaMoto. The MegaMoto does not