MSK4223D Ver la hoja de datos (PDF) - M.S. Kennedy Corporation
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MSK4223D Datasheet PDF : 6 Pages
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APPLICATION NOTES
MSK4223 PIN DESCRIPTIONS
VCC - Is the low voltage supply for powering internal logic
and drivers for the lowside and highside MOSFETS.
The supplies for the highside drivers are derived from this
voltage.
V+ - Is the higher voltage H-bridge supply. The MOSFETS
obtain the drive current from this supply pin. The voltage
on this pin is limited by the drive IC. The MOSFETS are
rated at 100 volts. Proper by-passing to
GND with sufficient capacitance to suppress any voltage
transients, and to ensure removing any drooping during
switching, should be done as close to the pins of the mod-
ule as possible.
OUTPUT A - Is the output pin for one half of the bridge.
Decreasing the input voltage causes increasing duty cycles
at this output.
OUTPUT B - Is the output pin for the other half of the
bridge. Increasing the input voltage causes increasing duty
cycles at this output.
RSENSE A - Is the connection for the bottom of the A half
bridge. This can have a sense resistor connection to the
V+ return ground for current limit sensing, or can be con-
nected directly to ground. The maximum voltage on this
pin is ±2 volts with respect to GND.
RSENSE B - Is the connection for the bottom of the B half
bridge. This can have a sense resistor connection to the
V+ return ground for current limit sensing, or can be con-
nected directly to ground. The maximum voltage on this
pin is ±2 volts with respect to GND.
GND - Is the return connection for the input logic and VCC
INPUT - Is an analog input for controlling the PWM pulse
width of the bridge. A voltage lower than VCC/2 will pro-
duce greater than 50% duty cycle pulses out of OUTPUT
A. A voltage higher than VCC/2 will produce greater than
50% duty cycle pulses out of OUTPUT B.
DISABLE - Is the connection for disabling all 4 output
switches. DISABLE high overrides all other inputs. When
taken low, everything functions normally. An internal pullup
to VCC will keep DISABLE high if left unconnected.
HEN - Is the connection for enabling the high side out-
put switches. When taken low, HEN overrides other in-
puts and the high side switches remain off. When HEN is
high everything functions normally. An internal pullup to
VCC will keep HEN high if left unconnected.
3
TYPICAL SYSTEM OPERATION
This is a diagram of a typical application of the MSK4223.
The design VCC voltage is +12 volts and should have a good
low ESR bypass capacitor such as a tantalum electrolytic. The
analog input can be an analog speed control voltage from a
IN potentiometer, other analog circuitry or by microprocessor and
a D/A converter. This analog input gets pulled by the current
control circuitry in the proper direction to reduce the current
flow in the bridge if it gets too high. The gain of the current
control amplifier will have to be set to obtain the proper amount
of current limiting required by the system.
Current sensing is done in this case by a 0.1 ohm sense
resistor to sense current from both legs of the bridge sepa-
rately. It is important to make the high current traces as big as
possible to keep inductance down. The storage capacitor con-
nected to the V+ and the module should be large enough to
provide the high energy pulse without the voltage sagging too
far. A low ESR ceramic capacitor or large polypropylene ca-
pacitor will be required. Mount the capacitor as close to the
module as possible. The connection between GND and the
V+ return should not be carrying any motor current. The sense
resistor signal is common mode filtered as necessary to feed
the limiting circuitry for the microprocessor. This application
will allow full four quadrant torque control for a closed loop
servo system.
A snubber network is usually required, due to the induc-
tance in the power loop. It is important to design the snubber
network to suppress any positive spikes above 75V and nega-
tive spikes below -2V with respect to ground.
8548-140 Rev. J 10/14
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