MSK4204RH M. S Kennedy, MSK4204RH Datasheet - Page 3

• Manufacturer Part Number: MSK4204RH
• Description: 100 Volt 10 Amp Rad-hard H-bridge Pwm Motor Driver/amplifier
• Manufacturer: M. S Kennedy

+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. Optimum operation occurs with V
AV+, BV+ - Are the high voltage H-bridge supply pins.
The MOSFETS obtain the drive current from these supply
pins. The MOSFETS are rated at 100 volts. Proper by-
passing to GND with sufficient capacitance to suppress any
voltage transients, and ensure removal of any drooping dur-
ing switching, should be done as close to the pins on the
hybrid as possible.
AØ - Are the output pins for one half of the bridge. Increas-
ing the input voltage causes increasing duty cycles at this
output.
BØ - Are the output pins for the other half of the bridge.
Decreasing the input voltage causes increasing duty cycles
at this output.
AVB & BVB - Are the high-side bias pins. Some applications
require that the high-side be on for an indefinite period of
time. Under these conditions the charge in the boost capaci-
tor will not be adequate to keep the high-side output on. If
continuous on time is required, external floating power sup-
plies must be connected to the AVB and BVB pins to power
the high-side drive. Blocking diodes should be used to pre-
vent Vcc from sourcing current to the floating supply should
Vcc rise above the floating supply level. Reference typical
system operation schematic. If not used, the high-side bias
pins must remain high impedance.
AV- - Are the connections 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 these
pins is ±5 volts with respect to GND.
BV- - Are the connections 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 connected di-
rectly to ground. The maximum voltage on these pins is ±5
volts with respect to GND.
GND - Is the return connection for the input logic and Vcc.
MSK 4204RH PIN DESCRIPTIONS
APPLICATION NOTES
CC
set at 15V.
3
INPUT - Is an analog input for controlling the PWM pulse
width of the bridge. A voltage higher than 7.5V will produce
greater than 50% duty cycle pulses out of OUTPUT A. A
voltage lower than 7.5V will produce greater than 50% duty
cycle pulses out of OUTPUT B.
SHUTDOWN - Is the connection for disabling all 4 output
switches. SHUTDOWN high overrides all other inputs. When
taken low, everything functions normally. An internal pullup
to Vcc will keep SHUTDOWN high if left unconnected. This
pin should be grounded if not used.
UVLO - The under voltage lockout function of the MSK
4204RH prevents the device from starting before sufficient
bias voltage is available. The UVLO feature monitors the VCC
supply and holds the outputs low until the voltage level rises
above the threshold during start up. After start up the low
side UVLO curcuit will hold the low side switches off if VCC
falls below the threshold. The high side UVLO circuit will
hold the high side switches off any time the voltage on the
bootstrap capacitor falls below the threshold.
MAXIMUM DUTY CYLE AND HIGH SIDE BIAS - The MSK
4204RH uses two independent bootstrap circuits to power
each of the high side switches. When the switches are turned
on the high side drivers are powered by the charge in the
bootstrap capacitors. The voltage on the bootstrap capaci-
tors has an initial TBD V drop and decays at a rate of ap-
proximately TBD V every 100uS. The voltage can be approxi-
mated by the equation:
V
V
The lowside switches must be activated every cycle or held
active during static operation to provide a return path for
charging the highside bootstrap capacitor. If longer periods
of time are required between lowside switch cycles addi-
tional capacitance can be added to the highside bias pins
(AVB and BVB) to prevent VBS from falling below 10V. Should
continuous on time be required external floating power sup-
plies must be used.
BS
BS
V
BS
does not drop below the UVLO threshold.
should be greater or equal to 10 volts to ensure that
T
V
ON
=+V
BS
is the switch on time in mS
is the bootstrap capacitor voltage
CC
-TBD V-TBD x T
PRELIMINARY Rev. A 6/08
ON