MIL-PRF-38534 CERTIFIED FACILITY
M.S.KENNEDY CORP.
4707 Dey Road Liverpool, N.Y. 13088
10 AMP, 75V, H-BRIDGE
MOSFET BRUSHED
MOTOR CONTROLLER
4251
(315) 701-6751
FEATURES:
75 Volt Motor Supply Voltage
10 Amp Output Switch Capability
100% Duty Cycle High Side Conduction Capable
Shoot-Through/Cross Conduction Protection
"Real" Four Quadrant Torque Control Capability
Good Accuracy Around the Null Torque Point
Non-Hermetic Isolated Package
DESCRIPTION:
The MSK 4251 is a complete H-bridge MOSFET Brushed Motor Control System in an electrically isolated plastic encap-
sulated package. The hybrid is capable of 10 amps of output current and 75 volts of DC bus voltage. It has the normal
features for protecting the bridge. Included is all the bridge drive circuitry, and all the current sensing and analog circuitry
necessary for closed loop current mode (torque) control. When PWM'ing, the transistors are modulated in locked anti-
phase mode for the tightest control and the most bandwidth. Provisions for applying different compensation schemes are
included. The MSK 4251 has good thermal conductivity of the MOSFET's due to the electrically isolated substrate/package
design that allows direct heat sinking of the hybrid without insulators.
EQUIVALENT SCHEMATIC
TYPICAL APPLICATIONS
Brushed DC Motor Control
Servo Control
Fin Actuator Control
Voice Coil Control
Gimbal Control
AZ-EL Control
1
2
3
4
5
6
7
8
9
10
1
PIN-OUT INFORMATION
GND
DISABLE
CURRENT COMM.+
CURRENT COMM.-
CURRENT MONITOR
NC
E/A-
+15VIN
E/A OUT
-15VIN
20
19
18
17
16
15
14
13
12
11
AV+
AØ
AV-
BV+
NC
BØ
BV-
SENSE RESISTOR +
RTN
RTN
Rev. F 2/11
ABSOLUTE MAXIMUM RATINGS
V+ High Voltage Supply
6
V
IN
Current Command Input
+Vcc
-Vcc
I
OUT
Continuous Output Current
I
PK
Peak Output Current
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5
-40°C to +85°C
+150°C
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ELECTRICAL SPECIFICATIONS
All Ratings: Tc=+25°C Unless Otherwise Specified
Parameter
POWER SUPPLY REQUIREMENTS
+Vcc
-Vcc
PWM
Free Running Frequency
CONTROL
Transconductance
Current Monitor
Output Offset
ERROR AMP
Input Voltage Range 1
Slew Rate 1
Output Voltage Swing
Gain Bandwidth Product
Large Signal Voltage Gain
OUTPUT
Rise Time 1
Fall Time
1
1
@ 64V, +150°C Junction
@ 10 Amps
@10Amps, +150°C Junction
@ 10 Amps, 150°C Junction
@ 10 Amps, Each FET
IF=10 Amps, di/dt=100A/μS
Leakage Current
-
-
-
-
-
-
-
-
-
100
100
-
-
-
-
-
280
2
-
-
750
0.3
0.6
0.026
2.6
-
-
nSec
nSec
μAmps
Volts
Volts
Ω
Volts
nSec
μSec
1
1
1
±11
6.5
±12
-
175
±12
8
±13
6.5
275
-
-
-
-
-
Volts
V/μSec
Volts
MHz
V/mV
4
4
±10 Amps Output
±10 Amps Output
@ 0 Volts Command
1.8
0.425
-
2
0.5
±5.0
2.2
0.575
±35.0
Amp/Volt
V/Amp
mAmp
22
25
28
KHz
@ +15V
@ -15V
-
-
70
17
85
35
mA
mA
Test Conditions
2
MSK 4251
Min.
Typ.
Max.
Units
Voltage Drop Across Bridge (1 Upper and 1 Lower) 1
Voltage Drop Across Bridge (1 Upper and 1 Lower) 1
Drain-Source On Resistance (Each MOSFET) 3 1
Diode V
SD
T
RR
1
Dead Time 1
1
NOTES:
1
2
3
4
5
6
Guaranteed by design but not tested. Typical parameters are representative of actual device
performance but are for reference only.
±Vcc=+15V, V+=28V unless otherwise specified.
This is to be used for MOSFET thermal calculation only.
Measurements do not include offset current at 0V current command.
Continuous operation at or above absolute maximum ratings may adversly effect the device performance
and/or life cycle.
When applying power to the device, apply the low voltage followed by the high voltage or alternatively, apply both at the
same time. Do not apply high voltage without low voltage present.
2
Rev. F 2/11
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75V
±13.5V
+16V
-18V
10A
20A
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θ
JC
Thermal Resistance @ 125°C
T
ST
Storage Temperature Range
T
LD
Lead Temperature Range
(10 Seconds)
T
C
Case Operating Temperature
MSK4251
T
J
Junction Temperature
3.0°C/W
-40°C to +150°C
+300°C
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APPLICATION NOTES
MSK 4251 PIN DESCRIPTIONS
AV+, BV+ -
are the power connections from the hybrid to
the bus. All pins for the motor voltage supply should be con-
nected together to share the current through the pins in the
hybrid. The external wiring to these pins should be sized
according to the RMS current required by the motor. A high
quality monolithic ceramic capacitor for high frequencies and
enough bulk capacitance for keeping the V+ supply from
drooping should bypass these pins. 1000μF is recommended.
Capacitors should be placed as close to these pins as practi-
cal.
AØ, BØ -
are the connections to the motor phase windings
from the bridge output. The wiring to these pins should be
sized according to the required current by the motor. There
are no short circuit provisions for these outputs. Shorts to
V+ or gound from these pins must be avoided or the bridge
will be destroyed. All pins for each phase should be con-
nected together to share the current through the three pins in
the hybrid.
RTN -
is the power return connection from the module to the
bus. All internal ground returns connect to this point inside
the hybrid. All three pins should be connected together to
share the current. All capacitors from the V+ bus should
connect to this point as close as possible. All external V+
return connections should be made as close to these pins as
possible. Wiring sizing to this pin should be made according
to the required current.
GND -
is the return point for the low powered circuitry inside
the hybrid. All GND pins should be tied together. All capaci-
tors for bypassing the + and -15V supplies should be tied at
this point, as close to the pins as possible. Any ground plane
connections for low powered and analog citcuitry outside the
hybrid should be tied to this point.
+15VIN -
is the input for applying +15 volts to run the low
power section of the hybrid. Both pins should be used to-
gether for optimum operation. These pins should be bypassed
with a 10μF capacitor and a 0.1μF capacitor as close to these
pins as possible.
-15VIN -
is the input for applying -15 volts to run the low
power section of the hybrid. Both pins should be used to-
gether for optimum operation. These pins should be bypassed
with a 10μF capacitor and a 0.1μF capacitor as close to these
pins as possible.
SENSE RESISTOR + -
is the top of the sense resistor for
sensing the bridge current and closing the loop. The bottom
of the sense resistor is RTN. All the AV- and BV- pins should
be connected to this point.
AV-,BV- -
are the power pins for the bottom of the bridge.
These are to be connected to sense resistor +.
DISABLE -
is a pin for externally disabling the output bridge.
A TTL logic low will enable the bridge and a TTL high will
disable it. It is internally pulled up by a 100μAmp pull-up.
CURRENT COMMAND (+,-) -
are differential inputs for con-
trolling the module in current mode. Scaled at 2 amps per
volt of input command, the bipolar input allows both forward
and reverse current control capability regardless of motor com-
mutation direction. The maximum operational command volt-
age should be ±5 volts for ±10 amps of motor current.
Going beyond 5 volts of command voltage will force the bridge
to conduct more than the desired maximum current. There is
internal current limiting that will ultimately limit the absolute
maximum current being output by the bridge.
CURRENT MONITOR-
is a pin providing a current viewing
signal for external monitoring purposes. This is scaled at ±2
amps of motor current per volt output, up to a maximum of
±5 volts, or ±10 amps. Going beyond the 5 volt maximum
may result in clipping of the waveform peaks. In DISABLE
mode, the CURRENT MONITOR output may rail positive or
negative, depending on internal bias currents. When re-en-
abled, this output will resume expected operation.
IN
E/A OUT -
is the current loop error amplifier output. It is
brought out for allowing various loop compensation circuits
to be connected between this and E/A-.
E/A- -
is the current loop error amplifier inverting input. It is
brought out for allowing various loop compensation circuits
to be connected between this and E/A OUT.
3
Rev. F 2/11
APPLICATION NOTES CONTINUED
BUS VOLTAGE FILTER CAPACITORS
The size and placement of the capacitors for the DC bus has a direct bearing on the amount of noise filtered and also on
the size and duration of the voltage spikes seen by the bridge. What is being created is a series RLC tuned circuit with a
resonant frequency that is seen as a damped ringing every time one of the transistors switches. For the resistance, wire
resistance, power supply impedance and capacitor ESR all add up for the equivalent lumped resistance in the circuit. The
inductance can be figured at about 30nH per inch from the power supply. Any voltage spikes are on top of the bus voltage
and the back EMF from the motor. All this must be taken into account when designing and laying out the system. If
everything has been minimized, there is another solution. A second capacitance between 5 and 10 times the first capacitor
and it should either have some ESR or a resistor can be added in series with the second capacitor to help damp the voltage
spikes.
Be careful of the ripple current in all the capacitors. Excessive ripple current, beyond what the capacitors can handle, will
destroy the capacitors.
±15VIN FILTER CAPACITORS
It is recommended that about 10
μF
of capacitance (tantalum electrolytic) for bypassing the + and -15V inputs be placed as
close to the module pins as practical. Adding ceramic bypass capacitors of about 0.1
μF
or 1
μF
will aid in suppressing noise
transients.
GENERAL LAYOUT
Good PC layout techniques are important. Ground planes for the analog circuitry must be used and should be tied back to
the small signal grounds, pin 1. The high power grounds (RTN) pins 11 and 12 get tied back to the small signal ground
internally. DO NOT connect these grounds externally. A ground loop will result.
LOW POWER STARTUP
When starting up a system utilizing the MSK 4251 for the first time, there are a few things to keep in mind. First, because
of the small size of the module, short circuiting the output phases either to ground or the DC bus will destroy the bridge. The
current limiting and control only works for current actually flowing through the bridge. The current sense resistor has to
see the current in order for the electronics to control it. If possible, for startup use a lower voltage and lower current power
supply to test out connections and the low current stability. With a limited current supply, even if the controller locks up,
the dissipation will be limited. By observing the E/A OUT pin which is the error amp output, much can be found out about the
health and stability of the system. An even waveform with some rounded triangle wave should be observed. As current
goes up, the DC component of the waveform should move up or down. At full current (with a regular supply) the waveform
should not exceed +4 volts positive peak, or -4 volts negative peak. Some audible noise will be heard which will be the
commutation frequency. If the motor squeals, there is instability and power should be removed immediately unless power
dissipation isn't excessive due to limited supply current. For compensation calculations, refer to the block diagram for all
information to determine the amplifier gain for loop gain calculations. For the power up sequence, ±15 volts should be
powered at the same time or before the V+ voltage is applied.
4
Rev. F 2/11
MSK4251 TEST CIRCUIT
5
Rev. F 2/11
微控制器 MCU
