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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

4250

(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

Contact MSK for MIL-PRF-38535 Qualification Status

DESCRIPTION:

The MSK 4250 is a complete H-bridge MOSFET Brushed Motor Control System in an electrically isolated hermetic

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 compensa-

tion schemes are included. The MSK 4250 has good thermal conductivity of the MOSFET's due to 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

Rev. G 3/11

ABSOLUTE MAXIMUM RATINGS

V+ High Voltage Supply

Current Command Input

+Vcc

-Vcc

OUT

Continuous Output Current

Peak Output Current

○

-40°C to +125°C

-55°C to +125°C

+150°C

○

ELECTRICAL SPECIFICATIONS

All Ratings: Tc=+25°C Unless Otherwise Specified

Parameter

POWER SUPPLY REQUIREMENTS

+Vcc

-Vcc

PWM

Free Running Frequency

CONTROL

Transconductance

Current Monitor 7

Output Offset

ERROR AMP

Input Voltage Range 1

Slew Rate 1

Output Voltage Swing 1

Gain Bandwidth Product 1

Large Signal Voltage Gain 1

OUTPUT

Rise Time 1

Fall Time

@ 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 1

Voltage Drop Across Bridge (1 Upper and 1 Lower) 1

Drain-Source On Resistance (Each MOSFET) 6

Diode V

Dead Time 1

100

280

750

4.0

5.0

0.026

2.6

100

280

750

4.0

5.0

0.026

2.6

nSec

μAmps

Volts

nSec

μSec

±11

6.5

±12

175

±12

±13

6.5

275

±11

6.5

±12

175

±12

±13

6.5

275

Volts

V/μSec

Volts

MHz

V/mV

±10 Amps Output

@ 0 Volts Command

4,5,6

5,6

1.9

0.425

0.5

±5.0

2.1

0.575

±25.0

±50.0

1.8

0.40

0.5

±5.0

2.2

0.60

±35.0

Amp/Volt

V/Amp

mAmp

5,6

23.5

21.25

26.5

28.75

KHz

@ +15V

@ -15V

1,2,3

Test Conditions

Group A

Subgroup

MSK 4250H

Min.

Typ.

Max.

Min.

MSK 4250

Typ.

Max.

4 5

NOTES:

1 Guaranteed by design but not tested. Typical parameters are representative of actual device performance but are for reference

only.

2 Industrial grade devices shall be tested to subgroups 1 and 4 unless otherwise specified.

3 Military grade devices ("H" Suffix) shall be 100% tested to Subgroups 1, 2, 3 and 4.

4 Subgroups 5 and 6 testing available upon request.

5 Subgroup 1, 4 T

= T

= +25°C

2, 5 T

= T

= +125°C

3, 6 T

= T

= -55°C

6 This is to be used for MOSFET thermal calculation only.

7 Measurements do not include offset current at 0V current command.

8 Continuous operation at or above absolute maximum ratings may adversly effect the device performance and/or life cycle.

9 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.

Rev. G

3/11

○

75V

±13.5V

+16V

-18V

10A

20A

○

Thermal Resistance @ 125°C

Storage Temperature Range

Lead Temperature Range

(10 Seconds)

Case Operating Temperature

MSK4250

MSK4250H

Junction Temperature

4.9°C/W

-65°C to +150°C

+300°C

○

Units

APPLICATION NOTES

MSK 4250 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.

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.

Rev. G

3/11

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 17, 18, 23, 24, 33 and 34. The high power grounds (RTN) pins 1,2 and 3 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 4250 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.

Rev. G

3/11

MSK4250 TEST CIRCUIT

Rev. G

3/11