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ISO 9001 CERTIFIED BY DSCC
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
DESCRIPTION:
The MSK 4251 is a complete H-bridge MOSFET Brushed Motor Control System in an electrically isolated plastic encapsulated 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 antiphase 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+ AO AVBV+ NC BO BVSENSE RESISTOR + RTN RTN
Rev. B 1/05
ABSOLUTE MAXIMUM RATINGS
V+ High Voltage Supply VIN Current Command Input +Vcc -Vcc IOUT Continuous Output Current IPK Peak Output Current

5
-40C to +85C +150C

ELECTRICAL SPECIFICATIONS
All Ratings: Tc=+25C 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, +150C Junction @ 10 Amps @10Amps, +150C Junction @ 10 Amps, 150C Junction @ 10 Amps, Each FET IF=10 Amps, di/dt=100A/S 100 100 280 2 750 0.3 0.6 0.026 2.6 nSec nSec Amps Volts Volts Volts nSec Sec 1 1 1 11 6.5 12 175 12 8 13 6.5 275 Volts V/Sec 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 Min.
MSK 4251 Typ. Max.
Units
Leakage Current
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 VSD 1 trr 1
Dead Time 1
NOTES:
1 2 3 4 5 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.
2
Rev. B 1/05

75V 13.5V +16V -18V 10A 20A

JC Thermal Resistance @ 125C TST Storage Temperature Range TLD Lead Temperature Range (10 Seconds) TC Case Operating Temperature MSK4251 TJ Junction Temperature
3.0C/W -40C to +150C +300C

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 connected 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. 1000F is recommended. Capacitors should be placed as close to these pins as practical. 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 +.
AO, BO - 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 connected together to share the current through the three pins in the hybrid.
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 100Amp pull-up.
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.
CURRENT COMMAND (+,-) - are differential inputs for controlling 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 commutation direction. The maximum operational command voltage 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.
GND - is the return point for the low powered circuitry inside the hybrid. All GND pins should be tied together. All capacitors 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.
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-.
+15VIN - is the input for applying +15 volts to run the low power section of the hybrid. Both pins should be used together for optimum operation. These pins should be bypassed with a 10F capacitor and a 0.1F capacitor as close to these pins as possible.
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.
-15VIN - is the input for applying -15 volts to run the low power section of the hybrid. Both pins should be used together for optimum operation. These pins should be bypassed with a 10F capacitor and a 0.1F capacitor as close to these pins as possible.
3
Rev. B 1/05
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 30 nH 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 F 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 F or 1 F 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. B 1/05
MSK4251 TEST CIRCUIT
5
Rev. B 1/05
MECHANICAL SPECIFICATIONS
WEIGHT= 32 GRAMS TYPICAL NOTE: ALL DIMENSIONS ARE 0.010 INCHES UNLESS OTHERWISE LABELED. ESD Triangle indicates Pin 1.
ORDERING INFORMATION
Part Number MSK4251S MSK4251D MSK4251U MSK4251G Screening Level Industrial Industrial Industrial Industrial Lead Configuration Straight Down Up Gullwing
M.S. Kennedy Corp.
4707 Dey Road, Liverpool, New York 13088 Phone (315) 701-6751 FAX (315) 701-6752 www.mskennedy.com
The information contained herein is believed to be accurate at the time of printing. MSK reserves the right to make changes to its products or specifications without notice, however, and assumes no liability for the use of its products. Please visit our website for the most recent revision of this datasheet.
6
Rev. B 1/05

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