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4707 Dey Road Liverpool, N.Y. 13088

(315) 701-6751

M.S.KENNEDY CORP.

ISO 9001 CERTIFIED BY DSCC

75 VOLT 20 AMP MOSFET

H-BRIDGE PWM MOTOR

DRIVER/AMPLIFIER

4225

The MSK 4225 is a complete H-Bridge circuit to be used for DC brushed motor control or Class D switchmode amplifi-
cation. All of the drive/control circuitry for the lowside and highside switches are internal to the circuit. The 45KHz PWM
circuitry is internal as well, leaving the user to only provide an analog signal for the motor speed/direction, or audio signal for
switchmode audio amplification. The MSK 4225 is constructed in a space efficient plastic power package that can be
directly bolted to a heatsink.

DESCRIPTION:

EQUIVALENT SCHEMATIC

TYPICAL APPLICATIONS

PIN-OUT INFORMATION

1
2
3
4
5
6
7
8
9

PRELIMINARY Rev. - 7/03

FEATURES:

Low RDS(ON) 0.013

Typical

Low Cost Complete H-Bridge

20 Amp Capability, 75 Volt Maximum Rating

Self-contained Smart Lowside/Highside Drive Circuitry

Internal 45KHz PWM Generation, Shoot-through Protection

Isolated Case Allows Direct Heatsinking

Logic Level Disable Input

Logic Level High Side Enable Input for Special Modulation or Function

NC
VCC
HEN
DIS
NC
INPUT
NC
GND
GND
NC

RSENSE A
RSENSE A
OUTPUT A
OUTPUT A
V+
V+
OUTPUT B
OUTPUT B
RSENSE B
RSENSE B

Each MOSFET I

=20A

Each MOSFET I

=20A 3

Each MOSFET I

=20A Intrinsic Diode 3

Intrinsic Diode

Each MOSFET V+=70V

Analog Input=6V

Output A,B=50% Duty Cycle

Output A=100% Duty Cycle High

Output B=100% Duty Cycle High

Input Voltage LO

Input Voltage HI

Input Current (DISABLE=0V)

Input Voltage LO

Input Voltage HI

Input Current (HEN=0V)

=100

OUTPUT CHARACTERISTICS

RDS (ON) 1 4

VDS(ON) Voltage

Instantaneous Forward Voltage

Reverse Recovery Time 1

Leakage Current

PWM Frequency

Vcc SUPPLY CHARACTERISTICS

Quiescent Bias Current

Vcc Voltage Range 1

INPUT SIGNAL CHARACTERISTICS 1

Analog Input Voltage

LOGIC CONTROL INPUTS 1

SWITCHING CHARACTERISTICS 1

Rise Time

Fall Time

Dead Time

V+
V

OUT

ABSOLUTE MAXIMUM RATINGS

Parameter

ELECTRICAL SPECIFICATIONS

Units

KHz

Max.

0.013

TBD

280

TBD

0.8

135

0.8

270

MSK 4225

Typ.

TBD

1.0

TBD

100

Min.

TBD

2.7

Test Conditions 2

NOTES:

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

Vcc=+12V, V+=28V, RSENSE A,B=Ground, DIS=0V, HEN=N/C unless otherwise specified.

Measured using a 300µS pulse with a 2% Duty Cycle.

On Resistance is specified for the Internal MOSFET for Thermal Calculations. It does not include the package pin resistance.

Tc= +25°C Unless Otherwise Specified

Disable Input

HEN Input

PRELIMINARY Rev. - 7/03

High Voltage Supply
Logic Supply
Continuous Output Current
Peak Output Current
Output Voltage Range
Thermal Resistance
(Output Switches @ 125°C)

75V
16V

20A
40A

GND -2V min. to V + max.

3.0°C/W

Storage Temperature Range
Lead Temperature Range
(10 Seconds)
Case Operating Temperature
MSK4225
Junction Temperature

-40°C to +150°C

300°C

-40°C to +85°C

+150°C

APPLICATION NOTES

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.

OUTPUT B - Is the output pin for the other half of the
bridge. Increasing the input voltage causes increasing
duty cycles at this output.

OUTPUT A - Is the output pin for one half of the bridge.
Decreasing 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 connected 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 connected 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 produce 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
inputs 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.

This is a diagram of a typical application of the MSK4225.
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
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
capacitor 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 appli-
cation 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 70V and nega-
tive spikes below -2V with respect to ground.

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 75 volts. Proper by-passing to
GND with sufficient capacitance to suppress any volt-
age transients, and to ensure removing any drooping
during switching, should be done as close to the pins
of the module as possible.

MSK 4225 PIN DESCRIPTIONS

TYPICAL SYSTEM OPERATION

PRELIMINARY Rev. - 7/03

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