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FEATURES

• LOW COST

• HIGH VOLTAGE - 100 VOLTS

• HIGH OUTPUT CURRENT - 20 AMPS

• 2kW OUTPUT CAPABILITY

• VARIABLE SWITCHING FREQUENCY

APPLICATIONS

• BRUSH MOTOR CONTROL

• MRI

• MAGNETIC BEARINGS

• CLASS D SWITCHMODE AMPLIFIER

58-PIN DIP

PACKAGE STYLE KC

TYPICAL APPLICATION

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DESCRIPTION

The MSA240 is a surface mount constructed PWM ampliﬁer

that provides a cost effective solution in many industrial applica-

tions. The MSA240 offers outstanding performance that rivals

many much more expensive hybrid components. The MSA240

is a complete PWM ampliﬁer including an oscillator, comparator,

error ampliﬁer, current limit comparators, 5V reference, a smart

controller and a full bridge output circuit. The switching frequency

is user programmable up to 50 kHz. The MSA240 is built on

a thermally conductive but electrically insulating substrate that

can be mounted to a heatsink.

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EQUIVALENT CIRCUIT DIAGRAM

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TORQUE MOTOR CONTROL

With the addition of a few external components the MSA240

becomes a motor torque controller. In the MSA240 the source

terminal of each low side MOSFET driver is brought out for

current sensing via R

A and R

B. A1 is a differential ampliﬁer

that ampliﬁes the difference in currents of the two half bridges.

This signal is fed into the internal error ampliﬁer that mixes the

current signal and the control signal. The result is an input

signal to the MSA240 that controls the torque on the motor.

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EXTERNAL CONNECTIONS

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RAMP

VIEW FROM

COMPONENT SIDE

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OSC

SINGLE

POINT

GND

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APEX MICROTECHNOLOGY CORPORATION • TELEPHONE (520) 690-8600 • FAX (520) 888-3329 • ORDERS (520) 690-8601 • EMAIL prodlit@apexmicrotech.com

MSA240

ABSOLUTE MAXIMUM RATINGS

SUPPLY VOLTAGE, VS

SUPPLY VOLTAGE, VCC

OUTPUT CURRENT, peak

POWER DISSIPATION, internal, DC

SIGNAL INPUT VOLTAGES

TEMPERATURE, pin solder, 10s

TEMPERATURE, junction

TEMPERATURE RANGE, storage

OPERATING TEMPERATURE, case

ABSOLUTE MAXIMUM RATINGS

SPECIFICATIONS

100V

16V

30A, within SOA

250W

5.4V

225°C.

175°C.

-40° to 105°C.

-40° to 85°C.

SPECIFICATIONS

PARAMETER

ERROR AMPLIFIER

OFFSET VOLTAGE

BIAS CURRENT

OFFSET CURRENT

COMMON MODE VOLTAGE RANGE

SLEW RATE

OPEN LOOP GAIN

UNITY GAIN BANDWIDTH

CLOCK

LOW LEVEL OUTPUT VOLTAGE

HIGH LEVEL OUTPUT VOLTAGE

RISE TIME

FALL TIME

BIAS CURRENT, pin 22

5V REFERENCE OUTPUT

VOLTAGE

LOAD CURRENT

OUTPUT

TOTAL R

, both MOSFETs

CURRENT, continuous

CURRENT, peak

OUTPUT MOSFET BODY DIODE

CONTINUOUS CURRENT

FORWARD VOLTAGE

REVERSE RECOVERY

POWER SUPPLY

VOLTAGE, V

CURRENT, V

, quiescent

CURRENT, V

, quiescent

CURRENT, V

, shutdown

THERMAL

RESISTANCE, DC, junction to case

RESISTANCE, junction to air

TEMPERATURE RANGE, case

NOTES: 1.

= 20A , T

= 85°C

100mS

TEST CONDITIONS

Full temperature range

= 2KΩ

MIN

TYP

MAX

500

150

4.8

Full temperature range

4.85

0.6

5.15

155

I = 16A

= 16A

22kHz switching

1.3

250

100

1.2

UNITS

V/µS

MHz

µA

mΩ

°C/W

Full temperature range

-40

Unless otherwise noted: T

=25

C, V

= 15V, V

= 60V

Long term operation at the maximum junction temperature will result in reduced product life. Derate internal power dissipation

to achieve high MTBF.

Each of the two output transistors on at any one time can dissipate 125W.

Maximum speciﬁcation guaranteed but not tested.

APEX MICROTECHNOLOGY CORPORATION • 5980 NORTH SHANNON ROAD • TUCSON, ARIZONA 85741 • USA • APPLICATIONS HOTLINE: 1 (800) 546-2739

TYPICAL PERFORMANCE

GRAPHS

MSA240

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APEX MICROTECHNOLOGY CORPORATION • TELEPHONE (520) 690-8600 • FAX (520) 888-3329 • ORDERS (520) 690-8601 • EMAIL prodlit@apexmicrotech.com

MSA240

GENERAL

Please read Application Note 30 “PWM Basics”. Refer also

to Application Note 1 “General Operating Considerations” for

helpful information regarding power supplies, heat sinking,

mounting, SOA interpretation, and speciﬁcation interpreta-

tion. Visit www.apexmicrotech.com for design tools that help

automate tasks such as calculations for stability, internal power

dissipation, current limit, heat sink selection, Apex’s complete

Application Notes library, Technical Seminar Workbook and

Evaluation Kits.

OPERATING

CONSIDERATIONS

current limit occurs at I = 0.2/R

SENSE

for each half bridge. See

Figure 2. Accurate milliohm power resistors are required and

there are several sources for these listed in the Accessories

Vendors section of the Databook.

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OSCILLATOR

The MSA240 includes a user frequency programmable

oscillator. The oscillator determines the switching frequency

of the ampliﬁer. The switching frequency of the ampliﬁer is 1/2

the oscillator frequency. Two resistor values must be chosen

to properly program the switching frequency of the ampliﬁer.

One resistor, R

OSC

, sets the oscillator frequency. The other

resistor, R

RAMP

, sets the internal ramp amplitude. In all cases

the ramp voltage will oscillate between 1.5V and 3.5V. See

Figure 1. If an external oscillator is applied use the equations

to calculate R

RAMP

To program the oscillator, R

OSC

is given by:

OSC

= (1.32X10

/ F) - 2680

where F is the desired

switching frequency

and:

RAMP

= 2 X R

OSC

Use 1% resistors with 100ppm drift (RN55C type resistors,

for example). Maximum

switching frequency

is 50kHz.

Example:

If the desired switching frequency is 22kHz then R

OSC

3.32K and R

RAMP

= 6.64K. Choose the closest standard 1%

values:

OSC

= 3.32K and R

RAMP

= 6.65K.

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FIGURE 2. CURRENT LIMIT WITH OPTIONAL SHUTDOWN

POWER SUPPLY BYPASSING

Bypass capacitors to power supply terminals +V

must

be connected physically close to the pins to prevent local

parasitic oscillation and overshoot. All +V

pins must be con-

nected together. Place an electrolytic capacitor of at least

10µF per output amp required midpoint between these sets

of pins. In addition place a ceramic capacitor 1µF or greater

directly at each set of pins for high frequency bypassing. V

is bypassed internally.

GROUNDING AND PCB LAYOUT

Switching ampliﬁers combine millivolt level analog signals

and large amplitude switching voltages and currents with fast

rise times. As such grounding is crucial. Use a single point

ground at SIG GND (pin 26). Connect signal ground pins 2 and

18 directly to the single point ground on pin 26. Connect the

digital return pin 23 directly to pin 26 as well. Connect PWR

GND pin 58 also to pin 26. Connect AC BACKPLATE pin 28

also to the single point ground at pin 26. Connect the ground

terminal of the V

supply directly to pin 26 as well. Make sure

no current from the load return to PWR GND ﬂows in the analog

signal ground. Make sure that the power portion of the PCB

layout does not pass over low-level analog signal traces on

the opposite side of the PCB. Capacitive coupling through the

PCB may inject switching voltages into the analog signal path.

Further, make sure that the power side of the PCB layout does

not come close to the analog signal side. Fast rising output

signal can couple through the trace-to-trace capacitance on

the same side of the PCB.

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FIGURE 1. EXTERNAL OSCILLATOR CONNECTIONS

SHUTDOWN

The MSA240 output stage can be turned off with a shutdown

command voltage applied to Pin 10 as shown in Figure 2. The

shutdown signal is OR’ed with the current limit signal and

simply overrides it. As long as the shutdown signal remains

high the output will be off.

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DETERMINING THE OUTPUT STATE

The input signal is applied to +IN (Pin 13) and varies from

1.5 to 3.5 volts, zero to full scale. As +IN varies from 1.5 to

2.5 volts the A output "high" duty cycle (relative to ground) is

greater than the B output "high" duty cycle. The reverse occurs

as the input signal varies from 2.5 to 3.5 volts. When +IN =

2.5 volts the duty cycles of both A and B outputs are 50%.

Consequently, when the input voltage is 1.5V the A output

is close to 100% duty cycle and the B output is close to 0%

duty cycle. The reverse occurs with an input voltage of 3.5V.

The output duty cycle extremes vary somewhat with switching

frequency and are internally limited to approximately 5% to

95% at 10kHz and 7% to 93% at 50kHz.

CURRENT SENSING

The low side drive transistors of the MSA240 are brought

out for sensing the current in each half bridge. A resistor from

each sense line to PWR GND (pin 58) develops the current

sense voltage. Choose R and C such that the time constant

is equal to 10 periods of the selected switching frequency. The

internal current limit comparators trip at 200mV. Therefore,

This

MICROTECHNOLOGY

checked and is believed to be reliable,

SHANNON ROAD •

is assumed

ARIZONA 85741 USA • APPLICATIONS

are subject to

(800) 546-2739

APEX

data sheet has been carefully

CORPORATION • 5980 NORTH

however, no responsibility

TUCSON,

for possible inaccuracies

•

or omissions. All speciﬁcations

HOTLINE: 1

change without notice.