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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
DESCRIPTION
The MSA240 is a surface mount constructed PWM amplifier that provides a cost effective solution in many industrial applications. 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.

EQUIVALENT CIRCUIT DIAGRAM

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 RSA and RSB. 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.

EXTERNAL CONNECTIONS

RRAMP VIEW FROM COMPONENT SIDE
C1
C2 +
ROSC
C3
SINGLE POINT GND

APEX MICROTECHNOLOGY CORPORATION * TELEPHONE (520) 690-8600 * FAX (520) 888-3329 * ORDERS (520) 690-8601 * EMAIL prodlit@apexmicrotech.com
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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, junction2 TEMPERATURE RANGE, storage OPERATING TEMPERATURE, case
ABSOLUTE MAXIMUM RATINGS SPECIFICATIONS
100V 16V 30A, within SOA 250W3 5.4V 225C. 175C. -40 to 105C. -40 to 85C.
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 RON, both MOSFETs4 CURRENT, continuous CURRENT, peak OUTPUT MOSFET BODY DIODE CONTINUOUS CURRENT FORWARD VOLTAGE REVERSE RECOVERY POWER SUPPLY VOLTAGE, VS VOLTAGE, VCC CURRENT, VS, quiescent CURRENT, VCC, quiescent CURRENT, VCC, shutdown THERMAL RESISTANCE, DC, junction to case RESISTANCE, junction to air TEMPERATURE RANGE, case NOTES: 1. 2. 3. 4. IO = 20A , TJ = 85C 100mS TEST CONDITIONS1 Full temperature range Full temperature range Full temperature range Full temperature range Full temperature range RL = 2K MIN TYP MAX 9 500 150 4 1 96 1 .2 4.8 7 7 Full temperature range 4.85 0.6 5.15 2 155 20 30 20 I = 16A IF = 16A 3 14 22kHz switching 22kHz switching 1.3 250 60 15 4 100 16 28 18 10 1.2 14 85 UNITS mV nA nA V V/S dB MHz V V nS nS A V mA m A A A V nS V V mA mA mA C/W C/W C/W
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Full temperature range Full temperature range
Full temperature range Full temperature range -40
Unless otherwise noted: TC=25C, VCC = 15V, VS = 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
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TYPICAL PERFORMANCE GRAPHS
MSA240

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

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, ROSC, sets the oscillator frequency. The other resistor, RRAMP, 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 RRAMP . To program the oscillator, ROSC is given by: ROSC = (1.32X108 / F) - 2680 where F is the desired switching frequency and: RRAMP = 2 X ROSC 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 ROSC = 3.32K and RRAMP = 6.64K. Choose the closest standard 1% values: ROSC = 3.32K and RRAMP = 6.65K.

FIGURE 2. CURRENT LIMIT WITH OPTIONAL SHUTDOWN
POWER SUPPLY BYPASSING
Bypass capacitors to power supply terminals +VS must be connected physically close to the pins to prevent local parasitic oscillation and overshoot. All +VS pins must be connected together. Place an electrolytic capacitor of at least 10F per output amp required midpoint between these sets of pins. In addition place a ceramic capacitor 1F or greater directly at each set of pins for high frequency bypassing. VCC 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 VCC 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.

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.
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 APEXdata sheet has been carefullyCORPORATION * 5980 NORTHhowever, no responsibility TUCSON, for possible inaccuracies*or omissions. All specificationsHOTLINE: 1change without notice.
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MSA240U REV C JULY 2004 (c) 2004 Apex Microtechnology Corp.

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