MSA240 MSA240 P r o dMSA240 u c t IInnnnoovvaa t i o n FFr roomm Pulse Width Modulation Amplifiers FEATURES • LOW COST • HIGH VOLTAGE - 100 VOLTS • HIGH OUTPUT CURRENT - 20 AMPS • 2kW OUTPUT CAPABILITY • VARIABLE SWITCHING FREQUENCY APPLICATIONS 58-pin DIP PACKAGE STYLE KC • BRUSH MOTOR CONTROL • MRI • MAGNETIC BEARINGS • CLASS D SWITCHMODE AMPLIFIER TYPICAL APPLICATION SINGLE POINT GND @ 26 DESCRIPTION 20 RRAMP 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. 1 RRAMP IN 24 ROSC 22 19 A OUT CLK OUT 17 E/A OUT B OUT CONTROL SIGNAL 2.5V CLK/2 OUT R2 5.36K 1 21 AC BACK PLATE 28 APEX TP 27 PWR GND 58 MSA240U 40-43 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 NC 1 20 21 22 23 24 25 26 27 28 RRAMP I SENSE A - VIEW FROM COMPONENT SIDE 2200pF 20 CLK IN R3 + SIG GND APEX TP AC BACK PLATE 13 CLK OUT +IN I SENSE B DIG RTN + 54-57 CLK/2 OUT 15 Q4 CLK IN ROSC E/A +IN EXTERNAL CONNECTIONS B OUT D2 +5V OUT - 49-53 EA OUT 16 Q3 SIG GND E/A -IN OSC D1 NC 17 .01F EA -IN E/A OUT 2200pF A OUT SMART CONTROLLER EA +IN 24 35-39 - +IN CLK OUT Q2 NC 22 Q1 NC 2.68K + NC 10 + ILIM A/SHDN 1K +Vs ILIM B 7 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. 44-48 200mV DIGITAL RETURN 1K NC SIGNAL GND +Vs NC 2 TORQUE MOTOR CONTROL 30-34 NC SIGNAL GND NC 18 ROSC RRAMP IN Rs A 5V REF 26 .01F ILIM A/SHDN 40-43 Rs B 23 ILIM B Is A Is B 54-57 2.5V A1 NC SIGNAL GND 49-53 16 E/A -IN 15 E/A +IN RRAMP IN 29 19 PWM AMPLIFIER +5V REF OUT 13 +IN SIG GND VCC 35-39 ROSC EQUIVALENT CIRCUIT DIAGRAM 5V REF OUT 58 2,18,26 28 23 SIG DIG PWR AC GND RET GND BACK PLATE CLK/2 OUT CLK/2 C1 SINGLE POINT GND ROSC C2 + C3 BACK PLATE 1F http://www.cirrus.com 58 PWR GND 57 56 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 37 36 ISENSE B Copyright © Cirrus Logic, Inc. 2009 (All Rights Reserved) B OUT +Vs ISENSE A A OUT 35 34 33 32 31 +Vs 30 29 VCC NOTES: C2 IS ELECTROLYTIC ≥10UF PER AMP OUTPUT CURRENT C1,3 HIGH QUALITY CERAMIC ≥1.0UF ALL +Vs MUST BE TIED TOGETHER ALL SIG GND PINS MUST BE TIED TOGETHER SINGLE POINT GROUND @ PIN 26 MAY 20091 APEX − MSA240UREVD MSA240 P r o d u c t I n n o v a t i o nF r o m 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 100V 16V 30A, within SOA 250W3 5.4V 225°C. 175°C. -40° to 105°C. -40° to 85°C. SPECIFICATIONS PARAMETER TEST CONDITIONS1 ERROR AMPLIFIER OFFSET VOLTAGE BIAS CURRENT OFFSET CURRENT COMMON MODE VOLTAGE RANGE SLEW RATE OPEN LOOP GAIN UNITY GAIN BANDWIDTH Full temperature range Full temperature range Full temperature range Full temperature range Full temperature range RL = 2KΩ CLOCK LOW LEVEL OUTPUT VOLTAGE HIGH LEVEL OUTPUT VOLTAGE RISE TIME FALL TIME BIAS CURRENT, pin 22 Full temperature range Full temperature range OUTPUT MOSFET BODY DIODE CONTINUOUS CURRENT FORWARD VOLTAGE REVERSE RECOVERY I = 16A IF = 16A 2 3. 4. UNITS 1 96 1 9 500 150 4 mV nA nA V V/µS dB MHz .2 0.6 V V nS nS µA 5.15 2 V mA 155 20 30 mΩ A A 20 A V nS 100 16 28 18 10 V V mA mA mA 1.2 14 85 °C/W °C/W °C/W 0 4.8 4.85 100mS NOTES: 1. 2. MAX Full temperature range OUTPUT TOTAL RON, both MOSFETs4 CURRENT, continuous CURRENT, peak THERMAL RESISTANCE, DC, junction to case RESISTANCE, junction to air TEMPERATURE RANGE, case TYP 7 7 5V REFERENCE OUTPUT VOLTAGE LOAD CURRENT POWER SUPPLY VOLTAGE, VS VOLTAGE, VCC CURRENT, VS, quiescent CURRENT, VCC, quiescent CURRENT, VCC, shutdown MIN IO = 20A , TJ = 85°C 1.3 250 3 14 22kHz switching 22kHz switching Full temperature range Full temperature range -40 60 15 4 Unless otherwise noted: TC=25°C, 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. MSA240U MSA240 NORMALIZED FREQUENCY, (%) 100 75 50 25 20 40 60 80 100 CASE TEMPERATURE, (C) REVERSE DIODE =2 98 FREQUENCY = 44KHz 97 1M 100K 10K CLOCK LOAD RESISTANCE, () T CONTINUOUS OUTPUT 4 3 TC 2 =2 1 4 8 12 16 OUTPUT CURRENT, (A) 20 DUTY CYCLE, (%) CONTINUOUS AMPS A OUT 60 40 20 5 B OUT 102 25 50 75 CASE TEMPERATURE, (C) 0 1.5 100 VCC QUIESCENT CURRENT 101 100 99 98 NORMAL or SHUTDOWN OPERATION 97 -40 -20 0 20 40 60 80 100 CASE TEMPERATURE, (C) MSA240U VCC QUIESCENT CURRENT 2.0 2.5 3.0 3.5 ANALOG INPUT, (V) VS QUIESCENT CURRENT, (mA) NORMALIZED QUIESCENT CURRENT, (%) 0 0 99.2 -40 -20 0 20 40 60 80 100 CASE TEMPERATURE, (C) 5C TC 80 10 99.4 85 DUTY CYCLE VS. ANALOG INPUT 15 99.6 C = 100 20 99.8 TOTAL VOLTAGE DROP 0 0 0 0.4 0.6 0.8 1.0 1.2 SOURCE TO DRAIN DIODE VOLTAGE 25 99 VCC QUIESCENT CURRENT, (mA) =1 J 4 5C 25 C 12 8 100.0 5 16 T FLYBACK CURRENT, ISD (A) 20 CLOCK FREQUENCY OVER TEMP. 100.2 5 VS QUIESCENT CURRENT 4 3 2 1 0 F = 22kHz, 50% DUTY CYCLE 20 40 60 VS, (V) 80 100 24 20 16 12 8 50% DUTY CYCLE 4 0 10 20 30 40 50 SWITCHING FREQUENCY, F (kHz) VS QUIESCENT CURRENT vs. FREQUENCY VS QUIESCENT CURRENT, IQ (mA) 0 TOTAL VOLTAGE DROP, (V) 0 CLOCK LOADING 100 NORMALIZED FREQUENCY, (%) POWER DERATING 125 J INTERNAL POWER DISSIPATION, (W) P r o d u c t I n n o v a t i o nF r o m 8 6 4 2 VS = 60V, 50% DUTY CYCLE 0 0 10 20 30 40 50 SWITCHING FREQUENCY, F (kHz) 3 MSA240 P r o d u c t I n n o v a t i o nF r o m GENERAL OSCILLATOR 20 CLK/2 OUT CLK OUT 21 CLK IN 24 ROSC 22 RRAMP 1 RRAMP IN ROSC PWM AMPLIFIER 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. 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, current limit occurs at I = 0.2/RSENSE for each half bridge. See 10 7 R Isense B Isense A IlimB PWR GND 58 PWM AMPLIFIER 40-43 54-57 Rs A Rs B C 9R 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 1. EXTERNAL OSCILLATOR CONNECTIONS 4 Figure 2. Accurate milliohm power resistors are required and there are several sources for these listed in the Accessories Vendors section of the Databook. FIGURE 2. CURRENT LIMIT WITH OPTIONAL SHUTDOWN IlimA/SHDN 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.Cirrus.com for design tools that help automate tasks such as calculations for stability, internal power dissipation, current limit, heat sink selection, Apex Precision Power’s complete Application Notes library, Technical Seminar Workbook and Evaluation Kits. R C 5V SHDN SIGNAL 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 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. 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. 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. MSA240U P r o d u c t I n n o v a t i o nF r o m MSA240 Contacting Cirrus Logic Support For all Apex Precision Power product questions and inquiries, call toll free 800-546-2739 in North America. For inquiries via email, please contact [email protected]. International customers can also request support by contacting their local Cirrus Logic Sales Representative. To find the one nearest to you, go to www.cirrus.com IMPORTANT NOTICE Cirrus Logic, Inc. and its subsidiaries ("Cirrus") believe that the information contained in this document is accurate and reliable. However, the information is subject to change without notice and is provided "AS IS" without warranty of any kind (express or implied). Customers are advised to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. 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