MSA240 MSA240u 1 MSA240 pulse width modulation amplifiers MSA240 p r o d u c t i n n o v a t i o n f r o m 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 description the MSA240 is a surface mount constructed pwm amplifer 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 amplifer including an oscillator, comparator, error amplifer, 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 58-pin dip package style kc typical application 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 s a and r s b. a1 is a differential amplifer that amplifes the difference in currents of the two half bridges. this signal is fed into the internal error amplifer 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 49-53 a out 35-39 b out is b is a rs b rs a 40-43 54-57 control signal 15 2,18,26 dig ret pwr gnd 58 r osc a1 pwm amplifier +5v ref out clk out 17 22 24 20 1 r ramp in clk/2 out r osc r ramp e/a out 16 2.5v e/a -in e/a +in 19 single point gnd @ 26 +in 13 2.5v sig gnd ac back plate 28 23 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 view from component side r osc r ramp + single point gnd c3 c1 c2 notes: 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 5 10 9 8 7 6 15 14 13 12 11 20 19 18 17 16 25 24 23 22 21 26 27 28 2 1 v cc 4 3 +vs a out i sense a +vs b out i sense b pwr gnd dig rtn i lim b i lim a/shdn +in ea -in ea +in ea out r osc clk out clk/2 out clk in sig gnd nc nc nc nc nc nc nc sig gnd r ramp in 33 nc nc 32 30 29 31 +5v out ac back plate apex tp sig gnd nc 55 56 58 57 gnd +in a out i sense b +vs i sense a 35-39 54-57 40-43 58 1 13 5v signal r3 r2 29 v cc pwr +vs 44-48 49-53 b out smart controller gnd - + - + - + 200mv ref 5v ref 19 out r ramp in 20 clk/2 out 21 clk in osc clk out 24 r osc 22 7 i lim b 10 i lim a/shdn clk/2 - + 17 16 15 e/a out e/a -in e/a +in 30-34 signal gnd 26 signal gnd 18 2 27 apex tp digital return 23 2200pf 2200pf 1k 1k .01f .01f 2.68k 28 ac back plate 1f back plate q1 d2 d1 q4 q3 q2 5.36k copyright ? cirrus logic, inc. 2009 (all rights reserved) http://www.cirrus.com may 2009 apex ? MSA240urevd p r o d u c t i n n o v a t i o n f r o m
MSA240 2 MSA240u specifications absolute maximum ratings parameter test conditions 1 min typ max units error amplifier offset voltage full temperature range 9 mv bias current full temperature range 500 na offset current full temperature range 150 na common mode voltage range full temperature range 0 4 v slew rate full temperature range 1 v/s open loop gain r l = 2k? 96 db unity gain bandwidth 1 mhz clock low level output voltage full temperature range .2 v high level output voltage full temperature range 4.8 v rise time 7 ns fall time 7 ns bias current, pin 22 full temperature range 0.6 a 5v reference output voltage 4.85 5.15 v load current 2 ma output total r on , both mosfets 4 i o = 20a , t j = 85c 155 m? current, continuous 20 a current, peak 100ms 30 a output mosfet body diode continuous current 20 a forward voltage i = 16a 1.3 v reverse recovery i f = 16a 250 ns power supply voltage, v s 3 60 100 v voltage, v cc 14 15 16 v current, v s , quiescent 22khz switching 4 28 ma current, v cc , quiescent 22khz switching 18 ma current, v cc , shutdown 10 ma thermal resistance, dc, junction to case full temperature range 1.2 c/w resistance, junction to air full temperature range 14 c/w temperature range, case -40 85 c/w supply voltage, vs 100v supply voltage, vcc 16v output current, peak 30a, within soa power dissipation, internal, dc 250w 3 signal input voltages 5.4v temperature, pin solder, 10s 225c. temperature, junction 2 175c. temperature range, storage -40 to 105c. operating temperature, case -40 to 85c. notes: 1. unless otherwise noted: t c =25 c, v cc = 15v, v s = 60v 2. long term operation at the maximum junction temperature will result in reduced product life. derate internal power dissipation to achieve high mtbf. 3. each of the two output transistors on at any one time can dissipate 125w. 4. maximum specifcation guaranteed but not tested. p r o d u c t i n n o v a t i o n f r o m
MSA240 MSA240u 3 0 20 40 60 80 100 0 25 50 75 100 125 power derating case temperature, (c) internal power dissipation, (w) 97 98 99 100 frequency = 44khz 10k 100k 1m normalized frequency, (%) clock load resistance, () clock loading -40 -20 0 20 40 60 80 100 99.2 99.4 99.6 99.8 100.0 100.2 normalized frequency, (%) case temperature, (c) clock frequency over temp. 0.4 0.6 0.8 1.0 1.2 0 4 8 12 16 20 source to drain diode voltage flyback current, i sd (a) reverse diode t j = 125c t j = 25c 0 4 8 12 16 20 0 1 2 3 4 5 output current, (a) total voltage drop, (v) total voltage drop t c = 85c t c = 25c 0 25 50 75 100 0 5 10 15 20 25 continuous output continuous amps case temperature, (c) 1.5 2.0 2.5 3.0 3.5 0 20 40 60 80 100 duty cycle vs. analog input duty cycle, (%) analog input, (v) a out b out 0 10 20 30 40 50 4 8 12 16 20 24 v cc quiescent current v cc quiescent current, (ma) switching frequency, f (khz) 50% duty cycle -40 -20 0 20 40 60 80 100 97 98 99 100 101 102 v cc quiescent current normalized quiescent current, (%) case temperature, (c) normal or shutdown operation 0 20 40 60 80 100 1 2 3 4 5 v s quiescent current v s , (v) f = 22khz, 50% duty cycle v s quiescent current, (ma) 0 10 20 30 40 50 0 2 4 6 8 v s quiescent current vs. frequency v s quiescent current, i q (ma) switching frequency, f (khz) v s = 60v, 50% duty cycle p r o d u c t i n n o v a t i o n f r o m
MSA240 4 MSA240u 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 specifcation 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 powers com - plete application notes library, technical seminar workbook and evaluation kits. oscillator the MSA240 includes a user frequency programmable oscillator. the oscillator determines the switching frequency of the amplifer. the switching frequency of the amplifer is 1/2 the oscillator frequency. two resistor values must be chosen to properly program the switching frequency of the amplifer. 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: r osc = (1.32x10 8 / f) - 2680 where f is the desired switching frequency and: r 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: r osc = 3.32k and r ramp = 6.65k. 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 ored 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/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. figure 2. current limit with optional shutdown power supply bypassing bypass capacitors to power supply terminals +v s must be connected physically close to the pins to prevent local parasitic oscillation and overshoot. all +v s 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. v cc is bypassed internally. grounding and pcb layout switching amplifers 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 cc supply directly to pin 26 as well. make sure no current from the load return to pwr gnd fows 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. isense a isense b rs a rs b 40-43 54-57 pwr gnd 58 pwm amplifier r r ilima/shdn ilimb 7 10 c c 9r 5v shdn signal 24 20 t u o k l c t u o 2 / k l c 1 r c s o 22 pwm amplifier r osc 21 n i k l c r p m a r n i r ramp p r o d u c t i n n o v a t i o n f r o m
MSA240 MSA240u 5 cont acting 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 apex.support@cirrus.com. international customers can also request support by contacting their local cirrus logic sales representative. to fnd 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. all products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgment, including those pertaining to warranty, indemnifcation, and limitation of liability. no responsibility is assumed by cirrus for the use of this information, including use of this information as the basis for manufacture or sale of any items, or for infringement of patents or other rights of third parties. this document is the property of cirrus and by furnishing this information, cirrus grants no license, express or implied under any patents, mask work rights, copyrights, trademarks, trade secrets or other intellectual property rights. cirrus owns the copyrights associated with the information contained herein and gives con - sent for copies to be made of the information only for use within your organization with respect to cirrus integrated circuits or other products of cirrus. this consent does not extend to other copying such as copying for general distribution, advertising or promotional purposes, or for creating any work for resale. certain applications using semiconductor products may involve potential risks of death, personal injury, or severe prop - erty or environmental damage (critical applications). cirrus products are not designed, authorized or warranted to be suitable for use in products surgically implanted into the body, automotive safety or security devices, life support prod - ucts or other critical applications. inclusion of cirrus products in such applications is understood to be fully at the cus - tomers risk and cirrus disclaims and makes no warranty, express, statutory or implied, including the implied warranties of merchantability and fitness for particular purpose, with regard to any cirrus product that is used in such a manner. if the customer or customers customer uses or permits the use of cirrus products in critical applications, customer agrees, by such use, to fully indemnify cirrus, its officers, directors, employees, distributors and other agents from any and all liability, including attorneys fees and costs, that may result from or arise in connection with these uses. cirrus logic, cirrus, and the cirrus logic logo designs, apex precision power, apex and the apex precision power logo designs are trademarks of cirrus logic, inc. all other brand and product names in this document may be trademarks or service marks of their respective owners. p r o d u c t i n n o v a t i o n f r o m
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