c apex microtechnology corporation ?telephone (520) 690-8600 ?fax (520) 888-3329 ?orders (520) 690-8601 ?email prodlit@apexmicrotech.com 75 no longer supported for design-in m b 309 q 9 817 u s ab e o ? 6 0 0 2 4 sa0 2 fe a tures 250khz switching full bridge output 16-80v (160v p-p) 10a output fault protection shutdown control synchronizable clock hermetic package applic a tions aircraft audio amplifier brush type motor control vibration cancelling amplifier description the SA02 amplifier is an 80 volt, 250khz pwm amplifier. the full bridge output circuit provides 10 amps of continuous drive current for applications as diverse as aircraft audio and brush type motors. clock output and input pins can be used for synchronization with other amplifiers or an externally gener- ated clock. a separate integrator amplifier is also accessible and the integration may be varied for the application. direct access to the pwm input is provided for connection to digital motion control circuits. protection circuits guard against ther- mal overloads as well as shorts to supply or ground. the current limit is programmable with one or two external resistors depending on the application. a shutdown input disables all output bridge drivers. the 18 pin dip7 steel package is hermetically sealed. block diagram and typical application connections aircraft audio external connections b r i d g e d r i v e r thermal, short circuit protect. reg. 5v +v s nc a out b out ilim/shdn i sense a i sense b nc nc +pwm ramp / ?wm clk out 18k 100k 100 100 100 1000pf 1000pf 100pf clk in int out ?nt osc clk/2 r filter c filter r shdn 1k r limit signal gnd 5v load + int 5 4 8 7 6 3 2 1 14 17 13 15 18 12 16 9 11 10 vcc 2.5v 2.5v * * * * * * r limit * r limit 1 2 3 4 5 6 7 8 9 18 17 16 15 14 13 12 11 10 ilim/shdn nc isense b b out vs a out isense a nc vcc case tied to pin 6. bypassing of supplies is required. package is apex dip7. see outline dimensions/packages in apex data book. if +pwm > ramp/ pwm then a out > b out and isense b > isense a. * see text. t o p view int + int int out ramp/ pwm +pwm gnd clk in clk out nc http://www.apexmicrotech.com (800) 546-apex (800) 546-2739 microtechnology pulse width modulation amplifier SA02
apex microtechnology corporation 5980 north shannon road tucson, arizona 85741 usa applications hotline: 1 (800) 546-2739 76 no longer supported for design-in absolute maximum ratings specifications absolute maximum ratings supply voltage, vcc to gnd 15v supply voltage, +v s to gnd 80v output current, peak 15a pwm 0 to vcc clk in, int v in , ilim/shdn v in 0 to +6v power dissipation, internal 156w 1 temperature, pin solder - 10s 300 c temperature, junction 2 150 c temperature, storage 65 to +150 c operating temperature range, case 55 to +125 c SA02 the SA02 is constructed from mosfet transistors. esd handling procedures must be observed. the internal substrate contains beryllia (beo). do not break the seal. if accidentally broken, do not crush, machine, or subject to temperatures in excess of 850 c to avoid generating toxic fumes. caution notes: 1. 80w in each of the two active output transistors on at any one time. 2. unless otherwise noted: t c = 25 c. 3. min max values guaranteed but not tested. 4. long term operation at the maximum junction temperature will result in reduced product life. derate internal power dissipatio n to achieve high mttf. for guidance, refer to the heatsink data sheet. specifications parameter test conditions 2 min typ max units integrator, clock 3 offset voltage 2mv bias current 150 na offset current 30 na common mode voltage range 0 +3 v common mode rejection, dc 80 db slew rate 15 v/ s open loop gain r l = 10k ? 94 db gain bandwidth product 4.5 mhz clock out r l 10k ? 500 khz clock out, high level 4.7 5.3 v clock out, low level 0 .2 v clock in, low level 0 .3 v clock in, high level 2 5.6 v output efficiency, 10a output v s = 80v 94 % switching frequency 250 khz current, continuous 10 a current, peak 3 15 a r ds(on) 3 .42 ? power supply voltage, v cc full temperature range 10 12 15 v voltage, v s full temperature range 16 80 v current, v cc v cc = 12v 36 50 ma current, v s switching, no load, v s = 60v 70 90 ma inputs 3 i lim /shdn, trip point 90 110 mv pwm common mode voltage 1 vcc 1.5 v thermal 4 resistance, junction to case full temperature range 1.6 c/w resistance, junction to air full temperature range 15 c/w temperature range, case meets full range specifications 25 85 c
c apex microtechnology corporation telephone (520) 690-8600 fax (520) 888-3329 orders (520) 690-8601 email prodlit@apexmicrotech.com 77 no longer supported for design-in SA02 typical performance graphs 0 50 100 150 200 250 30 40 50 60 70 80 90 100 vcc quiescent current normalized vcc quiescent current, (%) 100 100k 97.5 99.0 99.5 100 clock loading 98.0 98.5 50 case temperature, ( c) clock frequency over temp normalized frequency, (%) 1k 10k 25 0 25 50 75 100 125 normalized frequency, (%) 98.0 98.5 99.0 99.5 100 100.5 101.0 101.5 102.0 switching frequency, f (khz) clock load resistance, ( ? ) 0.6 1.8 source to drain diode voltage 10 reverse diode flyback current, isd (a) 3 4 5 6 8 3 2 4 5 6 8 1 25 50 75 100 125 150 6 8 10 continuous output 4 frequency, f (hz) 180 integrator phase 0.8 1.0 1.2 1.4 1.6 50 10 20 30 40 50 60 70 80 125 25 0 25 50 75 100 10 100 1k 10k 100k 1m 10m case temperature, ( c) continuous amps 135 90 45 0 open loop phase, ( ) 0 2 0 75 100 case temperature, ( c) 0 power derating 80 25 duty cycle vs analog input duty cycle, (%) 50 125 20 40 60 0 20 40 60 80 100 internal power dissipation, (w) analog input, (v) 13 24 case temperature, t c ( c) vs, (v) 25 50 75 100 125 vcc quiescent current normalized vcc quiescent current, (%) 20 40 60 80 100 120 140 160 180 vs quiescent vs voltage 0 250 switching frequency, f (khz) 0 vs quiescent vs frequency normalized vs quiescent current, (%) normalized vs quiescent current, (%) 80 90 100 50 10 20 30 40 50 60 70 100 150 200 125 c 85 c 25 c 55 c normal operation shutdown operation each active output transistor vcc = 12v f = 250khz f nominal = 500khz open loop gain, a (db) integrator gain 20 60 100 80 20 0 40 100k frequency, f (hz) 1m 100 1k 10k 10m b output a output
apex microtechnology corporation 5980 north shannon road tucson, arizona 85741 usa applications hotline: 1 (800) 546-2739 78 no longer supported for design-in operating considerations SA02 general please read application note 30 on "pwm basics". refer to application note 1 "general operating considerations" for helpful information regarding power supplies, heat sinking and mounting. visit www.apexmicrotech.com for design tools that help automate pwm filter design and heat sink selection. the "application notes" and "technical seminar" sections contain a wealth of information on specific types of applications. information on package outlines, heat sinks, mounting hard- ware and other accessories are located in the "packages and accessories" section. evaluation kits are available for most apex product models, consult the "evaluation kit" section for details. for the most current version of all apex product data sheets, visit www.apexmicrotech.com. clock circuit and ramp generator the clock frequency is internally set to a frequency of approximately 500 khz. the clk out pin will normally be tied to the clk in pin. the clock is divided by two and applied to an rc network which produces a ramp signal at the ramp pin. an external clock signal can be applied to the clk in pin for synchronization purposes. if a clock frequency lower than 500khz is chosen an external capacitor must be tied to the ramp pin. this capacitor, which parallels an internal capaci- tor, must be selected so that the ramp oscillates 2.5 volts p-p with the lower peak 1.25 volts above ground. bypassing adequate bypassing of the power supplies is required for proper operation. failure to do so can cause erratic and low efficiency operation as well as excessive ringing at the outputs. the vs supply should be bypassed with at least a 1 f ceramic capacitor in parallel with another low esr capacitor of at least 10 f per amp of output current. capacitor types rated for switching applications are the only types that should be consid- ered. the bypass capacitors must be physically connected directly to the power supply pins. even one inch of lead length will cause excessive ringing at the outputs. this is due to the very fast switching times and the inductance of the lead connection. the bypassing requirements of the vcc supply are less stringent, but still necessary. a .1 f to .47 f ceramic capacitor connected directly to the vcc pin will suffice. noise filtering switching noise can enter the SA02 through the int out to +pwm connection. a wise precaution is to low pass filter this connection. adjust the pass band of the filter to 10 times the bandwidth required by the application. keep the resistor value to 100 ohms or less since this resistor becomes part of the hysteresis circuit on the pwm comparator. pcb layout the designer needs to appreciate that the SA02 combines in one circuit both high speed high power switching and low level analog signals. certain layout rules of thumb must be considered when a circuit board layout is designed using the SA02: 1. bypassing of the power supplies is critical. capacitors must be connected directly to the power supply pins with very short lead lengths (well under 1 inch). ceramic chip capaci- tors are best. 2. make all ground connections with a star pattern at pin 6. 3. beware of capacitive coupling between output connections and signal inputs through the parasitic capacitance be- tween layers in multilayer pcb designs. 4. do not run small signal traces between the pins of the output section (pins 11-17). 5. do not allow high currents to flow into the ground plane. 6. separate switching and analog grounds and connect the two only at pin 6 as part of the star pattern. integrator the integrator provides the inverted signal for negative feedback and also the open loop gain for the overall application circuit accuracy. recommended value of c int is 10 pf for stability. however, poles and zeroes can be added to the circuit for overall loop stability as required. current limit there are two load current sensing pins, i sense a and i sense b. the two pins can be shorted in the voltage mode connection but both must be used in the current mode connec- tion (see figures a and b). it is recommended that r limit resistors be non-inductive. load current flows in the i sense pins. to avoid errors due to lead lengths connect the i limit/ shdn pin directly to the r limit resistors (through the filter network and shutdown divider resistor) and connect the r limit resistors directly to the gnd pin. switching noise spikes will invariably be found at the i sense pins. the noise spikes could trip the current limit threshold which is only 100 mv. r filter and c filter should be adjusted so as to reduce the switching noise well below 100 02 46 810 output, i (a) 0 1 2 3 4 5 6 total voltage drop total voltage drop, (v) 125 c 100 c 85 c 25 c 55 c 25 c 70 c case temperature
c apex microtechnology corporation telephone (520) 690-8600 fax (520) 888-3329 orders (520) 690-8601 email prodlit@apexmicrotech.com 79 no longer supported for design-in mv to prevent false current limiting. the sum of the dc level plus the noise peak will determine the current limiting value. as in most switching circuits it may be difficult to determine the true noise amplitude without careful attention to grounding of the oscilloscope probe. use the shortest possible ground lead for the probe and connect exactly at the gnd terminal of the amplifier. suggested starting values are c filter = .001uf, r filter = 5k . the required value of r limit in voltage mode may be calcu- lated by: r limit = .1 v / i limit where r limit is the required resistor value, and i limit is the maximum desired current. in current mode the required value of each r limit is 2 times this value since the sense voltage is divided down by 2 (see figure b). if r shdn is used it will further divide down the sense voltage. the shutdown divider network will also have an effect on the filtering circuit. shutdown the shutdown circuitry makes use of the internal current limiting circuitry. the two functions may be externally com- bined in voltage and current modes as shown below in figures operating considerations SA02 i sense a i sense b i limit/shdn r filter c filter r limit r shdn shutdown signal 1k figure a. current limit with shutdown voltage mode. i sense a i sense b i limit/shdn r filter c filter r shdn shutdown signal 1k 1k figure b. current limit with shutdown current mode. r limit r limit a and b. the r limit resistors will normally be very low values and can be considered zero for this application. in figure a, r shdn and 1k form a voltage divider for the shutdown signal. after a suitable noise filter is designed for the current limit, adjust the value of r shdn to give a minimum 110 mv of shutdown signal at the i limit/shdn pin when the shutdown signal is high. note that c filter will filter both the current limit noise spikes and the shutdown signal. shutdown and current limit operate on each cycle of the internal switching rate. as long as the shutdown signal is high the output will be disabled. protection circuits circuits monitor the temperature and load on each of the bridge output transistors. on each cycle should any fault condition be detected all output transistors in the bridge are shut off. faults protected against are: shorts across the out- puts, shorts to ground, and over temperature conditions. should any of these faults be detected, the output transistors will be latched off. the fault must be removed and v cc power recycled to restart the SA02. in addition there is a built in dead time during which all the output transistors are off. the dead time removes the possibility of a momentary conduction path through the upper and lower transistors of each half bridge during the switching interval. noise or flyback may be ob- served at the outputs during this time due to the high imped- ance of the outputs in the off state. this will vary with the nature of the load. this data sheet has been carefully checked and is believed to be reliable, however, no responsibility is assumed for possible i naccuracies or omissions. all specifications are subject to change without notice. SA02u rev. e december 1998 ? 1998 apex microtechnology corp.
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