apex microtechnology corporation ? telephone (520) 690-8600 ? fax (520) 888-3329 ? orders (520) 690-8601 ? email prodlit@apexmicrotech.com 1 note : refer to hs11 heatsink in accessories section introduction this easy-to-use kit provides a platform for the evaluation of power op amps that use the pa74 pin-out con?guration. it can be used to analyze a multitude of standard or proprietary circuit con?gurations. in addition, it is ?exible enough to do most standard ampli?er test con?gurations. the schematic for 1/2 of the pc board is shown in figure 2. the schematic for the other half is identical except part refer - ence designators are primed (i.e. r1 = r1'). note that all of the components shown on the schematic will probably not be used for any single circuit. the component locations on the pc board (see figure 3) provide maximum ?exibility for a variety of con?gurations. also included are loops for current probes as well as connection pads on the edge of the pc board for easy interconnects. the hardware required to mount the pc board and the device under evaluation to the heatsink are included in the kit. because of the limitless combination of con?gurations and component values that can be used, no other parts are included in this kit. however, generic formulas and guidelines are included in the apex databook and this evaluation kit documentation. before you get started ? all apex ampli?ers should be handled using proper esd precautions! ? initially set all power supplies to the minimum operating levels allowed in the device data sheet. ? check for oscillations. ? always use the heatsink included in this kit with thermal grease or a tw03 and torque the part to the speci?ed 4-7 in-lbs (.45-.79 n?m). ? do not change connections while the circuit is under pow - er. ? never exceed any of the absolute maximums listed in the device data sheet. ? always use adequate power supply bypassing. ? remember that internal power does not equal load power. ? do not count on internal diodes to protect the output against sustained, high frequency, high energy kickback pulses. ????????????? ???????????????? ???????? ????????????? ???????????? ??????? ???????? ????????????? ???????? ???????? ???????? ?????????? ???????? ???????????? ???????? figure 1 parts list part # description quantity hs11 heatsink 1 eval02 pc board 1 ms03 mating socket 2 hwre01 hardware kit 1 tw03 thermal washer 1 box/10 hwre01 contains the following: 4 #8 panhead screw 4 #6 x 1.25" panhead screw 4 #8 .375" hex spacer 4 #6 x 5/16" hex nut 4 #8 1.00" hex standoff 2 #6 x 1/4" hex nut assembly hints the mating sockets included with this kit have recessed nut sockets for mounting the device under evaluation. this allows assembly from one side of the heatsink, making it easy to swap devices under evaluation. the sizes of the stand-offs were selected to allow proper spacing of the board-to-heatsink and allow enough height for components when the assembly is inverted. assembly 1. insert a #6 x 5/16" hex nut in each of the nut socket recesses located on the bottom of the mating socket. 2. insert the socket into the pc board until it is ?rmly pressed against the ground plane side of the pc board. 3. solder the socket in place (see figure 1). be sure the nuts are in the recesses prior to soldering. 4. mount the pc board assembly to the heatsink using the stand-offs and spacers included. 5. apply thermal grease or a tw03 to the bottom of the device under evaluation. insert into the mating socket through the heatsink. 6. use the #6 x 1.25" panhead screws to mount the ampli?er to the heat sink. do not overtorque. recommended mounting torque is 4-7 in-lbs (.45-.79 n?m). mounting precautions, general operating considerations, and heatsinking information may be found in the apex data book. ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ??????????????????????????????? ????
apex microtechnology corporation ? 5980 north shannon road ? tucson, arizona 85741 ? usa ? applications hotline: 1 (800) 546-2739 2 typical component functions component function r1 feedback resistor, a side r2 input resistor, b side, bridge mode r3 feedback resistor, b side r4 input resistor, b side r5 input resistor, a side r6 input bias current measurement (note 4) r7 output current sense resistor or loop for current probe r8 output current sense resistor or loop for current probe r9 input bias current measurement (note 4) r10 noise gain compensation (note 1) r11 resistor divider network for single supply bias (note 2) r12 resistor divider network for single supply bias (note 2) r13 noise gain compensation (note 1) r14 input bias current measurement r15 input bias current measurement r16 resistor divider network for single supply bias (note 2) r17 resistor divider network for single supply bias (note 2) c1 input coupling c2 ac gain set c3 ac gain or stability (note 1) c4 power supply bypass c5 power supply bypass c6 ac gain or stability (note 1) c7 ac gain set c8 input coupling c9 noise gain compensation (note 1) c10 noise gain compensation (note 1) c11 power supply bypass (note 3) c12 power supply bypass (note 3) d1,2,3,4 flyback protection (note 5) c13-16 bias node noise bypass (note 2) EK21 evaluation kit for pa74 pin-out ? ? ?? ? ? ?? ?? ?? ??? ??? ??? ??? ?? ? ??? ??? ?? ?? ??? ??? ??? ?? ?? ?? ?? ?? ?? ?? ?? ?? ? ?? ?? ?? ?? ?? ?? ??? ?? ??? ??? ??? ??? ? ? ? ?? ?? ??? ? ?? ? ?? ? ?? ? ?? ? ? ? figure 2 figure 3. ? ? ? ? ?????????? ????????????? ?? ????? ?? ?? ?? ?? ?? ????? ?? ?? ?? ?? ?? ??? ?? ?? ??? ?? ?? ?? ?? ?? ?? ??? ??? ??? ?? ??? ??? ??? ??? ??? ??? ?? ?? ??? ??? ??? ?? ?? ? ? ? ??? ?? ? ? ??? ? ?? ? ? ??? ?????? ?????? ??? ??? ???? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ???? ???? ???? ???? ???? ???? ???? ???? ???? ???? ???? ??? ??? ??? ??? ??? ??? ??? ??? ???? ???? ???? ?? ?? ??? ?? ?? ?? ??? ?? ?? ?? ???????? ??????????? ???? ????
apex microtechnology corporation ? telephone (520) 690-8600 ? fax (520) 888-3329 ? orders (520) 690-8601 ? email prodlit@apexmicrotech.com 3 EK21 ? ? ?? ??? ?? ? ??? ??? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ? ?? ?? ? ?? ??? ? ? ? ?? ?? ? ?? ? ?? ? ?? ? figure 4 dual supply bridge evaluation kit for pa74 pin-out ? ? ?? ? ?? ?? ??? ??? ??? ??? ?? ? ?? ?? ??? ?? ?? ?? ?? ?? ?? ?? ?? ? ?? ?? ?? ??? ? ?? ? ?? ? ?? ? ? ? figure 5 single supply bridge across the load. to set the gain of the circuit you must deter - mine the desired voltage across the load at vin = full scale. inserting these values into the following equation will yield the ratio of r1 to r5. (v ab /(2*vin)) = r1/r5 the values of r 1,2,3, and 5 should be chosen such that input bias current will not cause an error voltage that is unac - ceptable. set r2 equal to r3 to con?gure the slave ampli?er as a unity gain inverter. figure 5 shows a typical single supply bridge circuit for an ac coupled input signal. dc coupled inputs may require a different topology to accommodate proper gain and offset terms for a desired transfer function. the gain and output voltage capability for the single supply bridge are determined the same way as the dual supply bridge (see an#2). the difference is the bias requirement for the slave ampli?er. the noninverting input of the slave ampli?er should be biased at mid supply, and must be bypassed. bridge mode operation there are two types of bridge mode operation that will be covered in this section; dual (or split) supply and single supply. the pa74 is well suited for both types of bridge mode opera - tion. if another vendors pin compatible part is to be compared to the pa74, a close look at output swing and input common mode range is in order. the features that make the pa74 an excellent choice for bridge operation are not included in most other ampli?ers. a lack of common mode range may cause permanent damage to other pin compatible parts and the in - ability of other ampli?ers to swing close to the supply rails may cause a lack of available output voltage at the load as well as increase internal dissipation. the circuit shown in figure 4 is a dual supply bridge using the master-slave con?guration. resistors r 6,7,8,9,14,15 and j1 should be shorts. the available output voltage swing is vssC(2*vsat). if operating a pa74a at 3 amps and 30 volts total supply this translates to: v ab (max) = 30C(2*3.5) = 23 of course this 23 volts may be applied in either direction
apex microtechnology corporation ? 5980 north shannon road ? tucson, arizona 85741 ? usa ? applications hotline: 1 (800) 546-2739 4 this data sheet has been carefully checked and is believed to be reliable, however, no responsibility is assumed for possible inaccuracies or omissions. all speci?cations are subject to change without notice. EK21u rev i january 2005 ? 2005 apex microtechnology corp. hs11 heatsink note the hs11 heatsink is provided in this evaluation kit to guar - antee adequate thermal design through heat removal from the part under evaluation. once maximum power dissipation for the application is determined (refer to general operating considerations and application note 11 in the apex data book), the ?nal mechanical design will probably require sub - stantially less heatsinking. apex microtechnology makes no representation that the use or interconnection of the circuits described herein will not infringe on existing or future patent rights, nor do the descriptions contained herein imply the granting of licenses to make, use or sell equipment constructed in accordance therewith. EK21 evaluation kit for pa74 pin-out notes: refer to the following sections of the apex data book as noted. 1. see stability section of general operating considerations. 2. see gen. operating considerations, and an3 bridge circuit drives. 3. see power supplies section of general operating considerations. 4. see parameter de?nitions and test methods. 5. see ampli? er protection section of gen. operating considerations.
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