pa12 ? pa12a pa12u 1 pa12, pa12a features ? low thermal resistance 1.4c/w ? current foldover protection new ? high temperature version pa12h ? excellent linearity class a/b output ? wide supply range 10v to 50v ? high output current up to 15a peak applications ? motor, valve and actuator control ? magnetic deflection circuits up to 10a ? power transducers up to 100khz ? temperature control up to 360w ? programmable power supplies up to 90v ? audio amplifiers up to 120w rms description the pa12 is a state of the art high voltage, very high output current operational amplifer designed to drive resistive, induc - tive and capacitive loads. for optimum linearity, especially at low levels, the output stage is biased for class a/b operation using a thermistor compensated base-emitter voltage multiplier circuit. the safe operating area (soa) can be observed for all operating conditions by selection of user programmable current limiting resistors. for continuous operation under load, a heatsink of proper rating is recommended. the pa12 is not recommended for gains below C3 (inverting) or +4 (non-inverting). this hybrid integrated circuit utilizes thick flm (cermet) resistors, ceramic capacitors and semiconductor chips to maximize reliability, minimize size and give top performance. ultrasonically bonded aluminum wires provide reliable inter - connections at all operating temperatures. the 8-pin to-3 package is hermetically sealed and electrically isolated. the use of compressible isolation washers voids the warranty. equivalent schematic 3 4 5 6 2 1 8 a1 d1 q1 q4 q3 q5 c1 q2a q2b q6b q6a 7 power rating not all vendors use the same method to rate the power handling capability of a power op amp. apex precision power rates the internal dissipation, which is consistent with rating methods used by transistor manufacturers and gives conser - vative results. rating delivered power is highly application dependent and therefore can be misleading. for example, the 125w internal dissipation rating of the pa12 could be expressed as an output rating of 250w for audio (sine wave) or as 440w if using a single ended dc load. please note that all vendors rate maximum power using an infnite heatsink. thermal stability apex precision power has eliminated the tendency of class a/b output stages toward thermal runaway and thus has vastly increased amplifer reliability. this feature, not found in most other power op amps, was pioneered by apex precision power in 1981 using thermistors which assure a negative temperature coefficient in the quiescent current. the reliability benefts of this added circuitry far outweigh the slight increase in component count. external connections cl+ +v s +in Cin Cv s f.o. clC out top view r cl+ r cl- output 1 2 3 4 5 6 7 8 8-pin to-3 package style ce power operational amplifier pa12 ? pa12a p r o d u c t i n n o v a t i o n f r o m copyright ? cirrus logic, inc. 2009 (all rights reserved) http://www.cirrus.com may 2009 apex ? pa12urevs p r o d u c t i n n o v a t i o n f r o m
125w internal dissipation rating of the pa12 could be expressed as an output rating of 250w for audio (sine wave) or as 440w if using a single ended dc load. please note that all vendors rate maximum power using an in nite heatsink. 5 ) & 3 . " - 4 5 " # * - * 5 : apex precision power has eliminated the tendency of class a/b output stages toward thermal runaway and thus has vastly increased ampli er reliability. this feature, not found in most other power op amps, was pioneered by apex precision power in 1981 using thermistors which assure a negative temperature coefficient in the quiescent current. the reliability bene ts of this added circuitry far outweigh the slight increase in component count. & 9 5 & 3 / " - $ 0 / / & $ 5 * 0 / 4 $ - 7 4 * / m * / m 7 4 ' 0 $ - m 0 6 5 5 0 1 7 * & 8 3 $ - 3 $ - 0 6 5 1 6 5 1 * / 5 0 1 " $ , " ( & 4 5 : - & $ & power operational amplifier 3 $ ? 3 $ $
pa12 ? pa12a pa12u 3 0 20 40 60 80 100 120 case temperature, tc (c) 0 20 60 100 power derating internal power dissipation, p (w) C50 0 100 .7 1.9 2.2 bias current 1.3 .4 10 100 10k .1m frequency, f (hz) input noise voltage, v n (nv/hz) 1 100 10m frequency, f (hz) C20 0 60 120 small signal response open loop gain, a (db) 20 40 80 100 1 100 .1m 10m C210 C150 C60 0 phase response C90 C30 10k 20k 50k .1m frequency, f (hz) 4.6 output voltage, v o (v p-p ) 100 1k 3k .1m frequency, f (hz) .003 .3 3 harmonic distortion distortion, (%) .01 .1 1 40 100 total supply voltage, v s (v) .4 .6 1.6 quiescent current normalized, i q (x) .8 1.4 0 output current, i o (a) output voltage swing voltage drop from supply (v) 1 10k frequency, f (hz) 0 common mode rejection common mode rejection, cmr (db) 40 80 120 .1m 10 100 0 time, t (s) pulse response output voltage, v o (v) C50 C25 50 100 case temperature, t c (c) 0 15.0 current limit current limit, i lim (a) 12.5 300 10k 30k 1 input noise 1k 10 20 30 1k C25 25 50 75 1.6 40 140 power response 30k 50 60 70 80 90 1.2 0 25 75 5.0 7.5 -8 10 1k 10k .1m 1m 140 80 120 10 10k 1m frequency, f (hz) phase, () normalized bias current, i b (x) 2.5 10.0 1k 1m 20 60 100 2 4 6 8 10 12 -6 -4 -2 0 2 4 6 8 70k 6.8 10 15 22 32 46 68 100 .03 1.0 125 1.0 125 17.5 case temperature, t c (c) C180 C120 40 50 70 100 2.5 3 6 9 12 15 2 3 4 5 6 pa12 pa12a r cl = .18 ,r fo = 0 r cl = .06 ,r fo = v o = 0 v o = 24v v o = 0 v o = C24v | +v s | + | Cv s | = 100v | +v s | C | Cv s | = 80v | +v s | + | Cv s | = 30v v in = 5v, t r = 100ns p o = 100mw t c = C25c p o = 4w a v =10 v s = 37v r l = 4 p o = 120w t c = 25c t c = 85c t c = 125c Cv o +v o p r o d u c t i n n o v a t i o n f r o m
pa12 ? pa12a 4 pa12u load and short circuits to the supply rail or common if the current limits are set as follows at t c = 25c: short to v s short to v s c, l, or emf load common 50v .30a 2.4a 40v .58a 2.9a 35v .87a 3.7a 30v 1.5a 4.1a 25v 2.4a 4.9a 20v 2.9a 6.3a 15v 4.2a 8.0a these simplifed limits may be exceeded with further analysis using the operating conditions for a specifc application. current limiting refer to application note 9, "current limiting", for details of both fxed and foldover current limit operation. visit the apex precision power web site at www.cirrus.com for a copy of the power design spreadsheet (excel) which plots current limits vs. steady state soa. beware that current limit should be thought of as a +/C20% function initially and varies about 2:1 over the range of C55c to 125c. for fxed current limit, leave pin 7 open and use equations 1 and 2. r cl = 0.65/l cl (1) i cl = 0.65/r cl (2) where: i cl is the current limit in amperes. r cl is the current limit resistor in ohms. for certain applications, foldover current limit adds a slope to the current limit which allows more power to be delivered to the load without violating the soa. for maximum foldover slope, ground pin 7 and use equations 3 and 4. 0.65 + (vo * 0.014) i cl = (3) r cl 0.65 + (vo * 0.014) r cl = (4) i cl where: vo is the output voltage in volts. most designers start with either equation 1 to set r cl for the desired current at 0v out, or with equation 4 to set r cl at the maximum output voltage. equation 3 should then be used to plot the resulting foldover limits on the soa graph. if equa - tion 3 results in a negative current limit, foldover slope must be reduced. this can happen when the output voltage is the opposite polarity of the supply conducting the current. in applications where a reduced foldover slope is desired, this can be achieved by adding a resistor (r fo ) between pin 7 and ground. use equations 4 and 5 with this new resistor in the circuit. vo * 0.14 0.65 + 10.14 + r fo i cl = (5) r cl vo * 0.14 0.65 + 10.14 + r fo r cl = (6) i cl where: r fo is in k ohms. general please read application note 1 "general operating con - siderations" which covers stability, supplies, heat sinking, mounting, current limit, 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 complete application notes library; technical seminar workbook; and evaluation kits. safe operating area (soa) the output stage of most power amplifers has three distinct limitations: 1. the current handling capability of the transistor geometry and the wire bonds. 2. the second breakdown effect which occurs whenever the simultaneous collector current and collector-emitter voltage exceeds specifed limits. 3. the junction temperature of the output transistors. the soa curves combine the effect of all limits for this power op amp. for a given application, the direction and magnitude of the output current should be calculated or measured and checked against the soa curves. this is simple for resistive loads but more complex for reactive and emf generating loads. however, the following guidelines may save extensive analytical efforts. 1. capacitive and dynamic* inductive loads up to the following maximum are safe with the current limits set as specifed. capacitive load inductive load v s i lim = 5a i lim = 10a i lim = 5a i lim = 10a 50v 200f 125f 5mh 2.0mh 40v 500f 350f 15mh 3.0mh 35v 2.0mf 850f 50mh 5.0mh 30v 7.0mf 2.5mf 150mh 10mh 25v 25mf 10mf 500mh 20mh 20v 60mf 20mf 1,000mh 30mh 15v 150mf 60mf 2,500mh 50mh *if the inductive load is driven near steady state conditions, allowing the output voltage to drop more than 8v below the supply rail with i lim = 15a or 25v below the supply rail with i lim = 5a while the amplifer is current limiting, the inductor must be capacitively coupled or the current limit must be lowered to meet soa criteria. 2. the amplifer can handle any emf generating or reactive t c = 25c t c = 125c t c = 85c t = 0.5ms t = 5ms t = 1ms thermal steady state second breakdown soa 20 50 70 100 40 30 10 supply to output differential voltage, v s - v o (v) 15 .6 .4 10 6.0 4.0 2.0 3.0 .3 1.0 output current from +v s or -v s (a) p r o d u c t i n n o v a t i o n f r o m
pa12 ? pa12a pa12u 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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