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TDA7454 4 x 35w high efficiency quad bridge car radio amplifier preliminary data high output power capability: 4 x 40w/4 w max. 4 x 35w/4 w eiaj. 4 x 25w/4 w @14.4v, 1khz, 10% 4 x 60w/2 w max. 2 w driving capability dual mode operating externally presettable: conventional class a- b mode, high efficiency mode low external components count: no bootstrap capacitors no external compensation internally fixed gain (26db) clipping detector st-by function (cmos compatible) mute function (cmos compatible) automute at minimum supply voltage detection low radiation protections: ouput short circuit to gnd; to v s ; across the load 3 steps overrating chip tempera- ture with thermal warning load dump voltage fortuitous open gnd loudspeaker dc current esd description the TDA7454 is a new bcd technology quad bridge type of car radio amplifier in flexiwatt25 packagespecially intendedfor car radio applications. among the features, its superior efficiency per- formance coming from the internal exclusive structure, makes it the most suitable device to simplify the thermal management in high power sets. the dissipated output power under average listening condition is in fact reduced up to 50% when compared to the level provided by conven- tional class ab solutions. this is preliminary information on a new product now in development or undergoing evaluation. details are subject to change without notice. september 1998 flexiwatt 25 7 8 9 - + 5 2 3 + - 19 18 17 21 24 23 - + + - right front right rear left front left rear svr 11 12 15 14 mute 22 st-by 4 in left rear in left front 100 m f in right front in right rear 0.22 m f 0.22 m f 0.22 m f 0.22 m f 10 cd 25 1 tab 13 s-gnd std/hi- eff 16 v cc2 v cc1 v cc 20 6 d94au172c block & application diagram multipower bcd technology 1/13
absolute maximum ratings symbol parameter value unit v op operating supply voltage 18 v v s dc supply voltage 28 v v peak peak supply voltage (for t = 50ms) 40 v i o output peak current (not repetitive t = 100 m s) 8 a i o output peak current (repetitive f > 10hz) 6 a p tot power dissipation t case =70 c86w t stg ,t j storage and junction temperature -55 to 150 c thermal data symbol description value unit r th j-case thermal resistance junction-case max 1 c/w d94au173a tab pw gnd rr out rr- st-by out rr+ v cc1 out rf- pw gnd rf out rf+ svr in rf in rr s gnd in lr in lf std/heff out lf+ pw gnd lf out lf- v cc2 out lr+ mute out lr- pw gnd lr cd 1 25 2 3 4 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 22 23 24 pin connection (top view) TDA7454 2/13
electrical characteristics (refer to the test circuit v s = 14.4v; r l =4 w ; f = 1khz; t amb =25 c, unless otherwise specified symbol parameter test condition min. typ. max. unit v s supply voltage range 8 18 v i d total quiescent drain current 60 140 250 ma p o output power thd = 10% thd = 1% thd = 10% rl = 2 w ; thd = 1% r l =2 w ; 23 18 40 28 25 20 42 30 w w w w p o eiaj eiaj output power (*) vs = 13.7v vs = 13.7v, rl = 2 w 32 50 35 52 w w p o max. max. output power (*) vs = 14.4v vs = 14.4v, rl = 2 w 38 55 40 60 w w thd total harmonic distortion p o = 1w to 10w; std mode p o = 1w; he mode p o = 10w; he mode 0.03 0.04 0.1 0.3 0.3 0.5 % % % r l =2 w ; he mode; p o =3w r l =2 w ; he mode; p o = 15w 0.06 0.15 0.3 0.5 % % c t cross talk f = 1khz to 10khz 45 55 db r in input impedance 11 15 19 k w g v voltage gain 25 26 27 db d g v voltage gain match 1 db e in output noise voltage r g = 600 w 100 150 mv svr supply voltage rejection f = 300hz; vr = 1vrms; r g = 0 to 100 w ; 45 52 db bw power bandwidth (3db) 75 khz a sb stand-by attenuation 90 100 db v sb in stand-by in threshold 1.5 v v sb out stand-by out threshold 3.5 v i sb stand-by current consumption 100 m a a m mute attenuation 80 90 db v min mute in thereshold 1.5 v v m out mute out threshold 3.5 v i m mute pin current (sourced) v = 0 to v s v s max = 18v -10 1 10 m a mode select switch standard btl mode op. (v pin 16 ) open high efficiency mode (v pin 16 ) 0.5 v cd clip det. out current (pull up to 5v with 10k w ) cd off: p omin = 10w cd on: thd = 5% 150 5 m a m a (*) saturated square wave output. TDA7454 3/13
in rf 0.22 m f c6 0.1 m f in rr c2 0.22 m f out rf out rr in lf c3 0.22 m f in lr c4 0.22 m f out lf out lr d95au416 (*) sw1 c5 100 m f svr tab vcc1 vcc2 c8 0.1 m f c9 2200 m f c7 1 m f st-by r1 10k r2 10k mute c1 14 15 12 11 22 4 13 s-gnd TDA7454 16 10 25 1 clip det 620 9 8 7 5 2 3 17 18 19 21 24 23 (*) open = standard btl closed=hi-eff btl figure 1: standard test and application circuit. TDA7454 4/13
figure 2: p.c.b. and components layout of fig. 1 circuit. (1.25 :1 scale) components & top copper layer bottom copper layer TDA7454 5/13
8 1012141618 vs (v) 40 80 120 160 200 240 id (ma) vi = 0 rl = 4 ohm figure 3: quiescent current vs. supply voltage 8 9 10 11 12 13 14 15 16 17 18 vs (v) 5 10 15 20 25 30 35 40 45 po (w) rl= 4 ohm f= 1 khz thd= 10 % thd= 1 % figure 4: output power vs. supply voltage 8 9 10 11 12 13 14 15 16 17 18 vs (v) 5 10 15 20 25 30 35 40 45 50 55 60 po (w) rl= 4 ohm f= 1 khz figure 5: max. output power vs. supply voltage 8 9 10 11 12 13 14 15 16 vs (v) 5 10 15 20 25 30 35 40 45 50 po (w) rl = 2 ohm f=1khz thd = 10 % thd = 1 % figure 6: output power vs. supply voltage 8 9 10 11 12 13 14 15 16 vs (v) 15 20 25 30 35 40 45 50 55 60 65 70 75 po (w) rl= 2 ohm f= 1 khz figure 7: max. output power vs. supply voltage 0110 po (w) 0 0.1 1 10 thd (%) f = 10 khz rl = 4 ohm f= 1khz hi-eff mode figure 8: thd vs. output power TDA7454 6/13
0110 po (w) 0 0.1 1 10 thd (%) f=1khz f = 10 khz rl = 2 ohm hi-eff mode figure 9: thd vs. output power 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 vpin22 (v) 0 10 20 30 40 50 60 70 80 90 100 out attn po= 4 w f= 20 to 20,000 hz figure 10: muting attenuation vs. vpin 22 10 100 1000 10000 f(hz) 0 0.1 1 10 thd (%) po = 1 w hi-eff mode rl = 4 ohm figure 11: thd vs. frequency 10 100 1000 10000 f(hz) 20 30 40 50 60 70 80 90 100 svr (db) vripple= 1 vrms rg= 0 figure 12: supply voltage rejection vs. fre- quency 10 100 1000 10000 f (hz) 20 30 40 50 60 70 80 90 crosstalk (db) po = 4 w rl = 4 ohm rg = 0 hi-e ff mode figure 13: cross-talk vs. frequency 0.1 1 10 po (w) 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 ptot (w) 0 10 20 30 40 50 60 70 n (%) vs= 14.4 v rl = 4 x 4 ohm f = 1 khz hi-eff mode ptot n figure 14: power dissipation and efficiency vs. output power TDA7454 7/13
operating principle. thanks to its unique operating principle, the TDA7454 obtains a substantial reduction of power dissipation from traditional class-ab amplifiers without being affected by the massive radiation effects and complex circuitry normally associated with class-d solutions. its is composed of 8 amplifier blocks, making up 4 bridge-equivalent channels. half of this struc- ture is drafted in fig 15. these blocks continu- ously change their connections during every sin- gle signal event, according to the instantaneous power demand. this means that at low volumes (output power steadily lower than 2.5 w) the TDA7454 acts as a single ended amplifier, condi- tion where block aco remains disabled and the block ado behaves like a buffer, which, by furnish- ing the correct dc biasing (half-vcc) to each pair of speakers, eliminate the needs of otherwise re- quired output-decoupling capacitors. at the same time, sw1 keeps closed. thus ensuring a com- mon biasing point for l-r front / l-r rear speak- ers couples. as a result, the equivalent circuit be- comes that of fig. 16. the internal switches (sw1) are high-speed, dis- sipation-free power mos types, whose realization has been made possible by the st- exclusive by- polar-cmos-dmos mixed technology process (bcd). from fig. 16 it can be observed that aao and abo amplifiers work in phase opposition. sup- posing their output have the same signal (equal shape/amplitude), the current sourced by abo will be entirely sunk by aao, while no current will flow into ado, causing no power dissipation in the lat- ter. aao and abo are practically configured as a bridge whose load is constituted by ra + rb (= 8 ohm, if 4 ohm speakers are used), with considerable ad- vantages in terms of power dissipation. designat- ing aao and abo for the reproduction of either front or rear sections of the same channel (left or right), keeping the fader in centre po- sition (same amplitude for front and rear sections) and using the same speakers, as it hap- pens during most of the time, will transpose this best-case dissipation condition into practical ap- plications. to fully take advantage of the TDA7454's low-dis- sipation feature, it is then especially important to adopt some criteria in the channels assignment, using the schematic of fig. 1 as a reference. when the power demand increases to more than 2.5 w, all the blocks will operate as amplifiers, sw1 is opened, leading to the seemingly conven- tional bridge configuration of fig. 17. the efficiency enhancement is based upon the concept that the average output power during the reproduction of normal music/speech programs will stand anywhere between 10 % and 15 % of the rated power (@ thd= 10 %) that the amplifier can deliver. this holds true even at high volumes and frequent clipping occurrence. applied to the TDA7454 (rated power= 25 w), this will result into an average output level of 2.5 - 3 w in sine-wave operation, region where the dissipated power is about 50 % less than that of a traditional amplifier of equivalent power class (see TDA7454 vs. class-ab characteristics, fig. 18). equally favourable is the case shown by fig. 19, when gaussian-distributed signal amplitudes, which best simulates the amplifier's real working conditions, are used. application hints (ref. to the circuit of fig. 1) stand-by and muting (pins 4 & 22) both stand-by and muting pins are cmos- compatible. the current sunk by each of them is about 1 m a. for pop prevention it is essential that during turn on/off sequences the muting be preventively inserted before making stand-by transitions. but, if for any reason, either muting or stand-by are not used, they have to be connected to vcc through a 100 kohm (minimum) resis- tance. the r-c networks values in fig. 1 (r1-c6 and r2- c7) are meant to be the minimum-necessary for obtaining the lowest pop levels possible. any re- ductions (especially for r2-c7) will inevitably im- pair this parameter. svr (pin 10) the duty of the svr capacitor (c5) is double: as- suring adequate supply-ripple rejection and con- trolling turn on/off operations. its indicated value (100 uf) is the minimum-recommended to correctly serve both the purposes. inputs (pins 11-12-13-14) the inputs are internally biased at half-vcc level. the typical input impedance is 15 kohm, which implies using cin (c1-c2-c3-c4) = 220 nf for ob- taining a theoretical minimum-reproducible fre- quency of 48 hz (-3 db). in any case, cin val- ues can be enlarged if a lower frequency bound is desired, but, at any cin enlargement must cor- respond a proportional increase of csvr (c5), to safeguard the on/off pop aspect. the following table indicates the right values to be used for cin and csvr, whose operating voltage can be 10 v. low frequency roll-off (-3db) cin ( m f) csvr ( m f) 48 0.22 100 22 0.47 220 16 0.68 330 11 1 470 TDA7454 8/13
table 1: mode selection table operation of the device 1) std/hi-eff (pin 16 = open) standard quad bridge mode high-eff quad bridge mode standard quad single-ended mode st-by mode 100 150 17 0 tchip (deg) 2) std/hi-eff (pin 16 = gnd) high-eff quad bridge mode standard quad single-ended mode st-by mode 150 170 tchip (deg) 3) std/hi-eff (pin 16 connected as shown in the figure below. standard quad bridge mode or high-eff mode (theatsink dependent) high-eff quad bridge mode standard quad single-ended mode st-by mode 100 150 17 0 tchip (deg) vref ntc t(theatsink) std/hi-eff (pin 16) d94au174a output stage stability the TDA7454's is intrinsically stable and will properly drive any kind of conventional car-radio speakers without the need of supplementary out- put compensation (e.g. boucherot cells), thus al- lowing a drastic reduction of the external parts whose number, abated to the essentials, reflects that of traditional amplifiers. in this respect, per- fect pin-to-pin compatibility with the entire sgs- thomson's 4-btl family (tda738x) exists. standard / high-efficiency operation (pin 16) the TDA7454's operating mode can be selected by changing the connection of pin 16, according to table 1. at low battery levels (<10 v), the device will auto- matically turn into standard bridge mode, in- dependently from the status of pin 16. condition # 3 in table 1 is particularly useful when the TDA7454's operation has to be conditioned by the temperature in other more heat-sensitive devices in the same environment. the ntc resis- tor is a temperature sensor, to be situated near the critical part(s), will appropriately drive pin 16 through a low-power transitor. initially the TDA7454 can be set to operate as a standard bridge, turning into high efficiency mode only if overheating is recognised in the critical spot, thus reducing the overall temperature in the circuit. clipping detector / diagnostic (pin 25) the TDA7454 is equipped with a diagnostic func- tion whose output is available at pin 25. this pin requires a pull-up resistor (10 kohm min.) to a dc source that may range from 5 v to vcc. the following events will be recognized and signaled out: clipping a train of negative-going pulses will appear, each of them syncronized with every single clipping event taking place in ant of the outputs. a possible application consists of filtering / inte- grating the pulses and implement a routine for automatically reducing / restoring the volume us- ing microprocessor - driven audioprocessors, to counteract the clipping sound-damagingeffects. overheating chip temperatures above 150 oc will be signaled out at pin 25 in the form of longer-lasting pulses, as the stepping back into the operating tempera- ture requires some time. TDA7454 9/13
this constitues a substantial difference from the aclippingo situation, making the two information unmistakable. associated to a suitable external circuitry, this awarningo signal could be used to mute some portions of the i.c. (e.g. the rear channels) or to attenuate the volume. short circuit some kinds of short circuit (out - gnd, out- vcc), either present before the power-on or made afterwards, will cause pin 25 to remain steadily low as long as the faulty condition persists. short-circuits across the speakers will give inter- mittent (pulsed) signalling, proportional to the output voltage amplitude. external layout grounding the 4 bridge stuctures have independent power ground accesses (pins 2,8,18,24), while the sig- nal ground is common to all of them (pin 13). the tab (pin 1) is connected to the chip substrate and has to be grounded to the best-filtered ground spot (usually nearby the minus terminal of the vcc-filtering electrolytic capacitor). this same point should be used as the centre of a multi-track star-like configuration, or, alternatively, as the ori- gin of only two separate tracks, one for p-gnd, one for s-gnd, each of them routed to their spe- cific ground pin(s). this will provide the right degree of separation between p-gnd and s-gnd yet assuring the (necessary) electrical connection between them. the correct ground assignment for the each ele- ment of the circuit will then be: power gnd: battery (-), supply filters (c8, c9), tab (pin 1). signal gnd: pre-amplifier (audiprocessor) ground, svr ca- pacitor (c5), muting/st-by capacitors (c6, c7). a c b d f-channel r-channel inf inr control logic rr rf sw1 - + + - d97au792 figure 15: TDA7454's half structure ab d inf inr rr rf r on2 - + + - d97au793 v f v r i f i f -i r figure 16: single ended operation (po < 2.5w) a c b d inf inr rr rf - + + - d97au794 v f v r figure 17: he bridge operation (po < 2.5w) TDA7454 10/13
0.1 1 10 po each channel (w) 0 5 10 15 20 25 30 35 40 45 50 55 pdiss (w) class-ab TDA7454 vs = 14.4 v rl = 4 x 4 ohm figure 18: power dissipation (sine-wave) 0.1 1 10 pout each channel (w) 0 5 10 15 20 25 30 35 40 45 pdiss (w) class-ab TDA7454 vs = 14.4 v rl = 4 x 4 ohm figure 19: power dissipation (gaussian signals) TDA7454 11/13
flexiwatt25 dim. mm inch min. typ. max. min. typ. max. a 4.45 4.65 0.175 0.183 b 1.80 1.90 2.00 0.070 0.074 0.079 c 1.40 0.055 d 0.75 0.90 1.05 0.029 0.035 0.041 e 0.37 0.39 0.42 0.014 0.015 0.016 f 0.57 0.022 g 0.80 1.00 1.20 0.031 0.040 0.047 g1 23.75 24.00 24.25 0.935 0.945 0.955 h 28.90 29.23 29.30 1.138 1.150 1.153 h1 17.00 0.669 h2 12.80 0.503 h3 0.80 0.031 l 21.57 21.97 22.37 0.849 0.865 0.880 l1 18.57 18.97 19.37 0.731 0.786 0.762 l2 15.50 15.70 15.90 0.610 0.618 0.626 l3 7.70 7.85 7.95 0.303 0.309 0.313 m 3.70 4.00 4.30 0.145 0.157 0.169 m1 3.60 4.00 4.40 0.142 0.157 0.173 n 2.20 0.086 o 2 0.079 r 1.70 0.067 r4 0.50 0.019 v2 20 v3 45 h3 r4 g g1 l2 h1 h f m1 l flex25 v3 o l3 h2 r3 n v2 r c b l1 m e d a outline and mechanical data TDA7454 12/13
information furnished is believed to be accurate and reliable. however, stmicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. no license is granted by implication or otherwise under any patent or patent rights of stmicroelectronics. specification mentioned in this publication are subject to change without notice. this publication supersedes and replaces all information previously supplied. stmicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of stmicroelectronics. the st logo is a registered trademark of stmicroelectronics ? 1998 stmicroelectronics printed in italy all rights reserved stmicroelectronics group of companies australia - brazil - canada - china - france - germany - italy - japan - korea - malaysia - malta - mexico - morocco - the netherlands - singapore - spain - sweden - switzerland - taiwan - thailand - united kingdom - u.s.a. http://www.st.com TDA7454 13/13

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