LINEAR INTEGRATED CIRCUIT PRELIMINARY DATA AUDIO POWER AMPLIFIER WITH SHORT CIRCUIT PROTECTION AND THERMAL SHUT-DOWN The TCA 940E is a monolithic integrated circuit in a 12-lead quad in-line plastic package, intended for use as a low frequency class B amplifier. The TCA 940E provides 6.5W output power @ 20 V/8 9 and 5.4 W @ 18 V/8 Q. It gives very low harmonic and cross-over distortion. Besides the thermal shut-down, the device contains a current limiting circuit which restricts the operation within the safe operating area of the power transistors. The TCA 940 is pin to pin equivalent to the TBA 8108S. ABSOLUTE MAXIMUM RATINGS V; Supply voltage 24 Vv ly Output peak current (non-repetitive) 3.5 A I, Output peak current (repetitive) 3 A Prot Power dissipation: at Tamp = 80 C 1 Ww at Trap = 90C 5 Ww Tstg . Tj Storage and junction temperature -40 to 150 C ORDERING NUMBER: TCA 940E MECHANICAL DATA Dimensions in mm Supersedes issue dated 11/74 459 6/75CONNECTION AND SCHEMATIC DIAGRAMS v1 Re 12[]} output o-____ wh} nc. Fs 460. tof] GROUND o> GROUND For GROUND Ra (SUBSTRATE) 8] INPUT ah) RIPPLE CY REJECTION $-0289 SUBSTRATE S-o6871 4 yy) o. R2 100k CQ c2 = 500 pF bv 10 ome | TPR, $-0986 %=C3,C7 SEE FIG.6 460THERMAL DATA Rth j-tap Thermal resistance junction-tab max 12 C/W Rth j-amb Thermal resistance junction-ambient max 70" C/W * Obtained with tabs soldered to printed circuit with minimized copper area ELECTRICAL CHARACTERISTICS (Refer to the test circuit, Tamp = 25 C) Parameter Test conditions Min. Typ. Max.| Unit Vy Supply voltage (pin 1) 6 24; V Vo Quiescent output voltage |V, = 18V 8.2 9 9.8) V (pin 12) ly Quiescent drain current Vo =24V 20 42} mA lb Bias current (pin 8) V, = 18V 0.5 3} WA Py Output power d = 10% f =1kHz V, = 20V, Rp = 82 6.5 Ww V, = 18V, RL =82 5 5.4 Ww Vicrms) Voltage for input saturation 250 mV Vi Input sensitivity Ps =5.4W V, =18V RR, =82 f =1kHz 110 mV B Frequency response V, = 18V RL =82 (-3 dB) C3 = 1000 pF 40 to 20,000 Hz d Distortion P, = 50 mW to 3.5W V, = 18V RL =8Q f =1kHz 0.2 % 461ELECTRICAL CHARACTERISTICS (continued) Parameter Test conditions Min. Typ. Max.| Unit R, Input resistance (pin 8) 5 M2 G, Voltage gain V, = 18V RL =82 (open loop) f =1kHz 75 dB Gy Voltage gain V, = 18V R, =82 (closed loop) f =1kHz 34 37 40| dB en Input noise voltage V, = 18V Rz =0 B (-3 dB) = 40 Hz to 20,000 Hz 3 LV in Input noise current V, = 18V B (-3 dB) = 40 Hz to 20,000 Hz 0.15 nA n Efficiency P, =5.4W V, = 18V RL =82 f =1kHz 70 % SVR _ Supply voltage rejection ratio V, = 22V Ri = 82 frippie = 100 Hz 45 dB lg Drain current P, =5.4W V, = 18V R, =82 460 mA * Thermal shut-down case temperature Prot = 2.8W 120 C * See figs. 8 and 14 462Fig. 1 - Typical output power vs. sup- ply voltage G-tha2 (w) 0 4 8 12 16 Vg () Fig. 3- Typical distortion vs. output power G-1664 d (he) 6 Vg = 18V R= an Ry = $60 6 4 2 9 2 i , 10-1 1 Py (W) Fig. 2- Maximum power dissipation vs. supply voltage (sine wave operation) G46} Prot (w) & 3 2 1 0 4 8 12 16 V5() Fig.4- Typical voltage gain (closed loop) and typical input volta- ge vs. feedback resistance (R+) G-1445 ie (mV)6 Po =5-4W 120 Ry (O) 463Fig.5- Typical distortion vs. fre- quency G- 1241 (%) 2 4 68 2 4 68 2 4 68 z ws 68 # (Hz) Fig. 7- Typical supply voltage rejec- tion ratio SVR (a8) Vs R= 60 C5100 uF 100rz 0 80 100 R, (a) C3 (pry 6 4 Prot (w) Fig.6 - Typical value of C3 vs. Ry; for different bandwidths G-1242 8=10 kHz Be 20 kHz a Ry (A) Fig. 8- Typical power dissipation and efficiency vs. output power G-1446 fn (th) 60 40 20 V5 = 18 Rips 82 B Py (W) 464Fig. 9- Typical quiescent output vol- Fig. 10 -Typical quiescent current vs. tage (pin 12) vs. supply vol- supply voltage tage G-1246/} G-1247 5 10 1S 20 Va() 5 0 15 20, CV) APPLICATION INFORMATION The application diagram in fig. 11 is advised if the device's gain spread is to be contained within 1 dB (for stereo applications) Fig. 11 - Recommended circuit for maintaining the gain spread within + 1 dB max. Vs o- ore ae MF cae 1 ys 4 100pF o-. 8 SV t Ta8 ITC A 940E 2 TL == 500 uF 100k0 @ re Inf Seisy 10 6 loon 4700pF] 3309 | NAF vo b Ry | 2B, 4.70 Ope RL 25% 1 sa whe $-0984 465SHORT CIRCUIT PROTECTION The most important innovation in the TCA 940E is an original circuit which limits the current of the output transistors. Fig. 12 shows that the maximum output current is a function of the collector-emitter voltage; hence the circuit works within the safe operat- ing area of the output power transistors. This can therefore be considered as being power limiting rather than simple current limiting. The TCA 940E is thus protected against tem- porary overloads or short circuit by the above circuit. Should the short circuit exists for a longer time, the thermal shut-down comes into action and keeps the junction temperatu- re within safe limits. Fig. 12 ~Maximum output current vs. Fig. 13 -Test circuit for the limiting voltage (Vc_) across each out- characteristics put transistor G-14467 IgMAX (a) 3 = 100pF oY 1 son 1000p 1900 sigan at: Vg 218 Ho 1 : om |e. iuan 0 5 10 18 Voge (V) 466THERMAL SHUT-DOWN The presence of a thermal limiting circuit offers the following advantages: 1) an overload on the output (even if it is permanent), or an above-limit ambient tempe- rature can be easily supported 2) the heatsink can have a smaller factor of safety compared with that of a conventional circuit. There is no device damage in the case of too high a junction temperature: all that happens is that P, (and therefore P,,.;) and ly are reduced (fig. 14) Fig. 14 ~Output power and drain cur- rent vs. package temperature Vg 218V RL =80 0 20 40 60 80 100 Tease (*C) 467TCA 940E MOUNTING INSTRUCTION The power dissipated in the circuit may be removed by connecting the tabs to an external heatsink, or by soldering them to an area of copper on the printed circuit board (Fig. 15). Fig. 16 shows a simple type of heatsink; assuming an area of copper on the printed circuit board of only 2 cm?, the total Ry, between junction and ambient is approximately 28 C/W. The external heatsink or area of printed circuit copper must be connected to electrical ground. Fig. 17 gives the maximum dissipable power (for Tamp = 55 and 70 C) as a function of the side of two equal square copper areas having a thickness of 35 pu (1.4 mil). During soldering the tabs temperature must not exceed 260C and .the soldering time must not be longer than 12 seconds. Fig. 15 -Example of area of P.C. board Fig. 16 -Example of TCA940E with copper soldered to the tabs of external heatsink the TCA940E which is used as a heatsink COPPER AREA 35y THICKNESS MEATSING Rtn: BY W 4 4 2C_ BOARD P.C.BOARO $0983 468Fig. 17 -Power that can be dissipated vs. "2" Prot Rth (Ww) 8 80 6 60 Rth j-amb 4 40 2 20 0 0 10 20 30 40 (mm) tot (w) Fig. 18-Maximum allowable power dissipation vs. ambient tem- perature G-1288 HEATSINK % % THOUT HEATSINK -50 0 50 100 Tamb(C) Fig. 19 -P.C. board and component layout of the test and application circuit (1:1 Scale) +Vy aT et CS-0038