Audio. Description. Output Stage. 5k (10k) + - Out. Ref

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1 Low-Noise, High Performance udio Preamplifier I THT 1510, 1512 TURS Low Noise: 1 nv/ Hz input noise (60d gain) 34 nv/ Hz input noise (0d gain) (1512) Low TH+N (full audio bandwidth): 0.001% 40 d gain 60 d gain Low urrent: 6m typ. Wide andwidth: =100 High Slew Rate: 19 V/μs Wide put Swing: ±13.3V on ±15V supplies ain adjustable from 0 to >60 d with one external resistor Industry Standard Pinouts PPLITIONS ifferential Low Noise Preamplifiers ifferential Summing mplifiers ifferential Variable ain mplifiers Microphone Preamplifiers Moving-oil Transducer mplifiers Line Input Stages udio Sonar Instrumentation The THT 1510 and 1512 are high performance audio preamplifiers suitable for microphone preamp and bus summing applications. The Is are available in a variety of packages and pin configurations, making them pin compatible with the nalog evices SSM2019 and SSM2017 (discontinued), and the Texas Instruments IN217 and IN163. ain for both parts is adjustable via one external resistor, making it possible to control gain over a wide range with a single-gang potentiometer. The 1510 gain equation is identical to that of the SSM 2019, reaching 6 d gain with a 10 kω resistor. The 1512 reaches 0 d gain with a 10 kω resistor. ecause the 1512 exhibits escription significantly lower noise at lower gain settings, it is recommended over the 1510 for new designs. esigned from the ground up in THT s complementary dielectric isolation process and including laser-trimmed Si-hrome thin film resistors, the THT 1510 and 1512 improve on existing integrated microphone preamps by offering lower noise at low gains, wider bandwidth, higher slew rate, lower distortion, and lower supply current. The parts feature internal S overload protection on all critical pins. In short, the THT 1510 and 1512 provide superior performance in a popular format at an affordable price. R 1 V- Input Stage -V -V R R put Stage (10k) (10k) + - Pin Name R1 V- Part Type IP8 IP SO SO Table 1. Pin ssignments SO P08-U 1512S08-U SO16 Inquire SO SO P08-U 1510S08-U 1510W16-U 1510S14-U 1512S14-U igure 1. THT 1510 / 1512 quivalent ircuit iagram (THT 1512 values shown in parentheses) Table 2. Ordering Information. ocument Rev 08

2 ocument Rev 08 Page 2 of 8 THT 1510/1512 Low-Noise High Performance udio Preamplifier I SPIITIONS 1 bsolute Maximum Ratings 2,3 Positive Supply Voltage (V ) +20 V Negative Supply Voltage (V ) -20 V Input Voltage (V IN MX) V + 0.5V, V - 0.5V put Short-ircuit uration (t SH) ontinuous Lead Temp. (T L) (Soldering 10 sec) 260 Operating Temperature Range (T OP) -40 to +85 Storage Temperature Range (T ST) -40 to +125 Junction Temperature (T J) 150 Recommended Operating onditions Parameter Symbol onditions Min Typ Max Units Positive Supply Voltage V V Negative Supply Voltage V V lectrical haracteristics Parameter Symbol onditions Min Typ Max Min Typ Max Units Supply urrent I, -I No signal m V = -V = 20V m Input ias urrent I No signal; ither input µ connected to N Input Offset urrent I -O No signal µ Offset Voltage put Stage put Offset Vos OO No Signal, V M= mv Input Stage Input Offset Vos II µv Total put Offset =voltage gain mv Input Voltage Range ommon Mode V IN-M ommon mode, all gains ± 13 ± 13 V ifferential Mode V IN-UNL Unbalanced V One input to N, 0d gain ifferential ain diff d Input Voltage Range ± 8 ± 8 V Input Impedance kω Input ain to put 0 0 d Input Impedance Z IN-I ifferential 0d gain MΩ p 20d gain MΩ p 40d gain MΩ p 60d gain MΩ p Z IN-M ommon mode all gains MΩ p 1. ll specifications are subject to change without notice. 2. Unless otherwise noted, T=25º, V=+15V, V= -15V. 3. Stresses above those listed under bsolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only; the functional operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not impli ed. xposure to absolute maximum rating conditions for extended periods may affect device reliability.

3 THT 1510/1512 Low-Noise Page 3 of 8 ocument Rev 08 High Performance udio Preamplifier lectrical haracteristics (con t) Parameter Symbol onditions Min Typ Max Min Typ Max Units ommon Mode Rejection MR V M =± 10V; to 60 Hz 0 d gain d 20 d gain d 40 d gain d 60 d gain d Power Supply Rejection PSR V = -V ; ±5V to ±20V; to 60 Hz 0 d gain d 20 d gain d 40 d gain d 60 d gain d Total Harmonic istortion TH+N V OUT = 7Vrms; R L = 5 kω f = 1kHz; W = 20 khz 0 d gain % 20 d gain % 40 d gain % 60 d gain % quivalent Input Noise e n(in) f = 1kHz, 0 d gain nv/ Hz 20 d gain nv/ Hz 40 d gain nv/ Hz 60 d gain 1 1 nv/ Hz Input urrent Noise i n(in) 60 d gain p/ Hz Noise igure N 60 d gain R S = 150 Ω d R S = 200 Ω d Slew Rate SR R L = 2 kω L = 50 p V/µs andwidth -3d W -3d R L = 2 kω; L = 10 p 0 d gain MHz 20 d gain 8 9 MHz 40 d gain 7 7 MHz 60 d gain MHz put ain rror R (OUT) f = 1kHz; R L = 2 kω R =infinite, =0 d d R = 1.1 kω, =20 d d R = 101 Ω, =40 d d R = 10 Ω, =60 d d R = 10 kω, =0 d d R = Ω, =20 d d R = 50.3 Ω, =40 d d R = 5 Ω, =60 d d put Voltage Swing V O R L = 2 kω all gains ±13 ±13.3 ±13 ±13.3 V put Short ircuit urrent I S R L = 0 Ω ± 17 ± 17 m Minimum Resistive Load R Lmin 2 2 kω Maximum apacitive Load Lmax p ain quation V = k R V = k R

4 ocument Rev 08 Page 4 of 8 THT 1510/1512 Low-Noise High Performance udio Preamplifier I ain Setting single external resistor (R ) between the R 1 and R 2 pins is all that is needed to set the gain of the THT 1510/1512, according to the formulae: for the 1510: for the 1512: V = k R V = R V is the voltage gain of the part. or where ither part may reach unity gain, but the value of R required varies significantly between the two parts. or the 1510, gain is 0d when R is infinite (open); this is the minimum gain for the t infinite R, the 1512 reaches -6d gain; this is the minimum gain for the With R =10kΩ, the 1512 reaches 0d gain. Overall gain accuracy depends on the tolerance of R and the accuracy of the internal thin-film resistors connected to pins R 1 and R 2 in the 1510/1512 (R & R in igure 1). These internal resistors have a typical initial accuracy (at room temperature) of ±0.5%, and are typically stable with temperature to within ±100 ppm/. ain will drift with temperature based on the mismatch between the temperature coefficient of the external R and that of the internal resistors R & R. or variable-gain applications where gain accuracy is important, THT recommends using discrete, switched resistors for R. Where continuous control is required, or where gain accuracy is less pplications critical, a potentiometer may be used. In such applications, designers should take care in specifying the element construction to avoid excess noise. The potentiometer taper will set the circuit s characteristic of gain vs. pot rotation. Typically, reverse log (reverse audio) taper elements offer the desired behavior in which gain increases with clockwise rotation (and lower values for R ). See THT esign Note 138 for a discussion of potentiometer taper and gain for the 1510 and 1512 compared to similar parts from other manufacturers. Noise Performance oth parts exhibit excellent voltage noise performance of ~1 nv/ Hz at high gains. With ~2 p/ Hz current noise, they are optimized for relatively low source impedance applications, such as dynamic microphones with typically a few hundred ohm output impedances. ut, because they have different internal gain structures, the 1510 has higher equivalent input noise at 0d gain (~57 nv/ Hz) than the 1512, which runs 4.5 d lower at ~34 nv/ Hz. The unusual and superior topology of the THT 1512 makes its noise performance comparable to some of the better discrete designs currently available. Inputs Simple onfigurations s shown in igure 2, the 1510/1512 includes protection diodes at all pins except and V-. Input Stage put Stage - V - V R (10k) (10k) - + R 1 R 2 R V- igure 2. THT 1510 / 1512 quivalent ircuit with Protection iodes

5 THT 1510/1512 Low-Noise Page 5 of 8 ocument Rev 08 High Performance udio Preamplifier R1 1k R R1 6 V- U1 THT 1510/ p R2 1k 9-15 igure 3. asic 1510 / 1512 ircuit These diodes reduce the likelihood that accidental electrostatic discharge (S) or electrical over stress (OS) will damage the Is. Other diodes across the base-emitter junctions of the input transistors prevent excessive reverse biasing of these junctions (which would degrade the noise performance of the input devices). Other than the protection diodes, the 1510/1512 input pins are connected only to the bases of their respective input devices. or proper operation, the bases must be provided a source of dc bias that will maintain the inputs within the I's input commonmode range. igure 3 shows the simplest approach; dc bias is supplied via R 1 and R 2. t 1 kω each, they will minimize pickup of unwanted noise and interference, as well as generate relatively little noise due to input current noise in the 1510/1512. However, at high gains, their inherent voltage noise, plus the 1510/1512's input current noise drawn across these resistors, adds significantly to the noise at the 1510/1512's output. ecause R is dc coupled in the circuit of igure 3, the dc level at the output of the 1510/1512 will vary with gain. In most applications, the output should be ac-coupled to the next stage. or applications where R is variable (via a pot or switched resistors) to allow gain adjustment, R should be ac-coupled as shown in igure 4. y adding in series with R, dc gain is fixed (at unity for the 1510, and ½ for the 1512). This constrains the output dc offset to just over +/-5 mv, and prevents it from varying with gain. With this low offset, ac coupling of the output is usually unnecessary. must be large enough not to interfere with low-frequency response at the smallest values of R. or 60 d gain, R =10 Ω (1510) or R =5 Ω (1512). or a -3 d point of approximately 5 Hz, =3,300 μ (1510), or =6,800 μ (1512). or other maximum gains or minimum frequencies, scale accordingly. Phantom Power Phantom power is required for many condenser microphones. THT recommends the circuit of igure 5 when phantom power is included 4. R 3, R 4, and 1-6 are used to limit the current that flows through the 1510/1512 inputs when the circuit inputs ( and ) are shorted to ground while phantom power is turned on. This causes 4 and/or 5 to discharge through other circuit components, often generating transient currents of several amps. R 3 and R 4 should be at least 10 Ω to limit destructive 4. In revisions 0 and 1 of this data sheet, we recommended using Schottky diodes (1N5819 types) at 1 ~ 4 to protect the 1510/1512 inputs against overloads. Subsequently, we discovered that the leakage of these diodes could cause problems with fluctuations (hence noise) at the 1510/1512 output. Upon further investigation, we concluded that conventional rectifier diodes like the 1N4004 (the glass-passivated P version) provide adequate protection and d o not introduce unacceptable leakage. dditionally, 1N4004 diodes are much cheaper and more readily available than the Schottky types. Since publishing revision 4, we determined that the internal reverse-bias diodes between the pins / and /R1 may be damaged by phantom power faults under certain conditions. Small-signal diodes (5 and 6) avoid this problem by appearing in parallel with the internal diodes, diverting excess current around the 1510/1512.

6 ocument Rev 08 Page 6 of 8 THT 1510/1512 Low-Noise High Performance udio Preamplifier I currents. (Higher values further limit current flow, but introduce additional source impedance and noise.) 1 through 4 prevent the I s inputs from significantly exceeding the supply rails. 5 and 6 steer currents around the input stage in the 1510/1512, preventing damage. The series combination of 4 and 5 should be made large to minimize high-pass filtering of the signal based upon the sum of the values of R 1+R 2. s well, keeping their reactance low relative to the external microphone's source impedance will avoid increasing the effects of low-frequency current noise in the 1510/1512 input stage. Other manufacturers have recommended, and many pro audio products include, a zener diode arrangement connected to the bridge rectifier instead of the connection to and V- as shown in igure 5. THT does not recommend this approach, because we find that R 3 and R 4 must be made much larger (e.g., 51 Ω) in order to limit peak currents enough to protect reasonably sized zener diodes (eg. 1/2 W). Such large series input resistors will limit the noise performance of the preamp. The ultimate floor is set by the impedance of the microphone, but any additional series resistance further degrades performance. or further insights into this subject, see the udio ngineering Society preprints "The 48 Volt Phantom Menace," by ary K. Hebert and rank W. Thomas, presented at the 110th S onvention and The 48 Volt Phantom Menace Returns, by Rosalfonso ortoni and Wayne Kirkwood presented at the 127th S onvention. Impedance and Line Input onfigurations higher common-mode input impedance is desirable (compared with that of igures 3 and 4) when input coupling capacitors ( 4 and 5) are used to block phantom power. t low frequencies where the reactance of 4 and 5 become significant (compared to the common-mode input impedances), the two capacitors interact with the common-mode input impedance (seen looking to the right-side of both capacitors) to form voltage dividers for common-mode signals. ifferences in the two capacitors' values leads to different voltage dividers, spoiling the low-frequency common-mode rejection of the stage. Since 4 and 5 are generally large, electrolytic types, precise matching is difficult and expensive to achieve. High common-mode input impedance reduces the matching requirement by decreasing the frequency at which the capacitive reactance becomes significant inversely with the common-mode input impedance. The "T-bias" circuit (R 1, R 2, and R 7) shown in igure 5 accommodates this objective. In this circuit, R 1 and R 2 are connected to a third resistor R 7, boosting the low-frequency common mode input R1 1k R R1 6 V- U1 THT 1510/ p R2 1k 9-15 igure 4. asic 1510 / 1512 ircuit with Variable ain

7 THT 1510/1512 Low-Noise Page 7 of 8 ocument Rev 08 High Performance udio Preamplifier impedance (as "seen looking in" from the coupling capacitors) to the value of R 1 + (2*R 7) -- approximately 45 kω with the values shown. The increased common mode impedance from T-bias improves L common mode rejection by reducing capacitor matching requirements by more than a factor of ten over the simpler circuit wherein R 7=0 Ω. The circuit works well with the values shown. Note also that the overall common-mode input impedance of the circuit is dominated by the phantom-power resistors (R 5 and R 6). or the circuit of igure 5, this is approximately 5.9 kω per leg. The 1510/1512 can be used as a line input receiver by adding attenuation to the preamplifier inputs and changing the circuit topology to allow switching of input, fixed attenuation, and gain adjustment. The optimum circuit depends on the specific requirements of the application. or more details and specific applications advice, please consult THT's application notes, or our applications engineers at the address and telephone below or via at [email protected]. erence Terminal The "" pin provides a reference for the output signal, and is normally connected to analog ground. If necessary, the "" pin can be used for offset correction or level shifting. However, in order to prevent spoiling the excellent common-mode rejection of the 1510/1512, the source impedance driving the pin should be under 1Ω. R6 6k p 4 22u R5 6k8 5 22u ON +48V R N4004P 4 1N4004P R N4004P 2 1N4004P R7 22k R1 1k2 R2 1k2 5 1N N4148 R R1 V- U1 THT 1510/ igure 5. Recommended 1510 / 1512 ircuit with Phantom Power Package Information oth the THT 1510 and 1512 are available in 8-pin SOI, 8-pin IP, and 14-pin SOI packages. The 1510 is also available in a 16-pin (widebody) SOI package. Other version/package combinations will be considered based on customer demand. The package dimensions are shown in igures 6, 7, 8, & 9, while pinouts are given in Table 1. ll versions of the 1510 and 1512 are lead free and RoHS compliant. Material eclaration ata Sheets on the parts are available at our web site, or upon request.

8 ocument Rev 08 Page 8 of 8 THT 1510/1512 Low-Noise High Performance udio Preamplifier I J 1 K H ITM H J K MILLIMTRS 9.52± ± / / ± / ±0.10 INHS 0.375± ± / / ± / ±0.004 igure 6. 8-pin IP package outline igure pin SO Wide package outline H 1 H ITM MILLIMTRS 4.80/4.98 INHS 0.189/ / / / / / / / / / / H 0.41/ /0.05 ITM MILLIMTRS INHS 8.56/ / / / / / / / / / / / H 0.41/ /0.05 igure 8. 8-pin SOI package outline igure pin SOI package outline Revision History Revision O ate hanges Page /16/09 dded Max. Input Voltage specification /02/13 orrected typographical error in specification table. 3