Class A Amplifier with 3 Gain Blocks & Schottky Diodes LS509 DATA SHEET DESCRIPTION FEATURES • 140 µA typical current drain • The LS509 is a Class A amplifier utilizing Gennum’s proprietary low voltage JFET technology. It consists of two singleended, low noise inverting gain blocks, a Class A output stage, an on-chip microphone decoupling resistor and a pair of Schottky diodes for symmetrical peak clipping. low noise and distortion • 1.0 to 5 VDC operating range • independent preamplifier • 2 DC coupled stages • class A output stage • variable transducer current • Schottky diodes for MPO control • 4 kΩ microphone decoupling resistor Blocks A and B typically have an open loop voltage gain of 56 dB, with the closed loop gain set by the ratio of the feedback resistor to the source impedance. It is recommended that the maximum closed loop gain be 20 dB lower than the open loop gain. All blocks of the device are internally bias compensated, preventing any DC current flow via external feedback resistors. Without this compensation, audible scratchiness would be present during changes in volume control settings. STANDARD PACKAGING The output stage of the LS509 is a Class A current drive. It has a fixed reference voltage of typically 29 mV at pin 2 of the device. The current that flows in the transducer is the ratio of the 29 mV reference voltage and the on-chip emitter resistor (R ). To increase the bias current in the E transducer, simply place an external RE resistor from pin 2 to ground, thereby decreasing the equivalent emitter resistance and increasing the current. • 10 pin PLID® • 10 pin SLT • Chip (61 x 55 mils) The LS509 also contains a pair of Schottky diodes in the feedback configuration of the output stage, which provides approximately 12 dB of MPO control. VB 8 VMIC 7 RMIC 9 MPO 21k A I/P 6 -A -B -C 10 2 C O/P RE RE 5 A O/P 4 B I/P 3 B O/P 1 GND All resistors in ohms, all capacitors in farads unless otherwise stated BLOCK DIAGRAM Revision Date: January 2001 Document No. 510 - 12 - 08 GENNUM CORPORATION P.O. Box 489, Stn. A, Burlington, Ontario, Canada L7R 3Y3 tel. +1 (905) 632-2996 Web Site: www.gennum.com E-mail: [email protected] ABSOLUTE MAXIMUM RATINGS PIN CONNECTION PARAMETER VALUE/UNITS Supply Voltage A OUT 5 V DC Power Dissipation 25 mW Operating Temperature Range A IN 6 VMIC B OUT -10°C to 40° C Storage Temperature Range 5 B IN VB RE -20°C to 70° C GND MPO C OUT 10 1 CAUTION CLASS 1 ESD SENSITIVITY ELECTRICAL CHARACTERISTICS VP - Pin voltage measured with conditions as shown in Test Circuit. Positive current corresponds to current INTO the pin. Negative current corresponds with current OUT of the pin. Conditions: Frequency = 1 kHz, Temperature = 25°C, Supply Voltage VB = 1.3 V PARAMETER SYMBOL Amplifier Current IAMP Transducer Current ITRANS Maximum Transducer Current ITRANS (MAX) CONDITIONS V P2 = 0 V MIN TYP MAX UNITS 75 140 205 µA 170 230 290 µA 2 - - mA A Input Bias Voltage (pin 6) VBIAS A 500 570 650 mV A Input Bias Current (pin 6) IBIAS A RFA = 1 M (Note 1) -50 0 50 nA B Input Bias Current (pin 4) IBIAS B RFB = 1 M (Note 2) -50 0 50 nA A O/P Voltage Swing-Hi (pin 5) VOH A 200 580 - mV A Output Swing-Lo (pin 5) V OL A 200 280 - mV A Open Loop Voltage Gain AOL C Output Sat. Voltage (pin 10) VSAT C A Output Current Capability (pin 5) AOUT Diode Voltage Drop VD Emitter Bias Voltage (pin 2) VRE On-chip Microphone Resistor RMIC On-chip Emitter Resistor RE Input Referred Noise IRN Harmonic Distortion THD V IN = 0.4 V DC, RFA = ∞ , IP5 = -10 µA (Note 3) IIN = +1µA, RFA = ∞ , IP5 = +10 µA (Note 4) 46 56 - dB - 100 180 mV - 30 - µA 140 265 325 mV 21.5 28.5 35.5 mV 3 4 5 kΩ 90 125 160 Ω NFB 0.2 to10kHz at 12dB/Oct - 1 - µVRMS V OUT = 500 mVRMS - 1 - % RL = 1 kΩ, VP2 = 0 V (S2 = b) R L = ∞, (Note 5) All parameters and switches remain as shown in Test Circuit unless otherwise stated in "Conditions" column Notes 1. IBIAS A = (V P6 -VP6[RFA = 1M])/1M 2. IBIAS B = (VP4 -VP4 [RFB = 1M])/1M 3. VOH A = (V P5-VP5 [VIN = 0.4 VDC, RFA = ∞, IP5 = -10µA]) 4. VOL A = (VP5 -VP5 [IIN = +1µA, RFA = ∞, IP5 =+10µA]) V ) 5. VD = (V P10 [Id = +(1.5 x ITRANS)] - P10 [Id = +(0.5 x ITRANS)] 510 - 12 - 08 2 1.3 VDC I AMP I TRANS 8 7 RMIC 9 a VIN S2 b RL =0 21k a RS CS 3k92 1µ0 b S1 6 -A -B -C 10 2 Id = 0µA RE 5 180 µV RMS 1kHz 1 3 4 RFB = 0 RFA = 0 IP5 = 0µA All resistors in ohms, all capacitors in farads unless otherwise stated. Fig. 1 Test Circuit RMIC 8 7 9 5 10 BASE CURRENT COMPENSATION 2 6 3 4 RE 1 All resistors in ohms, all capacitors in farads unless otherwise stated. Fig. 2 Functional Schematic 3 510 - 12 - 08 VB = 1.3 V DC ED1913 8 7 RLAC 50k 9 RMIC 1µ0 0µ1 21k R MPO RS ≈ 3k9 CS -A 6 0µ22 - B 10 -C 2 0µ1 RE 5 3 4 100k 56 1 100k RGT RVC 0µ1 5k6 All resistors in ohms, all capacitors in farads unless otherwise stated. RGT Gain of Stage A = 20 log Gain of Stage B = 20 log RS RVC 5.6 k RLAC//21K Gain of Stage C = 20 log 56//RE Fig 3 Typical Hearing Instrument Application 0 5 -2 -5 RVC = 100K RMPO = 50k -4 -15 RMPO = 22k OUTPUT (dBV) OUTPUT (dBV) -6 RVC = 47K -25 RVC = 10K -35 RVC = 3.3K -45 -55 -8 RMPO = 10k -10 -12 RMPO = 0k -14 RMPO = 3.3k -16 RVC = 22K -65 -18 -20 -75 -140 -120 -100 -80 -60 -90 -40 -80 -70 -60 -50 -40 INPUT (dBV) INPUT (dBV) Fig. 5 I/O Curves at Various RMPO Values Fig. 4 I/O Curves at Various RVC Settings 4 5 CS = 0.22µ 0 0 -5 CS = 0.033µ -4 -8 RELATIVE GAIN (dB) RELATIVE GAIN (dB) CS = 0.1µ CS = 0.047µ -12 -16 -15 -20 -25 -30 -20 20 200 2k 0.7 20k FREQUENCY (Hz) 0.8 0.9 1 1.1 1.2 SUPPLY VOLTAGE (V) Fig. 6 Closed Loop Frequency Response with Various CS Values 510 - 12 - 08 -10 Fig. 7 Gain vs Supply Voltage 4 1.3 1.4 RELATIVE TRANSDUCER CURRENT (µA) 0.5 RELATIVE GAIN (dB) 0.4 0.3 0.2 0.1 0 -0.1 -0.2 -0.3 -20 -10 0 10 20 30 40 50 10 6 2 -2 -6 -10 -14 -18 -20 -10 0 TEMPERATURE (oC) 24 60 16 55 8 50 0 45 -8 35 -24 30 -32 25 20 0 10 20 30 40 50 40 -16 -10 20 Fig. 9 Transducer Current vs Temperature Gain (dB) RELATIVE AMPLIFIER CURRENT (µA) Fig. 8 Gain vs Temperature -40 -20 10 TEMPERATURE (oC) 30 40 50 10 100 1k 10k 100k FREQUENCY (Hz) TEMPERATURE (oC) Fig. 11 Preamplifier A Open Loop Frequency Response Fig. 10 Amplifier Current vs Temperature GENNUM CORPORATION DOCUMENT IDENTIFICATION: DATA SHEET The product is in production. Gennum reserves the right to make changes at any time to improve reliability, function or design, in order to provide the best product possible. MAILING ADDRESS: P.O. Box 489, Stn. A, Burlington, Ontario, Canada L7R 3Y3 Tel. +1 (905) 632-2996 Fax +1 (905) 632-2814 SHIPPING ADDRESS: 970 Fraser Drive, Burlington, Ontario, Canada L7L 5P5 REVISION NOTES: GENNUM JAPAN CORPORATION Changes to standard packaging information. C-101, Miyamae Village, 2-10-42 Miyamae, Suginami-ku, Tokyo 168-0081, Japan Tel. +81 (3) 3334-7700 Fax: +81 (3) 3247-8839 Gennum Corporation assumes no responsibility for the use of any circuits described herein and makes no representations that they are free from patent infringement. © Copyright October 1987 Gennum Corporation. All rights reserved. 5 Printed in Canada. 510 - 12 - 08