LM386N-1

LM386-1 Low Voltage Audio Power Amplifier General Description The LM386-1 is a power amplifier designed for use in low voltage consumer applications. The gain is internally set to 20 to keep external part count low, but the addition of an external resistor and capacitor between pins 1 and 8 will increase the gain to any value from 20 to 200. Low Voltage Audio Power Amplifier Features n n n n n n n n Battery operation Minimum external parts Wide supply voltage range: 4V–12V Low quiescent current drain: 4mA Voltage gains from 20 to 200 Ground referenced input Self-centering output quiescent voltage Low distortion: 0.2% (AV = 20, VS = 6V, RL = 8Ω, PO = 125mW, f = 1kHz) n Available in 8 pin SOP package and DIP package The inputs are ground referenced while the output automatically biases to one-half the supply voltage. The quiescent power drain is only 24 milliwatts when operating from a 6 volt supply, making the WS386M-1 ideal for battery operation Applications n n n n n n n n AM-FM radio amplifiers Portable tape player amplifiers Intercoms TV sound systems Line drivers Ultrasonic drivers Small servo drivers Power converters Ordering Information PART NO. PACKAGE SOP-8 DIP-8 LM386M-1 LM386N-1 Equivalent Schematic and Connection Diagrams Small Outline, Dual in Line Package Pin Connection Wing Shing Computer Components Co., (H.K.)Ltd. Homepage: http://www.wingshing.com Tel:(852)2341 9276 Fax:(852)2797 8153 E-mail: wsccltd@hkstar.com 8-1 LM386-1 Absolute Maximum Ratings Supply Voltage (WS386-1) Package Dissipation(Note3) (WS386N) 1.25W Soldering Information 15V Dual-In-Line Package Soldering (10 sec) Small Outline Package (SOIC ) Vapor Phase (60 sec) Infrared (15 sec) +260˚C +215˚C +220˚C (WS386M) Input Voltage Storage Temperature 0.73W +.4V - 65 C to +150 C Operating Temperature Junction Temperature 0 C to+70 C +150 C Electrical Characteristics (Notes 1, 2) TA = 25˚C ,Vcc=6V,R =8 ,f=1KHZ, unless otherwise specified Parameter Operating Supply Voltage (VS) 4 12 Conditions Min Typ Max Units V Quiescent Current (IQ) Output Power (POUT) VS = 6V, VIN = 0 V S = 6V, RL = 8Ω, THD = 10% 4 250 325 8 mA mW V s = 9V,RL =8 , THD =10% Bandwidth (BW) Voltage Gain (AV) Bandwidth (BW) Total Harmonic Distortion (THD) Power Supply Rejection Ratio (PSRR) Input Resistance (RIN) Input Bias Current (IBIAS) Vs = 6V,10uF from Pin 1 to 8 VS = 6V, f = 1 kHz 10 µF from Pin 1 to 8 VS = 6V, Pins 1 and 8 Open VS = 6V, RL = 8Ω, POUT = 125 mW f = 1 kHz, Pins 1 and 8 Open VS = 6V, f = 1 kHz, CBYPASS = 10 µF Pins 1 and 8 Open, Referred to Output 50 0 700 60 26 46 300 0.2 50 50 kHz dB dB kHz % dB kΩ nA Pins 1 and 8 Open VS = 6V, Pins 2 and 3 Open 250 Note 1: All voltages are measured with respect to the ground pin, unless otherwise specified. Note 2: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is functional, but do not guarantee specific performance limits. Electrical Characteristics state DC and AC electrical specifications under particular test conditions which guarantee specific performance limits. This assumes that the device is within the Operating Ratings. Specifications are not guaranteed for parameters where no limit is given, however, the typical value is a good indication of device performance. Note 3: For operation in ambient temperatures above 25˚C, the device must be derated based on a 150˚C maximum junction temperature and a thermal resistance of 170˚C/W for the small outline package. 8-2 LM386-1 Application Hints GAIN CONTROL INPUT BIASING The schematic shows that both inputs are biased to ground with a 50 kΩ resistor. The base current of the input transistors is about 250 nA, so the inputs are at about 12.5 mV when left open. If the dc source resistance driving the LM386 is higher than 250 kΩ it will contribute very little additional offset (about 2.5 mV at the input, 50 mV at the output). If the dc source resistance is less than 10 kΩ, then shorting the unused input to ground will keep the offset low (about 2.5 mV at the input, 50 mV at the output). For dc source resistances between these values we can eliminate excess offset by putting a resistor from the unused input to ground, equal in value to the dc source resistance. Of course all offset problems are eliminated if the input is capacitively coupled. When using LM386-1 with higher gains (bypassing the 1.35 kΩ resistor between pins 1 and 8) it is necessary to bypass the unused input, preventing degradation of gain and possible instabilities. This is done with a 0.1 µF capacitor or a short to ground depending on the dc source resistance on the driven input. To make LM386-1 a more versatile amplifier, two pins (1 and 8) are provided for gain control. With pins 1 and 8 open the 1.35 kΩ resistor sets the gain at 20 (26 dB). If a capacitor is put from pin 1 to 8, bypassing the 1.35 kΩ resistor, the gain will go up to 200 (46 dB). If a resistor is placed in series with the capacitor, the gain can be set to any value from 20 to 200. Gain control can also be done by capacitively coupling a resistor (or FET) from pin 1 to ground. Additional external components can be placed in parallel with the internal feedback resistors to tailor the gain and frequency response for individual applications. For example, we can compensate poor speaker bass response by frequency shaping the feedback path. This is done with a series RC from pin 1 to 5 (paralleling the internal 15 kΩ resistor). For 6 dB effective bass boost: R . 15 kΩ, the lowest value for good stable operation is R = 10 kΩ if pin 8 is open. If pins 1 and 8 are bypassed then R as low as 2 kΩ can be used. This restriction is because the amplifier is only compensated for closed-loop gains greater than 9. Pad Location 8 1 90 90 7 6 5 2 4B Y 0 3 X 4A Chip size 1.4 x 1.6 mm Pad Location Coordinates Pad N 1 2 3 4A 4B 5 6 7 8 Pad Name Gain -input +input GND GND VOUT VCC BYPASS Gain Coordinates X 120 120 120 550 600 600 750 440 120 Y 975 665 100 100 390 1015 1405 1405 1405 8-3 LM386-1 Typical Performance Characteristics Quiescent Supply Current vs Supply Voltage Power Supply Rejection Ratio (Referred to the Output) vs Frequency Peak-to-Peak Output Voltage Swing vs Supply Voltage Voltage Gain vs Frequency Distortion vs Frequency Distortion vs Output Power Device Dissipation vs Output Power — 4Ω Load Device Dissipation vs Output Power — 8Ω Load Device Dissipation vs Output Power — 16Ω Load 8-4 LM386-1 Typical Applications Amplifier with Gain = 20 Minimum Parts Amplifier with Gain = 200 Amplifier with Gain = 50 Low Distortion Power Wienbridge Oscillator Amplifier with Bass Boost Square Wave Oscillator 8-5 LM386-1 Typical Applications (Continued) Frequency Response with Bass Boost AM Radio Power Amplifier Note 4: Twist Supply lead and supply ground very tightly. Note 5: Twist speaker lead and ground very tightly. Note 6: Ferrite bead in Ferroxcube K5-001-001/3B with 3 turns of wire. Note 7: R1C1 band limits input signals. Note 8: All components must be spaced very closely to IC. 8-6 Physical Dimensions inches (millimeters) unless otherwise noted (Continued) Dual-In-Line Package LM386N-1 8-7 LM386-1 Physical Dimensions inches (millimeters) unless otherwise noted SO Package LM386M-1 8-8