Low Cost, 40V, 3A Dual Power Amplifier
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Power Dual Operational Amplifiers FEATURES • LOW COST • WIDE COMMON MODE RANGE — Includes negative supply • WIDE SUPPLY VOLTAGE RANGE Single supply: 5V to 40V Split supplies: ±2.5V to ±20V • HIGH EFFICIENCY — |Vs–2.2V| at 2.5A typ • HIGH OUTPUT CURRENT — 3A • LOW DISTORTION • HALF & FULL BRIDGE MOTOR DRIVERS • AUDIO POWER AMPLIFIER STEREO — 30W RMS per channel BRIDGE — 60W RMS per package • IDEAL FOR SINGLE SUPPLY SYSTEMS 5V — Peripherals, 12V — Automotive 28V — Avionic FIGURE 1: BIDIRECTIONAL SPEED CONTROL FROM A SINGLE SUPPLY. TYPICAL APPLICATION The amplifier design consists of dual monolithic input and output stages to achieve the desired input and output characteristics of the PA74 and PA76. The input stage utilizes a dual power op amp on a single chip monolithic that drives the output stages. The output stages are configured in a non inverting unity gain buffer configuration. The output stages of the amplifier are also compensated for stability. The PA74 and PA76 dual amplifiers are designed with both monolithic and hybrid technologies providing a cost effective solution for applications requiring multiple amplifiers per board or bridge mode configurations. Both amplifiers are internally compensated but are not recommended for use as unity gain followers. This dual hybrid circuit utilizes a beryllia (BeO) substrate, thick film resistors, ceramic capacitors and monolithic amplifiers to maximize reliability and power handling capability, minimize size and give top performance. Ultrasonically bonded aluminum wires provide reliable interconnections at all operating temperatures. The 8-Pin TO-3 package is hermetically sealed and electrically isolated. The use of compressible isolation washers voids the warranty. R1 and R2 set up amplifier A in a non-inverting gain of 2.8. Amp B is set up as a unity gain inverter driven from the output of amp A. Note that amp B inverts signals about the reference node, which is set at mid-supply (14V) by R5 and R6. When the command input is 5V, the output of amp A is 14V. Since this is equal to the reference node voltage, the output of amp B is also 14V, resulting in 0V across the motor. Inputs more positive than 5V result in motor current flow from left to right (see Figure 1). Inputs less positive than 5V drive the motor in the opposite direction. The amplifiers are especially well-suited for this application. The extended common mode range allows command inputs as low as 0V. Its superior output swing abilities let it drive within 2V of supply at an output current of 2A. This means that a command input that ranges from 0.714V to 9.286V will drive a 24V motor from full scale CCW to full scale CW at up to ±2A. A single power op amp with an output swing capability of Vs –6 would require ±30V supplies and would be required to swing 48V p-p at twice the speed to deliver an equivalent drive. EQUIVALENT SCHEMATIC ONE CHANNEL OUT,B CURRENT GAIN THERMAL PROTECT CURRENT GAIN Copyright © Apex Microtechnology, Inc. 2012 (All Rights Reserved)

PA74/76 • PA74A/76A ABSOLUTE MAXIMUM RATINGS SUPPLY VOLTAGE, total OUTPUT CURRENT POWER DISSIPATION, internal (per amplifier) POWER DISSIPATION, internal (both amplifiers) INPUT VOLTAGE, differential INPUT VOLTAGE, common mode JUNCTION TEMPERATURE, max1 TEMPERATURE, pin solder–10 sec max TEMPERATURE RANGE, storage OPERATING TEMPERATURE RANGE, case PARAMETER INPUT OFFSET VOLTAGE, initial OFFSET VOLTAGE, vs. temperature BIAS CURRENT, initial COMMON MODE RANGE COMMON MODE REJECTION, DC POWER SUPPLY REJECTION CHANNEL SEPARATION INPUT NOISE VOLTAGE GAIN OPEN LOOP GAIN GAIN BANDWIDTH PRODUCT...

PULSE RESPONSE PULSE RESPONSE VOLTAGE GAIN vs. FREQUENCY VOLTAGE DROP FROM SUPPLY, VDROP (V) OUTPUT VOLTAGE SWING NORMALIZED BIAS CURRENT, IB (X) NORMALIZED QUIESCENT CURRENT vs. SUPPLY VOTAGE NORMALIZED OFFSET VOLTAGE, VOS (X) NORMALIZED QUIESCENT CURRENT, IQ (X) NORMALIZED QUIESCENT CURRENT vs. CASE TEMPERATURE NORMALIZED QUIESCENT CURRENT, IQ (X)

PA74/76 • PA74A/76A GENERAL Please read Application Note 1 "General Operating Considerations" which covers stability, supplies, heatsinking, mounting, SOA interpretation, and specification interpretation. Visit www. apexanalog.com for design tools that help automate tasks such as calculations for stability, internal power dissipation, heatsink selection; Apex Microtechnology's complete Application Notes library; Technical Seminar Workbook; and Evaluation Kits. PARALLEL CONFIGURATION CONSIDERATIONS LOSSES The PA74 and PA76 utilize a parallel configuration to achieve the desired current...

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