OPA1622 Datasheet, PDF (14/36 Pages) Texas Instruments – OPA1622 SoundPlus™ High-Fidelity, Bipolar-Input, Audio Operational Amplifier

OPA1622
SBOS727A – NOVEMBER 2015 – REVISED NOVEMBER 2015
7 Detailed Description
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7.1 Overview
The OPA1622, dual, bipolar-input, audio operational amplifier uses a unique internal topology to deliver high
output current with extremely low distortion while consuming minimal supply current. A single gain stage
architecture, combining a high-gain transconductance input stage and a unity gain output stage, allows the
OPA1622 to achieve an open-loop gain of 136 dB, even with 600-Ω loads.
The output stage of the OPA1622 is designed specifically to source and sink large amounts of current without
degrading amplifier linearity. High-order distortion harmonics, produced by output stage crossover distortion, are
greatly reduced with this design. The OPA1622 output stage also provides exceptionally low open-loop output
impedance that improves stability with capacitive loads and is protected against short-circuit events.
A separate enable circuit maintains control of the input and output stage when the amplifier is placed into its
shutdown mode and limits transients at the amplifier output when transitioning to and from this state. The enable
circuit features logic levels referenced to the amplifier ground pin. This configuration simplifies the interface
between the amplifier and the ground-referenced GPIO pins of microcontrollers. The addition of a ground pin to
the amplifier provides several additional benefits. For example, the compensation capacitor between the input
and output stages of the OPA1622 is referenced to the ground pin, greatly improving PSRR.
7.2 Functional Block Diagram
Short Circuit Current Limit
+IN
±IN
GND
EN
High-Gain Input Stage
+
±
High-Current Output
Stage
Compensation
Capacitor
±
+
Enable Circuitry
OUT
Figure 41. OPA1622 Simplified Schematic
7.3 Feature Description
7.3.1 Power Dissipation
The OPA1622 is capable of high output current with power-supply voltages up to ±18 V. Internal power
dissipation increases when operating at high supply voltages. The power dissipated in the op amp (P_OPA) is
calculated using Equation 1:
P_OPA
V V_OUT u I_OUT
V
V_OUT
u ^VOUT
R_L
(1)
14
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