OPA1622 Datasheet, PDF (16/36 Pages) Texas Instruments – OPA1622 SoundPlus™ High-Fidelity, Bipolar-Input, Audio Operational Amplifier

OPA1622
SBOS727A – NOVEMBER 2015 – REVISED NOVEMBER 2015
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Feature Description (continued)
7.3.3 Enable Pin
The enable pin (EN) of the OPA1622 is used to toggle the amplifier enabled and disabled states. The logic levels
defining these two states are: V_EN ≤ 0.78 V (shutdown mode), and V_EN ≥ 0.82 V (enabled). These threshold
levels are referenced to the device ground pin. The enable pin can be driven by a GPIO pin from the system
controller, discrete logic gates, or can be connected directly to the V+ supply. Do not leave the enable pin
floating because the amplifier is prevented from being enabled. Likewise, do not place GPIO pins used to control
the enable pin in a high-impedance state because this placement also prevents the amplifier from being enabled.
A small current flows into the enable pin when a voltage is applied. Using the simplified internal schematic shown
in Figure 43, use Equation 4 to estimate the enable pin current:
I_EN
V_EN 0.7 V
700 k
(4)
As illustrated in Figure 43, the enable pin is protected by diodes to the amplifier power supplies. Do not connect
the enable pin to voltages outside the limits defined in the Specifications section.
VCC
To
Amplifier
500 k
EN
VEE
VCC
200 k
GND
VEE
Figure 43. Enable Pin Simplified Internal Schematic
7.3.4 Ground Pin
The inclusion of a ground pin in the OPA1622 architecture allows the internal enable circuitry to be referenced to
the system ground, eliminating the need for level shifting circuitry in many applications. The internal amplifier
compensation capacitors are also referenced to this pin, greatly increasing the ac PSRR. For highest
performance, connect the ground pin to a low-impedance reference point with minimal noise present. As shown
in Figure 43, the ground pin is protected by ESD diodes to the amplifier power supplies. Do not connect the
ground pin to voltages outside the limits defined in Specifications.
7.3.5 Electrical Overstress
Designers often ask questions about the capability of an operational amplifier to withstand electrical overstress.
These questions tend to focus on the device inputs, but may involve the supply voltage pins or even the output
pin. Each of these different pin functions have electrical stress limits determined by the voltage breakdown
characteristics of the particular semiconductor fabrication process and specific circuits connected to the pin.
Additionally, internal electrostatic discharge (ESD) protection is built into these circuits to protect them from
accidental ESD events both before and during product assembly.
Having a good understanding of this basic ESD circuitry and its relevance to an electrical overstress event is
helpful. Figure 44 shows the ESD circuits contained in the OPA1622. The ESD protection circuitry involves
several current-steering diodes connected from the input and output pins and routed back to the internal power-
supply lines, where they meet at an absorption device internal to the operational amplifier. This protection
circuitry is intended to remain inactive during normal circuit operation.
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