7.3.4 Output Enable and Disable

The OPA593 incorporates an enable and disable feature that uses the E/D pin to disable the output stage of the

amplifier, which lowers the power consumption of the op amp and switches the output to a high-impedance state.

The E/D pin is referenced to the E/D Com pin. If left floating, the E/D pin is internally pulled up to enable the

device. If externally controlled, the E/D pin must be supplied with a voltage between 2.5 V and 5 V greater

than the E/D Com pin voltage. Even though the OPA593 output is enabled with a floating E/D pin, a moderately

fast, negative-going signal capacitively coupled to the E/D pin can overpower the internal pullup and cause

device shutdown. If the enable function is not used, a conservative and recommended approach is to connect

E/D through a 30-pF capacitor to a low-impedance source. Another alternative is to connect an external current

source from V+ (positive supply) that is sufficient to hold the enable level greater than the shutdown threshold.

Figure 7-3 shows a circuit that connects E/D and E/D Com.

IN

+IN

V

V+

E/D Com

E/D

V

OUT

DVDD

(Digital Supply)

5-V Logic

R

P

V+

(Positive Op-Amp Supply)

V

(Negative Op-Amp Supply)

I

P

Figure 7-3. E/D and E/D Com

When the E/D pin is dropped to a voltage between 0 V and 0.65 V greater than the E/D Com pin voltage,

the output of the OPA593 is disabled. Because the inputs are still active, an input signal might be passed to

the output of the amplifier, despite being in a high-output-impedance state. The voltage at the amplifier output

is reduced because of a drop across this output impedance, and may appear distorted compared to a normal

operation output.

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OPA593

SBOS659A – JANUARY 2022 – REVISED MARCH 2022

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Product Folder Links: OPA593