Bias

+

±

OPA607

Signal and bias to

next stage

5 V

Signal and bias from

previous stage

Gain × Bias

+

±

OPA607

2.5 V

-2.5 V

Signal and bias to

next stage

Gain × Bias

Bias

Signal and bias from

previous stage

11

OPAX607

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SBOS981B – OCTOBER 2019 – REVISED FEBRUARY 2020

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8.4 Device Functional Modes

The OPAX607 has two functional modes: normal operating mode and power-down (PD) mode.

8.4.1 Normal Operating Mode

The OPAX607 is operational when the power-supply voltage is between 2.2 V (±1.1 V) and 5.5 V (±2.75 V). Most

newer systems use a single power supply to improve efficiency and simplify the power tree design. The

split supply, as long as the input and output pins are biased within the linear operating region of the device. The

valid input and output voltage ranges are given in the Electrical Characteristics table. The outputs nominally

swing rail-to-rail with approximately 10-mV headroom required for linear operation. The inputs can typically swing

up to the negative rail (typically ground) and to within 1.1 V from the positive supply. Figure 3 shows changing

from a ±2.5-V split supply to a 5-V single-supply.

Figure 3. Single-Supply and Dual-Supply Operation

8.4.2 Power-Down Mode

The OPAX607 features a power-down mode for power critical applications. Under logic control, the amplifier can

be switched from normal operation (consuming

≤ 1 mA) to a power-down current of less than 1 µA. When the PD

pin is connected high, the amplifier is active. Connecting the PD pin to logic low disables the amplifier and places

the output in a high-impedance state. The output of an op amp is high impedance similar to a tri-state high-

impedance gate under a power-down condition; however, the feedback network behaves as a parallel load. If the

power-down mode is not used, connect PD to the positive supply pin or leave floating. See the Power Down

(Device Enabled When Floating) section in the Electrical Characteristics table for the enable and disable

threshold voltages. The PD pin can be left floating to keep the op amp always enabled, which is primarily

possible because of the presence of an internal pullup resistor within the op amp that, by default, always keeps

noise/transient pick up on the PD pin.

ground and an open-collector type of interface with a pullup resistor is more appropriate.