THS3095D datasheet(19/46 Pages) TI2

19 / 46 page

Figure 8-1 shows the total system output impedance, which includes the amplifier output impedance in parallel

with the feedback plus gain resistors, and cumulates to 2416 Ω. Figure 8-2 shows this circuit configuration for

reference.

Frequency (Hz)

500

1000

1500

2000

2500

100k

10M

100M

Figure 8-1. Power-Down Output Impedance vs Frequency

As with most current feedback amplifiers, the internal architecture places some limitations on the system when

in Power-Down mode. Most notably is the fact that the amplifier actually turns on if there is a ±0.7 V or greater

difference between the two input nodes (VIN+ and VIN-) of the amplifier. If this difference exceeds ±0.7 V, then

the output of the amplifier creates an output voltage equal to approximately [(VIN+ – VIN–) – 0.7 V] × Gain. This

also implies that if a voltage is applied to the output while in Power-Down mode, the V– node voltage is equal to

VO(applied) × RG / (RF + RG). For low-gain configurations and a large applied voltage at the output, the amplifier

can actually turn on due to the aforementioned behavior.

The time delays associated with turning the device on and off are specified as the time required for the amplifier

to reach either 10% or 90% of the final output voltage. The time delays are in the order of microseconds because

the amplifier moves in and out of the linear mode of operation in these transitions.

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THS3091, THS3095

SLOS423K – SEPTEMBER 2003 – REVISED APRIL 2023

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THS3095D Datasheet(PDF) 19 Page - Texas Instruments