9.2.1.3 Application Curve

Figure 9-4 shows the typical example output response of a speaker with 4-Ω impedance measurement from 20

Hz to 20 kHz.

Re

Impedance at

Resonance

Inductive Rise

(Le)

Frequency (hZ)

20

100

500

1000

10000

20000

4

12

16

20

24

28

Figure 9-4. Speaker Impedance Measurement

10 Power Supply Recommendations

The INA254 makes accurate measurements beyond the connected power-supply voltage (VS) because the

inputs (IN+ and IN–) operate anywhere between –4 V and +80 V, independent of VS. For example, the VS

power supply equals 5 V and the common-mode voltage of the measured shunt can be as high as 80 V.

Although the common-mode voltage of the input can be beyond the supply voltage, the output voltage range of

the INA254 is constrained to the supply voltage.

Place the power-supply bypass capacitor as close as possible to the supply and ground pins. The recommended

value of this bypass capacitor is 0.1 μF. Additional decoupling capacitance can be added to compensate for

noisy or high-impedance power supplies. If the INA254 output is set to mid-supply, then take extreme care to

minimize noise on the power supply.

INA254

SLOS974 – JUNE 2021

www.ti.com

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