OPA375 datasheet(32/64 Pages) TI

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9 Application and Implementation

Note

Information in the following applications sections is not part of the TI component specification, and

TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining

suitability of components for their purposes. Customers should validate and test their design

implementation to confirm system functionality.

9.1 Application Information

The OPAx375 family features 10-MHz bandwidth and 4.75-V/µs slew rate with 890 µA (OPA375), 990 µA

(OPA2375/4375) of supply current per channel, providing good AC performance at low-power consumption.

DC applications are well served with a low input noise voltage of 3.5 nV/√ Hz (OPA2375/4375), 3.7 nV/√ Hz

(OPA375) at 10 kHz, low input bias current, and a typical input offset voltage of 0.15 mV.

9.2 Single-Supply Electret Microphone Preamplifier With Speech Filter

Electret microphones are commonly used in portable electronics because of the small size, low cost, and

relatively good signal-to-noise ratio (SNR). The small package size, low operating voltage and AC performance

of the OPA375 make the device a viable option for preamplifier circuits for electret microphones. The circuit

shown in Figure 9-1 is a single-supply preamplifier circuit for electret microphones.

200 k

3 V

RF 165 k

3.4 k

VOUT

OPA375

3 V

2.2 k

3 V

Electret

Microphone

CG 68 nF

CF 3.3 nF

Figure 9-1. Microphone Preamplifier

9.2.1 Design Requirements

The design requirements are as follows:

• Supply voltage: 3 V

• Input voltage: 7.93 mVRMS (0.63 Pa with a –38-dB SPL microphone)

• Output: 1 VRMS

• Bandwidth: 300 Hz to 3 kHz

OPA375, OPA2375

SBOS886E – NOVEMBER 2017 – REVISED AUGUST 2021

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