The MAX9814ETD+T is a high-quality Microphone Amplifier IC with automatic gain control (AGC) and low-noise microphone bias. The device features a low-noise preamplifier, variable gain amplifier (VGA), output amplifier, microphone-bias-voltage generator and AGC control circuitry. The low-noise preamplifier has a fixed 12dB gain, while the VGA gain automatically adjusts from 20 to 0dB, depending on the output voltage and the AGC threshold. The output amplifier offers selectable gains of 8, 18 and 28dB. With no compression, the cascade of the amplifiers results in an overall gain of 40, 50 or 60dB. A tri-level digital input programs the output amplifier gain. An external resistive divider controls the AGC threshold and a single capacitor programs the attack/release times. A tri-level digital input programs the ratio of attack-to-release time. The hold time of the AGC is fixed at 30ms. The low-noise microphone-bias-voltage generator can bias most electret microphones.
- Automatic Gain Control (AGC)
- Three Gain Settings (40, 50 and 60dB)
- Programmable Attack Time
- Programmable Attack and Release Ratio
- Low Input-referred Noise Density of 30nV/√Hz
- 0.04% (Typical) Low THD
- Low-power Shutdown Mode
- Internal Low-noise Microphone Bias, 2V
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