The MAX9814 is a low-cost, high-quality microphone amplifier 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 20dB to 0dB, depending on the output voltage and the AGC threshold. The output amplifier offers selectable gains of 8dB, 18dB, and 28dB. With no compression, the cascade of the amplifiers results in an overall gain of 40dB, 50dB, or 60dB. A trilevel 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 trilevel 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.
The MAX9814 is available in the space-saving 12-bump UCSP™ (1.5mm x 2mm) and 14-pin TDFN packages. This device is specified over the -40°C to +85°C extended temperature range.
Key Features
Applications/Uses
Automatic Gain Control (AGC)
Three Gain Settings (40dB, 50dB, 60dB)
Programmable Attack Time
Programmable Attack and Release Ratio
2.7V to 5.5V Supply Voltage Range
Low Input-Referred Noise Density of 30nV/
Low THD: 0.04% (typ)
Low-Power Shutdown Mode
Internal Low-Noise Microphone Bias, 2V
Available in the Space-Saving 12-Bump UCSP (1.5mm x 2mm) and TDFN (3mm x 3mm) Packages
Notes: **This pricing is BUDGETARY, for comparing similar parts. Prices are in
U.S. dollars and subject to change. Quantity pricing may vary
substantially and international prices may differ due to local
duties, taxes, fees, and exchange rates. For volume-specific prices
and delivery, please see the price and availability page
or contact an authorized distributor.
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