MAX9814

19-0764; Rev 0; 3/07 KIT ATION EVALU E L B AVAILA Microphone Amplifier with AGC and Low-Noise Microphone Bias General Description o Automatic Gain Control (AGC) o Three Gain Settings (40dB, 50dB, 60dB) o Programmable Attack Time o Programmable Attack and Release Ratio o 2.7V to 5.5V Supply Voltage Range o Low Input-Referred Noise Density of 30nV/√Hz o Low THD: 0.04% (typ) o Low-Power Shutdown Mode o Internal Low-Noise Microphone Bias, 2V o Available in the Space-Saving 12-Bump UCSP (1.5mm x 2mm) and 14-Pin TDFN (3mm x 3mm) Packages o -40°C to +85°C Extended Temperature Range www.datasheet4u.com Features MAX9814 The MAX9814 is a low-cost, high-quality microphone amplifier with automatic gain control (AGC) and lownoise 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 tim...