Datasheet MAX9812, MAX9813 (Maxim) - 7

MAX9812/MAX9813 Tiny, Low-Cost, Single/Dual-Input, Fixed-Gain Microphone Amplifiers with Integrated Bias Pin Description PIN MAX9812L/ MAX9813L/ NAME FUNCTION MAX9812H MAX9813H
Active-Low Shutdown Input. Connect SHDN to VCC for normal operation. Connect SHDN 1 3 SHDN to GND for shutdown. SHDN is a high-impedance input; do not leave unconnected. 2 2 GND Ground 3 1 OUT Amplifier Output 4 8 VCC Positive Supply. Bypass VCC to GND with a 0.1µF capacitor. Low-Noise Microphone Bias Output. 2.3V output for MAX9812L/MAX9813L. 4V output for 5 7 BIAS MAX9812H/MAX9813H. 6 — IN Amplifier Input (MAX9812) — 6 IN1 Amplifer Input 1 (MAX9813) — 5 IN2 Amplifier Input 2 (MAX9813) — 4 IN1/IN2 Input Selector. When IN1/IN2 is high, IN1 is selected. When IN1/IN2 low, IN2 is selected.
Detailed Description
The output DC bias point is set to 1.5V for the MAX9812L/ MAX9813L and 2.5V for the MAX9812H/MAX9813H. The MAX9812_/MAX9813_ are low-power fixed-gain microphone amplifiers available in a single- or dual-
Shutdown Mode
input configuration. The gain is set at 10V/V (20dB) with SHDN controls whether the MAX9812_/MAX9813_ is a 400kHz, -3dB bandwidth. They also feature a low- active or in shutdown mode. Driving SHDN low forces a noise, integrated microphone input bias voltage. low-power (100nA) shutdown mode. In this mode, the OUT pin is set to a high-impedance state and the BIAS
Single/Dual Input
pin is pulled down (70kΩ). Driving SHDN high enables The MAX9812L/MAX9812H are single-input amplifiers the MAX9812_/MAX9813_. SHDN is a high-impedance and the MAX9813L/MAX9813H are dual-input ampli- input and cannot be left unconnected. fiers. All devices typically have an input impedance of 85kΩ. The inputs to the dual version are controlled
Driving Capacitive Loads
through a fast 2:1 mux, selectable through the IN1/IN2 The MAX9812_/MAX9813_ output can drive up to 50pF pin. Driving IN1/IN2 high selects IN1 and driving the of capacitance without sustained oscillations. IN1/IN2 low selects IN2. IN1/IN2 is designed to be dri-
Thermal Shutdown
ven by a logic high of ≥2V and a logic low ≤ The thermal shutdown feature protects the 0.8V. The IN1/IN2 has a 10µs switching time from one MAX9812_/MAX9813_ from destruction due to overheat- channel to the other. ing caused by shorting the outputs. This protection fea-
PC2001 Low-Noise Microphone BIAS
ture causes OUT and BIAS to shut down and go high The MAX9812_/MAX9813_ provide a low-noise voltage impedance when the die temperature reaches +140°C. BIAS designed for biasing electret condenser micro- The device restarts after the die temperature falls below phone (ECM) cartridges. The BIAS output is regulated +120°C. to typically 2.3V for the MAX9812L/MAX9813L and 4V for the MAX9812H/MAX9813H. In the single-input ver-
Applications Information
sion (MAX9812_), the BIAS output can source up to
Power-Up
1mA. In the dual-input version (MAX9813_), the BIAS The MAX9812_/MAX9813_ output typically settles to output can source up to 2mA. The MAX9812H/ 95% within 10ms after power-up. MAX9813H provides a PC2001-compliant BIAS voltage.
Typical Application Circuit Output Stage
Figure 1 shows the MAX9813H used as a preamplifier The MAX9812_/MAX9813_ rail-to-rail output (OUT) typical- with the MAX9760 3W audio power amplifier. ly swings to within 100mV of the rails when driving 10kΩ. Maxim Integrated 7