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1 9-904; Rev 0; 7/0 MAX406 Evaluation Kit General Description The MAX406 evaluation kit (EV kit) is a fully assembled and tested circuit board that uses the MAX406 lownoise microphone amplifier IC designed for a single.4v to 5.5V application. The MAX406 IC contains two microphone amplifiers. The main amplifier is typically used to sense an internal (built-in) system microphone, and an auxiliary amplifier that can be used to sense an external (plug-in) microphone. The differential and single-ended gains of the amplifiers are adjustable with jumpers and resistors. The differential output allows the EV kit to drive a load at up to 6V P-P. The EV kit also features low quiescent current and a shutdown control to minimize power consumption. The EV kit demonstrates how the MAX406 can provide a complete microphone solution for a notebook PC. The MAX406 is available in 4-pin TSSOP and 6-pin QFN (4mm x 4mm x 0.8mm) packages. DESIGNATION QTY DESCRIPTION C C, C, C4 C5, C6 C7, C8 C9 0.µF ±0%, 6V X7R ceramic capacitor (060) Taiyo Yuden EMK07BJ04KA 0µF ±0%, 0V tantalum capacitors (Case A) AVX TAJA06K00R.0µF ±0%, 6.V X5R ceramic capacitors (060) Taiyo Yuden JMK07BJ05KA.0µF ±0%, 6V tantalum capacitors (Case A) AVX TAJA05K06R 0pF ±5%, 50V C0G ceramic capacitor (060) TDK C608C0GH00J.4V to 5.5V Single-Supply Operation High 95dB PSRR Low-Noise Integrated Microphone Bias Single-Ended and Differential Inputs Differential Output Externally Adjustable Gain 0.µA Shutdown Current Small 4-Pin TSSOP Package Fully Assembled and Tested Features Ordering Information PART TEMP RANGE IC PACKAGE MAX406EVKIT 0 C to +70 C 4 TSSOP Component List DESIGNATION QTY DESCRIPTION J.5mm stereo jack J Nonswitched PC mount jack, red R, R6 kω ±% resistors (0805) R 4.75kΩ ±% resistor (0805) R 8.kΩ ±% resistor (0805) R4, R5, R7, R9, R0 5 00kΩ ±5% resistors (0805) R8, R 0 Not installed resistors (0805) JU, JU, JU -pin headers JU4, JU5 -pin headers U MAX406EUD (4-pin TSSOP) None Shunts (JU, JU4, JU5) None MAX406 PC board Component List Evaluates: MAX406 SUPPLIER PHONE FAX WEBSITE AVX Taiyo Yuden TDK Note: Please indicate that you are using the MAX406 when contacting these component suppliers. Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at , or visit Maxim s website at

2 MAX406 Evaluation Kit Evaluates: MAX406 Quick Start The MAX406 EV kit is fully assembled and tested. Follow the steps listed below to verify board operation. Do not turn on the power supply until all connections are completed. Recommended Equipment 5V power supply AC source 00mVAC, khz sine wave Oscilloscope Procedures ) Install a shunt across pins and of jumper JU4 (EV kit ON). ) Install a shunt across pins and of jumper JU5 (INT mode). ) Install a shunt across jumper JU (0dB gain). 4) Connect channel of the oscilloscope to the pad, and channel of the oscilloscope to the pad. Connect the oscilloscope ground leads to the EV kit connection. 5) Connect the 5V terminal of the power supply to the VCC pad and the ground terminal of the power supply to the pad. Turn on the power supply. 6) Connect the 00mV, khz AC source sine wave across the IN+ and IN- pads. 7) Verify that the output across the and pads is a VAC, khz sine wave. 8) Remove the shunt from pins and of JU5 and install the shunt across pins and of JU5 (AUX mode). 9) Connect the 00mV, khz AC source sine wave across the AUXIN jack (see Figure ). 0) Verify that the output across the and pads is a VAC, khz sine wave. TIP (AUXIN) RING (BIAS) SLEEVE () Figure. Typical Microphone Jack Detailed Description The MAX406 microphone preamplifier features two selectable inputs, differential outputs, adjustable gain, an integrated low-noise bias source, and a low-power shutdown mode. Two input paths provide both differential and single-ended microphone sensing. The high noise rejection of the differential input is ideally suited to an internal microphone where system noise and long-run PC board traces can degrade low-level signals. The single-ended input provides a simple connection to an external microphone. The differential and single-ended inputs have independent, adjustable gains. The Differential Gain Setting on the EV kit is controlled by jumpers JU, JU, and JU to select from three preset gains (0dB, 40dB, and 60dB); see Table. The single-ended (AUX) gain is set to the default 6dB. This can by changed by adding resistor R8: R8 = MΩ/(A VAUX - 6) A LOG V V VAUX = 0 VAUX _ IN and A VAUX must be greater than 6dB. When R8 is opened, the gain A VAUX is 6dB. Differential outputs provide a full-scale signal of up to 6V P-P from a single V, supply optimizing the dynamic range of the amplified signal. The EV kit operates from a single.4v to 5.5V supply.

3 MAX406 Evaluation Kit Jumper Selection Differential Gain JU, JU, and JU select the differential gain for the MAX406 EV kit. JU, JU, and JU should all be left open or installed one at a time. See Table for shunt positions. Table. JU, JU, JU Jumper Selection JUMPER JU JU JU SHUNT POSITION (JU and JU open) (JU and JU open) (JU and JU open) DIFFERENTIAL GAIN (db) JU, JU, JU None +6 Shutdown Jumper JU4 controls the shutdown pin (SHDN) on the MAX406 IC. The shutdown function may be activated on the EV kit by installing a shunt across pins and of JU4. The shutdown function may also be controlled by an external controller connected to the SHDN pad and removing the shunt on JU4. See Table for shunt positions. Input Mode Jumper JU5 provides an option to select between single-ended mode (AUX) and differential mode (INT) inputs. The input mode (INT/AUX) may also be controlled by an external controller connected to the (INT/AUX) pad and removing the shunt on JU5. See Table for shunt positions. Table. JU5 Jumper Selection SHUNT POSITION INT/AUX PIN EV KIT INPUT MODE (INT) Pulled down to Differential (AUX) Pulled up to V CC Single ended None. External controller connected to (INT/AUX) pad. External controller controls (INT/AUX) driven by external source Evaluates: MAX406 Table. JU4 Jumper Selection SHUNT POSITION SHDN PIN EV KIT FUNCTION (SHDN = high) Pulled up to V CC EV kit ON. (SHDN = low) Pulled down to EV kit OFF. None. External controller connected to SHDN pad. External controller controls SHDN driven by external source. Shutdown is active low.

4 Evaluates: MAX406 MAX406 Evaluation Kit 4 MAX406 U G IN C5.0µF C6.0µF C9 0pF 5 7 IN- AUX_IN ADJ BIAS SHDN INT/AUX G R kω % R 4.75kΩ % C 0µF 0V IN+ IN- BIAS J C4 0µF 0V R4 00kΩ R5 00kΩ R OPEN R6 kω % R7 00kΩ R8 OPEN R 8.kΩ % JU 40dB JU 0dB JU 0dB V CC VCC JU4 C 0.µF C 0µF 0V R9 00kΩ R0 00kΩ JU5 4 6 N.C. SHDN VCC C7.0µF 6V C8.0µF 6V INT/AUX J Figure. MAX406 EV Kit Schematic

5 MAX406 Evaluation Kit Evaluates: MAX406 Figure. MAX406 EV Kit Component Placement Guide Component Side Figure 4. MAX406 EV Kit PC Board Layout Component Side Figure 5. MAX406 EV Kit PC Board Layout Solder Side Figure 6. MAX406 EV Kit Component Placement Guide Solder Side Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 0 San Gabriel Drive, Sunnyvale, CA Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.