BLK-MD-SPK-B Bluetooth stereo transceiving module provides remote control key interface, working status indicator interface and stereo sound output interface. Features: Class 2 power level Built-in lithium battery charging circuit Powerful noise elimination circuit Effective transmission distance : 20 meters Very low VBAT : 3.4 - 4.2 V Small Surface Mount Package: about 14 x 23 x 2 mm Bluetooth Specification: V2.0+EDR Support A2DP V1.2, AVRCP V1.4 profiles Intergrated with EEPROM set working mode and parameters Stereo audio output can directly drive 40mW@32 ?speeker without blocking condenser. Integrated with POR and programmable low voltage monitoring funtion. PCB LAYOUT NOTES: 1. Power supply decoupling capacitor shall close to module pin position. 2. Module substratum shall full floored (must not floored under antenna), and insulation white oil paved on the substratum position. 3. All ground wires of audio circuit and module shall be seperated with others" and full grounded in the power supply grounding location after independent routing. 4. All ground wires shall be paved of copper largely. 5. Module antenna shall be placed at the edge of the plate (extension better) and away from metals to ensure good communication with outside. 1 X Bluetooth audio module