NJW1124

NJW1124 Voice Switched Speakerphone circuit ! GENERAL DESCRIPTION The NJW1124 is a Voice Switched Speakerphone Circuit. NJW1124 includes all of functions processing a high quality hands–free speakerphone system, such as the necessary amplifiers ( Microphone , Receive ,Line), attenuators, level detectors functions. All external capacitors are sufficient small so that ceramic capacitors are applied. ! APPLICATION Video Door Phone Conference System Wireless Application Security System ! FEATURES Operating voltage range Force to Receive, Transmit, or Idle modes Mode –watching monitor Attenuator gain range between Transmit and Receive Microphone amplifier with mute function Background noise monitor for each path Volume control range 4-point signal sensing Microphone and Receive Amplifiers pinned out for flexibility Package Outline 2.9 to 4.5V 52dB 40dB SSOP32 ! PACKAGE OUTLINE NJW1124V ! BLOCK DIAGRAM Microphone C6 R2 100n 5.1k R3 C7 51k 100n MCI MCO R4 51k TLI2 C8 C9 R6 100n 100n 5.1k R5 10k TLI1 TXO LII R7 51k C10 LiO- LiO+ Line Out V+ V+ R1 300k C1 1µ C3 470n C4 470n C2 1u M UT TLO2 RLO2 CPT C23 1µ VREF VREF2 VREF Mic Amplifier Tx Attenuator Lev el Detector Background NoiseMonitor Attenuator Control VREF -1 Line Amplifier Background NoiseMonitor Lev el Detector C11 V+ 1µ M onit or CT RTSW C5 1µ V+ CPR C22 1µ TLO1 RLO1 C20 470n C21 470n BIAS IC1 NJW1124 Rx Attenuator 1.2µ A Receive Amplifier GND VREF V+ R10 1...