Part # LM1865 datasheet

Part Manufacturer: National Semiconductor

National Semiconductor

Part Description: LM1865 Advanced FM IF System

Part Details:

LM1865 February 1995 Advanced LM1865 Advanced FM IF System General Description Y Meter output proportional to signal level Reduced external component cost improved performance Y Stop detector with open-collector output and additonal functions are key features to the LM1865 FM Y Adjustable signal level mute stop threshold controlled IF system The LM1865 is designed for use in electronically either by ultrasonic noise in the recovered audio or by FM tuned radio applications It contains both deviation and sig- the meter output nal level stop circuitry in addition to an open-collector stop Y Adjustable deviation mute stop threshold output The LM1865 generates a reverse AGC voltage (ie IF Y Separate time constants for signal level and deviation decreasing AGC voltage with increasing signal) mute stop System Features Y Dual threshold AGC eliminates need for local distanceswitch and offers improved immunity from third order in- Y On-chip buffer to provide gain and terminate two ce- termodulation products due to tuner overload ramic filters Y User control of both AGC thresholds Y Low distortion 0 1% typical with a single tuned quadra-ture coil for 100% modulation Y Excellent signal to noise ratio AM rejection and systemlimiting sensitivity Y Broad off frequency distortion characteristic Y Low THD at minimum AFT offset Block Diagram Order Number LM1865M or LM1865N See NS Package Number M20B or N20A TL H 7509 ­ 1 FIGURE 1 C1995 National Semiconductor Corporation TL H 7509 RRD-B30M115 Printed in U S A

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LM1865.pdf Datasheet