LM1865 datasheet(6/16 Pages) NSC

6 / 16 page

Typical Application

LAYOUT CONSIDERATIONS

Although the pinout of the LM1865 has been chosen to min-

imize layout problems some care is required to insure sta-

bility The ground terminal on CF1 should return to both

the input signal ground and the buffer ground pin 19 The

ground terminal on CF2 should return to the ground side of

C4 The quadrature coil T1 and inductor L1 should be sepa-

rated from the input circuitry as far as possible

PC Layout (Component Side)

TLH7509 – 6

PERFORMANCE CHARACTERISTICS OF TYPICAL

APPLICATION WITH TUNER

The following data was taken using the typical application

circuit in conjunction with an FM tuner with 43 dB of gain a

55 dB noise figure and 30 dB of AGC range The tuner was

driven from a 50X source 75 ms of de-emphasis was used

on the audio output pin 15 The 0 dB reference is for g75

kHz deviation at 400 Hz modulation

Meter Output and

Signal-to-Noise

vs Tuner Input

Total Harmonic Distortion vs

Tuner Input

AM Rejection vs Tuner

Input

TLH7509 – 7

3 dB limiting e 09 mV

30 dB quieting e 14 mV

Level stopmute threshold e 14 mV

Deviation mute window (b3 dB) e g45 kHz

LM1865 Datasheet(PDF) 6 Page - National Semiconductor (TI)