LA8518NM Datasheet, PDF (17/31 Pages) Sanyo Semicon Device – Signal Processor for Cordless Telephone Base Sets

Usage Explanations
c Speech network
c External Transistors
Line
LA8518NM
LA8518NM
Fig. 1
Because the IC has a built-in power amplifier, for reasons concerning allowable power dissipation, connect a transistor for
heat dissipation purposes as shown in Fig. 1 so that the line current is consumed externally from the IC. In addition, when
establishing the allowable power for R1 and R2, take into consideration the maximum line current that can be expected.
* When oscillation is generated due to the load state between V_L-GND, insert C1 (about 0.1µF).
c DC resistance conversion method
By varying R2 in Fig. 1, it is possible to change the DC resistance. (Refer to the graphs below.)
* Note that varying R2 will also change the transmitting system gain and the balancing network conditions.
c AC impedance setting method
The AC impedance is basically determined by R3 (620 Ω) and C2 (220 µF) in Fig. 1. Because AC loads other than the speech
network will be placed on the line, adjust the AC impedance in conjunction with the speech network impedance.
* Note that varying R3 changes the DC resistance.
DC characteristics (Power on)
DC characteristics (Power off)
Line current, I_L − mA
Line current, I_L − mA
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