LA1267 Datasheet, PDF (5/14 Pages) Sanyo Semicon Device – FM/AM Tuner of Electronic Tuning Type

LA1267
6. If the coupling coefficient of the local OSC coil is small and an antiresonance point of approximately 100MHz is
present or the stray capacitance across pins 24 and 23 is large, a parasitic oscillation of approximately 100MHz may
occur in the buffer output (pin 24). In this case, connect a capacitance of approximately 30pF across pin 24 and GND.
7. AM OSC coil
Generally speaking, the following should be noted. Avoid winding with loose coupling between primary side and
secondary side (especially SW1, SW2). To put it concretely, the pot core type is better than the screw core type which
is loose in coupling. This prevents the local OSC frequency from turning third resonance frequency related to the
coupling coefficient.
8. Resistance across pin 8 and V_DD.
If pin 8 is used for the stop signal (SD) only, without using LED, it is recommended to fix resistance R_L across pin 8
and GND to be 51kΩ to 100kΩ.
9. To prevent whistle from worsening, make the pattern of AM output pin 14 as short as possible.
Input/Output Admittance
FM
– Parameter Frequency – Admittance Unit
IF
γi1
10.7MHz r_i
330
Ω
c_i
20
pF
AM
–
Parameter Frequency –
Admittance
AGC-off (V16=1.4V) AGC-on (V16=2.5V)
Unit
RF
γi21
1MHz
r_i
15
16
kΩ
c_i
4
4
pF
MIX
γo19 500kHz ^ro
–
–
kΩ
c_o
3
3
pF
IF
γi17
500kHz ^ri
2
2
kΩ
c_o
10
8
pF
Test Circuit : FM, AM-MW
T1 : 4147-1457-177 (Sumida)
T2 : HW-40174 (Mitsumi)
T3 : HW-40130, 40131 (Mitsumi)
Unit (resistance : Ω, capacitance : F)
No.2012-5/14