|
LIGHTNING Semiconductor |
LIGHTNING
Semiconductor
Devices
LS1691BM
FM/AM RADIO CIRCUIT
DESCRIPTION
The LS1691BM is a one-chip FM/AM radio IC
designed for radio -cassette tape recorders and
headphone tape recorders.
Outline Drawing
FEATURE
l Small number of peripheral components
l Low current consumption (Vcc=3V)
FM: ID=5.3mA (Typ.)
AM: ID=3.4mA(Typ.)
l Built-in FM/AM select switch
l Large output of AF amplifier
LS1691BM
FUNCTIONS
FM section
l RF amplifier; Mixer and OSC
(in corporating AFC variable capacitor);
l IF amplifier,
l Quadrature detection;
l Tuning LED driver.
AM section
l RF amplifier, Mixer and OSC (with RF AGC);
l IF amplifier (with IF AGC)
l Detector
l Tuning LED driver
AF section
l Electronic volume control
l FM muting
This Data Sheet is subject to change without notice
1/9
LIGHTNING
Semiconductor
Devices
BLOCK DIAGRAM
LS1691BM
AF Ripple AF
GND OUT Vcc Filter IN
28 27 26 25 24
DET
OUT
23
AFC
AGC
22
AFC IF
AGC GND
21 20
FM
AM
FM/AM
Band
Meter NC IF IN IF IN Select
19 18 17 16 15
AF POWER AMP
AF IF DET AGC
AM FE
Tuning Meter
FM Discrinminator
FM IF
FM FE
123 4
Mute FM NF VOL
Discri
56
AM AFC
OSC
7 8 9 10 11 12 13
FM Reg FM AM NC FM FE
OSC OUT RF RF IN
RF IN GND
14
FM/AM
FE OUT
PIN CONFIGURATIONS
Pin Symbol
1 MUTE
Description
Voltage (V)
Vcc=3V Vcc=6V
FM AM FM AM
0000
Equivalent circuit
2 FM DISCRI
P h a s e-Shift circuit,
Connect ceramic
discriminator
2.18 2.70 4.88 5.43
3 NF Negative feedback pin 1.5 1.5 3.0 3.0
27 AF OUT
Power amplifier
output pin
1.5 1.5 3.0 3.0
2
1K
1.2K
Vcc
*100
27
*100
GND
3
This Data Sheet is subject to change without notice
2/9
|